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  • 1
    Digitale Medien
    Digitale Medien
    Polymer blend containing a thermotropic polyester with long flexible spacer in the main chain (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 22-29 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polymer blends of nylon 66 and thermotropic polyester with long flexible spacers in the main chains were prepared by melt mixing. The samples were made as single filaments by passing the polymer blend through a small and round die of a capillary rheometer. Mechanical properties of blends showed that the modulus and strength of nylon 66 could be improved without reduction of extensibility. The morphology of fractured surfaces was observed by a scanning electron microscope (SEM). It showed that the microfibrillar structure of a thermotropic polyester was formed by extensional flow while the spherical and ellipsoidal particles in the nylon 66 (matrix polymer) were produced by shear flow. The polyester particles were occasionally covered with adhering matrix polymer because of good adhesion between these two polymers. They were highly elongated by tensile stress without loss of elongational characteristics of blends. This fact was explained by very good adhesion between the two phases.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300105
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  • 2
    Digitale Medien
    Digitale Medien
    Gelation in thermosets formed by chain addition polymerization (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 83-89 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The physical behavior of the diglycidyl ether of bisphenol A, cured with different concentrations of 2-ethyl-4-methylimidazole, was examined with dynamic mechanical and dielectric analyses, differential scanning calorimetry, and solvent extraction studies, ‘The network formation process was shown to depend strongly on the imidazole concentration’. At high imidazole concentrations, the gel point was characterized by a decrease in sol fraction, the crossover of the dynamic moduli and a rapid increase in viscosity. At low imidazole concentrations, the viscosity remained low until the sol fraction approached zero. For this system, the gel point, which occurred prior to the dynamic moduli crossover, was characterized by comparing the thermal properties of the network with the viscosity and dielectric behavior of the resin system during cure.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300204
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  • 3
    Digitale Medien
    Digitale Medien
    Calculated stresses in dual coated optical fibers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 108-117 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: We examine several practically important problems, related to the mechanical behavior of dual coated optical fibers: low temperature microbending, evaluation of spring constant due to coating layers, strength of the end portions of fibers clamped in terminal fixtures, and prediction of stresses caused by the misalignment of the openings in the frame and in the terminal fixture. The developed formulas are simple, easy-to-use, and clearly indicate the role of the major factors affecting the mechanical behavior of the fibers. The obtained results can be of help in physical design of dual coated fibers and optical interconnections.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300207
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  • 4
    Digitale Medien
    Digitale Medien
    Energy absorption characteristics of polymeric foams used as cushioning materials (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 129-133 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The “Efficiency of Energy Absorption” (or “Efficiency”) and “Ideality” parameters were evaluated for several plastic foams and were found to be very useful in choosing an appropriate cushion for the protection of a specific product. The maxima in these parameters were found to be in the same range of stresses, when derived from dynamic measurements or from predicted stress-strain curves based on previously proposed “Reference” and “Modified Boltzman Superposition” Models. For the rate independent foams the maxima in these parameters do not change with strain rate and can therefore be derived from slow, constant rate (“static”) experiments. For rate dependent foams however, the maxima from “static” measurements were found to be in a lower range of stresses than those derived from dynamic ones. As a result, slow rate compressive measurements do not predict well the behavior of the foams during impact and the use of the “Reference” and “Modified Boltzman Superposition” Models is required for good predictions. It was found that the suffer PS and PE foams attain maximum Efficiency and Ideality at higher stresses than the more flexible PUR foams.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300210
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  • 5
    Digitale Medien
    Digitale Medien
    Transition mechanism from elastic deformation to plastic flow in poly(methyl methacrylate) (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 96-107 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Sudden changes of compressive strain-rate on glassy poly(methyl methacrylate) lead to the conclusion that the post-yield state under a constant stress is a state of steady flow in the polymer. Non-linearity between the stress divided by temperature and the logarithm of strain rate for this steady plastic flow can successfully be analyzed using the Eyring equation with structural factors variable depending on stress and temperature. This analysis gives a unique functional relationship between the activation entropy and the activation enthalpy, which agrees fairly well with that for the melt derived from the WLF equation. This agreement provides a direct evidence verifying structural change of the glass into liquid-like structure and enables us to recognize the conformational arrangement as an essential structural parameter controlling molecular mobility. Another experimental relation between the Eyring factors - the activation volume and the activation enthalpy - permits us to estimate the magnitude of an elementary volume for the molecular movement in the melt as a function of temperature. Moreover, the experimental finding of the steady flow in the glassy polymer motivated us to propose a transition mechanism from elastic deformation to plastic flow in which the internal viscosity or the activation volume is introduced as a single parameter representing the transient state of the structure.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300206
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  • 6
    Digitale Medien
    Digitale Medien
    Experimental modeling of solvent-casting thin polymer films (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 118-123 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An apparatus was designed and assembled to study the solvent removal from solution-cast thin polymer films. The computer interfacing of a thermogravimetric analyzer, spectrophotometer, electronic flowmeters, and control valves for the apparatus enabled the preprogramming of the carrier gas velocity, carrier gas solvent content, and temperature profiles to simulate the environment experienced in large parallel flow industrial driers. The apparatus has also been designed and operated to enable the visual observation of the drying film with an optical microscope. Initial experimental studies conducted with the apparatus involved the effect of temperature on solvent removal. The results indicate that high dryer gas temperatures can apparently cause skinning of the film surface resulting in slower solvent removal rates. The skin formation can be suppressed by higher solvent concentration in the carrier gas. The visual observations revealed the formation of standing waves in the film surface during drying at high gas velocities (〉2OO cm/min). The wave formation at least partially overcomes the effect of skinning by increasing the surface area of the film, and may be the manifestation of flow instabilities involving circulation within the film.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300208
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  • 7
    Digitale Medien
    Digitale Medien
    Ultrasonic processing of thermoplastic foam (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 147-152 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Ultrasonically induced bubble formation for the production of thermoplastic foam was investigated experimentally and theoretically as a basic study. A general purpose polystyrene and blends of low density polyethylene and polyethylene wax were saturated with nitrogen gas under various pressures and the ultrasonic excitation was applied to the polymer system upon release of gas pressure. The ultrasonic nucleation of bubbles in the polymer matrix was modeled by utilizing the classical nucleation theory. The negative pressure generated by the ultrasonic excitation was considered as the environmental pressure at the moment of nucleation. The experimental results showed that the heterogeneous nucleation must be used for ultrasonic foaming of the viscous fluid and the homogeneous nucleation for the low viscosity fluid. The theoretical analysis also indicated that the ultrasonic nucleation can be applied to the production of thermoplastic foam if the ultrasonic excitation generates large enough negative pressure.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300304
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  • 8
    Digitale Medien
    Digitale Medien
    Rheology-morphology relationships in nylon 6/liquid-crystalline polymer blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 7-12 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Extrusion measurements have been carried out on blends of nylon 6 and a liquid-crystalline copolyesteramide (LCP). The flow curves at low temperature show a behavior similar to that of pure LCP with a rapid rise of the viscosity at low shear rates. At high shear rates the viscosity is lower than that for each of the two components. This minimum has been attributed to the lack of interactions between the two phases and to the formation of fibrils of the LCP phase. The SEM analysis shows, indeed, that fibrils of the LCP phase are produced in the convergent flow at the inlet of the capillary at high shear rates. These fibrils are lost during the flow in the long capillary.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300103
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  • 9
    Digitale Medien
    Digitale Medien
    Rheological properties of a liquid crystalline copolyester (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 124-128 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Rheological studies of an experimental liquid crystalline (LC) copolyester were carried out using a capillary rheometer and a cone and plate rheometer. Rheological characteristics of the polymer in the nematic state were observed. The nematic melt was found to be pseudoplastic and the degree of pseudoplasticity varied with shear rate. Melt viscosity was found to decrease with shear rate. Negative die swelling was observed at the exit of the capillary rheometer at temperatures marginally above the solid-nematic transition temperature of the polymer and was also found to be a function of shear rate. The dynamic mechanical properties of the polymer were studied as a function of temperature. The activation energies of flow and of dynamic mechanical deformation were calculated.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300209
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  • 10
    Digitale Medien
    Digitale Medien
    Enhancing adhesion by ion beam-induced atomic mixing at the interface between copper film and polyimide substrate (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 137-141 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Ion beam mixing was used to improve the adhesion between deposited Cu film (400 Å) and polyimide (PI) substrate. Ar+ ion with the energy levels between 180 and 200 keV, and the dose between 1014 to 4 × 1016 ions/cm2 were used. The surface analyses were carried out by Rutherford Backscattering Spectroscopy (SEM). RBS analysis, using 2 MeV He+ ions, showed mixing of Cu and FI and the mixing depended on the Ar+ energy and dose. The X-ray study showed a very broad halo for deposited Cu film but the (111) peak appeared after the Ar+ implantation and the peak increased with Ar+ ion dose. Optical micrographs showed that Cu film formed circular bubbles after many thermal cycles when adhesion was poor and fracture cracks when adhesion was good.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300302
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  • 11
    Digitale Medien
    Digitale Medien
    Measures of mixing in laminar flow (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 153-161 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The general domain in which this work resides is that of mixing in creeping flows. Mixing, in this context, refers to the stretch of an interfacial line, or area in a strain field. The advancement of mixing technology is applied to the design of continuous mixers used in polymer processing. The geometric designs included single screw extruders, static motionless mixers, and co- and counter-rotating twin screw extruders. The co-rotating twin screw extruder was chosen to be studied in detail since it enjoys wide applications and, for which, little understanding of the contribution to mixing in the different screw geometries is known. In order to evaluate the rate of mixing for the non-uniform strain history flows, the method for measuring mixing had to be reexamined and broadened. An automated method has been developed which incorporates a digital camera and a computer to analyze the cross-sections of interest. Two measures of mixing - the correlation function and the distribution function - are developed to describe mixing in these regimes. These measures are applied successfully to the mixer geometries revealing subtle differences as to the nature of mixing in each.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300305
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  • 12
    Digitale Medien
    Digitale Medien
