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  • Articles  (998)
  • Chemical Engineering  (998)
  • Wiley-Blackwell  (998)
  • International Union of Crystallography (IUCr)
  • 1980-1984  (998)
  • Physics  (998)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of polymeric additives on the rheological properties of talc-filled polypropylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 198-201 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of small amounts of low molecular weight polypropylene oxide on the rheological properties of talc-filled polypropylene composites was studied experimentally using a capillary viscometer. The elastic behavior of the system was investigated by exit pressure and die swell methods. Initial studies showed that the talc filler does not influence the viscosity of the polypropylene but decreases the elasticity of the polymer system. Addition of oligomer concentration in a 40 wt percent talc-filled polypropylene not only decreases the viscosity but also further decreases considerably the elasticity of the filled polymer composite. In both cases about 3 wt percent oligomer cone entration appears to be optimal, and further addition of oligomer does not significantly influence the rheological characteristics of the talc-filled polypropylene composite.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200305
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of permselective membranes by radiation induced grafting of hydrophilic monomers into poly(tetrafluoroethylene) filmsPresented in part at the following conference: IVPAC Internation Symposium Macromol. Chem.; 1961, Montreal, 1961, Montreal, 1967, Bruxelles, 1976, Jerusalem; A.C.S. National Meeting, April 1968, San-Francisco (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 202-205 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A large variety of permselective membranes were prepared by radiation grafting techniques. Grafting of styrene into poly-(tetrafluoroethylene) films followed by sulfonation led to strong anionic membranes showing good performance in reverse osmosis. Carboxylic membranes were prepared by grafting acrylic and methacrylic acids. Cationic membranes were obtained via grafting 4-vinylpyridine. These membranes were tested in various fractionation processes including reverse osmosis. N-vinylpyrrolidone grafts exhibited high selectivity for separating water from organic solvents by pervaporation. Bifunctional membranes containing both carboxylic and pyridine groups were obtained by two successive grafting steps either in bulk giving rise to “homogeneous” membranes with unusual swelling properties, or into localized areas generating mosaic membranes which exhibit negative osmosis and increased rates of ion-pair diffusion.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200306
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  • 3
    Electronic Resource
    Electronic Resource
    Topomorphic states and phase transitions connected with the crystallization of polymersPresented at the 5th Discussion Conference on Phases and Interphases in Polymers, Prague (1976) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 206-211 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The crystallization of flexible-chain molecules of different degrees of coiling is considered. The nature of the phase transition during crystallization is discussed. The revision of established notions on phase transitions in polymers leads to the concept of crystalline topomorphism, i.e., the existence of two crystalline types with different modes of packing of macromolecules in the macroscopic crystal though they belong to the same lattice class: folded-chain crystal (FCC) and extended-chain crystal (ECC). Phase diagrams in coordinates of degree of coiling vs temperature are plotted. The values of molecular orientation and temperatures at which each of both mechanisms of crystallization takes place are evaluated. The mechanisms of ECC growth under equilibrium conditions and under conditions of molecular orientation are discussed. It is shown that the melting of ECC obtained by the process of orientational crystallization is a second order phase transition, being analogous to a crystal-nematic phase transition. At the same time the melting of FCC provides all the features of a first order transition.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200307
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  • 4
    Electronic Resource
    Electronic Resource
    Plane stress and plane strain fractures in polypropylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 215-220 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The concepts of Linear Elastic Fracture Mechanics (LEFM) are applied to polypropylene, a homopolymer and two copolymers, with a view to characterizing their brittle behavior at slow rates (0.5 cm/min) in terms of a fracture toughness, KIc. The effect of thickness, notch sharpness, and the mode of loading on KIc have been investigated in order to determine the plane strain toughness values, KcI for the materials. The two types of material are compared in terms of their toughness values over a range of temperatures between +30 and -160°C. Evidently, the small amounts of ethylene added to the copolymers show plasticizing effects, suppressing the yield stress and the ductile-brittle transition temperature. In addition, the copolymers exhibit a ductile-brittle region between -100 and -45°C where notch strengthening is apparent in the tension mode and a slow crack growth region between -45 and -30°C where slow growth precedes unstable fracture. The homopolymer, however, shows no clear evidence of such intermediate regions, except for slight amounts of slow growth above 0°C, and becomes ductile around 30°C.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200309
