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  • Analytical Chemistry and Spectroscopy  (1,920)
  • General Chemistry  (1,916)
  • Cell & Developmental Biology  (1,421)
  • GEOPHYSICS  (1,211)
  • Chemical Engineering  (1,040)
  • 1990-1994  (4,963)
  • 1975-1979  (2,545)
  • 1970-1974
  • 1910-1914
  • 1990  (4,963)
  • 1976  (2,545)
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  • 1990-1994  (4,963)
  • 1975-1979  (2,545)
  • 1970-1974
  • 1910-1914
Year
  • 101
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    The fine structure of the encysting salt marsh heterotrich ciliate Fabrea salina (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 335-341 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Wall and internal organelles of the encysting salt marsh heterotrich ciliate Fabrea salina were examined by bright field and Nomarski interference contrast microscopy and by transmission and scanning electron microscopy. A mucoid sheath believed to be derived from bacteria covers the ectocyst. The possible bacterial origin of this sheath has been demonstrated experimentally by its removal and reappearence after 24 hours. Control ectocyst maintained in sterile seawater did not replace the sheath. The ectocyst has a crinkled appearance. The endocyst is composed of two layers. The inner endocyst material is continuous with that of the plug located at one end of the cyst. The two membranes are separated from one another by an interwall space filled with fibrous material. The cytoplasm, covered by an outer double membrane pellicle, contains mucocysts, pigment granules, microtubules, non-ciliated kinetosomes, Golgi complexes, ribosome-studded endoplasmic reticulum, and mitochondria. The endoplasm contains numerous autophagosomes, mitochondria, and food reserve materials. The macronucleus is centrally located in the cytoplasm of the encysting organism.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052050308
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  • 102
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    Mastication in springhares, Pedetes capensis: A cineradiographic study (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 353-367 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Analysis of lateral and dorsoventral radiographic films shows that ingestion, transport, and mastication in Pedetes capensis (Rodentia) are cyclic and their movement patterns are essentially similar for the three food types offered. During the ingestion cycle, closing of the mouth is accompanied by a backward translation of the condyles, so that movement is predominantly orthal. During the opening stage, the extent of the anterior condylar translation is smaller. As a result the mandibular incisors move ventrally and posteriorly. During the ingestion cycles, food is transported to the back of the tongue, with the transverse rugae and the folds of the upper lip playing important roles.Springhares show a bilateral masticatory pattern; food is chewed on both sides simultaneously. During chewing, the condyles lie in their most forward position at maximum opening of the mouth. The mouth is closed by rotation of the lower jaw around the temporomandibular joint coupled with posterior condylar translation. At the beginning of the slow-closing stage, the upward rotation of the mandible slows and the jaw slowly shifts forward. During the grinding stage, the mandible is shifted forward with both toothrows in occlusion. During the opening stage, the jaw returns to its starting position.Comparison of kinematic and anatomical data on rodent mastication suggests that some dental characteristics form the most important factors regulating the masticatory pattern and consequently allow reasonably reliable prediction of rodent masticatory patterns.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052050310
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  • 103
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    Paralysis and growth of the musculoskeletal system in the embryonic chick (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 45-56 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Avian embryos can be completely paralyzed by injection of neuromuscular-blocking agents. We used a single injection of decamethonium iodide to paralyze embryos at 7, 8, or 10 days of incubation and analyzed the growth of individual bones (clavicle, mandible, ulna, femur, tibia, humerus) and of individual muscles that act upon some of those bones (clavicular and sternal heads of m. pectoralis, and mm. biceps brachii, depressor mandibulae, pseudotemporalis, and adductor externus). Growth of the bones is not equally affected by paralysis. Only 27% of clavicular growth (by mass) but 77% of mandibular growth occurred in paralyzed embryos, whereas the four long bones exhibited 52-63% of their normal growth. Analysis of muscle weight, fiber length and physiological cross-sectional area (weight/fiber length) indicate that there was greater reduction of the muscles acting on the limbs than of those acting on the mandible, i.e., diminished growth of the skeleton is correlated with reduced muscular activity. Specific retardation of clavicular growth is due to fusion of sternal rudiments and collapse of the thorax, as well as virtual absence of the musculature that normally attaches to the clavicle. We discuss these results in the light of intrinsic and extrinsic factors governing growth of tne embryonic skeleton. Paralysis reduces skeletal growth by reducing both the movements taking place in ovo, and the loads imposed on the bones by muscle contraction, changes that represent alterations in the mechanical environment of the skeleton.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060105
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  • 104
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    Light microscopic and ultrastructural study of the development of the saccus vasculosus in the rainbow trout, Oncorhynchus mykiss (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 79-93 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study using light and electron microscopy indicates that the saccus vasculosus is distinguishable in 9-mm embryos and grows continuously throughout embryonic development to the adult stage. In the saccus vasculosus, epithelial mitoses are observed in all stages studied. Phases of centriologenesis, ciliogenesis, and globule formation have been characterized in developing coronet cells. During the phase of centriologenesis, new centrioles appear in association with pre-existing centrioles and not on deuterosomes. After ciliogenesis, each cilium differentiates to a globule almost at the same time as the other cilia of the coronet cell. The inner membrane system of the globules seems to derive from the ciliary plasma membrane. This membrane system often produces membrane whorls during the development. The different phases of coronet cell development have been found in the same individual and in all the stages studied except the 9-mm embryo. Cerebrospinal fluid-contacting neurons are observed in the saccus epithelium from the 12-mm embryos on and are distinguishable from coronet cells in their early formative stages. The three cell types of the saccus vasculosus increase continuously in number during development. Nerve processes are found in the saccus vasculosus of embryos, whereas differentiated synapses appear later in the fry. The significance of continued coronet cell formation is discussed in relation to a putative coronet cell and/or a globule renewal cycle in the adult.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060109
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  • 105
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    Effects of growth on architecture and functional characteristics of adult rat gastrocnemius muscle (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 119-132 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Changes of architecture of adult rat gastrocnemius medialis muscle (GM) due to growth were studied in relation to length-force characteristics. Myofilament lengths were unchanged, indicating constant sarcomere length-force characteristics. Number of sarcomeres within fibers was unchanged as a consequence of growth, allowing persistence of differences between proximal and distal fibers in all age groups. Distal fiber length at muscle optimum length was shorter for the 14- than for the 10- and 16-week age groups despite a lack of difference of number of sarcomeres. This is indicative of a shift of optimum fiber length with respect to muscle length to lengths higher than optimum length. Some evidence for the occurrence of distribution of fiber optimum lengths with respect to muscle optimum length was found in other age groups as well, albeit of a smaller magnitude. Muscle and aponeurosis length increased substantially with growth. Functional effects of increased aponeurosis lengths were increased contributions to muscle length changes by the aponeurosis, allowing smaller fiber contributions in older animals. Fiber angle increased approximately 5° with growth. Despite the differences of architecture indicated above, muscle length range between optimum length and active slack length was constant. This was probably caused by widening of this length range in the youngest age group by variations of architecture within the muscle. It is concluded that adaptation of aspects of muscle architecture is an important mechanism for adult muscle growth in rat GM. Of these aspects regulation of muscle length seems a dominant factor.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060112
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  • 106
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    Speculation on interfacial adhesion and mechanical properties of blends of PET and thermotropic polyester with flexible spacer groups (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 13-21 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A thermotropic liquid crystalline polyester (LCP) with a long flexible spacer group in the main chain was prepared by melt polymerization and mixed with poly(ethylene terephthalate) (PET). Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) studies revealed that the crystallization of PET was accelerated by the addition of LCP in the matrix. Interfacial adhesion between PET and LCP was much improved by introduction of a long flexible spacer in the main chain. Fibers of the blend with 30 wt percent of LCP had fine microfibrillar structure with a large aspect ratio formed in the matrix. Initial modulus and ultimate strength were highly elevated by the addition of LCP due to good interfacial adhesion and microfibrillar structure of LCP in the blend.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300104
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  • 107
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300201
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  • 108
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    The effects of blending small amounts of homopolystyrene on the mechanical properties of a low styrene content styrene-butadiene-styrene block copolymer (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 49-58 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Tensile, cyclic, and tear properties were compared for several styrene-butadiene-styrene (SBS) triblock copolymers, KRATON D2104, D1101 and D1102, and blends of D2104 with monodisperse polystyrene of various molecular weights. D2104 is expected to have a morphology of polystyrene spheres in a polybutadiene continuous matrix. The mechanical properties of D2104 were compared to the properties of SBS materials which have higher styrene contents and exhibit cylindrical or lamellar morphologies. Blending the D2104 with polystyrene (molecular weights ranging from 2000 to 51,000) to 24 and 28 wt % total styrene content showed that the tensile strength obtained for a blend was dependent on the molecular weight of the polystyrene added. Cycle testing of the D2104-polystyrene blends showed that with increasing polystyrene content the softening effect increases with increasing strain. This indicates that the degree of phase continuity of the polystyrene domains may be changing from a spherical morphology to a cylindrical morphology similar to that of pure SBS with 28 wt % styrene content. Tear test results for the blends were also observed to be similar to the results for pure SBS of the same total polystyrene content.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300108
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  • 109
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    Flexible microcellular foam from polymethylpentene/cyclohexane (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 90-95 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rapid freezing of a polymethylpentene (PMP)/cyclohexane solution to -80°C gives a tough, flexible foam, in marked contrast to the weak, friable foams obtained by phase-separation of PMP from other solvents. X-ray diffraction and differential scanning calorimetry (DSC) data indicate that the isotactic PMP is in an amorphous state. The production of a flexible, robust foam tube from PMP/cyclohexane implies that this material could find applications as replacement parts for arteries and veins or as filter devices. In sheet form, this material seems ideally suited for use as light-weight insulation for clothing because its open, microcellular structure permits moisture to escape as vapors, but retards air flow. This study demonstrates that process parameters, such as solvent composition, play an important role in determining the various microstructures and physical properties that can be obtained from a single polymer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300205
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  • 110
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300301
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  • 111
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    Process parameters estimation for structural reaction injection molding and resin transfer molding (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 142-146 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Some design strategies for structural reaction injection molding (S-RIM) and resin transfer molding (RTM) are presented. Our approach makes use of moldability diagrams to define the parameters necessary to meet the process requirements. Moldability diagrams are presented for the filling and curing steps. The criterion for selecting the amount of fiber reinforcement, injection time, catalyst level, and process temperatures in order to optimize properties and demold time is described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300303
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  • 112
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    Some properties of polyethylene compounds with surface-modified fillers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 263-269 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dispersion of variously surface-treated CaCo3 fillers in linear low density polyethylene has been studied, along with mechanical properties of the filled compounds. Microwave plasma discharges were used to modify the filler surfaces. Inverse gas chromatographic analyses showed that plasma treatments could change the dispersive and non-dispersive components of filler surface characteristics. A reduction in these surface energies facilitated the dispersion of the filler in the non-polar polyethylene. Mechanical properties, particularly those at high deformation of the filled plastic, also responded to filler surface treatments, the ductility at failure increasing with a decrease in the filler's surface polarity. For any given elongation at failure, it was found that the amount of filler accommodated by the host polymer was raised by the appropriate surface modification procedure. The work illustrates the important contribution made by interfacial phenomena to various performance aspects of complex polymer systems.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300503
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  • 113
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    Mechanical and thermal properties of epoxy resins with reversible crosslinks (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 303-307 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile properties: Young's modulus, ultimate tensile strength, ultimate elongation, the glass transition temperature, and the dynamic mechanical properties (dynamic shear modulus (G'), loss tangent (Tan δ)), of three epoxy resins (Epon 828, Epon 836, Epon HPT 1071) cured with the disulfide-containing crosslinking agent - 4.4-dithiodianilme (DTDA) have been characterized. The results show that DTDA is a satisfactory crosslinking agent for the epoxide resins that have been studied as compared to the well-known curing agent methylene dianiline (MDA). There are no significant differences between the properties of Epon 828 cured with DTDA at stoichiometric ratio (2:1) and Epon 828 cured with DTDA at small amine excess ratio (1.75:1). The glass transition temperature of the cured tetrafunctional epoxy resin Epon HPT 1971 (235°C) is significantly higher than that of difunctional epoxy resins such as Epon 828 (Tg-175°C), but the product is too brittle to be used without plasticizer.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300507
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  • 114
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300601
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  • 115
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    Dynamic behavior of continuous vinyl chloride bulk and suspension polymerization reactors. A simple model analysis (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 291-302 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Based on previous works, a simple model is built to simulate the vinyl chloride monomer (VCM) polymerization in continuous suspension and bulk reactors. The branches of steady-state solutions are computed and their dynamic behavior is analyzed. It is observed that these systems present multiple steady-state solutions for some ranges of parameter values and that non-adiabatic reactors can also present ISOLAs. These reactors can also experience self-sustained oscillations in a very wide region of operation conditions.