    Rotary injection reaction injection molding (RI-RIM). Part II: Interfacial segregation of release systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 175-186 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This paper describes the shear imposed interfacial segregation of release systems for the facilitated attenuation of polyurethane (PU) adhesion to metal coun-terfaces using a RI-RIM system. It is shown that the migration rate of the dispersed release additives due to a shear imposed stress in the resin fluid is much greater than that arising from Fickian diffusion, thereby removing a vital constraint from conventional practice. The novel rotary injection RIM system is presented to simulate the on-line injection and shear induced interfacial segregation in model PU/abherent systems. A wide range of recipes comprising single (liquids or solids) and multicomponent (liquid-liquid and solid-liquid) release materials were injected into the polymerizing resin mixture to provide cohesively weak and friable “particle” boundary layer assemblies at the PU/metal interface. An instrumented Blister Test was employed to evaluate the quality of the molded interfaces in terms of adhesion and the concentration distribution of the injected species in the final cured moldings was determined through high pressure liquid chromatography (HPLC). A comparison of the results on the shear modified and the compounded interfaces confirm an accentuated lateral migration of the additives to the interface resulting in an appreciable diminution in the adhesion of the system. Finally, transport models are suggested to account for the observed augmented transport.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300307
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  • 13
    Digitale Medien
    Digitale Medien
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300401
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  • 14
    Digitale Medien
    Digitale Medien
    Mechanical properties and behavior of open cell foams used as cushioning materialsFirst part appeared in Polymer Engineering & science, Jan. 1990, 30, 129. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 197-201 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: It is the purpose of the present publication to show that most of the phenomenological viscoelastic theories developed for bulk polymers can be readily adapted to plastic foams in order to evaluate their mechanical properties. In addition it will be demonstrated how the mechanical properties of open cell plastic foams can be predicted from a few simple compression and relaxation experiments.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300402
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  • 15
    Digitale Medien
    Digitale Medien
    The plane-strain essential work of fracture as a measure of the fracture toughness of ductile polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 211-218 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: We have extended the essential work of fracture technique to allow for the determination of the plane-strain essential work of fracture. The new technique is to measure the specific work of fracture as a function of ligament length in deeply double edge notched samples. This type of data is then experimentally corrected to remove the plastic work of fracture and leave only the essential work of fracture as a function of ligament length. By extrapolating the essential work of fracture to zero-ligament length, we claim to be measuring the plane-strain essential work of fracture. This new technique was applied to two rubber toughened nylons and to a series of polyethylenes. The plane-strain essential work of fracture was found to be independent of thickness. Where comparison can be made to J-integral testing, the plane-strain essential work of fracture was similar to the critical J-integral, JIc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300404
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  • 16
    Digitale Medien
    Digitale Medien
    Liquid crystal polymer-carbon fiber composites. Molecular orientation (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 228-234 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The objective of this work has been to study composite systems in which carbon fibers are dispersed in a liquid crystal polymer matrix. The fundamental point of interest here has been the interfacial response that fiber surfaces can potentially induce in self-ordering polymers. The matrix material used was a thermotropic liquid crystal polyester synthesized in our laboratory from the monomers p-acetoxybenzoic acid, diacetoxyhydroquinone, and pimelic acid. The aromatic-aliphatic polymer was characterized by NMR as a chemically disordered polymer of the three structural units which exhibits a nematic phase at temperatures above 150°C. Breadline proton NMR above the solid to liquid crystal transition was used to measure the rate of magnetic alignment of molecules in the matrix and polarized optical microscopy was used to analyze interfacial zones in composite samples. Fiber surfaces were found to influence the orientation and orientational dynamics of a liquid crystal polymer matrix. This was revealed by enhanced rates of magnetic orientation in the polymer melt when carbon fibers are dispersed in the medium. Fiber surfaces were also found to stabilize nematic ordering of the polymer as the melt was heated towards complete isotropization. The phenomena discovered here may originate in the development of zones around fibers with a common molecular orientation anchored by the carbon surface.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300406
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  • 17
    Digitale Medien
    Digitale Medien
    Impact fracture toughness tests on polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 241-248 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A series of impact tests are described in which the plane strain fracture toughness, Kc1, of five different polymers is measured using a three point bend specimen at striker speeds up to 5m/s. At low speeds Kc1 is determined using the maximum load and a static analysis, but at speeds greater than 1 m/s the dynamic effects render the load signal unusable. For the higher speeds the fracture is timed using contact and crack propagation gages and the analysis is performed using the striker displacement at fracture. A dynamic analysis is used to convert this measurement to the true specimen displacement and Kc1 is determined from this. The apparent downward trends in the Kc1 results obtained, especially at speeds above 3m/s, are discussed.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300408
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  • 18
    Digitale Medien
    Digitale Medien
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300501
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  • 19
    Digitale Medien
    Digitale Medien
    Temperature measurements of polymer melts in the heating barrel during injection molding. Part 3: Effects of screw geometry (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 385-393 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: We have developed a new method to measure the true temperature of the polymer melt and its three-dimensional distribution of a shot stored in the reservoir during injection. By means of this method, it is demonstrated that the temperature distribution of the polymer melt stored in the reservoir is strongly dependent on the setup molding conditions, the polymer investigated, and the geometry of the screw used. Further, it is noted qualitatively that there are two major effects of screw geometry on the temperature distribution of polymer melts. One, which governs strongly the temperature in the high temperature zone, is shear heat generated within the polymer itself in the metering zone of the screw during the transporting process. The second is the ability to preheat and plasticate the polymer in the compression zone, which is indispensable for uniform plastication.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300702
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  • 20
    Digitale Medien
    Digitale Medien
    The breaking strength of perfect polymer fibersThis paper was presented at the American Chemical Society Meeting in Dallas Texas, April 1989, in the Polymer Science Award Symposium Honoring W. R. Krigbaum. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 437-443 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The breaking strength, strain at break, and work to rupture of perfect fibers prepared with polymers of finite molecular weight are calculated by treating the perfect fiber as a stressed crystal undergoing a crystal-melt phase transition. In this view, a tensile load destabilizes the crystal and depresses its melting point. When the load is sufficient to lower the melting temperature to the ambient condition the fiber melts - i.e., fails. The theoretical equations (extremely simple) are applied to several common polymer fibers. The maximum tensile strength of polyethylene, for example, is calculated to be 7 to 9 GPa, in good agreement with current experimental results.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300802
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  • 21
    Digitale Medien
    Digitale Medien
    Relationship between electron sensitivity and chemical structures of polymers as electron beam resist. VII: Electron sensitivity of vinyl polymers containing pendant 1,3-dioxolan groups (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 449-452 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Vinyl polymers containing pendant acetal groups were synthesized using (2,2-dimethyl-l,3-dioxolan-4-yl)methyl acrylate (DMA) and (2,2-dimethyl-l,3-dioxo-lan-4-yl)methyl methacrylate (DMM), and were evaluated as negative electron beam (EB) resists. It was found that the EB sensitivity of polymers containing acetal groups in the side chain was higher than that of polymers containing acetal groups in the main chain. A high sensitivity of 3.6 × 10-8 C/cm2 was observed. Copolymers of DMA or DMM with styrene were also synthesized in order to improve the durability for dry etching process. It was found that the copolymers had an excellent dry etching durability and were adaptable to EB lithography.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300804
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  • 22
    Digitale Medien
    Digitale Medien
    Thermal behavior of transparent poly(etheretherketone)(PEEK) film (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 453-458 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The thermal behavior of poly(etheretherketone)(PEEK) film heated in an open differential scanning calorimetry (DSC) pan at 20°C/min is distorted by relaxation of the strained film. PEEK film in a closed pan or quenched PEEK in open or closed pans shows a glass-transition temperature (Tg) around 144°C, cold crystallization (∼22 J/g) at 177°C, melt-temperature (Tm) peaking at 335-340°C, with an enthalpy of fusion of 32-34 J/g, and recrystallization on cooling at 285°C, with a crystallization exotherm of about 40 J/g. The enthalpy of fusion decreases with increasing heating rate from 2-100°C/min and approaches the enthalpy of cold crystallization. With increasing heating rate, further crystallization of PEEK during the DSC scan is suppressed. With increasing cooling rate, PEEK melt crystallizes at larger supercoolings to a lesser extent. Crystallization on cooling the melt was more complete than cold crystallization and annealing on heating.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300805
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  • 23
    Digitale Medien
    Digitale Medien
    Electrical and dielectric properties of segregated carbon black-polyethylene systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 459-468 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The electrical and dielectric properties of compression-molded segregated polyethylene-carbon black mixtures are described in the frequency range between 10 and 8000 kHz as a function of frequency, temperature, and carbon black loading. The segregated systems investigated exhibit insulator-conductor transitions in the range 0.25-0.65% (volume/volume) carbon black. The dielectric constant and the dissipation factor of the conductive samples are relatively very high in the frequency range studied. The dielectric constant increased sharply with the carbon black concentration, and then increased moderately beyond the insulator-conductor transition. The dissipation factor-concentration curves for different carbon blacks show maximum values in the vicinity of the critical concentration values. The dielectric properties of these systems are discussed in terms of interfacial Maxwell-Wagner polarization effects.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300806
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  • 24
    Digitale Medien
    Digitale Medien
    Heat capacity of polypropylene composite at high pressure and temperature (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 476-479 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The heat capacities of isotactic polypropylene and its composite with glass fiber have been measured at high pressure, up to 7 MPa, in the melt state by high pressure differential scanning calorimetry (HPDSC). The values also have been calculated from the data of specific volume (V) measured by dilatometry and thermal conductivity (κ) and thermal diffusivity (α) measured by a compensating hot wire method. The values of the heat capacity measured from HPDSC are consistent with those from the calculation method. The heat capacities of molten polypropylene and its composite increase linearly with temperature at a constant pressure and decrease with pressure at a constant temperature. It was found that the heat capacity of polypropylene is insensitive to molecular weight. The heat capacities of molten polypropylene composites are found to be predicted by an additive rule from the weight fractions of heat capacities of polypropylene and glass fiber.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300808
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  • 25
    Digitale Medien
    Digitale Medien
    Measurement and correlation of mutual diffusion coefficients for styrene-butadiene rubber (SBR)-ethylbenzene systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 480-484 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The mutual diffusion coefficients for styrene-butadiene rubber (SBR)-ethylbenzene systems were measured using a sorption apparatus with a quartz spring at 100 and 130°C for mass fractions of ethylbenzene ranging from 0 to 0.17. The mutual diffusion coefficients were correlated with good agreement by the free-volume theory.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300809
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  • 26
    Digitale Medien
    Digitale Medien
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300901
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  • 27
    Digitale Medien
    Digitale Medien