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  • 5
    Electronic Resource
    Electronic Resource
    Diffusion with discontinuous swelling. IV. Type II diffusion into spherical particles (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 238-243 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the last few years some new features of the so-called type II diffusion have been established which confirm the first theoretical description of such a material transport into a semi-infinite glassy medium which at a certain concentration of the sorbate is transformed into a gel. The boundary between the glass and the gel progresses at a constant velocity into the interior of the sample thus yielding a linear term in the weight gain. The gradual establishment of the concentration profile in front of this boundary yields at the beginning a square root term in the weight gain. A detailed analysis of the extensive measurements of Hopfenberg, et al. of the diffusion of n-hexane into extremely small polystyrene spheres demonstrates that the weight gain always starts with a square root of time term. In sufficiently large spheres this contribution is soon completely overridden by the term linear in time. The spherical geometry substantially modifies the concentration profile and the weight gain. In particular the weight gain divided by the square root of time vs the square root of time shows a maximum as soon as the geometrical factors prevail over the effect of the constant velocity progression of the boundary between the glass and the gel.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200403
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  • 6
    Electronic Resource
    Electronic Resource
    A study of crosslinking in polyimides by viscoelastic and diffusion techniques (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 244-251 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper is concerned with detecting crosslinking and changes in crosslink densities in cured polyimides. The methods used include diffusional weight gain and dynamic mechanical measurements on thin films of the cured polymers. In this study changes in diffusivities (D) for dimethylformamide (DMF) sorption into polyimide films as well as dynamic mechanical moduli and loss tangents are shown to be related to differences in polyimide cure schedule and composition. In all cases studied there is a β loss dispersion in the range 120 to 150°C and a γ loss dispersion in the range -50 to -80°C. The position and intensity of the β and γ relaxation processes vary primarily with cure cycle. There is a significant correlation between the magnitude of the diffusion coefficient and β and γ transition temperatures (Tβ and Tγ). Tβ increases and Tγ decreases with higher values of D so that T*, the difference Tβ - Tγ, is directly proportional to the diffusivity. By relating these results to data in the literature and the known curing behavior of polyimides, this trend is shown to be consistent with the presence of crosslinking and to be related to the crosslink density of the polymers. The data of this study indicate that measurements of diffusion coefficients for solvent sorption can be used to study changes in crosslink densities in glassy thermosetting polymers. Since the method is best suited for studying one dimensional diffusion, it also is suggested as a possibility for determining relative crosslink densities in adhesives bonded between substrates.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200404
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  • 7
    Electronic Resource
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    Introductory remarks (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1-1 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200102
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  • 8
    Electronic Resource
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    Sorption and transport in glassy polymers-a review (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 2-13 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: After defining Fickian diffusion in rubbery polymers an overview of transport behavior in polymers is presented. Diffusion and sorption below the glass transition are discussed, followed by a review and classification of the various theoretical models which have been proposed to account for these phenomena. A short list of recommendations for future work is included.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/pen.760200103
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  • 9
    Electronic Resource
    Electronic Resource
    Pressure dependence of diffusion coefficient for CO2 in glassy polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 30-35 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The pressure dependence of the apparent diffusion and permeation coefficients were observed by using the permeation time-lag method for CO2 in glassy poly(ethylene terephthalate) (PET), polystyrene (PS) and poly(vinyl chloride) (PVC) below 1 atm. The results show that the permeation coefficient is constant whereas the diffusion coefficient increases with pressure. According to the theoretical prediction of Paul, it can be concluded that the adsorbed CO2 in these glassy polymers is completely immobilized and does not participate directly in the diffusion. A computer was used in the numerical calculation to determine the true diffusion coefficient from the model of Paul, et al. A comparison of the curves calculated with these constants and experimental values gave excellent agreement for the three glassy polymers. But there is a large difference between the values of one of the parameters obtained by this time-lag method and the sorption method. Relations between this difference and the magnitude of the parameters are discussed.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200106