    Additional Material: 24 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300506
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  • 116
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    Internal antiplasticization in diglycidyl ether of bisphenol A diamino diphenyl methane non-stoichiometric epoxy networks (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 321-325 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: DGEBA-DDM (diglycicyl ether of bisphenol-A-diamino diphenyl methane) networks of various epoxide/amine molar ratios ranging from 0.7 to 1.4, were studied by density, quasi static (10-4 s-1), and ultrasonic (5 106 s-1) modulus, and thermostimulated creep measurements. Any step aside stoichiometry leads to an antiplasticization, e.g. an increase of the quasi static modulus, whereas Tg decreases. The previous interpretations (based on volumetric property considerations), of this phenomenon are questionable. The only common feature of all the antiplasticized systems is an unexplained decrease of the population of macro-molecular segments involved in beta motions.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300602
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  • 117
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    Dynamic-mechanical and dielectric characterization of PEEK crystallization (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 314-320 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic-mechanical and dielectric characterization of the cold crystallization of PEEK has been performed in order to develop a non-destructive evaluation method of crystallinity in thermoplastic matrices. The Avrami approach is applied here to describe the Poly(ether ether ketone) (PEEK) crystallization kinetics after an appropriate reduction of dynamic-mechanical and dielectric parameters. Avrami exponents obtained from dielectric characterization are comparable with those obtained with DSC measurements reported in literature, while the exponents obtained from the dynamic-mechanical characterization are higher, reflecting also changes in the aspect ratio of the growing crystals. Variations in the glass transition temperature detected during cold crystallization are analyzed and analogies between PEEK and PET are discussed.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300509
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  • 118
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    Bubble-free devolatilization in counterrotating nonintermeshing twin-screw extruder (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 424-430 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theoretical analysis of the diffusion-controlled, essentially bubble-free, mass transfer regime of polymer solution devolatilization has been performed for a counterrotating, nonintermeshing twin-screw extruder (1). The commonly used penetration diffusion approach is applied specifically to this geometry. Mass transfer from the recirculating pool and barrel film in the closed channel and the pool only in the open channel is taken into account. Use is made in this study of the recently determined pumping characteristics of this geometry (2), which allow the estimation of the length of the extraction section. Mass transfer rate measurements have been taken on a 20-mm extruder using the model system polystyrene/ethylbenzene. The agreement between the mass transfer calculations and the experimental results is very good.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300707
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  • 119
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    Viscoelastic response of epoxy glasses subjected to different thermal treatments (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 431-435 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Isothermal aging after a quench from above the glass-transition temperature (Tg) to below it was studied as a function of cross-link density for model epoxy networks using small deformation stress relaxation experiments. We found that time-aging time and time-cross-link density superposition principles described the changes observed in the Viscoelastic behavior of the epoxy networks. The aging response in the nonlinear Viscoelastic regime was also studied using creep experiments for one of the networks. It was found that upon aging near to the conventional glass-transition temperature, the time required for the glass to age into structural equilibrium was independent of the magnitude of the applied stress. This result suggests that large stresses do not erase physical aging (or cause rejuvenation of the glasses).
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300708
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  • 120
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    Morphology-processing relationships in polyethylene-polyamide blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 553-565 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of polyethylene (PE) and polyamide (PA) were prepared by a melt mixing process. The dependence of the number average size An of the dispersed phase on hydrodynamic conditions not only of shear rate but also temperature, inter-facial tension, viscosity of the blends (WU's treatment), and dispersed phase concentration were studied. The analysis of PE-PA blend morphology shows An to be the result of a balance between coalescence and disruption of the particles in the melt, and to display a strong increase in particle size when the minor component concentration is enhanced. These observations can be explained by a change in the rheology of the system. These assumptions are confirmed by the insertion in the blend of an ethylenemaleic anhydride (EMA) copolymer that yields EMA-g-PA graft copolymer during mechanical processing. Formation of this graft copolymer has been indicated by a strong particle size reduction and its concentration was measured by infrared experiments. The EMA-g-PA copolymer seems to decrease the blend interfacial tension and to deter the coalescence process.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300908
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    Analysis of the performance of plasticating single-screw extruders with a new concept of solid-bed deformation (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 665-676 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The performance of plasticating single-screw extruders is analyzed by combining three functional sections: (a) solids-conveying section, (b) melting section, and (c) melt-conveying section. In the analysis of the melting section, we have incorporated a new concept of solid-bed deformation (i.e., the rheology of the solid bed) into Lindt-Elbirli's analysis and included convective heat transfer in the energy equation. Specifically, we have computed stresses on the surfaces of the solid bed, which is surrounded by thin melt films and a melt pool, and, also, computed the apparent modulus of the solid bed in the bulk state as a function of temperature and position within the solid bed, along the extruder axis. From this information, we were able to compute the extent of solid-bed deformation, by assuming a linear stress-strain relationship as the constitutive equation of the solid bed. In this approach, we do not assume a priori whether the solid bed is rigid or freely deformable. The solution of the system equations gives us the following information: (a) whether or not the solid bed deforms and if it does, then, how much; (b) the solid-bed velocity along the extruder axis; (c) pressure profiles along the extruder axis; (d) solid-bed profiles in the melting zone along the extruder axis; (e) temperature profiles along the extruder axis; (f) velocity and temperature distributions in the melt pool along the extruder axis; and (g) thicknesses of thin melt films surrounding the solid bed. Theoretically predicted solid bed and pressure profiles along the extruder axis are compared with experimental results reported in the literature. We have pointed out an urgent need for measurements of the apparent modulus of the solid bed in the bulk state as a function of temperature and pressure, under a combined shear/drag flow field.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301106
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    Effect of strain rate and temperature on the performance of epoxy mortar (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 734-740 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The behavior of epoxy mortar was studied under various curing conditions, temperature and strain rate. The effect of aggregate size and distribution on the mechanical properties of epoxy mortar was also studied. Epoxy mortar with a uniform fine sand was cured at various temperatures to determine the optimum curing condition. The strain rate was varied between 0.01 to 6 percent strain per minute and the testing temperature between 22°C and 80°C. The strength, modulus, and compressive strain-strain relationship of polymer mortar are influenced by the curing method, testing temperature, and strain rate to varying degrees. The influence of test variables on the mechanical properties of epoxy mortar are quantified. Compared to the uniformly graded fine aggregate fillers the gap-graded aggregates produced polymer mortar with better mechanical properties. The compressive modulus and splitting tensile strength of epoxy mortar are related to their compressive strength. A new nonlinear constitutive model is proposed to predict the complete compressive stress-strain behavior of epoxy mortar. The constitutive relationship parameters are also related to the testing temperature and logarithmic strain rate.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301206
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    The interface in binary mixtures of polymers containing a corresponding block copolymer: Effects of industrial mixing processes and of coalescencePresented in part at the Annual Meeting of AIChE, Symposium ‘8A’ on Polymer Engineering and Science. New York, November 18, 1987, and at IMRI-NRCC Conference, ‘Polyblends’ 88. April 6, 1988. Montreal. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 741-752 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In theories of the minor phase (domain) formation in polyblends rendered as emulsions it is usually assumed that the size and shape of the domains are the result of melt viscosity effects (Taylor, Wu) or viscoelasticity effects (VanOene, Elmendorp) being balanced by interfacial tension. This assumption would predict a monotonic decrease of the domain size to a final limiting size with increasing energy of mixing. However, a systematic study of the dependence of domain morphology on industrial mixing processes which was carried out on a “model” LDPE/PS (2/1) mixture and the related polyalloy (i.e., the same mixture with a corresponding block copolymer as compatibilizer) does not support this expectation. Doirain size was found to go through a minimum as mixing energy was increased. A similar minimum was seen in data on specific volume of the melt vs. mixing energy, which indicates a correlation between melt specific volume and domain size. Calculation of the approximate surface area of the domains using a simple model of domain shape indicated that total interfacial energy in the polyblend and/or polyalloy is a trivial part of the mixing energy introduced. These calculations also indicated that if compatibilizer was located entirely at the interface, the surface layer would have a thickness of about 90 nm. Some micrographs seem to show such a surface layer. We propose that an abrasion mechanism is responsible for the early stage of the dispersion process, and that the final domain size may be controlled by a dispersion-coalescence equilibrium. This is compared with the theories of final particle size proposed by VanOene and Wu.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301207
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301401
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    Viscous dissipation effect on solidification of a liquid onto a tube wallThis paper was presented at the 26th National Heat Transfer Conference and Exhibition. Philadelphia. Pa., August 6-9. 1989. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 776-782 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of viscous dissipation on solidification onto the inner surface of a straight circular tube of a liquid flowing laminarly with a specified volumetric rate is analytically determined. Steady conditions and a constant tube wall temperature below the solidification temperature of the liquid are assumed. Solutions for the thickness of the solidified shell and for the pressure drop are obtained. The pressure gradient versus volumetric flow rate curve exhibits a minimum, suggesting that it might be possible to design runners for injection molding machines to have a minimum pressure drop if the volumetric flow rate is specified.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301305
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    Analysis of the birefringence distributions in compact discs of polycarbonate (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 813-820 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The birefringence distributions in injection-molded Compact Discs (CD) are determined in radial and tangential cross-sections and interpreted in terms of the process. The influence of processing conditions is discussed in several examples. It is shown that despite the high birefringence level the retardation of a beam of normal incidence is almost zero due to several compensation mechanisms. One optical axis is almost perpendicular to the surface. The medium, however, is biaxial with the preferential directions depending on the distance from the surface and the radial position. In contrast to a parallel beam, zero retardation cannot be achieved with a convergent beam in injection-molded polycarbonate disks for that reason.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301403
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    Dimensional stability and property gradients in thick sheet molding compound (SMC) sectionsPresented in part at the 34th International SAMPE Symposium and Exhibition, May 8-11, 1989, Reno, Nevada (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 805-812 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dimensional stability of sample cylinders cured with sheet molding compound pastes was investigated. A significant amount of dimensional change was found for these samples when they were annealed. Furthermore, the amount of change varied with location from the center to the wall along the radial direction of the sample cylinder to form a strain gradient. A series of experiments were then carried out to determine property gradients along the same direction in search of the source of the dimensional instability. It was found that the sample also had a gradient in cure and a gradient in dynamic mechanical properties. But these gradients are not in full agreement. In particular, the gradient of cure appears to be opposite to the direction of the strain gradient, while the gradient of the dynamic mechanical properties coincides with it. These results, therefore, suggest that the dimensional stability may be predominantly governed by the viscoelastic behavior of the material.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301402