    Studies on the effect of electrode type and substrate temperature on plasma polymerization of two model compounds: Acrylonitrile and hexamethyldisiloxane (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 485-489 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polymers were prepared from saturated (HMDS) and unsaturated (AN) monomers in a radio frequency discharge (plasma). The effect of selected parameters such as electrode type (such as Cu, Zn, Ni, Al), reactor type, and substrate temperature (other parameters constant) on chemical structure and the rate of polymer deposition was examined by Fourier transform infrared (FTIR) spectroscopy. Differences in the nature of electrodes and reactor types were found to yield similar plasma products with similar rates of deposition for two monomers. In the tubular reactor used, deposition rates were observed to decrease with increasing substrate temperatures showing different dependencies on temperature for the monomers tested.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300810
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  • 28
    Digitale Medien
    Digitale Medien
    Dielectric and magnetic properties of random and segregated ferrite polystyrene composites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 469-475 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The dielectric and magnetic properties of polystyrene composites containing barium or nickel-zinc ferrites were studied as function of the ferrite concentration and field frequency. The composites were prepared by methods yielding a random distribution of the ferrite particles or segregated structures. Barium ferrite-poly-styrene composites exhibited a typical insulator behavior, and only above 60% ferrite were high values of the dielectric properties noted at the lower frequencies, decreasing gradually with frequency to the low values typical of the higher frequencies. The mode of barium ferrite particle distribution did not affect the dielectric properties. The nickel-zinc ferrite systems demonstrated a conductor type behavior. An apparent insulator-conductor transition was observed, having lower values for segregated than for random distributions. The magnetic permability of barium ferrite-polystyrene composites above 10% ferrite increases with the ferrite concentration, whereas the magnetic dissipation factor steeply increases with concentration above 40% ferrite.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300807
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  • 29
    Digitale Medien
    Digitale Medien
    Morphology and properties control on rubber-epoxy alloy systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 493-510 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Morphology and properties of polymer alloys can be controlled by thermody-namlcally reversible (structure freeze-in) or irreversible (structure lock-in) processes by simultaneously manipulating miscibility, mechanisms of phase separation, glass transition temperature (structural relaxation), and cure kinetics of polymer systems. Using phase diagrams consisting of binodal and spinodal curves, the morphology of epoxy/CTBN (carboxyl-terminated butadiene acryloni-trile copolymer) systems can be controlled by the mechanism of nucleation and growth or by spinodal decomposition via simultaneously manipulating the kinetic processes of phase separation and curing reactions. We have found that the particle size of the rubber reinforcement in epoxies is affected by the mechanisms of phase separation. Phase separation by nucleation and growth gives larger rubber particles than the corresponding phase separation by spinodal decomposition. This contrast in the morphology development is the consequence of controlling phase separation through chemorheological behavior. Medication of the phase separation kinetics in epoxy/CTBN systems was extremely effective at altering both morphology and properties of these alloys. This technique offers a means to shift the glass transition temperature of the rubber-rich phase drastically without reducing the glass transition temperature of the epoxy-rich phase significantly. Such control over morphology is the key to ultimately controlling material properties. This morphology manipulation allows us to tailor the mechanical properties of alloy systems.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300902
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  • 30
    Digitale Medien
    Digitale Medien
    Morphology of plastic/rubber blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 511-518 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Blends of polypropylene (PP) and ethylene-propylene rubber (EPR) and blends of polystyrene (PS) and styrene-butadiene rubber (SBR) were prepared in a laboratory-scale internal mixer at various blend compositions and rotor rates. Blend morphology was studied by means of electron microscopy. For each blend pair under the given processing conditions, the phase inversion process occurred progressively with respect to the variation in blend composition; it is within this composition range of phase inversion that dual-phase continuity was observed. In addition, Characteristic torque values of blends were found to deviate negatively from a linear additivity rule; the composition range of maximum deviation from linear additivity corresponded approximately to the composition range where dual-phase continuity was observed. Sperling's predictive scheme was found to yield acceptable (although not completely satisfactory) estimates for compositions of dual-phase continuity in the present systems. It was also observed that partial cross-linking of SBR during the mechanical blending process, as suggested by the appearance of a cure peak in the torque curve and supported by infrared spectroscopic evidence, resulted in morphological features drastically different from those of the uncured blends.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300903
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  • 31
    Digitale Medien
    Digitale Medien
    Characterization and processing of blends of polyethylene terephthalate with several liquid crystalline polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 519-526 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Blends of an engineering thermoplastic, poly(ethylene terephthalate) (PET), and two liquid crystalline polymers (LCPs) viz., copolyesters of PET and parahydrox-ybenzoic acid (PHB) in 40/60 mole percent (LCP60) and in 20/80 mole percent (LCP80) were prepared. A blend of LCP60 and LCP80 in 50/50 weight percent (LCP60-80) was blended with PET. Both flat films and rods were extruded and their properties examined. The morphology of the films investigated using Scanning Electron Microscopy (SEM) revealed that the LCP phase remained as dispersed droplets in the PET matrix. In spite of the lack of fibrillation in these films, the mechanical properties were enhanced to some extent with a maximum at 10 weight percent of the LCP phase. However, in the case of the rods thin fibrils of the LCP phase of the order of 1 μm in diameter were observed provided the composition of the LCP was 20 weight percent or greater. This success In achieving fibrillation is through to be due to the extensional flow fields present at the entrance of the capillary die and the fact that a short L/D ratio die was used. Differential Scanning Calorimetry (DSC) thermograms of the extruded films indicated that the LCP phase may act as a nucleating agent for the crystallization of PET. Rheology of the blends revealed that the complex viscosity of the blends is not much different from that of pure PET. This is attributed to the partial miscibility of the two components. Based on the DSC results and residence times in the extruder, it is concluded that no significant transesterification reactions appear to have: taken place in the blends. The rheology is studied further with respect to the cooling behavior of the pure components and factors important to the fibrillation of the LCP phase and the formation of in-situ reinforced composites are discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760300904
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  • 32
    Digitale Medien
    Digitale Medien
    Corrections (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 618-618 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301009
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  • 33
    Digitale Medien
    Digitale Medien
    Thermomechanical properties of 1C molding compoundsPresented at the Annual Meeting of American Institute of Chemical Engineers in San Francisco, California on November 6, 1989. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 609-617 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Eight commercial semiconductor grade epoxy compounds that are used to encapsulate 1C (integrated circuit) devices have been evaluated for their ability to minimize the development of thermal stresses which can cause failure during device temperature cycling. Thermal expansion, dynamic modulus and adhesion studies are used to describe the mechanical interaction between the plastic package and the silicon device it surrounds. A “figure of merit” is defined for the development of stress on the 1C device as it is cooled after the packaging process. The stress is shown to be proportional to the product of three terms: (αp-αs) Ep (Tanch-T) where αp and αs are the expansion coefficients for the plastic and silicon, respectively, Ep is the modulus of the epoxy and Tanch is the temperature at which the epoxy becomes anchored to the silicon device during transfer molding. In addition, the importance of good adhesion between the epoxy encapsulant and the silicon device to prevent package cracking has been demonstrated by finite element analysis and a novel adhesion test.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301008
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  • 34
    Digitale Medien
    Digitale Medien
    Grafting of a liquid crystal polymer on carbon fibers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 603-608 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Covalent grafting of mesogenic chains on carbon fiber surfaces was attempted as part of a study on composite materials containing liquid crystal polymer matrices. Grafting in these composite systems is viewed not only as a mechanism to achieve interfacial bonding but also as an approach to modify the interphase physical structure. The synthetic approach to grafting involved the in-situ polymerization of monomers in the presence of functionalized fibers in order to grow chains covalently attached to the fibers. The chemical mechanism may be viewed as the “transesterification of car boxy lated fibers” with acetylated monomers. The monomers used were pimelic acid, p-acetoxybenzoic acid and diacetoxy hydroquinone which are known to yield upon condensation a chemically aperiodic nematic polymer. Evidence for grafting was obtained from X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis on fibers retrieved from composite samples. Interestingly, SEM micrographs of fractured composite specimens containing the mesogen-grafted fibers reveal excellent wetting and interfacial bonding of a liquid crystalline matrix on the carbon surfaces. Based on theoretical considerations for end-adsorbed macromolecules and the nematogenic nature of the grafted chains we infer that dense layers of adsorbed polymer may form at the interfaces studied. From a materials point of view the in situ growth of liquid crystal polymer chains on fibers may offer mechanisms to control composite properties through both bonding and molecular orientation in interfacial regions.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301007
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  • 35
    Digitale Medien
    Digitale Medien
    Chain structure, phase morphology, and toughness relationships in polymers and blendsPresented at the Asilomar Conference on Polymeric Materials, Monterey, California, January 30-February 2, 1990, and 32nd Microsymposium on Macromolecules “Polymer Blends,” Prague, Czechoslovakia, July 17-20, 1989. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 753-761 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: We present chain structure, phase morphology, and toughness relationships in thermoplastic polymers and polymer/rubber blends. In neat polymers, molecular aspects of craze/yield behavior are controlled by two chain parameters: entanglement density νe and characteristic ratio C∞. The crazing stress is proportional to νe1/2, and the yield stress is proportional to C∞. The dispersed rubber toughens a polymer/rubber blend mainly by promoting energy dissipation of the matrix. The toughening efficiency correlates with the rubber phase morphology and the chain structure of the matrix.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301302
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  • 36
    Digitale Medien
    Digitale Medien
    Isothermal volume relaxation in aged polycarbonate measured by positron annihilation lifetime spectroscopy (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 762-768 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The positron annihilation lifetime spectroscopy (PALS) technique is used to measure volume relaxation in physically aged glassy polycarbonate. The relaxation times and activation energy calculated for the isothermal relaxations in the aged polycarbonate are greater than those parameters calculated for unaged polycarbonate. The activation energy of 8.2 kcal/mol in the aged polycarbonate is used to identify the phenyl group motion or the cooperative carbonate-phenyl interaction as the molecular features responsible for the thermally induced open volume relaxations. It is postulated that the open volume relaxation kinetics as measured by PALS can be used as a nondestructive indication of property differences between aged and unaged polycarbonate.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301303
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  • 37
    Digitale Medien
    Digitale Medien
    Crystallization of isotactic (D,L) poly(propylene oxide) in the presence of fine-particle silica. I: Radial growth rates of spherulites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 769-775 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effect of added silica on the spherulite radial growth rates of isotactic poly(propylene oxide) (i-PPrO) has been investigated by optical photomicroscopy. Two different i-PPrO samples were used of different molecular weights and isotacticity, 87 and 100% as determined by 13C NMR. The addition of fine particle silica, an effective nucleating agent, depresses the spherulite growth rates throughout the entire temperature range, but the effect is more dramatic for the i-PPrO of lower isotacticity. For a given sample, the retardation increases as the quantity of filler increases. The growth rate-temperature behavior is analyzed in terms of the classical Hoffman-Lauritzen equation, modified to take into account the polymer-filler interaction.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301304
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  • 38