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  • 10
    Electronic Resource
    Electronic Resource
    Application of the ‘dual sorption’ model to drug transport through skin (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 36-39 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dual sorption theory has been extended to the transport of drug molecules through human skin in vitro. By assuming that sorption of drug molecules occurs by both dissolution and binding of drug to immobile sites in the skin, the experimental sorption isotherm can be predicted, and the disparity between steady state and time lag diffusivities can be reconciled. Furthermore, the dual sorption model has been used to develop techniques for controlling these sorption transport processes in order to rapidly achieve predictable transdermal drug delivery in vivo.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200107
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  • 11
    Electronic Resource
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    Statistical mechanical model of sorption and diffusion of simple penetrants in polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 51-58 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Amorphous polymers are assumed to possess a quasicrystalline structure with chain bundles that are locally parallel over distances ∼1 nm. Two possible types of random motion for a spherical penetrant in such a substrate are described, one type determining the jump frequency and activation energy of diffusion, the other type determining the jump length. The former quantities may be calculated from the model, but not the latter. Sorption of simple gases at low penetrant pressures is assumed to occur mostly in pre-existing holes, both above and below Tg, and the same penetrant diffusion mechanism is assumed to hold in the two regions. The changes in apparent heat of solution and activation energy of diffusion observed at Tg are explained in terms of additional hole formation with increase in temperature above Tg. The theory is shown to be consistent with experimental diffusion data for several glassy and rubbery systems. Evidence is given that hole formation in simple polymers such as polyethylene may occur by chain “kinking”. For polymers possessing articulated side groups, however, it appears that hole formation arises principally from motions within these groups.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200109
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  • 12
    Electronic Resource
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    Conformation and shear stability of xanthan gum in solution (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 512-516 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Xanthan gum, the extracellular polysacchuride produced by the microorganism Xanthomonas campestris has unique rheological properties and as a result found many industrial uses. The primary structure o xanthan consists of a cellulose backbone substituted on alternate residues with charged trisaccharide side chains. The polymer undergoes an ordered ⇄ disordered conformation transformation, Very recently determinations of the secondary and tertiary structures have shown that the ordered conformation is helical. The two conformations have different solution properties. Rheological evidence indicates that xanthan conformation is critically dependent on the presence or absence of-salt. In this work we show that the polymer shear degrades to a larger extent in the disordered conformation than in the ordered conformation. That is, the ordered conformation is more shear stable.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200712
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  • 13
    Electronic Resource
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    Scission of non-interpenetrating macromolecules in transient extensional flows (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 505-511 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Solutions of the random coiling polymers; polystyrene, poly (methylmethacrylate), and sodium polystyrene sulfonate (NaPSS), all at concentrations well below the critical value for entanglement, were subjected to transient, high, elongational strain rates by passage from a cylinder through an orifice into a gently diverging section, driven by a piston at constant, high velocity over a short stroke. It is shown that a critical orifice flow velocity Vc. exists for each polymer species, above which scission of polymer molecules occurs creating new molecules. By gel permeation chromatography, the number of additional polymer molecules created per initial polymer molecule, the scission index, was determined as Mn,0/Mn - 1 where Mn is the number average molecular weight, and Mn,0 is the initial value thereof. Vc is found to vary as approximately Mn-0.53. Above Vc the scission index was found to be proportional to Mn2.23, to the difference: orifice velocity V less Vc, and to the number of passes N of the polymer solution through the orifice. Expansion of NaPSS coils by reducing ionic strength of their aqueous solutions, at constant polymer molecular weight, decreases the scission index, The hypothesis is proposed that intramolecular entanglements are responsible for scission. The random coiling macromolecules in the solution cannot respond to the strain rate (imposed in ca, 100 microseconds) so as to avoid having internal sections, caught by loop entanglement, pulled to nearly full extension and thus broken.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200711
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  • 14
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    The SPE International Award Address - 1979. Recent aspects of research in macromolecules (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 525-529 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200802