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    Thermorheological analysis of glass beads-filled polymer melts (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 821-828 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The complex viscosity of two thermoplastic polymer melts (high density polyethylene and polystyrene) filled with polydisperse glass beads (10-53 μm) has been studied in the domain of linear viscoelasticity as a function of frequency, temperature, and filler concentration. In the experimental windows examined, the complex viscosity can be well described by a new empirical model, which contains a Cross-type viscosity model for the frequency dependence, a Quemada-type model for the filler concentration dependence, and a compensation effect for the temperature dependence. This model allows the prediction of the complex viscosity of a glass bead-filled thermoplastic melt provided only four parameters are known, namely: the average maximum packing volume fraction characteristic of the filler geometry and size distribution, the flow activation energy of the thermoplastic, the shear-thinning parameter, and an adjustable parameter, also characteristic of the thermoplastic.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301404
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    On the modeling of continuous mixers. Part II: The cokneader (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 893-904 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Buss cokneader is a single-screw extruder with interrupted flights. Pins from the barrel are inserted into the screw channel. The screw is both rotating and oscillating. Due to this action, screw flights are continuously wiped by the pins. During one passage of the pin, the material is not only subjected to high shear stress, but it is reoriented as well, thus promoting the distributive mixing process by the local weaving action of the pins and screw flights. Attempts to model the cokneader tend to focus on a single pin passing through the hole in a screw flight (1, 2). However, a more comprehensive model can start with the same equations that apply to the corotating twin-screw extruder (3). Because the effect of leakage flows on the local pressure gradient has to be considered along with the effect of the local dragging action of the pins (neglecting the oscillatory action), experiments with model liquids have been performed to evaluate the comprehensive model. Additional experiments with a Plexiglas-wailed cokneader support the calculations concerning filled lengths in various screw geometries. These results, and those of model calculations, which are extended to the nonisothermal, non-Newtonian situation, are presented.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301504
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    Dynamic behavior of continuous vinyl chloride suspension polymerization reactors: Effects of segregation (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 925-930 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Assumed is that there is no mass transfer among the droplets of reacting organic phase in a continuous vinyl chloride (VCM) suspension polymerization reactor. A mathematical model is thus developed to allow the calculation of steady states and the analysis of their dynamic stability. The results obtained are compared with those obtained with the hypothesis of perfect micromixing. It Is shown that both assumptions lead to similar dynamic structures, which confirms the complex behavior of these reactors. There are major differences, however, that can be exploited in future experimental work.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301507
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301601
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    The V-notch at weld lines in polystyrene injection moldings (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 931-936 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A major factor that weakens the weld line in injection moldings is the V-notch structure. Though the existence of a V-notch is well known, its depth variation with molding conditions has not been detailed. The aim of this paper is to clarify the V-notch structure and its effect on the strength of general purpose polystyrene injection moldings. A dog bone type tensile specimen with a weld line was molded under several molding conditions. The surface of the weld line was partially eliminated by cutting with a milling machine to seven levels of cut depth (Dc). As a result, the weld strength increased with Dc to about 50%. The relationship between the weld strength and Dc made it possible to determine the V-notch depth, which vas defined as the “depth of the weld line.” From these results, a hypothesis is proposed that the V-notch has a structure with a fine groove on the surface and a poorly bonded inner layer. This study considered the relationships among the weld strength, the depth of the weld line, and molding conditions.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301508
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    Crystallization kinetics and nucleating agents for enhancing the crystallization of poly(p-phenylene sulfide) (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 944-949 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental study of crystallization kinetics and the influence of nucleating agents on the solidification of poly(p-phenylene sulfide) (PPS) is described. The effect of molecular weight is considered by investigating PPS samples having different viscosity levels. We studied the effect of a range of nucleating agents including aluminum oxide, calcium oxide, silicon dioxide, titanium dioxide, kaolin, and talc. All of these compounds were found to enhance the rate of crystallization; in particular, silicon dioxide, kaolin, and talc were the most effective nucleating agents. An effort to study particle size effects of the silicon dioxide showed that the nucleation was very sensitive to the source of the material. These studies did, however, show that nucleation rates tended to increase with decreasing particle size and increasing loading of silicon dioxide. Comparison of PPS crystallization rates with those of other polymers indicates that it crystallizes much more slowly than polyethylene or isotactic polypropylene and is slower than polyetherether-ketone, when comparisons are made on an equivalent basis. PPS crystallizes at similar rates to polyethylene terephthalate (PET). However, our nucleated PPS does not crystallize as rapidly as nucleated PET.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301603
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    Molecular design of multicomponent polymer systems. XVIII: Emulsification of high-impact polystyrene and low density polyethylene blends into high-impact alloys (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 937-943 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The interfacial activity of a hydrogenated polybutadiene-polystyrene tapered diblock copolymer, (HPB-b-PS) is investigated in blends of a low density polyethylene (LDPE) with a high impact polystyrene (HIPS) prepared in the melt state on a two-roll mill. Optical and scanning electron microscopy examinations of smoothed or fracture surfaces and also surfaces obtained after THF-extraction of PS phases demonstrate that the copolymer promotes the dispersion and interfacial adhesion of the components, whatever the composition and is able to create and stabilize particular dispersions of the rubber particles in these blends. Tensile and Charpy impact properties are also very significantly improved. All these features demonstrate that the ductility and toughness of PS and LDPE/PS blends can be closely controlled by adequate combinations of rubber particles and a HPB-b-PS copolymer.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301602
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    New approaches to the processing of rutile-filled polyolefins (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 950-956 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The performance of a fluorocarbon elastomer processing additive in rutile-filled linear low density polyethylene (LLDPE) compounds was evaluated by capillary rheometry, and blown film extrusion. Different compounding sequences were considered and their effects on the performance of the processing additive in the presence of various rutiles examined. Lower apparent melt viscosities and higher shear rates for the onset of melt fracture were observed when using certain surface treated rutiles. The nature of the surface coating applied to rutiles was found to have a great influence on the Theological properties of the filled compounds and on the dispersibility of the solids. The acid-base characteristics of rutiles were determined by inverse gas chromatography techniques, and inherent agglomeration indexes for the pigments were measured by an application of powder rheology principles. It was found that those rutiles with high agglomeration indexes or those with highly basic surfaces interfered the most with the processing additive. Mechanisms by which rutile dispersibility and acid-base character influence the effectiveness of the fluorocarbon elastomer processing additive are discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301604
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    Prediction of fiber orientation in injection molded parts of short-fiber-reinforced thermoplasticsThis paper was presented on the 37th annual meeting of the Society Of Polymer Science, Japan, in 1988. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 957-966 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fiber orientation induced by injection mold filling of short-fiber-reinforced thermoplastics (FRTP) causes anisotropy in material properties and warps molded parts. Predicting fiber orientation is important for part and mold design to produce sound molded parts. A numerical scheme is presented to predict fiber orientation in three-dimensional thin-walled molded parts of FRTP. Folgar and Tucker's orientation equation is used to represent planar orientation behavior of rigid cylindrical fibers in concentrated suspensions. The equation is solved about a distribution function of fiber orientation by using a finite difference method with input of velocity data from a mold filling analysis. The mold filling is assumed to be nonisothermal Hele-Shaw flow of a non-Newtonian fluid and analyzed by using a finite element method. To define a degree of fiber orientation, an orientation parameter is calculated from the distribution function against a typical orientation angle. Computed orientation parameters were compared with measured thermal expansion coefficients for molded square plates of glass-fiber-reinforced polypropylene. A good correlation was found.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301605
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    Injection molding of polypropylene/polycarbonate blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1051-1055 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This work deals with the effects of material and processing parameters on the mechanical behavior and morphology of noncompatlbilized polypropylene-polycarbonate (PP-PC) blends. The blends containing between 0 and 40 vol. percent of polycarbonate were compounded using a twin screw extruder and converted by injection molding using molds with rectangular as well as dogbone shaped cavities. The blends exhibit a complex skin-core morphology which evolves with the composition. Despite the absence of interfacial adhesion, the low strain modulus increases with PC concentration and follows approximately the Takayanagi model for systems with perfect adhesion. A slight increase of stiffness and strength with increasing PP/PC viscosity ratio is also observed. Weldline strength of these blends is generally poor and decreases with the increasing PC concentration.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301708
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    Evaluation of poly(1,4-cyclohexylene dimethylene terephthalate) blends for improved processability (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1041-1050 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(l,4-cyclohexylene dimethylene terephthalate) (PCT) exhibits superior heat deflection temperature when compared to conventional polyesters such as poly(butylene terephthalate) or poly(ethylene terephthalate). It is subject to degradation, however, at the processing temperatures normally employed to extrude or mold this material. Several approaches were taken to broaden the processing window of this material including: blending PCT with other crystalline and amorphous polymers to allow for lower processing temperatures, addition of conventional stabilizers, addition of crosslinking agents to maintain viscosity during processing and the addition of lubricants to improve processing. Key parameters included physical properties, rate of degradation, extruder torque measurements vs. time, and Differential Scanning Calorimetry (DSC) analysis (melting point and glass transition). All systems tested produced significant reduction of the intrinsic viscosity (molecular weight) for PCT during processing. The most successful approach was the blending of various polymers with PCT to lower extruder processing temperatures. Reductions in processing temperature may have resulted from improved heat transfer due to the presence of a lower melting polymer, reduction in melting point of the blend, or changes in the frictional characteristics of the PCT in the extruder. Transesterification may have played a role in compatibilizing some polyester mixtures. As expected, certain polymers had major'effects on the flow behavior of the blend. Tradeoffs were obtained in physical and thermal properties. A combined approach of polymer blending and the use of lubricants, stabilizers or crosslinking agent may hold the most promise for future development work. Thermal resistance under vapor phase soldering conditions was best for LCP/PCT blends and worst for PBT/PCT blends. Additional evaluations of the blend materials will include solvent resistance, processability, thermal resistance, dimensional stability, heat aging resistance, flammability, and specific end use tests.