    Digitale Medien
    Digitale Medien
    Structural heterogeneity in epoxies (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 835-840 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effects of different cure procedures on the structure and properties of epoxy samples made from diglycidyl ether of bisphenol A (DGEBA) and mixtures of two linear aliphatic diamines were studied. The elastic modulus, fracture toughness, impact resistance, and glass transition temperature were determined for various cure schemes. The morphologies of the cured resins were characterized with small angle X-ray scattering. The results show that samples with the same average morphology (molecular network structure) have similar elastic moduli and glass transition temperatures. If some heterogeneity is introduced in the molecular network structure without changing the average structure, however, the experiments indicate that the toughness can be increased without significantly sacrificing other properties.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301406
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  • 39
    Digitale Medien
    Digitale Medien
    Effect of dispersion of particles on viscoelasticity of CaCo3-filled polypropylene melts (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 841-847 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Viscoelastic properties of polypropylene melts filled with small (0.15 μm) and large (4.0 μm) CaCO3 particles have been measured. The effects of particle size, loading, and rheological history on the dispersion of particles have been investigated. The dispersion of particles was found to decisively influence the viscoelastic properties of these filled polymers. The systems filled with large particles exhibit a relatively stable viscoelastic behavior. The small particle-filled polymers with low loading are stable similarly to the large particle-filled system. For the system filled with 30 wt% small particles, there appears a “second plateau” in the storage modulus G′ curve in low frequency region and the height of the second plateau depends strongly on the rheological history. The results are interpreted in terms of the formation of an internal structure of particles. It was found that the internal structure of particles is broken up by a steady shear flow and the dispersion of particles is changed.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301407
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  • 40
    Digitale Medien
    Digitale Medien
    Physical properties of perfluoropolyethers: Dependence on composition and molecular weight (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 829-834 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Three copolymeric perfluoroethers with the structure CF3[(OCF2CF2)p(OCF2)q] OCF3, having different p/q ratios, have been fractionated. The fractions obtained have been characterized by Gel Permeation Chromatography and 19F-NMR. The viscosity η the specific volume v and the glass transition temperature, Tg have been measured by standard techniques for all the above samples as well as for some other perfluorinated polyethers.The temperature dependence of viscosity of the unfractionated samples is described by the W.L.F. equation. The values of fg (fractional free-volume at Tg) and of af (free-volume expansion coefficient) are independent of composition, for p/q ratios from 0.53 to 1.15. The critical molecular weight, Mc, is of the order of 8-9,000. From the molecular weight dependence of specific volume, the contribution to the molar volume of the in-chain CF2 group and the excess molar free volume of the chain ends have been determined. The limiting value of Tg for an infinite molecular weight polymer was found to depend linearly on the compositional ratio O/C and the extrapolated values for polytetrafluoroethylene and for the homopolymer (CF2O)n were found to be respectively 200 K and 120 K.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301405
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  • 41
    Digitale Medien
    Digitale Medien
    Thermotropic liquid crystalline halatopolymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1146-1150 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Divalent metal (I.e.) Ba(2+), Ca(2+i), Mg(2+), Mn(2+), Cd(2+), Zn(2+), Pb(2+), and Sn(2+) salts of monovalent organic acids (i.e. p-methoxycinnamic, cinnamic, p-methoxybenzoic, and 4-n-butoxybenzoic) were synthesized via the double decomposition reaction from aqueous solution. Optical microscopy and differential scanning calorimetry (DSC) analysis showed that this series of salts formed nematic liquid crystals. DSC thermograms were characterized by broad nematic-to-isotropic transitions indicative of biphasic regions in which the nematic and isotropic phases coexist. These liquid crystalline salts were polymeric when melted due to ionic crosslinking which took place through the coordination of the divalent metal ion. Except Sn (2+) and Pb(2+), all the liquid crystalline halato-polymers were spun into fibers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301806
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  • 42
    Digitale Medien
    Digitale Medien
    Model-Filled polymers. III: Rheological behavior of polystyrene containing cross-linked polystyrene beads (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1158-1164 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The steady shear viscosity and dynamic moduli, at 180 and 200°C, of polystyrene composites, containing cross-linked monodisperse polystyrene beads varying in diameter from 0.2 to 0.8 μm, are independent of bead size and cross-link density, but increase with the volume fraction of beads. Steady shear viscosities exhibit power-law regions up to 40% concentration of beads, but no yield stress. Storage and loss moduli are initially linear with frequency, on double logarithmic plots, with limiting slopes of 1.3 and 0.9, respectively. Uncross-linked beads and beads cross-linked with 0.1% divinylbenzene are destroyed by thermomechanical dispersion in the melt.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301808
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  • 43
    Digitale Medien
    Digitale Medien
    Criteria for selecting cure cycles in autoclave processing of graphite/epoxy composites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1140-1145 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Room temperature mechanical properties, such as flexural strength and impact resistance, of epoxies and graphite/epoxy composites go through a maximum as a function of epoxy conversion. For tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM)-4,4′-diamlnodiphenylsulfone (DDS) formulations, the recommended cure cycle prescribes a maximum temperature close to 177°C. The maximum extent of reaction that may be obtained at this temperature is determined from the vitrification curve. At this maximum conversion, balanced mechanical and physical properties are attained in the partially cured specimen. However, if the standard cycle is used to cure thick parts, the maximum temperature inside the sample increases beyond 177°C. This leads to a complete conversion in most of the part and a consequent impairment of resulting physical and mechanical properties. It is shown how numerical solutions of differential energy and mass balances may be used to propose alternative cure cycles such that the maximum conversion at every point remains bounded by the vitrification curve. An illustration for a particular thickness is provided.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301805
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  • 44
    Digitale Medien
    Digitale Medien
    Poly(ethylene terephthalate) crystallization as a method for microlithography (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1165-1170 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Thermal lithography on poly(ethylene terephthalate) (PET) is carried out by inducing crystallization through selective exposure of amorphous films to Infrared radiation. The obtained images can be smaller than the wavelength of the CO2 laser light. This circumvention of the diffraction limit is accomplished by taking advantage of the non-linear temperature dependence of the crystallization rate. The optical marking process is reversible through simple melting of the crystalline images. The complementary process, selective melting of an initially crystalline film, can also be accomplished. The use as a heat sink of a mask which forms the image pattern is demonstrated.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301809
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  • 45
    Digitale Medien
    Digitale Medien
    Correction (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1182-1182 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301813
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  • 46
    Digitale Medien
    Digitale Medien
    The effects of blending small amounts of homopolystyrene on the mechanical properties of a low styrene content styrene-butadiene-styrene block copolymer-corrections (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1180-1181 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301812
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  • 47
    Digitale Medien
    Digitale Medien
    Phenolic triazine (PT) resins. II: Cure characterization by dynamic melt rheology and its comparison to DSC (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1171-1174 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new approach involving dynamic melt rheology i.e. dynamic mechanical analysis in a molten inert matrix, is presented for studying the cure of thermoset resins. The degree of cure by dynamic melt rheology has been correlated with that from differential scanning calorimetry, DSC (correlation coefficient = 0.87) and the lack of an excellent correlation is attributed to the uncertainties with the DSC method at higher cure levels. A kinetic expression with appropriate constants, “E, A, and n” from our new approach is presented for predicting the time-temperature dependence of the degree of cure. Advantages of dynamic melt rheology are discussed in relationship to conventional dynamic mechanical and DSC methods.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301810
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  • 48
    Digitale Medien
    Digitale Medien
    Accelerated test for evaluating slow crack growth of polyethylene copolymers in igepal and air (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1175-1179 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The time for brittle failure by slow crack growth for 22 polyethylene copolymers was measured in Igepal and air. The notched tensile tests were conducted in Igepal and air at 50°C and 4.2 MPa and in air at 80°C and 2.4 MPa. For failure times less than 103 min, the difference between the Igepal and air environments was not measurable. As the failure time increased beyond 103 min, the ratio of failure in air compared to that in Igepal increased so that for the very highest failure times of 5 × 105 to 108 min in air, the failure time in Igepal was reduced by 25 - 50 times. The correlation between the Igepal and air tests was generally good with respect to all types of polyethylene. However, a separation of the polyethylenes with respect to their comonomer, butene, hexene, or octene improved the correlation. The resistance to slow crack growth of all the current commercial polyethylene copolymers can be assessed by a notched tensile test in Igepal in about a week or less.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301811
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  • 49
    Digitale Medien
    Digitale Medien
    International union of pure and applied chemistry (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1183-1183 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301814
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  • 50
    Digitale Medien
    Digitale Medien
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301901
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  • 51
    Digitale Medien
    Digitale Medien
    Conduction melting of polymer pellets (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1200-1204 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A study of melting a polymer pellet immersed in a hot silicone oil bath was conducted. The temperature rise at the center of the pellet was recorded. This experiment simulates the conduction melting mechanism of polymer solid pieces mixed in the hot melt inside an extruder screw channel. The pellets immersed in the silicone oil melted quite slowly, taking around one minute to melt a spherical pellet of about 4.5 mm diameter. The heating time could be greatly decreased by stirring the silicone oil to increase the heat transfer from the silicone oil to the pellet. Analysis of the conduction melting mechanism showed that the size reduction of the solid would be most effective in decreasing the heating time.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301903
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  • 52
    Digitale Medien
    Digitale Medien
    Optimizing blown film polyethylene using a merit function (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1205-1208 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The extrusion of blown film polyethylene is a complex process characterized by a large number of interdependent process variables. In order to derive the set of process conditions necessary for a desired film solid state property, the processor normally utilizes a laborious trial-and-error method. In this work, a technique is described to establish more directly the set of extruder settings for producing film with an optimum value of a given property. Biaxial toughness was optimized in the present work, but the technique is applicable to any quantifiable film property.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301904
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  • 53
    Digitale Medien
    Digitale Medien