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  • 15
    Electronic Resource
    Electronic Resource
    Hydrostatic extrusion of linear polyethylene in tubular and non-circular sections (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 540-545 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Tubular and non-circular section components have been produced by solid-phase hydrostatic extrusion of linear polyethylene. Although the extrusion pressures were found to increase with the degree of complexity of the product sections, the module of the products were greatly enhanced and increased linearly with deformation ratio in the manner reported previously for circular section extrusions. Factors influencing the mechanics and stability of the process are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200805
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  • 16
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    A rheometer for measuring the viscoelastic response of polymer melts in arbitrary planar and biaxial extensional flow fieldsBased on a paper presented at the VIIIth International Congress of Rheology, Gothenburg, Sweden (1976) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 535-539 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this paper we describe the operation of a rheometer that is capable of measuring the viscoelastic response of a polymer melt in a biaxial or planar extensional flow field under circumstances wherein the deformation history can be varied in an arbitrary manner. The principal feature of this rheometer is the use of a closed loop feedback system to control the inflation of a flat, molten polymer sheet clamped around its periphery. The feedback system is especially designed so that either stress or strain can be used as the reference point, thus permitting the deformation history to be varied arbitrarily. Illustrative data are presented on the viscoelastic response of a molten acrylonitrile-butadiene-styrene copolymer subjected to a planar extensional flow for the following deformation histories: constant stress, constant strain, constant strain rate, oscillatory stress and oscillatory strain.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200804
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  • 17
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    High temperature dielectric study of epoxy resins (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 546-550 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Four common 177°C-curing organic resin formulations were studied dielectrically. Results and discussion are presented on the variation of resin electronic properties during cure. In particular, capacitance and dissipation curves are discussed as a function of time in the cure cycle. Variations in frequency are shown to affect the other electronic properties and a frequency “shift” in dissipation sensitivity is noted.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200806
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  • 18
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    Solid state extrusion of ultra high molecular weight polyethylene. Processing and properties (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 555-561 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The techniques of solid state coextrusion and powder extrusion have been employed for the deformation of ultra high molecular weight polyethylene. Chain folded and chain extended morphologies obtained under different crystallization conditions were coextruded within a nylon 11 casing acting as a processing aid at an extrusion draw ratio (EDR) of 5 at ≤ 120°C and 0.20 GPa. The powder was compacted and extruded at ≤ 128°C and 0.23 GPa up to an EDR of 24. The physical and mechanical properties of the extrudates were evaluated and found to be dependent on intial morphology. An extrudate from the chain-folded morphology gave a low modulus of 0.71 GPa, the chain-extended morphology a modulus of 6.7 GPa, and the compacted powder a modulus of 15 GPa.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200808
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  • 19
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    A comparative study of the tensile and charpy impact tests from a fracture mechanics viewpoint (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 572-578 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Charpy and tensile impact tests have been conducted on two materials poly(methyl methaerylate) (PMMA) and polycarbonate. It is shown that by adopting a fracture mechanics approach, it is possible to measure meaningful values of material toughness, and that the results obtained in bending are consistent with those in tension. A discussion of the assessment of “kinetic energy” errors is also presented.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200810
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  • 20
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    Melting performance in the single screw extrusion of thermoplastics (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 562-571 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Melting performance experiments involving three different thermoplastics and three different screw designs have been carried out on a well-instrumented single screw extruder equipped for cold screw extractions. In the case of the particular polystyrene used it was possible to deduce, from measurements made on the extracted screw, the velocity, and hence acceleration, of the solid bed of compacted polymer at points along the screw channel. The experimental results are successfully compared with the performance predicted by a previously established model, the most important feature of which is the ability to allow the solid bed to deform freely and hence to accelerate. The results show that the bed does indeed suffer significant and non-uniform acceleration and that the model can predict both this acceleration and the resulting bed break-up which leads to surging.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200809