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    URL: http://dx.doi.org/10.1002/pen.760301707
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    Poly(Phenylene oxide)/polyamide blends via reactive extrusion (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1056-1062 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Reactive extrusion of functionalized polymers provides a convenient, commercially attractive route for the preparation of copolymers useful in compatibilization of polymer blends. In the current study, the grafting chemistry of maleic anhydride to poly(phenylene oxide) in the absence of a radical initiator is contrasted to that of efficient quinone-methide trapping agents such as maleimides. In the case of maleic anhydride, functionalization is shown to occur randomly along the polymer backbone whereas maleimides react to give both main chain and end-group derivatives. Use of this anhydride-functionalized polyfphenylene oxide and an end-group functionalized analog in blends with polyamide-6,6 affords high levels of graft and diblock copolymers respectively, sufficient for the preparation of highly ductile materials. The properties of these polyamide blends are found to depend on the amount of copolymer formed during extrusion with final copolymer levels being in turn returned to the degree of anhydride functionalization. The properties and morphology of blends containing graft or diblock copolymers derived from main-chain and end-group functionality respectively, are rationalized in terms of the relative effectiveness of different copolymer structures in blend compatibilization.
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    Experimental analysis of inertial effects in the impact testing of polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1117-1124 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Inertial effects occurring In the impact testing of polymers were experimentally probed by measuring the force versus time response of various materials with two different instrumented impact testers, both with and without anvil. The analysis focused on the first force peak, which was modeled using a mass-spring analog to account for machine-specimen interaction.
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    Birefringence-An important property of plastic substrates for magneto-optical storage disks (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1133-1139 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Birefringence is an important substrate property for optical data storage media. The basic definitions of birefringence and its relation to the chemical nature of polycarbonate are outlined. The polarizability of the monomer unit, expressed in the rheo-optical constant and the degree of remaining polymer chain orientation, determines the level of birefringence in polycarbonate disk substrates. Based on this theory, the theory of blending materials with positive and negative rheo-optical constants Is developed, and the current work with polycarbonate/polystyrene blends is reviewed. The biggest disadvantage of the reviewed system Js that only binary systems with low LCST (lower critical solution temperature) (〈240°C) can be formulated. Finally, we report on successful development work of a single-phase blend of a modified polycarbonate with a special styrene-acrylonitrile copolymer. The experimental results are compared with the theoretical expectations, and the implications on the injection molding of disk substrates are discussed.
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    Polymeric stannous dicarboxylates: Synthesis, properties, and structure (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1151-1157 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of polymeric stannous dicarboxylates (i.e., suberate, sebacate, do-decanedioate, terephthalate, propoxyterephthalate, and isophthalate) has been synthesized from aqueous solution using various conditions of temperature (20, 50, and 98°C) and pH (6.4, 8.0, and 11.6). These were obtained as highly viscous adhesive-like emulsion phases when synthesized at 50 and 98°C. Polymeric stannous suberate when synthesized at pH 11.6 and temperature of 50°C crystallized to spherulites. When molten they behaved like hot-melt adhesives. They could be spun into fibers. On the other hand, melt-synthesized stannous dicarboxylates exhibit simple non-polymeric salt structures.
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    Dermal extracellular lipid in birds (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 203 (1990), S. 55-68 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A light and electron microscopic study of the skin of domestic chickens, seagulls, and antarctic penguins revealed abundant extracellular dermal lipid and intracellular epidermal lipid. Dermal lipid appeared ultrastructurally as extracellular droplets varying from less than 1 μm to more than 25 μm in diameter. The droplets were often irregularly contoured, sometimes round, and of relatively low electron density. Processes of fibrocytes were often seen in contact with extracellular lipid droplets. Sometimes a portion of such a droplet was missing, and this missing part appeared to have been “digested away” by the cell process. In places where cells or cell processes are in contact with fat droplets, there are sometimes extracellular membranous whorls or fragments which have been associated with the presence of fatty acids. Occasionally (in the comb) free fat particles were seen in intimate contact with extravasated erythrocytes. Fat droplets were seen in the lumen of small dermal blood and lymph vessels. We suggest that the dermal extracellular lipid originates in the adipocyte layer and following hydrolysis the free fatty acids diffuse into the epidermis. Here they become the raw material for forming the abundant neutral lipid contained in many of the epidermal cells of both birds and dolphins. The heretofore unreported presence and apparently normal utilization of abundant extracellular lipid in birds, as well as the presence of relatively large droplets of neutral lipid in dermal vessels, pose questions which require a thorough reappraisal of present concepts of the ways in which fat is distributed and utilized in the body.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 203 (1990) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052030101
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    Neuronal differentiation in the thalamic area triangularis of a lizard (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 123-134 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Development of neurons in the area triangularis of Gallotia galloti was investigated in Golgi-impregnated brain tissue. Four major neuronal types present in adults were found to originate from two migratory neuroblast types, which were followed from embryonic stage S.32. One type has a thick main medial process, whereas the second type has a long main lateral process. As they migrate toward the periphery of the nucleus, morphological characteristics of maturation appear, including growth cones, filopodia, and outgrowth of axons. Neuroblasts with a main lateral process differentiate into two immature neuronal types, bipolars and pyramidals, observed at S.33 and thereafter. The neuroblasts with a main medial process undergo some somatic translocation through a transitory tangential shaft. Then they develop into monopolar immature forms with a long varicose medial, process, appearing from S.36. onward. Immature bipolar neurons do not experience great changes in their dendritic arborization during development to the adult stage, but pyramidals and monopolars undergo a rapid development of the dendritic tree after S.36. By S.38 archetypes of adult neuronal forms are established. Hairlike appendages first appear on neurons at S.36 They decrease suddenly in S.38 and then proliferate in S.39 when spines first appear. Around the time of hatching, the hairlike appendages begin to disappear and spines become established. Reduction of spines occurs after hatching and continues to the adult stage. Possible influences of several external factors on neuronal maturation are discussed.
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    Morphology of the ovaries of Sphaerodema (Diplonychus) rusticum (Heteroptera, Belostomatidae) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 183-192 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The female reproductive system of Sphaerodema rusticum consists of a pair of ovaries, two lateral oviducts, a median common oviduct, and a median spermatheca. Accessory glands are absent. Each ovary has five free ovarioles branching from the oviduct. Each ovariole consists of a terminal filament, germarium, vitellarium, brown mass, and an exceptionally long pedicel. The terminal filament consists of a central core, interstitial cells, and an outer sheath. In the germarium, which consists of trophic and prefollicular regions, the trophic region or nurse cell chamber is divided into four histologically differentiated zones, distinguished as zones I-IV. Nutritive cords, originating from the posterior end of the trophic core in zone IV extend centrally and join the developing oocytes in the prefollicular chamber and the vitellarium. The compact prefollicular tissue at the base of the trophic core gives rise to prefollicular cells which, after encircling the young oocytes, become modified into follicular epithelial cells, the interfollicular plug, and epithelial plug. The young oocytes descend into the vitellarium and gradually develop into mature oocytes. A compound corpus luteum is observed simultaneously in all the ovarioles of both ovaries after ovulation. Below the epithelial plug there is an accumulation of material, the “brown mass,” which develops cyclically in correlation with the ovulation cycle. Each pedicel stores five mature chorionated eggs ready for oviposition. The epithelium of the anterior region of the pedicel secretes a PAS-positive material. General morphology and histology of the subdivisions of the ovarioles are described.
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    URL: http://dx.doi.org/10.1002/jmor.1052050207
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    Feeding mechanics of teleost fishes (Labridae; Perciformes): A test of four-bar linkage models (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 269-295 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The feeding mechanisms of two labrid fishes (Cheilinus chlorurus and C. diagrammus: Labridae: Perciformes) are modeled using four-bar linkage theory from mechanical engineering. The actions of the feeding mechanisms are simulated by a computer program that uses morphometric data to calculate the geometry of mechanism structure. The predictions of three different four-bar linkages regarding the kinematics of feeding are compared to the movements observed through hign speed (200 fps) cinematography. A previously unidentified four-bar chain was found to be an accurate model of the mechanism by which upper jaw protrusion, maxillary rotation, and gape increase occur in Cheilinus. This mechanism involves the anterior jaws including the mandible, maxilla, premaxilla, palatine, and suspensorium. The accuracy of two previously described four-bar linkages was also tested by comparison of model predictions and film results. The opercular linkage proposed by Anker ('74) as a mechanism of jaw depression via opercular levation was found to be a poor predictor of feeding movements. This four-bar chain involves the opercle, suspensorium, interopercle, and mandible. Muller ('87) proposed a mechanism of hyoid depression involving cranial elevation due to epaxial muscle contraction as input motion The links in this mechanism include the neurocranium and hyomandibula, hyoid, sternohyoideus muscle, and pectoral girdle. This model was an accurate predictor of hyoid depression in Cheilinus when simultaneous cranial elevation and sternohyoideus contraction were simulated. Quantitative kinematic models involve simplifying assumptions when applied to complex musculoskeletal systems, but such models have a wide range of applications to vertebrate functional morphology.
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    URL: http://dx.doi.org/10.1002/jmor.1052050304
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    Olfactory and vomeronasal systems of caecilians (Amphibia: Gymnophiona) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 255-268 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of both the main nasal cavity and the vomeronasal organ differs among species representing six families of caecilians. The main nasal cavity is either divided or undivided. The vomeronasal organ differs in position (mediolateral, lateral), size (large vomeronasal organ in the aquatic species), and shape (mediolateral extension, vomeronasal organ with a lateral rostral projection). The great amount of respiratory epithelium of the main nasal cavity, the large vomeronasal organ, and its extensive innervation in typhlonectids may reflect both phylogeny and habitat adaptation, for these taxa are secondarily aquatic or semiaquatic and have several concomitant morphological and physiological modifications. The vomeronasal organ is associated with the caecilian tentacle as the tentacular ducts open into it. This association is further evidence for the involvement of the caecilian tentacle in vomeronasal chemoperception and may represent the mechanism by which these animals smell though the main nasal cavity is closed during burrowing or swimming. Labelings of primary olfactory and vomeronasal projections by means of horseradish peroxidase reaction reveal that the pattern of vomeronasal projections is similar in Ichthyophis kohtaoensis, Dermophis mexicanus, and Typhlonectes natans, even though T. natans possess stronger vomeronasal projections relative to olfactory projections than I. kohtaoensis and D. mexicanus. However, there are differences with respect to the patterns of olfactory projections. The olfactory projection of I. kohtaoensis is characterized by many displaced glomeruli. T. natans has the smallest olfactory projection. The nervus terminalis is associated with the olfactory system as shown by selective labelings of olfactory projections.Six characters potentially useful for phylogenetic analysis emerge from this study of comparative morphology. The characters were subjected to analysis using PAUP to see (1) if any resolution occurred and (2) if any groups were distinguished, whether they corresponded to phylogenetic arrangements based on other morphological characters. The characters are too few to produce nested dichotomous sets for all cases, but they do support the two typhlonectid genera examined and Dermophis and Gymnopis as sister taxa discrete from other groups, and they show that species within genera cluster together.