    Deep drawing self-reinforced thermoplastic sheet (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1185-1199 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The conventional sheet metal forming technique known as Deep Drawing was used to investigate the formability of self-reinforced thermoplastic sheets. The materials studied included uniaxially roll-drawn oriented polypropylene (OPP), cross-rolled biaxially oriented polypropylene (BOPP), and cross-ply laminated OPP (LOPP). OPP exhibits poor room temperature formability as determined by its Limiting Drawing Ratio (LDR). Its formability is improved at elevated temperatures, but samples suffer from non-uniform material flow, temperature sensitivity during forming, and a loss of mechanical properties due to the relaxation of orientation caused by the need for forming temperatures above the normal melting point. Although BOPP attains only moderate Improvements in mechanical properties compared to the machine direction of OPP, it exhibits much better room temperature formability. This difference in drawability between uniaxial and biaxial orientation states is a consequence of the difference in planar anisotropy between these two materials. LOPP has the potential of producing a material with superior performance compared to BOPP while still possessing the desirable formability of BOPP. The formed parts, however, undergo cracking in the outer ply parallel to the orientation direction as a consequence of the OPP small elongation to break in the transverse direction. In addition to forming problems, ordered polypropylene exhibits large shrinkage stresses at elevated temperatures. This may preclude its use in applications requiring a high level of dimensional stability. Classical plasticity theory for metals was appropriately modified to model the radial drawing stress for planar isotropic thermoplastic sheet materials.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301902
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  • 54
    Digitale Medien
    Digitale Medien
    Constrained optimal batch polymerization reactor control (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1209-1219 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The theory of optimal control is used to analyze the performance of a batch PMMA (poly(methylmethacrylate)) polymerization reactor. Optimal dynamic profiles of temperature, initiator feed rate, and initiator concentration in the reactor are generated in order for specified conversion of monomer, number molecular weight, and polydispersity of the final product to be obtained. Based on tae physical limitations of the system, some restrictions are imposed to the control variable variations. The application of Pontryagin's Minimum Principle leads to a mixed initial/final value problem, which is solved by discretizing the control law in the state-space, with the usage of a first order holder. A gradient method is used to minimize the Hamiltonian. The simulation results show that the gel-effect equation and restrictions imposed on the system are of primary importance to the analysis of the reactor performance.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301905
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  • 55
    Digitale Medien
    Digitale Medien
    Vortex formation in a dual-cavity coat-hanger die (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1220-1227 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effects of cavity shapes, particularly the expansion and contraction angles, and the Theological properties of polymeric liquids on vortex formation in the cuter cavity of a dual-cavity coat-hanger die have been examined. For power-law fluids, a vortex may appear in the expansion side of the outer cavity, and the size of the vortex is influenced by the expansion angle, the power-law index, and the Reynolds number. Two viscoelastic fluids were used in the flow visualization experiment; for an aqueous polyacrylamide solution, a vortex may appear in the contraction side of the outer cavity and this vortex is influenced by the contraction angle and the fluid elasticity, but no vortex was observed for a Boger fluid.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301906
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  • 56
    Digitale Medien
    Digitale Medien
    A double bubble tubular film process to produce biaxially oriented poly(p-phenylene sulfide) (PPS) film (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1228-1236 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A double bubble tubular film process to produce biaxially oriented poly(p-phenylene sulfide) (PPS) film is described. Operating windows were developed for stable operation of both the first and second bubbles. Films produced from single bubble tubular film extrusion were largely amorphous having only seven to nine percent crystallinity. Double bubble PPS tubular film had up to 20 percent crystallinity which was increased to 30 percent by further annealing. The first and second bubble films had surface roughness standard deviation heights of 0.01 to 0.04 μm. Orientation was characterized by birefringence and wide angle X-ray diffraction pole figures of the 110 and 112 reflections. Biaxial orientation factors were computed. The double bubble films had higher Young's modulus and tensile strength but lower elongation to break than the single bubble films. Annealing further increases Young's modulus and tensile strength but decreases elongation to break. Double bubble and annealed films with roughly equal second bubble drawdown ratio and second blow up ratio tend to have balanced properties in the plane of the film.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301907
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  • 57
    Digitale Medien
    Digitale Medien
    The manufacture of continuous polymeric filaments by the melt-blowing process (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1237-1251 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This paper presents an experimentally-based analysis of the continuous filament regime of the melt-blowing process. The experiments were performed with a versatile air-polymer die, several die operating temperatures, and three different polymer feed resins. The measurements discern the effects upon the final fiber diameter of the following input parameters: die dimensions, die temperature, polymer feed resin, and both the air and polymer mass flow rates. An empirical model equation is developed which relates these input parameters to the final fiber diameter. In addition, the conditions which result in a transition of the filament from continuous (or stable) to discontinuous (or unstable) are quantified. The model equation and the transition or stability information are then used to predict the behavior of the melt-blowing process for a wide range of case studies involving the input parameters noted above. The data and empirical model are of considerable utility for developing new die designs, for comparison with theoretical models, for predicting fiber stability, and for explaining the behavior of current industrial melt-blowing processes.
    Zusätzliches Material: 25 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760301908
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  • 58
    Digitale Medien
    Digitale Medien
    A process for making microcellular thermoplastic parts (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1323-1329 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A novel process to produce microcellular thermoplastic parts is described. This is achieved by integrating the deformation process in the foaming cycle in such a way that the cell nucleation and growth processes are effectively uncoupled from deformation. The nitrogen-polystyrene system is studied and the relationships between the essential process parameters are established. It is experimentally shown that the pressures associated with deformation do not reduce the number of bubbles nucleated. The process synthesized is demonstrated by making a microcellular polystyrene container.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302010
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  • 59
    Digitale Medien
    Digitale Medien
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302101
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  • 60
    Digitale Medien
    Digitale Medien
    Reply to “comments on ‘fracture toughness of impact modified polymers based on the J-integral’” by D. D. Huang and J. G. Williams (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1345-1345 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302103
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  • 61
    Digitale Medien
    Digitale Medien
    Comments on “fracture toughness of impact modified polymers based on the J-integral” (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1341-1344 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In (1), Narisawa and Takemori examined the physical interpretations and some experimental techniques of the J-Integral (ASTM E813-81) as applied to toughened polymers. Their results and conclusions are reexamined and discussed in terms of recent developments in J testing.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302102
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  • 62
    Digitale Medien
    Digitale Medien
    A numerical study of bubble growth during low pressure structural foam molding process (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1330-1337 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The bubble size distribution created by the expanding foam plays a key role in controlling the load-bearing and other mechanical properties of the manufactured structural foam part. A numerical method to study the bubble growth and predict the bubble size distribution in polymeric foams is presented. On the microscopic scale, a cell model has been used. A cell is a system composed of a hypothetical spherical gas bubble and an envelope of polymer with constant mass surrounding the bubble. On the macroscopic scale, the foam has been modeled as a compressible medium consisting of a number of cells growing in close proximity to each other. The coupled system of the bubble growth equations for a cell and the field equations for the polymeric fluid are solved numerically to predict the spatial bubble size distribution and the flow front movement during the expansion process. The influence of different dimensionless parameters on the growth of spatially distributed bubbles and on the relative reduction in the transient bulk foam density, under isothermal condition; has been predicted. The existence of an axial pressure gradient in the mold due to the spatial variation of bubble growth is demonstrated through numerical experiments.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302011
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  • 63
    Digitale Medien
    Digitale Medien
    Image reversal in a negative deep UV resist (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1346-1351 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A negative deep UV resist, XP 8843 (Shipley Co.),Since this paper was written the name of this resist has been changed from XP 8843 to SNR 248-10. has been made positive by the addition of 1,2,4-triazole. This is achieved by exposing the resist in the presence of the additive thereby inhibiting the crosslinking reaction. After exposure the additive is removed by heating under a vacuum. Unexposed areas of the resist may then be exposed and the resist crosslinked under normal processing conditions.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302104
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  • 64
    Digitale Medien
    Digitale Medien
    Mathematical model and experimental investigation of polycarbonate pellet drying (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1352-1360 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An easy to use, spreadsheet based, mathematical model for drying of strand cut polymer pellets has been developed and experimentally verified. This particle-scale model is based on internal mass-transfer controlled diffusion in the pellet. Examples of its usage in correlation and prediction of the effects of the drying-gas temperature, humidity, and pellet dimensions are presented. Application of the particle-scale model to the design of a countercurrent hopper drier is discussed. Even though examples are limited to water removal from poly(bisphenol-A)carbonate pellets, the model is general and may be used for the removal of other non-solvating low-concentration molecules from polymers with isotropic morphology.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302105
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  • 65
    Digitale Medien
    Digitale Medien
    Impact modification of styrene-acrylonitrile copolymers by methyl methacrylate grafted rubbers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1373-1381 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Monodisperse methyl methacrylate grafted latex rubber (MMA-g) particles (0.12-0.13 µm) have been used for the impact toughening of a series of styrene-acrylonitrile (SAN) copolymers of varied AN content. It was found that the MMA-g particles are most effective in toughening SANs containing about 25 to 34% AN. Mechanical properties, interphase adhesion, mechanical dilatometry, and phase morphology by transmission electron microscopy were determined on blends containing 20-30% rubber. Also, the miscibility range of SANs and poly(methyl methacrylate) (PMMA) graft was considered in attempting to analyze the relationships between the mechanical properties and the characteristic features of the blends. Issues relating the impact strength and deformation mechanisms, interphase adhesion, and particle morphology are discussed. It appears that the high impact strength of some of the blends may be caused primarily by certain morphological features such as particle clustering or small interparticle distances. Thus, craze initiation, shear yielding, and significant matrix deformation may all contribute to the overall ductility of the blend.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302107
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  • 66
    Digitale Medien
    Digitale Medien
    Numerical and experimental studies of the flow in the nip region of a partially intermeshing co-rotating twin-screw extruder (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1382-1398 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The flow pattern within a partially intermeshing co-rotating twin-screw extruder is three dimensional and extremely complex. In order to simplify the problem, a slice perpendicular to the axis of the twin-screw extruder has been considered for flow analysis as a two-dimensional or a quasi-three-dimensional problem. The flow in this slice may be considered to consist of a nip region (located between the two screws) and a translation region in which the movement of the material is very similar to the one found in single-screw extruders. The flow in these two regions have been studied separately. This paper presents the numerical and experimental results of the nip region study. The flow division in the nip region has been quantified and results are presented in terms of a flow division ratio Xf. The flow field patterns have also been obtained. Newtonian as well as non-Newtonian behavior has been investigated. The influences of such factors as (i) the geometry (the radius of the barrel, radius of the screw, distance between the two screws), (ii) the material properties (the power-law index for shear rate dependent viscosity), and (iii) processing conditions (the screw speed), have also been studied.