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  • 21
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    Masthead (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980) 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200901
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  • 22
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    An anomaly in the necking behavior of polyethylene, Part 2 (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 579-584 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dumb-bell shaped specimens of three polyethylenes were subjected to constant uniaxial tensile loads at test temperatures from 298 to 353 K. For the high density polyethylenes, a marked transition appeared in the neck/fracture behavior. At a certain stress level, the instantaneous fracture of the neck formed at high loads was replaced by the formation of a neck that resisted fracture for a considerable time. This transition was more gradual for the medium density polyethylene. Furthermore, at all test temperatures the transition shifts towards higher nominal stresses with increasing molecular weight. Mainly on the basis of measurements of the local strain rate in the neck forming region, a hypothesis is proposed which explains the appearance of the marked transition. The draw ratios and the densities of the fractured neck fibers were also measured and are in accordance with current molecular deformation theories.
    Additional Material: 9 Ill.
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    Manufacture of high stiffness solid rods by the hydrostatic extrusion of linear polyethylene. Part I: Influence of processing conditions (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 589-596 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: High stiffness solid rods, up to 25 mm diameter, have been produced by the solid phase hydrostatic extrusion of a single linear polyethylene grade. Factors affecting the processing behavior and the product properties, as characterized by the enhanced axial Young's modulus and long term creep behavior, have been examined and sources of product flaws have been identified. At high product diameters extrusion occurred in a predominantly adiabatic thermal régime, for which the magnitude of the temperature rise was estimated by measurement of the long periods of the products. This adiabatic regime allowed high production rates to be obtained at lower extrusion pressures, but caused a reduction in the Young's modulus of the products and limited the maximum degree of deformation which could be obtained in stable extrusions.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200902
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    Effect of ferric ions on drag reduction effectiveness of polyacrylamide (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 493-498 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The drag reduction performance of polyaerylarnide polymers is severely degraded by the presence of ferric ions in solution. This effect has been noticed during the course of earlier experimental work and may have contributed greatly to poor reproducibility of results. The present work provides a more quantitative basis for estimating the effect of ferric ions on the drag reduction performance of polyacrylamide. Tests i a capillary-tube rheometer and in a one-in. pipe-flow facility provide data for estimating the possible degradation effect o several different commercial polyacrylamides. In some case the degradation products deposit on the pipe wall, causing a increased roughness effect.
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    On the rheology of packed polymer powdersPresented at the 2nd Joint Meeting, U.S. and Japan Societies of Rheology, Kona, Hawaii, April 6-8, 1979. (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 778-782 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rheology of polystyrene powder beds was examined by two kinds of experiments. From stress relaxation measurements during powder compaction, it was found that relaxation at the shorter times could be attributed to sliding between particles. This is followed by a relaxation attributed to the deformation of the polystyrene particles themselves. From dynamic mechanical measurements, an increase was found in the value of vibrational absorption coefficient (Q-1 value) at a temperature below that of the main relaxation dispersion of bulk polystyrene, attributed to the slipping around tight particle junctions. These phenomena appear characteristic of powder-like materials.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201203
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    Rheological characterization of polycaprolactam anionically synthesized in the presence of lithium chloride (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 783-786 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Melt viscosity and dynamic-mechanical data are reported for samples obtained by anionic polymerization of caprolactam, in the presence of LiCl. The full body of results is essentially in line with those previously reported relative to mixtures of inorganic salts and commercial nylon 6, In particular a drastic-decrease of the melting point and of the rate of crystallization is confirmed as well as an increase of the glass transition temperature and of the melt viscosity. Some quantitative differences exist, which may be attributed to the different molecular weight distribution in the polymers employed in the present work.