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    Cellular basis of an avian countercurrent multiplier system (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 1-11 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A kidney from the budgerigar (budgie, parakeet; Melopsittacus undulatus) is composed of cortical reptilian-type nephrons (without loops of Henle) and mammalian-type nephrons (with loops) grouped together in medullary cones. The loop of the mammalian-type nephrons has a descending segment composed of thin and highly interdigitated cells. These thin limb cells have few mitochondria (15% of cell volume), undetectable Na+, K+-ATPase activity, and virtually no basolateral surface amplification. Prior to the hairpin turn, the descending limb thickens, but the cells continue to lack basolateral amplification. Cells just prior to and within the hairpin turn resemble cells of the entire ascending limb. These cells are thick (there is no thin ascending segment in the avian loop), with extensive infoldings of the basolateral membrane surrounding numerous mitochondria (45% of cell volume). The area of basolateral membrane is 25 times that of the apical membrane. The basolateral membrane (but not the apical membrane) is enriched in Na+, K+-ATPase activity. The structure of the avian mammalian-type nephron (as epitomized by the budgie nephron) and the fact that NaCl accounts for over 90% of the osmotic activity of avian urine leads to the conclusion that the countercurrent multiplier of the avian kidney functions by active NaCl transport from the entire ascending limb. No explanation is offered for the transport specializations found in the thick descending segment of the loop, just prior to the hairpin turn.
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    Interhemispheric connections through the pallial commissures in the brain of Podarcis hispanica and Gallotia stehlinii (Reptilia, Lacertidae) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 17-31 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cells-of-origin and the mode and site of termination of the interhemispheric connections passing through the anterior and posterior pallial commissures in the telencephalon of two lizards (Podarcis hispanica and Gallotia stehlinii) were investigated by studying the anterograde and retrograde transport of unilaterally injected horseradish peroxidase. The commissural projections arise mainly from pyramidal cells in the medial, dorsomedial, and dorsal cortices (medial subfield). Additionally some non-pyramidal neurons in the medial and dorsal cortices contribute to the commissural system. Medial cortex neurons project to the contralateral anterior septum through the anterior pallial commissure. The dorsomedial cortex projects contralaterally via the anterior pallial commissure to the dorsolateral septum and to the medial, dorsomedial, and dorsal cortices. The projection to the medial cortex terminates in two bands at the inner and outer border, respectively, of the cell layer; the projection to the dorsomedial and dorsal cortex ends in a zone in layer 1 which previously has been described to be Timm-negative, and in a diffuse band in the inner half of layer 3. The medial subfield of the dorsal cortex projects through the anterior pallial commissure to the dorsomedial and dorsal cortices with a similar pattern of termination to that found for the dorsomedial cortex. The posterior pallial commissure contains only the projections from the ventral cortex to its contralateral counterpart and to the ventral part of the caudal medial cortex. The similarities found between this commissural system and the mammalian hippocampal interhemispheric connections are discussed.
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    Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. I. Gastric region (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 1-8 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin-biotinperoxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA-I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA.-I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA-I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA-I, SBA, and WGA; and for Con A, RCA -I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly idpntifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA-I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.
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    Ultrastructure of sperm development and mature sperm morphology in three species of commensal bivalves (Mollusca: Galeommatoidea) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 63-75 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural features of the ovotestes, spermatogenesis, and the mature sperm are described for three galeommatid bivalves, Divariscintilla yoyo, Divariscintilla troglodytes, and Scintilla sp., from stomatopod burrows in eastern Florida. All three species yielded similar results except with respect to mature sperm dimensions. The ovotestis contains three types of somatic cells within the testicular portion: flattened myoepithelial cells defining the outer acinal wall; underlying pleomorphic follicle cells containing abundant glycogen deposits; and scattered, amoeboid cells containing lysosomal-like inclusions which are closely associated with developing sperm. Early spermatogenesis is typical of that reported from other bivalves. In contrast, the late stages of spermiogenesis involve the migration and gradual rotation of the acrosomal vesicle, resulting in a mature acrosome tilted about 70° from the long axis of the cell. The mature sperm possesses an elongated, slightly curved nucleus; a subterminal, concave acrosome with a nipple-like central projection; five spherical mitochondria and two centnoles in the middlepiece; and a long flagellum. The rotational asymmetry and the presence of perimitochondrial glycogen deposits in these sperm are unusual in the Bivalvia and may be associated with fertilization specializations and larval brooding common among galeommatoideans.
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    Ultrastructure of nuchal organs in some marine polychaetes (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 95-107 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Polychaetes normally possess one pair of nuchal organs at the posterior edge of the prostomium or peristomium. They have been regarded as chemosensory organs. The nuchal organs of four marine polychaete species with different habits were investigated by electron microscopy.Although the shapes of nuchal organs can vary greatly from simple ciliary bands (Scolelepis squamata, Spionidae) to retractile tongue-like, piston- or finger-shaped forms (Eteone longa, Anaitides mucosa, Phyllodocidae; Heteromastus filiformis, Capitellidae), the structural components, including the ciliated supporting cells, sensory cells, and nuchal epidermal cells, are essentially similar. The differences basically concern 1) the position of the sensory cells with relation to the ciliated supporting cells, 2) the location and structure of the nuchal nerve, and 3) the structure of the nuchal cuticle.The diverging nature of this modified cuticle is described and discussed in detail. Comparisons are made with the fine structure of nuchal organs of other polychaete species. Similarities of cellular components of nuchal organs are found not only in the four species studied here but also in all nuchal organs investigated so far. This is hypothesized to be due to the fact that the polychaete stem species already possessed nuchal organs with the respective cell types. Differences in the number and distribution of cellular components and in the overall shape of nuchal organs are thought to have evolved in correlation with the equipment of other cephalic appendages and with different habits and modes of nutrition.
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    Morphology and innervation of the buccal glands of the southern hemisphere lamprey, Geotria australis (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 133-145 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark-staining inclusions and numerous lipid-like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark-staining inclusions increase whereas those of lipid-like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra-epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed-back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.
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    The early embryonic development of the jumping bristletail Pedetontus unimaculatus machida (Hexapoda: Microcoryphia, Machilidae) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 181-195 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The early development of Pedetontus unimaculatus from maturation to germ rudiment formation has been described by light and electron microscopy. Newly laid eggs of P. unimaculatus are in the metaphase of the first maturation division, and two successive maturation divisions produce two polar bodies. Nuclear divisions up to the eighth or ninth are accompanied by cytoplasmic divisions, and are holoblastic. Each resulting blastomere contains a single nucleus. Most cleavages are radial, but a few are tangential resulting in the formation of primary yolk nuclei. After the eighth or ninth nuclear division, cytoplasmic divisions are restricted to the egg periphery, and these later cleavages are superficial. Boundaries of blastomeres gradually disappear. Nuclei, which settle in the peripheral cytoplasm, proliferate and differentiate into blastoderm cells, and they also give rise to secondary yolk nuclei. A posterior circular region of blastoderm thickens and concentrates to form a germ rudiment 50-100 μm in diameter. During the formation of a germ rudiment the serosal cuticle begins to form.A similar pattern of cleavage was observed in other species of the Machilidae belonging to four genera in two subfamilies (Machilinae, genus Haslundichilis; Petrobiinae, genera Pedetontus, Pedetontinus, Petrobiellus). The cleavage pattern of the machilids closely resembles that found in the myriapod groups, the Symphyla, Diplopoda, ana Pauropoda, as well as in the apterygote Collembola, but it differs from the purely superficial cleavage pattern characteristic of the apterygote Thysanura sensu stricto (Zygentoma) and the Pterygota.It is concluded 1) that the pattern of early total cleavage changing later to superficial cleavage is a plesiomorphic character for the Antennata, and 2) that the purely superficial pattern is an apomorphic character within the Hexapoda.
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    Masthead (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060301
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    The digestive system of the lobster, Homarus americanus: III. Removal of foreign particles from the blood by fixed phagocytes of the digestive gland (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 293-302 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), is permeated with terminal arterioles of the hepatic artery. Fixed phagocytes associated with the terminal hepatic arterioles removed two types of non-biogenic, foreign particles (carbon particles and latex beads) that were injected into the blood. These cells play an important role in the cell-mediated immunity of lobsters.
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    The digestive system of the lobster, Homarus americanus: II. Terminal hepatic arterioles of the digestive gland (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 283-291 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), is supplied with blood by the hepatic artery. Numerous branches, ending in terminal hepatic arterioles, permeate the organ and discharge blood into the hemal sinuses. Histological and ultrastructural studies show the arterioles to be elongate tubes that lie in the hemal spaces, interspersed among the digestive tubules of the digestive gland. The terminal hepatic arterioles comprise three distinct populations of cells: endothelial cells form the wall of the blood vessel; hemocytes circulate through the lumen of the vessel; and fixed phagocytes are attached to the outer surface of the endothelium. In addition, extracellular membranes form an endothelial intima that lines the lumen and a perforated membrane that covers the outer surface of the arteriole.
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    Expression of the WE3 antigen in newt epithelium originating from subcutaneous grafts of skin (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 265-271 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: mAb WE3 recognizes an antigen that is developmentally regulated in the wound epithelium of regenerating newt limbs. The antigen is precociously expressed when pieces of WE3-negative wound epithelium axe grafted subcutaneously (Tassava et al.: Recent Trends in Regeneration Research. New York: Plenum Publishing Co., pp. 37-49, 1989). In the present study, we investigated whether the WE3 antigen is expressed in epidermis of subcutaneous grafts of skin. Small pieces of limb skin were grafted into small tunnels in the lower jaw, limb, and tail, oriented either the same as (epidermis facing out) or opposite to (epidermis facing in) the orientation of the host skin. In most cases, the epithelium migrated from the graft along the wounded surface of the tunnel, closed onto itself, and formed a multilayered “emigrant” epithelium. Infrequently, the migrating epithelium combined with the wound epithelium of the insertion wound. In no case did the epithelium migrate over the cut edge of the grafted dermis. Reactivity to mAb WE3 was first seen at 4 days after grafting, when the migrating epithelium had almost closed over onto itself. By 6 days and thereafter, the entire emigrant epithelium was reactive to mAb WE3. While initially restricted to the emigrant epithelium, at 10 days after grafting and thereafter, reactivity was also seen in the epidermis that remained in contact with the dermis. Expression of the WE3 antigen was not influenced by the orientation of the graft nor by the graft site. The results show that, compared to amputated limbs, the epithelium originating from these grafts precociously expresses the WE3 antigen. Also, epidermis of grafted skin is capable of expressing the WE3 antigen.
    Additional Material: 7 Ill.
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    Endocrine cells and brush cells at the bronchiolo-alveolar junctions of neonatal syrian hamster lungs (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 217-223 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Endocrine cells and brush cells at the bronchiolo-alveolar junctions of the lung of neonatal hamsters were studied by transmission electron microscopy. On both sides of the junctions (bronchiolar and alveolar), clusters of endocrine cells occur as neuroepithelial bodies (NEB). A few solitary endocrine cells are also present at the alveolar sides of the junctions. Some endocrine cells reach from the basement membrane to the air space but the area of apical cell membrane exposed to the airway is small as the cells are largely covered by Clara cells in the bronchioles and by thin attenuations of alveolar type 1 cells in the alveoli. Some Clara cells around NEB contain cytoplasmic lamellar bodies, similar to those characteristically associated with alveolar type 2 cells. A few brush cells are also seen at both sides of the junctions. Long wide microvilli with filamentous cores extend from the apices of the brush cells. Endoplasmic reticulum and Golgi apparatus are moderately developed. Well-developed bundles of intermediate filaments course throughout the cytoplasm of some of the brush cells. The functions of endocrine cells and brush cells are unknown. However, the presence of these cells at the bronchiolo-alveolar junctions of neonatal hamster lungs suggests a role in regulation of respiratory function.