    Zusätzliches Material: 29 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302108
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  • 67
    Digitale Medien
    Digitale Medien
    Methanol-Induced crack healing in poly(methyl methacrylate)This work was supported by national science council, taiwan, republic of china (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1399-1406 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Crack healing in poly(methyl methacrylate) (PMMA) by methanol treatment at 40°C-60°C has been investigated. It is found that the methanol treatment reduces the glass transition temperature in PMMA. Crack healing only occurs at an operating temperature higher than the effective glass transition temperature. There are two distinctive stages for crack healing based on the recovery of mechanical strength. The first stage corresponds to the progressive healing due to wetting, which has a constant crack closure rate at a given temperature. Immediately following the first stage, the second stage corresponding to diffusion enhances the quality of healing behavior. The surface morphologies obtained during healing and after fracture tests confirm these two stages. By comparing the fracture stress with the fractography, the fracture surface for stage I of crack healing is coplanar to the original crack surface. On the other hand, the original crack surface is destroyed in stage II of crack healing. It occurs in the region incorporating the original healed surface and appears to be like the Virgin fracture surface. It is also found that the tensile fracture stress of PMMA treated by methanol can recover to that of the virgin material. In addition, it is interesting to find that after sustained methanol treatment, the “snake bone” phenomenon on the fracture surface emerges.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302109
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  • 68
    Digitale Medien
    Digitale Medien
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302201
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  • 69
    Digitale Medien
    Digitale Medien
    Fluidity and optimum packing in suspensions of mixed dissimilar particles (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1407-1412 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This is a study on the rheological properties and packing efficiency of a fluid suspension, composed of a mixture of two dissimilar particulate species. A generalized analytic expression for the viscosity of the blend is first developed, and then utilized to derive quantitative ways of maximizing the fluidity and optimizing the filling capacity of the composite system. These, results are compared with earlier experimental and theoretical findings, and with the rheological measurements performed in the course of this work on a series of calcium carbonate-carbon black suspensions in poly-dimethylsiloxane.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302110
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  • 70
    Digitale Medien
    Digitale Medien
    Structure and filtration properties of melt blown polypropylene webs (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1413-1419 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polypropylene melt blown webs have been studied in terms of the relationships among the processing conditions, structure, and filtration efficiency. The effects of the processing conditions on filtration efficiency to aerosolized latex particles, pore size, fiber diameter, and air permeability have been investigated. The melt blowing process conditions investigated in this study were die and air temperatures, die-to-collector distance, and attenuation air flow rate at the die. The filtration efficiency has been found to increase linearly as mean pore size decreased. The degree of fiber-entanglement increased, therefore, the pore size and air permeability decreased with increasing processing temperature, increasing air flow rate at the die, or decreasing die-to-collector distance. Average fiber diameter appeared to change little with die-to-collector distance, but decreased with increasing die temperature or with increasing air flow rate.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302202
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  • 71
    Digitale Medien
    Digitale Medien
    3-D flow analysis of non-newtonian viscous fluids using “enriched” finite elements (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1420-1430 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: ‘Enriched’ element, Q1+Po, and ‘standard’ element, Q1Po, are compared for the simulation of 3-dimensional flow of non-Newtonian fluids. Several 3-dimensional polymer flow problems are analyzed. The pressure field obtained by using Q1Po elements suffers from spurious pressure modes. For complex flows, depending upon the flow geometry and the boundary conditions used, Q1+Po elements may fall to simulate even the velocity field. Q1Po elements, which satisfy the Babuska-Brezzi condition, give accurate velocity and pressure distributions for all the problems analyzed here.
    Zusätzliches Material: 26 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302203
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  • 72
    Digitale Medien
    Digitale Medien
    Detergent assisted stress cracking in low density polyethylene (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1431-1441 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Igepal assisted environmental stress cracking (ESC) of LDPE has shown three characteristic regions with increasing crack driving force: Region I-crack speed and craze length increased. Region II-crack speed and duplex plastic zone length were constant, and Region Ill-crack speed decreased while the deformation zone length increased. The activation energies for the three regions were 100, 23, 20 kJ/mole, respectively. The proposed rate controlling processes of ESC for the LDPE/Igepal system are: Region 1 is controlled by a;-relaxation, and Region II and III are controlled by lamellar orientation. The Igepal plasticizes the amorphous phase and facilitates the stress induced orientation of the lamellar.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302204
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  • 73
    Digitale Medien
    Digitale Medien
    The morphology of extruded blends containing a thermotropic liquid crystalline polymer (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1442-1453 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Three different polymer blends consisting of an isotropic matrix and a ther-motropic liquid crystalline polymer (LCP) as the reinforcement were extruded. Polycarbonate (PC) and polyetherimide (PEI) were the two matrices, and the LCPs used were Vectraw A950 of Hoechst-Celanese, a copolyester of hydroxybenzoic and 2,6 hydroxynaphthoic acids and an LCP of Granmont Inc., a condensation polymer of terephthalic acid, (l-phenylethyl)hydroquinone, and phenylhydroqui-none. These extrudates were characterized by a quantitative morphological technique to determine the percentage of LCP present as fibrils and the average domain diameter. These experimental observations were then coupled with the component Theological behavior and a simple heat transfer analysis to explain the morphology and property differences between the blends. Blends with the Granmont LCP showed no appreciable increase In the quantity of fibrils with draw ratio, for example, whereas the amount of fibrils in Vectra® blends tended to increase to a plateau with draw. The tensile modulus of the blends agreed well with composite theory, with average fibril moduli of 24.6 GPa and 23,3 GPa for Vectra® and the Granmont LCP, respectively. These differences can be explained in terms of the cooling behavior of the LCPs.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302205
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  • 74
    Digitale Medien
    Digitale Medien
    Characterization of network segment density from compression modulus measurements on swollen elastomersPresented at the 17th north american thermal analysis society conference oct. 9-12, 1988, orlando, fla. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1591-1594 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The characterization of network segment density of elastomers is discussed. Normally equilibrium solvent swelling is used as long as the polymer-solvent interaction parameter χ is available. However, χ is often not known or may be a function of the network segment density, or composition for a polymer whose structure is changed upon aging. The technique of measuring the modulus in tension or compression on solvent-swollen samples allows the network segment density to be calculated from the theory of rubber elasticity. This circumvents the problems associated with the solvent swelling technique. The modification of a commercially available thermomechanical analyzer is described, to enable compression modulus measurements on solvent swollen elastomers to be performed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302406
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  • 75
    Digitale Medien
    Digitale Medien
    Adaptation of photoacoustic fourier transform infrared spectroscopy for studying the thermal oxidation of nylon 66 at 150°c correlated to mechanical properties (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1595-1598 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Oven aged tensile bars of heat stabilized, glass reinforced nylon 66 material were studied by Fourier transform infrared (FTIR) spectroscopy using a photoacoustic detector. Flat weighed scrapings were removed from tensile bars whose tensile strength, elongation, impact, molecular weight, and thermal properties had previously been measured. Using the amide I band of nylon 66 as an internal standard, the thermal oxidation of nylon was followed using a commercially available photoacoustic detector. The infrared absorbance spectra demonstrate the formation of carbonyl stretching vibrations due to the thermal oxidation of nylon with a band center at 1713 cm-1 whose width at half height is 40 cm-1. The difference infrared spectra support reaction mechanisms dealing with an Initial increase in the degree of polymerization followed by transamidation reactions with subsequent formation of an α, β unsaturated carbonyl species and chain scissioning. By using data related to the percent retention of certain physical properties which had also been measured on these tensile bars, subtractive infrared spectroscopy yielded additional fundamental information regarding nylon 66 degradation. Consequently, nylon products being used in underhood automotive applications are currently being investigated for thermal oxidative degradation using this rapid and relatively non-destructive photoacoustic FTIR technique for durability considerations.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302407
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  • 76
    Digitale Medien
    Digitale Medien
    A barometer of crystallization rates of polymeric materials (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1615-1619 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A crystallization rate coefficient (CRC) parameter is introduced which has allowed a direct comparison of the crystallization rates of various polymers on a single scale for the first time. Basically, CRC represents a change in cooling rate required to bring about 1°C change in the supercooling of the polymer melt. For the polymers studied, this value varies between 35 h-1 (polyethylene terephthalate) and 155 h-1 (poly(tetrafluoroethylene)) and jumps to 295 h-1 for indium metal; the precision being better than ±5 percent. The reliability of CRC has been tested against the established trends e.g., (i) a large decrease in the crystallization rate of polyethylene terephthalate with increase in molecular weight, (ii) a lower crystallization rate of the “virgin” nylon 6 as compared to the processed nylon 6 resin, (iii) an increase in the crystallization rate of nylon 6 in the presence of nucleating agents, and (iv) a dramatic increase in crystallization rate as we go from poly(ethylene terephthalate) to poly(tetrafluoroethylene) and then from poly(tetrafluoroethylene) to the metals. The significance of the CRC barometer is discussed in the light of prior difficulties in directly comparing the crystallization rates of polymers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302410