    Additional Material: 7 Ill.
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    Preparation of aligned discontinuous fiber pre-pregs by deposition from a suspension (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 787-797 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a process for production of aligned short fiber pre-pregs, fiber suspension passes through a converging channel to emerge as a thin free-surf ace sheet which is laid down onto a reciprocating horizontal filter surface. Following our previous work on fiber alignment in the channel, detailed studies are reported of the suspension sheet falling under gravity, and of the deposition stage. Close agreement is found between computed and experimental velocity profiles for sheets of fiber-free liquid. Modification of the velocities resulting from the presence of fibers aligned in the flow direction is taken into account using an increased extensional viscosity. This is evaluated using pre-existing theory which is tested experimentally and found satisfactory. A simple relationship between velocity and fiber alignment change in the falling sheet is derived and tested experimentally. Alignment is marred by surface disturbances to the sheet. Comments are made on the stability of the free-surface sheet. An experimental study is made of alignment changes as fibers are deposited on the filter, and the results related qualitatively to operating conditions. In general there is little difference in alignment before and after deposition, except close to the leading edge of the filter where alignment loss occurs. Previous work is reviewed and recommendations made on optimum operating conditions.
    Additional Material: 16 Ill.
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    Infrared studies of deformation in semicrystalline polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 805-815 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Infrared (IR) spectroscopy was used to study molecular deformation processes in polymers as a function of stress, strain, time and temperature. Stress-induced frequency shifts were found to depend on temperature and morphology. Deformation of viscoelastic polypropylene was examined in terms of time dependent molecular stress distributions, orientation changes, conformational variations, and chain fracture. A tie chain length distribution model was used to quantitatively interpret the IR data. Molecular deformation processes of creep and stress relaxation were found to be opposite in nature, Observed long lifetimes of highly stressed chains suggest a reappraisal of existing fracture theories.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201207
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    Masthead (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200801
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    Preparation of an ionomer elastomer by continuous sulfonation in an extruder and neutralization in static mixers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 530-534 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rapid and efficient sulfonation of ethylene-propylene terpolymer elastomer (EPDM) was achieved in a continuous melt mixing process. A mixture of sulfuric acid and acetic anhydride was used as the sulfonating agent. The reaction of EPDM polymer and the sulfonating agent was carried out in an extruder. It was shown that the continuous melt sulfonation of EPDM polymer may be used as an alternative to the batch solution methods previously reported for the preparation of sulfonated EPDM polymer. The extruder-reactor method offers advantages of shorter process time, elimination of solvent handling hazards, and abatement of solvent removal and recovery problems.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200803
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    Rheological and mechanical properties of plasticized poly(vinyl chloride) (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1037-1045 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dependence of rheological properties of a plasticized, filled poly(vinyl chloride) compound on three different methods of thermomechanical treatments has been studied. These three different states of the compound are the dry blend mixed at a maximum temperature of 93°C, the two-roll milled sample prepared at 150°C from the dry blend and the molded sample pressed at 170°C from the previously milled material. At 150°C the viscosity and elasticity of the molded sample are considerably higher than those of the dry blend and the milled sample. At higher temperatures, although their flow curves more or less merge, extrudate swell, extrudate appearance and extrudate tensile properties of the three samples vary. The mechanical and Theological properties of the quenched and annealed molded samples and those of the same compound without filler have also been investigated.