    Additional Material: 8 Ill.
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    The mechanism of dewlap extension in Anolis carolinensis (Reptilia: Iguanidae) with histological analysis of the hyoid apparatus (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 225-244 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anolis carolinensis has two aggressive displays involving movements of the hyoid apparatus: erection of the throat and extension of the dewlap. Erection of the throat is an enlargement of the gular region and dewlap extension consists of a vertical erection of the gular flap. Cinefluoroscopy and high speed cinematography show that the dewlap is extended in three phases: 1) protraction of the entire hyoid apparatus; 2) forward pivoting movement of the ceratobranchials II; and 3) retraction of the ceratobranchials II and the entire hyoid apparatus. The cartilaginous elements of the hyoid apparatus are variably mineralized. The entoglossal process and the hypohyals are the most calcified elements. The mineralized portion of the hyoid body, to which the other elements articulate, presents a complex pattern. The calcification of entoglossal process and the hypohyals stop just where they are fused with the hyoid body. The hyoid body presents four mineralized masses, two central corresponding to the base of the ceratobranchials II and two lateral being the head of the ossified ceratobranchials I. The lateral masses articulate on the central masses by a synovial joint. Morphologically, the ceratobranchials II form the hyoid body and become separated at the mid length of the synovial articulation of the ceratobranchials I and the hyoid body. The calcified matrix of the ceratobranchials II gradually changes from a large calcified mass (within the hyoid body) to a semicircle, opened ventrally, which permits their bending during dewlap extension. The highly mineralized posterior tip of the entoglossal process and the hyoid body serve as a pivot to pivoting forward movement of the ceratobranchials II producing at the change of the pattern of mineralization. Forward movement of the ceratobranchials II is produced by electrical stimulation of the M. branchio hyoideus. The opposition of the throat skin to the movement of the ceratobranchials II produces the bending of those longest elements. Electrical stimulation of the hyoid muscles confirms the key role of M. branchiohyoideus during dewlap extension. Simultaneous contractions of all the hyoid and extrinsic tongue (retractor and protractor) muscles with the M. branchiohyoideus during dewlap extension may be a possible motor pattern for dewlap extension in Anolis lizards.
    Additional Material: 15 Ill.
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    Desmosome-like junctions between sertoli-sertoli and sertoli-germ cells in the ovotestis of Arion hortensis (Mollusca: Pulmonata) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 325-333 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ovotestis of Arion hortensis was investigated by electron microscopy, using serial ultrathin sections and freeze-fracture. Desmosome-like junctions between Sertoli-Sertoli and Sertoli-germ cells (spermatogonia, spermatocytes, spermatids, and spermatids just prior to spermiation) were studied. Desmosome-like junctions were circular when viewed en face and 90--180 nm in diameter. The intercellular space at the junctional site was 15-25 nm in width. An intermediate dense line was absent.Freeze-fracture replicas showed that these junctions formed groups, with one to ten junctions within each group. Groups of junctions were scattered over the Sertoli cell surface. The most prominent feature of this junction was an electron-dense plaque on the cytoplasmic face of the plasmalemma. We describe variation in the development of the electron-dense plaque on the germ cell side at different stages in the development of the germ cell. In the spermatogonium and spermatocyte stages, desmosome-like junctions had equally developed electron-dense plaques. The plaques are pronounced in junctions between Sertoli cells and spermatocytes/spermatids and less developed in relation to late spermatids where nuclear condensation is complete, and appear to be lost at spermiation. Finger-like processes arise from the Sertoli cell as desmosome-like junctions are lost at spermiation.Hypertonic fixative solutions containing dextrose were applied to the ovotestis resulting in cell shrinkage. The intercellular space between Sertoli cells and germ cells was increased except where the desmosome-like junctions were present. We suggest that desmosome-like junctions provide strong adhesive sites between Sertoli and germ cells.
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    Morphology and morphometry of motor endings on macaque intrafusal fibers (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 343-352 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructural studies have shown three types of motor endings in the macaque intrafusal fibers: (1) unindented axon terminals with smooth or shallowly folded postsynaptic membrane; (2) indented terminals with few postsynaptic folds; and (3) indented terminals with heavily folded postsynaptic membrane. The terminals on bag 1 and chain fibers were generally more indented than those on the bag 2 fibers. Deeply indented terminals with highly folded postsynaptic membranes were noticed on the bag 1 and chain endings in spindles from lumbrical but not the biceps muscle. In the individual intrafusal fibers from the biceps and lumbrical spindles, the degree of indentation did not correlate with the extent of postsynaptic folding (P〉.01). Endings on bag 1 and chain fibers in the lumbrical spindles showed a positive correlation between indentation of terminals and their distance from the primary sensory endings (P〈.01), whereas the lumbrical bag 2 endings and the biceps intrafusal endings did not (P〉.01). The shape of the intrafusal motor endings thus is independent of their location but dependent on the type of intrafusal fibers.
    Additional Material: 9 Ill.
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    Surface ultrastructural changes in the gills of sockeye salmon (teleostei: Oncorhynchus nerka) during seawater transfer: Comparison of successful and unsuccessful seawater adaptation (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 13-23 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sockeye salmon were transferred rapidly from freshwater to seawater and the changes in gill morphology, in particular the distribution and sizes of chloride and mucous cells on the afferent filamental surface examined. Salmon that successfully adapted to seawater were compared with salmon that did not adapt to seawater and died as a consequence of osmoregulatory failure. The number of mucus cells (density), determined from scanning electron microscopy, increased significantly after seawater challenge. A greater increase in mucus cell density occurred in the salmon that failed to adapt to seawater. Light microscopy of transverse sections of gills detected no difference in mucus cell numbers after seawater challenge. It is proposed that mucus cells that lie just beneath the gill epithelium are activated in response to the seawater challenge, and migrate and open onto the epithelium. Freshwater-adapted salmon that had low densities of chloride cells prior to the seawater challenge failed to adapt, whereas salmon that had high densities of chloride cells adapted successfully to seawater. In the latter, the density of chloride cells on the afferent surface decreased after 30 days in seawater. The apical surface of the chloride cells of freshwater-adapted sockeye were either smooth or covered with microvilli. A greater proportion of microvilli-covered chloride cells occurred in the freshwater-adapted salmon that subsequently adapted to seawater.
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    URL: http://dx.doi.org/10.1002/jmor.1052060103
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    Scalariform junctions in the malpighian tubules of the insects Rhodnius prolixus (Hemiptera: Reduviidae) and Aedes taeniorhynchus (Diptera: Culicidae) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 65-69 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of scalariform junctions in the Malpighian tubules of the hemipteran Rhodnius prolixus and the dipteran Aedes taeniorhynchus is described. Both autocellular and intercellular scalariform junctions are illustrated. This is the first report of scalariform junctions in the Malpighian tubules of a dipteran. When combined with previous observations by other authors, the presence of scalariform junctions has now been reported in the Malpighian tubules of insects from five orders, including ametabolous, hemimetabolous, and holometabolous forms. The cell types in which scalariform junctions were found in R. prolixus and A. taeniorhynchus differ in the direction of ion and fluid transport. The cells share the capacity to transport KCl. These same cells also possess morphological features promoting close associations of mitochondria and plasma membranes in the apical region of the cell. The possible role of scalariform junctions is discussed in light of these observations.
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300101
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    Nucleation in polymer crystallization: A physical or a chemical mechanism?Presented as an invited lecture at the 19th Europhyslcs Conference on Macromolecular Physics, Polymer Crystallization, Gargnano, Italy, June 1988. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 270-278 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Primary nucleation is in general heterogeneous in polymer crystallization. In unseeded polymers, the crystallization originates from a very small concentration (〈0.1 percent) of unknown submicroscopic heterogeneous nuclei. Only in three cases have the nucleation mechanisms been identified with precision. The first example is self-nucleation, which relates to the nucleation of a polymer melt by fragments of its own crystals previously present in the melt. Another example of heterogeneous nucleation is represented by epitaxial nucleation of polymers on inorganic and organic substrates recently established by Lotz and Wittmann. More recently, it was discovered that finely divided organic salts added to reactive polymers do not behave as inert heterogeneous substrates but rather dissolve and cut molten macromolecules producing ionic chain ends which precipitate into the melt and form organized aggregates which are the true nucleating species. It is clearly shown that mechanisms of physical and chemical origin are involved in heterogeneous primary nucleation of polymer crystallization.
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    Phenol/cresol-formaldehyde resin characterization and contribution to product hardness (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 257-262 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Lot-to-lot variations in a phenol/cresol-formaldehyde resin were fully characterized. Resin property-product hardness relationships were examined to elucidate the cause of variable hardness in product insulators and to establish acceptance criteria for the resin. A high methylol content (φCH2OH), determined by quantitative carbon-13 nuclear magnetic resonance (13C-NMR), and a narrow molecular weight distribution (MWD), determined by size exclusion chromatography, were found necessary for resin to produce insulator meeting the minimum Shore D durometer specification of 40.
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    Dynamics of a CSTR for styrene polymerization initiated by a binary initiator system (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 279-290 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The steady state and dynamic behavior of a continuous stirred tank reactor has been analyzed for free radical solution polymerization of styrene initiated by a mixture of two initiators having different thermal stabilities. From the steady state analysis of the reactor model with a mean residence time as a bifurcation parameter, four unique regions of steady state solutions are identified in an operating parameter space for a given initiator feed composition. A variety of complex bifurcation behavior such as multiple steady states, Hopf bifurcation and limit cycles have been observed and their stability characteristics have been analyzed. The effects of feed initiator composition and the concentration of the initiator in the feed stream on the reactor dynamics are also presented.
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    Dynamic mechanical response of adhesively bonded beams: Effect of environmental exposure and interfacial zone properties (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 249-255 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic mechanical response of adhesively bonded metal beams has been examined over a broad temperature range using a dynamic mechanical thermal analyzer (DMTA). The measured dynamic mechanical response of the bonded beam contains rich information about the viscoelastic properties of the adhesive resin such as glass transition temperatures. The measured storage moduli and loss factors of the bonded beams are very sensitive to changes in the properties of adhesive induced by exposing the beam specimens to environmental attack. Dynamic mechanical responses associated with dry adhesive resin, water plasticized resin, and aggregated water were observed for an electro-galvanized steel/epoxy beam exposed to water. The effect of the presence of an interfacial accommodation zone (IAZ) between adhesive resin and metal substrate was also examined; measured properties were very sensitive to the presence of a low modulus IAZ. It was successfully demonstrated in this study that the DMTA testing of bonded beams is a potentially useful tool for studying dynamic performance and durability of automotive adhesive joints.