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  • 77
    Digitale Medien
    Digitale Medien
    Migration of polymer blend components during melt compounding (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1628-1632 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In this paper it is shown that a core-shell impact modifier which is predispersed in one phase of a complex blend may migrate to another phase during melt compounding. The migration process appears to be driven by differences in the spreading behavior of the individual blend components. The details of the migration are analyzed by electron microscopy studies of partially compounded samples which were quenched, extracted, and separated from the extruder screw.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302412
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  • 78
    Digitale Medien
    Digitale Medien
    Knit line fractures in injection molded liquid crystalline polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1620-1627 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The microstructure and fracture behavior of Injection molded samples of unfilled and filled grades of liquid crystalline polymers (Vectra® and Ultrax®) containing cold and warm knit lines have been studied by scanning electron microscopy, X-ray scattering, and Instron tensile tests. Four process parameters - melt temperature, mold temperature, injection time, and holding pressure - have been varied in accordance with a 24 factorial design experiment. In cold knit lines a 200 µm thick region with transverse orientation with Hermans orientation function f ≈ 0.12-0.18 is formed on both sides on the weld area. The strength of the cold knit lines is very low, 9.0-19.8 MPa corresponding to 15-20% of the full strength of the material. The strength of the warm knit lines increases markedly with increasing distance from the insert and is generally significantly greater (40-45 MPa, 48 mm from the insert) than in the cold welds. Annealing at 260-300°C of samples containing cold knit lines causes first a partial healing of the knit line and later extensive chemical degradation of the polymer.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760302411
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  • 79
    Digitale Medien
    Digitale Medien
    Masthead (1921)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 35 (1921) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050350101
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  • 80
    Digitale Medien
    Digitale Medien
    The development of Asplanchna ebbesbornii (rotifer) (1920)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 33 (1920), S. 388-437 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050330205
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  • 81
    Digitale Medien
    Digitale Medien
    The hyobranchial apparatus of Spelerpes bislineatus (1920)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 33 (1920), S. 526-583 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050330208
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  • 82
    Digitale Medien
    Digitale Medien
    The meiotic phenomena in the spermatogenesis of blaps, with special reference to the X-complex (1920)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 34 (1920), S. 68-117 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050340103
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  • 83
    Digitale Medien
    Digitale Medien
    Freezing and survival of insects at low temperatures (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 521-546 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The literature on the general subject of freezing and survival both in plants and in animals is briefly reviewed and a bibliography given. Insects representing three ecological groups, (1) the oak borers - exposed to temperature extremes normally; (2) stored-products insects representing supposedly a tropical or subtropical group, and, (3) aquatic insects never exposed to temperatures lower than 0°C., were chosen for this study. Determinations of the freezing and undercooling points were made during the yearly cycle.Both the stored-products insects and the aquatic insects studied showed no periodicity in freezing or undercooling. The oak borers showed marked periodicity. The freezing-point varies directly with the moisture content. Cold-hardiness was produced experimentally by, (1) exposure of insects to low temperatures and, (2) by dehydration. Loss of cold-hardiness was produced experimentally by combinations of high temperature, food, and high relative humidity. The freezing-point ordinarily found corresponds with that of the blood. Repeated freezings of the same insect or tissue showed no hysteresis. There exists in certain insects a secondary freezing-point below that ordinarily found. Oak borers in summer condition die at the first freezing-point; in fully hardened condition they die at the secondary freezingpoint.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050430209
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  • 84
    Digitale Medien
    Digitale Medien
    Ant-mounds as to temperature and sunshine (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 1-20 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The ant Formica exsectoides F. builds mounds with some reference to sunlight, and measurements of internal temperatures have shown them higher in upper parts of the mound, but different in different faces of the mound - all higher than the earth outside the mound.Inside temperatures are not constant; they are due to the sunshine. The mound is so fabricated that the internal temperatures are conserved during the night. The ants make use of the differential internal temperatures for rearing broods.Some mounds show bilateral symmetry dependent upon sun exposure.Measurements of rate of running of these ants show a falling off with lower temperatures, and possibly this is one factor in the smaller development of northerly aspects of these mounds.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050440102
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  • 85
    Digitale Medien
    Digitale Medien
    Parental chromosome dimensions in Ascaris. A study of the effect of cellular environment on chromosome size (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 117-125 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In the early cleavage stages of Ascaris the homologous chromosomes are of unequal length. Measurements show that these homologues fall into two sharply defined groups suggesting their biparental origin. The shorter are considered to have come from the male.As the age of the embryo increases, these differences between the chromosome mates tend to become less, and it is suggested that at some later period in the history of the animal this difference will entirely disappear in response to the effect of continued existence in a common environment. The length of the chromosomes is very slightly shortened during the early cleavage divisions, while the area of the equatorial cross-section of the cells becomes enormously reduced.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050440106
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  • 86
    Digitale Medien
    Digitale Medien
    Oxygen consumption of individual pupae during metamorphosis (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 313-339 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The rates of oxygen consumption of single pupae of blowflies (Phormia terraenovae, Phormia regina, Lucilia sericata), of the flesh fly (Sarcophaga sarracenioides Aldrich), of the Mediterranean flour moth (Ephestia kuehniella), and of the bee moth (Galleria mellonella) during metamorphosis, until emergence, have been determined. The record for each pupa, with the exception of those of blowflies, is practically continuous day and night during the period of pupal development which lasted from 140 to 300 hours, according to the species, at the temperatures used. During pupal development there is first a period of decrease in rate, which is later followed by a steady increase until a short time before emergence, when a sudden decrease occurs.The ‘oxygen curves’ of the blowfly pupae (Diptera) are quite different from those of the flour-moth and bee-moth pupae (Lepidoptera), although all are of the same general U-shaped type. There are strong indications of a specific difference in the curves of the blow-fly pupae. The flour-moth pupae curves differ slightly from those of the bee-moth pupae. During the major part of development the rates of O2 consumption of pupae of both sexes of bee moth and flour moth are about the same, but near the end of metamorphosis the females have higher rates than the males. No such sex difference appears among the dipterous pupae used.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050440205
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  • 87
    Digitale Medien
    Digitale Medien
    The formation of contractile vacuoles in Amoeba proteus (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 363-372 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The history of investigations on the contractile vacuole is reviewed briefly and brought up to date.The study of the contractile vacuole in Amoeba proteus is considered from standpoints of origin, structure, behavior, and function. The results are obtained from a prolonged study of normal organisms and from their reactions when introduced into conductivity water.The origin of vacuoles is studied by means of dark-field illumination which reveals the vacuole to be formed from a fusion and coalescence of extremely minute droplets.The retaining ‘wall’ of the contractile vacuole is not a permanent structure, but is in the nature of a condensation membrane, totally disappearing with each contraction.The loci of the contractile vacuoles are not permanent, but vacuoles are formed more or less at random. It is unlikely that they are supported in gelated areas, for amoebae with a dozen vacuoles are quite active and there is no interference with amoeboid movement.Conductivity water increases the size, number, and rate of contraction of contractile vacuoles, which suggests that they may function in maintaining an osmotic gradient as well as in the elimination of metabolic waste.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050440207
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  • 88
    Digitale Medien
    Digitale Medien
    Developmental modification and elimination of the larval stage in the ascidian, Corella willmeriana (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 467-514 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The eggs of Corella develop in the atrial chamber of the parent at a pH below that of normal sea-water (pH 7.4 ±). When removed to normal sea-water in early stages and under certain other experimental conditions, larval development is more or less inhibited, the tail being most inhibited, the dorsal region somewhat less. The free larval stage may be eliminated and later development and metamorphosis may proceed normally to an advanced stage in the chorion and give rise to normal ascidians. The region most inhibited are, in general, those which possess the highest reducing power, as indicated by KMnO4. Experiments made in the attempt to control development all agree in indicating that the early stages are adjusted to a certain CO2 concentration approximately that of the atrial chamber and presumably near that of the body. Solutions of the same pH may or may not inhibit development according to their CO2 content.The tail, the region of highest reducing power in the embryo during its development, is most inhibited; the dorsal region, the next most rapidly reducing region, is next in degree of inhibition. All differences in reducing power disappear when, or soon after, the animals are killed by other agents before treatment with KMnO4.