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    Bulk and surface compression viscosities of high and low density polyethylenesDedicated to Professor Antonio G. Gonzalez on the occasion of his 75th birthday. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 326-334 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Bulk compression flow of high density polyethylene (HDPE) and low density polyethylene (LDPE) have been measured at temperatures of 423 to 463K, pressure up to 150 MPa, and bulk compression rates of about 1.0 to 200.00 × 10-5 s-1. Bulk and surface compression modulus of elasticity (L and Ks), longitudinal bulk compression viscosity (ηL), and surface compression viscosity (ηKs) are described as a function of compression rates (kv and ks), compression deformations (kv percent and Ks percent), and temperature (T). Bulk and surface compression flow activation energies are of the order of 40 to 100 KJ/mol and 3.84 KJ/mol, respectively.
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    Binary blends of nylons with ethylene vinyl alcohol copolymers: Morphological, thermal, rheological, and mechanical behavior (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 341-349 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Binary blends of ethylene vinyl alcohol copolymers, containing 62 (EVOH-62) and 71 (EVOH-71) mole percent vinyl alcohols, with nylons (nylon-6, nylon-6/12, and nylon-12) have been prepared from melt mixing in a twin screw compounding machine. Morphological, thermal, rheological, and mechanical properties were determined. EVOH-62/nylon-6 and EVOH-71/nylon-6 blends showed homogeneous phase morphologies in the nylon-6-rich region, and fine phase separations (c.a. 2 × 10-7 m) in the EVOH-rich region. Melting point depression, positive deviations in viscosity and flexural modulus, and negative deviation in impact strength from the simple additive rule were generally observed. And the results were possibly interpreted in terms of compatibility and increased nylon/EVOH interactions over the nylon/nylon interactions. On the contrary, clean phase separations in large domains were observed from EVOH-71/nylon-6/12 and EVOH-71 /nylon-12 blends. Fibrillation was also obtained from EVOH rich blends. Probably due to the incompatible nature of these blends, yield at low rate of shear and a mechanical property drop were also observed.
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300701
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    AC and DC dielectric properties of some polypropylene/calcium carbonate composites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 374-383 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: AC dielectric properties and thermally stimulated polarization (TSP) and depolarization (TSD) currents were studied in a series of CaCO3-filled polypropylene composites. The filler content (0 to 50 weight percent) and the average particle size (3.0 to 16.1 μm) at constant filler content (30 weight percent) were varied in separate groups of samples. In a third group of samples the filler (20 to 40 weight percent) was surface treated with stearates. The AC dielectric behavior of composites containing untreated fillers is largely determined by a small amount of adsorbed water. Upon heating, the dielectric properties show maxima (increasing with decreasing frequency) which disappear on cooling. In the case of stearate-treated fillers the dielectric loss level is higher, the dispersion and loss curves on heating reflect a combination of dipolar and protonic processes with water desorption. In the dry state the onset of an audio frequency relaxation process is observed in the pre-melting zone. The thermally stimulated currents of the composites containing treated and untreated fillers are also different. In the case of the untreated fillers the TSP curves show maxima indicating water desorption which are increasingly intense and roughly exponential with filler content. The high temperature conductivity and the intensity of the pre-melting depolarization peak pass through a minimum as a function of filler content. Above 20 weight percent filler content the activation energy of high temperature conductivity decreases. In the case of the surface treated samples, the thermally stimulated response is different for “wet” and dried samples. The dry samples exhibit a relaxation between the amorphous and crystalline transitions of the matrix polymer which is probably due to interfacial relaxation caused by the enhanced surface conductivity of the stearate-treated fillers.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300609
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    A simple model of nonisothermal coextrusion (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 408-415 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A numerical method has been developed that takes the streamline finite difference method for modeling fully developed multilayer polymer flows and adds to it a simple means of accounting for nonisothermal conditions. In industrial practice, temperature control is often used to match material viscosities and, thereby, to avoid flow instabilities. By numerically calculating both viscosity ratios and normal stress difference ratios, the numerical method allows one to judge the relative stability of different flows and to choose an intelligent set of experiments when designing a coextrusion process. The algorithm has been successfully tested for a number of polymer melt constitutive equations in flows where the viscosity jumps no more than two orders of magnitude between fluids. Results for a rheologically well characterized polystyrene low-density polyethylene system and for an industrially interesting high-density polyethylene/Ultem system show that the common practice of matching zero-shear viscosities is overly simplistic when interface shear rate, conduction, normal stress, and flow rate effects are taken into account.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300705
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300801
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    Morphology and mechanical properties of thermoplastic composites containing a thermotropic liquid crystalline polymer (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 532-542 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of two thermotropic liquid crystalline polymers (TLCPs), with brittle and ductile matrix materials were both injection molded and spun into fibers, in order to investigate the mechanism of in-situ mechanical reinforcement. In the injection molded samples, the TLCP was only moderately elongated into fibrils, and the mechanical properties were below predictions of the rule of mixtures. Fibers spun out of the blends contained numerous fine fibrils with nearly infinite aspect ratio, and as expected, the modulus increased linearly with the TLCP volume fraction, obeying the Tsai-Halpin equation for transversely isotropic composites. Wide angle X-ray diffraction measurements, as well as determination of the fiber-moduli, revealed that during spinning not only a macroscopic elongation of the fibrils was achieved, but also a considerable molecular orientation within the TLCP domains.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300906
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  • 178
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    Reprocessing polycarbonate/acrylonitrile-butadiene-styrene blends: Influence on physical properties (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 527-531 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A commercial polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend was reprocessed by injection molding to study the influence of reprocessing on the physical properties of the product. The modulus of elasticity and the yield stress are unaffected by reprocessing, whereas the break properties and the impact strength decrease. The effects observed are compared with those found in PC and ABS. The type of reactions taking place during reprocessing and the change of blend morphology are also discussed.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300905
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    Mechanical fracture behavior of polyacetal and thermoplastic polyurethane elastomer toughened polyacetal (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 543-552 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyacetal (POM) toughening with thermoplastic polyurethane (TPU) elastomer was investigated in terms of Theological, mechanical, and morphological properties. Polyacetal can be effectively toughened by the blending with TPU elastomer and the improvement on toughness is found most significant with TPU content from 20 to 30 percent. POM does fracture in ductile mode under extremely low deformation rate and the ductile-brittle transition rate is at 0.5 mm/min. The transition rate is increased with the increase of elastomer content. The precrack hysteresis energy is important in dictating the failure mode. The experimental results show the hysteresis energy (under constant load) increases with the increase of elastomer content and the decrease of deformation rate. Greater hysteresis energy results in larger precrack plastic zone size and thus tends to shift the fracture mode from brittle to ductile as the critical size of the plastic zone is reached. The adoption of the slow rate fracture method has the advantages of ranking toughness of very brittle polymeric materials vs. the conventional Izod or Charpy impact method by varying temperatures. FTIR shows significant interaction between POM and TPU which is probably responsible for the TPU elastomer being such an efficient toughening agent for POM. Delamination in the buffer zone between the plane-strain and the plane-stress is discovered and the possible mechanism is discussed.
    Additional Material: 21 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760300907
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    Modality of molecular weight distributions (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 569-570 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Even restricting attention to weight distributions, it is ambiguous to merely say that a polymer is “not bimodal.” A simple example is shown wherein the weight distribution of log (molecular weight) is bimodal, but the weight distribution of molecular weight is not bimodal.
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    URL: http://dx.doi.org/10.1002/pen.760301002
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    Bulk density of solid polymer resins as a function of temperature and pressure (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 571-576 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a plasticating extruder, solid polymers are heated and are subjected to high pressures before they are melted and delivered to a die. In both the solids conveying and melting sections, these temperature and pressure increases will compact the unmelted polymer bed as it moves down the screw channel. Performance of the extruder depends in part on how well the screw design matches the compaction behavior of the resin for a given set of process conditions. The design of these screw sections, however, is often done based on past experience and with little knowledge of the resin compaction behavior. A much improved design would include screw performance prediction using variable bulk density and computer simulations. Computer simulations, however, are often performed using constant solid bulk density because of the lack of reliable density data as a function of both pressure and temperature. An instrument was developed for studying the compaction behavior of pellet and powder resins. Bulk densities and storage friction coefficients are reported for several important thermoplastic resins as a function of temperature and pressure. The bulk density data were fitted to a semi-empirical model.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301003
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    Viscoelastic material characterization and modeling for polyethylene (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 577-586 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An extensive set of stress relaxation and constant strain rate tests for characterizing the mechanical responses of a medium density polyethylene and a high density polyethylene that are commonly used in natural gas distribution piping is described and analyzed. The development of coherent master curves for the relaxation modulus, maximum stress, and the time-to-failure for pressurized pipes through a combination of both horizontal and vertical shifting is presented. The relaxation data are used to develop a nonlinear Viscoelastic material model. The model is assessed by making comparisons of the predicted stress-strain response with the measured response in the constant strain rate tests.
    Additional Material: 20 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301004
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    A modified power law model for the steady shear viscosity of polystyrene melts (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 587-595 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An engineering equation that describes the steady shear viscosity of polystyrene melts is developed as an extension of the well known power law model for non-Newtonian viscosity. The parameters in the equation have been related to weight and number averaged molecular weights and temperature. The model is tested on data for both narrow and broad molecular weight polystyrenes whose properties span most materials of commercial importance. This equation predicts the melt viscosity-shear rate behavior for both narrow and broad distribution polystyrenes from knowledge of weight and number averaged molecular weights and temperature. Our analysis directly yields shift factors for the shear rate and viscosity axes. Therefore, no secondary calculations are necessary to generate master curves for polystyrenes. The shift factors are related to weight and number averaged molecular weights of the polystyrenes and temperature of the melt.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301005
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    Fracture mechanics parameters for polystyrene under high speed impact (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 596-602 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of commercial polystyrenes was tested using an instrumented impact tester to determine the fracture toughness Kc and critical strain energy release rate Gc. Over the range of Mw, 201,000 to 336,000, Kc increased from 1.38 MN/m3/2 to 1.76 MN/m3/2and Gc from 0.92 kJ/m2 to 1.60 kJ/m2. A linear correlation for Kc and Gc was seen with melt index, and an inverse relationship was obtained against molecular weight. Examination of the fracture surfaces revealed the presence of crack growth bands corresponding to the crack tip plastic zone size. It is suggested that these bands are the consequence of variations in crack growth along crazes that form in the crack tip stress field. As the crack propagates, the stress is relaxed locally, decreasing the growth rate allowing a new bundle of crazes to nucleate along which the crack advances. The spacing of these bands corresponds to the craze length formed in the plastic zone, and the band spacing increases with molecular weight.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301006
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    Mathematical modeling of the in-mold coating processBased on a paper presented at the 44th Annual Conference, Composites Institute. The Society of the Plastics Industry, February 6-9. 1989 (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 677-683 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fiber glass reinforced polyester parts compression molded from sheet molding compound (SMC) are prone to such surface inconsistencies as porosity and sinks. Even though it appears that some of these defects could be eliminated by techniques such as vacuum molding, the resulting surface, with current technology, is not yet consistently up to automotive standards for exterior body panels. In-mold coating (IMC) of SMC, is designed to fill porosity, reduce sinks, and furnish a primer-like coating, thus upgrading the part surface to automotive standards. As a consequence, IMC is generally an integral part of the molding cycle when producing compression molded SMC exterior automotive body panels. Most commonly, in-mold coating is injected after opening the press slightly so as to separate the mold cavity and the exterior surface of the part to make room for the coating. A second approach is to let the hydraulic pressure of the injected IMC open the mold. Here, we present a mathematical model of the process and show application in predicting injection pressures, fill times, and filling patterns. A comparison with experimental results is also presented. Cycle times required for IMC injection methods is also discussed.
    Additional Material: 14 Ill.
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301201
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    A free radical copolymerization model for simulating reactive processing of unsaturated polyester resins (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 684-692 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A free radical copolymerization model is proposed for simulating the reaction rates and conversions of styrene monomer and unsaturated polyester resins during curing. This model is based on film theory in which the rate constants reflect both reaction and diffusion resistances. Differential scanning calorimetry in combination with Fourier transform infrared spectroscopy is used to measure the overall and individual reactivities of reacting species. Model parameters are determined from experimental data. The applicability of this model is demonstrated in a cure simulation.
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    URL: http://dx.doi.org/10.1002/pen.760301108
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    Composites from compounding wood fibers with recycled high density polyethylenePresented at the Third Chemical Congress of North America, Toronto, Ontario, Canada, 1988 (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 693-699 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The development of composites consisting of wood fibers and recycled plastics offers not only an opportunity to utilize an abundant natural resource but also a means to alleviate the serious plastics disposal problem. In this work, aspen fibers are incorporated into recycled high density polyethylene with a co-rotating inter-meshing twin-screw extruder to study processing-property relationships. Tensile, impact, and flexural strengths are measured as functions of fiber concentration. The effects of fiber pretreatment, screw configuration, and compounding temperature on the properties of composites are discussed.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301109
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    Observation of carbon black agglomerate dispersion in simple shear flows (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 701-706 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experiments aimed at studying the mechanisms of agglomerate breakup due to the application of a simple shear flow field were performed in a cone and plate transparent device. Spherical compacts of carbon black (diameters 1-2 mm) in a range of different porosites were used in the experiments. Two distinct breakup mechanisms, denoted as “rupture” and “erosion”, were observed. The critical stress for erosion was found to be smaller than that for rupture. Once erosion starts, it continues for very long times. Rupture occurs shortly after reaching a critical stress and concludes abruptly. For this analysis of rupture, the dimen-sionless group \documentclass{article}\pagestyle{empty}\begin{document}$\alpha {\rm = \{ }\eta {\rm .}\mathop \gamma \limits^{\rm .} {\rm /K'}\phi ^{\rm 4} {\rm \} }$\end{document}, which is the ratio of applied stress to cohesive strength, was found to be a significant parameter for determining the final particle size distribution. The size analysis of fragments produced by shearing pellets for 1 minute showed a lognormal distribution function.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301202
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    Yield behavior of polypropylene filled with CaC03 and Mg(OH)2. I: “Zero” interfacial adhesion (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 707-713 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The composition dependence of tensile yield stress (σyc), and the effects of filler particle shape and surface treatment were investigated for polypropylene (PP) filled with CaCO3 or with Mg(OH)2. Poor adhesion between PP and CaCO3 accounted for a decrease of σyc with increasing σf. In spite of the poor adhesion between PP and Mg(OH)2, σyc either slowly decreased with increasing Vf or remained constant up to Vf = 0.25. Surface treatment of the fillers facilitated better dispersion in PP. On the other hand, σyc was reduced due to the lower thermodynamic work of adhesion (WA). The semiempirical one-parameter equation proposed by Turczanyi, Pukanszky, and Tüdüs (TPT) was considered plausible and was employed in the study of the effects of matrix-filler interaction.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760301203
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    Yield behavior of PP/CaC03 and PP/Mg(OH)2 composites. II: Enhanced interfacial adhesion (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 714-720 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effects of the variation of adhesion strength σA on the tensile yield behavior of particulate filled polypropylene (PP) were investigated. To enhance adhesion of PP toward calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2), maleated PP (MPP) was added to PP in various ratios. σA varied from 10-46 MPa. σA calculated from the Leidner-Woodhams model are in good agreement with SEM micrographs of the composite fracture surfaces. Dependences σyc vs. σA, at constant Vf = 0.18, were investigated and analyzed in terms of existing models. Using the Turczanyi, Pukanszky, Tüdös model (TPT) for the PP/CaCO3 composite, an effective interlayer “thickness” (teff) and the yield stress of the immobilized PP (σyi) were calculated. Both teff and σyi increased with enhancing of the adhesion.
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301301
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    Processing characteristics, structure development, and properties of uni and biaxially stretched poly(ethylene 2,6 naphthalate) (PEN) films (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 721-733 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(ethylene 2,6, naphthalene dicarboxilate), PEN, is very similar to poly(ethylene terephthalate), PET, in its chemical structure and was, therefore, expected to exhibit similar processing characteristics. We, however, observed a few problems during stretching of PEN, the most important of which was necking behavior at 145°C, which is between Tg (117°C) and Tcc (195°C). This is usually observed in PET only when it is stretched close to or below Tg. At temperatures between Tg and Tcc (cold crystallization temperature) PET stretches rather uniformly. The temperature window for film stretching appears to be rather wide, but our results indicate that this is not the case. Films stretched to high stretch ratios become uniform due to propagation and final disappearance of necks as a result of stress hardening. Our attempts at stretching these films at higher temperatures indicated that necking is eliminated, but so is stress induced crystallization, which causes stress hardening (unless high stretching rates are employed). The presence of stress hardening is essential for obtaining high quality, uniform films of these polymers. In addition, at high temperatures thermally activated crystallization which starts dominating the structure development, detrimentally affects the general appearance of the films. In brief, the PEN films we investigated have a narrower processing window than was anticipated based on their thermal behavior alone. At elevated temperatures the films are sensitive to the rate of stretching even more than typical PET processed at comparable conditions. The uniformity of the films depends on the stretch ratio, stretching mode, ratio(s) and rates and temperature. WAXS studies on the films indicate that the macromolecules packed into the low temperature crystal modification. In addition, WAXS pole figure studies suggest that naphthalene planes preferentially orient parallel to the film surface during biaxial stretching. The biaxially stretched films were observed to exhibit a bimodal chain orientation as evidenced by pole figure analysis of the (010) planes.
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    URL: http://dx.doi.org/10.1002/pen.760301205
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    Miscibility studies in blends of polybenzimidazoles and poly(4-vinyl pyridine) (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 798-801 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI) is shown to be miscible with poly(4-vinyl pyridine) over the entire composition range. Experiments were performed with commercial PBI as well as a lower molecular weight material synthesized by us. Blend miscibility is evidenced by single glass transition temperature intermediate between the pure polymers. Hydrogen bonding between the components was detected by infrared spectroscopy.
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    URL: http://dx.doi.org/10.1002/pen.760301307
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    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301501
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  • 196
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    Crystallization and structure-mechanical property relations in poly(aryl ether ether ketone) [PEEK] (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 860-869 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the development of advanced composite materials, the mechanical behavior of the matrix is of critical importance. The next generation of composite materials will be based on high modulus tough matrices, of which poly(aryl ether ether ketone) [hereinafter, referred to as PEEK] is one of the first crystalline thermoplastics to receive serious attention. As in all crystalline polymers, the matrix is itself a composite material whose properties depend significantly on the crystalline morphology developed during processing. In this contribution, the current understanding of crystallization in PEEK and its influence on mechanical properties is reviewed. Problems yet to be resolved are highlighted.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301409
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  • 197
    Electronic Resource
    Electronic Resource
    Numerical prediction of three-dimensional fiber orientation in Hele-Shaw flows (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 848-859 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A numerical technique is developed to determine the three-dimensional fiber orientation in complex flows. The fiber orientation state is specified in terms of orientation tensors, which are used in several constitutive models. This method is applied to quasi-steady state Hele-Shaw flows in order to predict the flow-induced fiber orientation during injection molding at zero volume fraction limit. At the inlet, a number of fibers are introduced at a specified rate into the flow and each fiber location is traced during the mold filling. Along these determined paths, the independent components of fourth order orientation tensors are solved, describing the orientation state. The numerical grid generation technique, which is suitable for complex mold shapes, is employed for the flow solution. Orientation ellipsoids are calculated from the second order tensors and are used to present the fiber orientation results. The numerical solutions are obtained for channel and converging flows. Planar, longitudinal, and transverse orientation results are generated from the orthogonal projections of the orientation ellipsoids.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301408
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  • 198
    Electronic Resource
    Electronic Resource
    Optimization of injection molding design. Part II: Molding conditions optimization (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 883-892 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The quality of an injection molded part is affected by many factors. These include geometric parameters associated with the mold design and the cooling system design as well as process parameters such as the molding conditions during the filling phase. In the companion paper, the problem of automatic optimization of gate location was addressed. In this paper, a methodology for molding condition optimization is presented. The optimization problem can be broken into three parts. An approximate feasible molding space (AFMS) is first determined to constrain the search space for the optimization algorithm. Quality is quantified as a function of flow simulation outputs and constitutes the objective function that must be minimized. The resulting optimization is solved by iterative search in the constrained space based on numerical optimization algorithms. The proposed methodology is not dependent on any particular simulation package and may be applied for any thermoplastic material and any complex mold geometry.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301503
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  • 199
    Electronic Resource
    Electronic Resource
    Optimization of injection molding design. Part I: Gate location optimization (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 873-882 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The placement of a gate in an injection mold is one of the most important variables of the total mold design. The quality of the molded part is greatly affected by the gate location, because it influences the manner in which the plastic flows into the mold cavity. Some defects, such as weldline and overpack, can be effectively controlled only by the gate location. Therefore, the product quality can be greatly improved by determining the optimum gate location. In this paper, we develop a general methodology for gate location optimization. We first quantify quality in terms of flow simulation outputs. We can thus assess detrimental effects such as warpage and dimensional instability as a function of the independent variable, which is in this case the gate location. Next we develop methods to search for the optimum gate location. The search method introduced in this paper is a method that combines a deterministic hill climbing search with a stochastic annealing search method. The method is appropriately called simulated annealing and hill climbing (SANHIL). The criteria used for evaluation during the search process are a function of the flow simulation outputs. We demonstrate the success of the method for a complex industrial mold. The approach is applicable to any complex mold geometry and any plastic.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301502
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  • 200
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    Microspheres and microcapsules, a survey of manufacturing techniques: Part III: Solvent evaporation (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 915-924 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A methodological survey of microsphere formation and microencapsulation techniques based on solvent extraction/evaporation techniques is presented. Thus, basic features of solvent extraction and solvent evaporation processes, including droplet formation, droplet/particle stabilization, and solvent removal, are outlined. Preparation of a wide range of microspherical and microcapsular products based on biodegradable polyesters, polysaccharides, and nonbiodegradable polymers are discussed. Dependence of microcapsule characteristics on manufacturing parameters, as well as performance evaluation of microspherical and microcapsular products, are also briefly covered.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301506
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