    Zusätzliches Material: 64 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050440305
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  • 89
    Digitale Medien
    Digitale Medien
    The structure of the testis and movement of sperms in chortophaga viridifasciata as demonstrated by intravitam techniqueA dissertation presented to the Faculty of Kansas University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy.I wish to express sincere gratitude to my major professor, Dr. W. J. Baumgartner, for his continual assistance and efficient direction during the development of this work. His helpful encouragement and invaluable suggestions, as well as the kindly interest manifested by other members of the faculty, will keep me ever a debtor to the University of Kansas. (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 321-345 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: By means of the ‘intravitam technic’ developed by Baumgartner and Payne (1931), the mature or maturing sperm of Chortophaga viridifasciata have been traced from the follicle of the testes in the male to the locus of fertilization in the female. The sperm aggregated into bundles, and held tight by a hyaline cytoplasmic cap, spiral up the follicle, turn and spiral back to the vas deferens by means of a periodic lashing and writhing of the sperm tails.The genital tract is described briefly. In the vasa deferentia and storage tubules, the sperm bundles are usually in a quiescent state, having been inactivated most probably by secretions from the tubules.Peristalsis and currents in the fluid contents of the tubules move the inactivated sperm from the vesicles of the male to the seminal receptacle of the female, where the cytoplasmic caps gradually disintegrate. This permits individual sperm to pass down the seminal duct and fertilize the ovum just before oviposition.Single photomicrographs and a series of photomicrographs show the sperm in various parts of the genital system and making actual progress up a follicle. A stained preparation was used for only one of the photos. The other nineteen are from living unstained tissue. The intravitam observations are, most probably, more ‘vital’ than any heretofore recorded.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050540205
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  • 90
    Digitale Medien
    Digitale Medien
    Masthead (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050540201
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  • 91
    Digitale Medien
    Digitale Medien
    A study of the Golgi elementsSubmitted from the Department of Zoology in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of the University of Missouri, 1931. (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 259-301 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This investigation was undertaken to determine some of the variables involved in the demonstration of the Golgi elements. Gland cells of vertebrates were studied vitally, after impregnation by osmic acid methods, and after autolysis.The duration of the staining period and the concentration of the stain condition the results obtained by vital staining with neutral red. The success of impregnation of Golgi elements with osmic acid varies with,(1) the type of tissue, (2) the time of initial fixation in relation to the time of the death of the animal, (3) the position of the cell in the piece of tissue, and, (4) the temperature of incubation with osmic acid. Stages in the impregnation of Golgi elements can be followed by examining preparations of the same tissue at frequent intervals during the incubation period. An increase in the amount of material which reduces osmic acid and which may form Golgi elements occurs in the cells during autolysis.The results are interpreted as indicating that Golgi elements are visible products of chemical reactions that occur in cells. They represent localized regions containing particular classes of chemical compounds which may be present, as such, in living cells or result from transformations in the cells during incubation. It is suggested that for the cells under consideration these substances may be unsaturated fatty acids.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050540203
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  • 92
    Digitale Medien
    Digitale Medien
    The architecture of the pectoral appendage of the dogfish (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 399-413 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The m. trapezius, with both brachial and branchial functions, is in seeming series with the mm. interarcuales laterales. The intrinsic muscles of the fin occur as a dorsal extensor sheet and three (or four) ventral flexor components. The spinal nerves, uncomplicated by extensive anastomoses, which supply the fin, clearly show that in the dogfish the fin muscles are derived not from dorsal and ventral elements, but from anterior and posterior, or protractor and retractor elements. The nerves prove that from the original protractor musculature only the anterior portion of the present flexor group is derived, while the original retractor musculature has become all of the extensor and the posterior part of the flexor series. Faradic stimulation of the live animal is satisfactory, although there is much variation in the sensitivity, particularly of different muscles.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050540209
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  • 93
    Digitale Medien
    Digitale Medien
    Observations on spermiogenesis in sciara coprophila (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 477-491 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The mitochondria in the male germ cells of Sciara exhibit peculiarities as regards both morphological characteristics and distribution. In form. they show superficial similarity with those of some of the scorpions, while their distribution may be peculiar to the genus and depend on unusual meiotic divisions.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050540305
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  • 94
    Digitale Medien
    Digitale Medien
    The anatomy and blood supply of the urogenital system of lepidosteus platystomus rafinesque (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 459-475 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A description of the urogenital system in both sexes of Lepidosteus platystomus Rafinesque, and new observations on the blood supply to this system as well as to the rest of the viscera is given.The testes resemble the true piscine type. The sperm are carried by numerous vasa efferentia to the kidney tubules, through the mesonephros to the wolffian duct, and to the exterior as in the elasmobranchs and amphibians. The most anterior of the vasa efferentia are non-functional. The ovaries are simple sac-like structures continuous with their ducts. The oviducts transverse the ventro-lateral surface of the mesonephros, and enter into the dilated portions of the wolffian ducts, where they join, directly anterior to the urogenital aperture. There are no ducts in the male homologous with the oviducts of the female. The kidneys fused posteriorly, appear to extend the entire length of the body cavity, but the anterior third is non-urinary.By injection methods, the celiaco-mesenteric artery is shown to be crowded to the posterior end of the body cavity by the complicated swim-bladder, and runs anteriorly to supply the entire viscera. Its anterior portion is incorporated in the liver.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050540304
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  • 95
    Digitale Medien
    Digitale Medien
    Masthead (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050550101
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  • 96
    Digitale Medien
    Digitale Medien
    Musculature of the lacewing (chrysopa plorabunda) neuroptera (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 29-51 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This article is an account of the complete musculature of an adult Neuropteran insect, Chrysopa plorabunda. Previous anatomical discussions on this order of insects include only a few of the muscles of the head and thoracic regions, while those of the abdomen are entirely lacking. The muscles here described include those of the head, thorax, and abdomen. The origin, insertion, and function of each muscle is given. The boundaries of several of the sclerites, especially those of the labium, are located by the observations on the musculature of these parts. The meso- and metathoracic wings are of the same size and for that reason the muscles of these regions are very much alike. The prothorax is greatly elonated, causing the muscles of that region to differ to a greater or less degree from the ‘general rule’ in insects. The abdominal muscles may be arranged in the several groups generally found in insects. In several cases, however, both the origin and insertion of the muscle have been shifted to accompany changes which have taken place in the abdominal segmentation. All of the muscles are shown in the four plates containing nineteen figures which accompany the text.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050550104
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  • 97
    Digitale Medien
    Digitale Medien
    Some ultraviolet photomicrographs made with different wave lengths (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 131-135 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Photomicrographs have been made of grasshopper spermatocytes using ultraviolet light of several wave lengths. For studying chromosomes this wave length should be between ca 2800 A and ca 2500 A. With higher frequencies the entire cell becomes strongly absorbing and relatively little detail is to be seen. All cell structures, including the chromosomes, are as transparent to λ = 3500 A and to longer ultraviolet waves as they are to visible light. The present experiments do not indicate the exact point between λ = 3500 A and λ = 2800 A at which the selective chromatin absorption commences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050550108
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  • 98
    Digitale Medien
    Digitale Medien
    An embryological study of a special strain of deformed x-rayed mice, with special reference to the etiology and morphogenesis of the abnormalitiesContribution from the Zoölogical Laboratory of the University of Michigan. (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 151-183 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This investigation consists of an extensive histological study of a special strain of abnormal x-rayed mice, in an attempt to determine the embryonic origin and development of certain congenital abnormalities that are hereditary.The study shows that development of the x-rayed strain is normal up to the thirteenth day after insemination, after which pathological structures appear in the form of blebs, hematomas, and thrombi. As a result of the formation of the blebs and hematomas a general condition is set up within the embryo which resembles that of thrombosis. The thrombi when formed exert a mechanical effect by crowding out the normal tissue. A chemical effect is also produced by the blood cells and fluid extravasated from the thrombus which penetrate into the forming tissues resulting in their perverted development. Thus the thrombi are the immediate factors causing the various regions of the body to be deformed.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050550110
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  • 99
    Digitale Medien
    Digitale Medien
    Viviparity superimposed upon ovo-viviparity in the goodeidae, a family of cyprinodont teleost fishes of the Mexican Plateau (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 207-251 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Goodeidae are a family of cyprinodonts containing about nine genera and twenty-six species. They are confined exclusively to the Mexican Plateau and to streams in the immediate vicinity. All are viviparous. Fertilization is internal. The eggs are extremely small and contain very little yolk. The embryos are retained in the ovarian follicles until the yolk is practically absorbed, in the meantime developing unique absorptive organs in the form of extensive ribbon-shaped proctodaeal processes. The embryos are evacuated into the intra-ovarian cavity where they are retained for several weeks, during which time the proctodaeal processes become extended. The ovary becomes a nutritive organ and produces secretions which are discharged into the intra-ovarian cavity and absorbed by the embryo through their unique processes. The processes differ in form, number, and histological structure, but are specific in their peculiarities for each species. These specific differences, together with marked differences in the ovary, will furnish a basis for a re-classification of the genera and species of the family. A comparison in made between this family and the other ovo-viviparous and viviparous cyprinodonts, on the basis of which it is concluded that the Goodeidae have arisen separately from an ovo-viviparous ancestor, which in turn was derived from an ovo-viviparous type. A comparison is also made between the peculiarities of reproduction in this family and those of other viviparous teleosts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050550202
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  • 100
    Digitale Medien
    Digitale Medien
    An experimental study of hemopoiesis in necturus: Effects of lead poisoning on normal and splenectomized animals (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 349-385 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Lead poisoning causes a selective destruction of mature erythrocytes, thereby depleting the spleen and stimulating differentiation and proliferation of erythrocytes in the blood. In conjunction with splenectomy, this intravascular erythropoiesis is markedly accelerated.During the progressive anemia and subsequent regeneration of erythrocytes in simple lead poisoning the major hemopoietic loci, spleen, mesonephros, liver, and epicardium were observed. The spleen is most rapidly affected. The red cell progenitor first present in the circulation is the hemoblast, but later numerous lymphocytes enter the blood stream and are transformed into erythrocytes.Following simple splenectomy the blood shows relatively little change. A mild regenerative activity of both erythrocytes and thrombocytes ensues. In lead poisoning after splenectomy the blood picture resembles that of simple lead poisoning. The anemia is produced more rapidly and the regeneration of erythrocytes is delayed.This study emphasizes the importance of the blood stream of Necturus as a site of red cell differentiation and proliferation, and shows that the lymphocyte may be a possible progenitor of erythrocytes and thrombocytes. Under normal conditions the hemoblast suffices as a source for red cells, but under abnormal or experimental conditions, where the demand for new cells is excessive and prolonged, the lymphocyte plays a major role.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050550206
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