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    Studies on physico-mechanical properties of some new light weight engineering materials (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1085-1091 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Industrial, agricultural, and naturally occurring waste materials in conjunction with liquid epoxy resin, silica and asbestos were employed to make light weight engineering composite materials. To bring down the cost of the expensive resin, additives such as linseed oil and urea formaldehyde were added to replace the bulk of epoxy resin. Various physico-mechanical properties of these composites were studied. In comparison with ordinary cement concrete, properties such as water absorption and fire resistance improved substantially for the majority of mixes, whereas other physico-mechanical properties did not improve greatly in many cases. Such composites, which are similar to (and in some cases better than) ordinary cement concrete can be of use in building technology because of substantially lower prices.
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    URL: http://dx.doi.org/10.1002/pen.760211607
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    Masthead (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760211701
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    Optimal thermal design of compression molds for chopped-fiber compositesPresented at the second world Congress of Chemical Engineering, Montreal (October 1981). (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1139-1148 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Because heat is convected by the motion of material in the cavity of a compression mold, the time-averaged heating load on the cavity surface is nonuniform. In rapid production of large, thin parts, this can lead to large variations in cavity surface temperature when the mold is heated by the usual uniform distribution of heating lines. In this paper, a new method is developed for optimizing the mold heating design so that this nonuniform heating requirement can be satisfied with a minimum variation in cavity surface temperature. Oil heating is considered specifically, but the method can also be used for stream or electric heat. The optimal position and power supply for each heating line in the mold is determined by combining mathematical programming techniques with an analysis of the steady temperature field in the mold. The nonuniform heating load on the cavity surface is represented by a time-averaged steady heat transfer coefficient calculated from the transient temperature distribution in a polyester sheet molding compound as it fills the mold cavity. The design method is applied to an example mold for a large flat panel. At a one-minute cycle, the optimal heating design dramatically reduces nonuniformity in cavity surface temperature compared with a conventional distribution of heating lines. The optimal design is remarkably simple, uses only conventional equipment, and involves only half the customary number of heating lines. Nevertheless, it still has sufficient flexibility to adjust for changes in cycle time without sacrificing uniformity in cavity surface temperature.
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    Pressure development in the melting zone of a single-screw extruder (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1162-1166 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analysis is given of the pressure generation mechanism in the tapered channel of a single-screw extruder. It is shown that when increasing the throughput the pressure build-up capacity of the melting zone tends to decrease. As a result, severe pressure drops may occur in the tapered sections. A relationship between the pressure profile and the melting mechanism (solid bed/melt pool configuration) is described in terms of the cross-channel melt circulation.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760211708
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    Sintering rheology of amorphous polymers (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1167-1170 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The activation energy for sintering of poly(methyl methacrylate) particle pairs is shown to be similar to their activation energy for Newtonian flow. Sintering progress with time is in good agreement with the Frenkel's coalescence theory. Typical sintering shear rates are shown to be very low and potential energy change (two particles) is small in comparison with the surface energy change. These results lead to the conclusion that the coalescence sintering mechanism of amorphous polymers above their glass transition temperature is essentially a Newtonian viscous flow mechanism where surface tension is the major driving force. A periodical phenomenon associated with sintering progress with time is reported and a supporting mechanism is proposed.
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    A theoretical analysis of non-isothermal flow in wire-coating co-extrusion dies (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1128-1138 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theoretical study of non-isothermal superimposed flow of two polymer melts in wire coating co-extrusion dies has been carried out. Numerical methods have been employed to solve the coupled momentum- and energy-balance equations. Various combinations of three polymers - namely, high density polyethylene (HDPE), polystyrene (PS) and low density polyethylene (LDPE) have been studied and least squares curve fitted quadratic polynomials have been used for constitutive equations for all three polymers in non-Newtonian high shear rate regions. A multitude of thermal and mechanical boundary conditions can be treated by this algorithm. It was found that temperature and velocity profiles in the die depend significantly on the arrangement of the polymers. Maximum temperature rise has been noted to increase sharply with wire velocity but it can be reduced by increasing the die radius. When the thickness of the outer layer is increased from zero, the shear stress at the wall undergoes a dramatic change (if the viscosities of the polymers are different) at small values of the flow rate ratio and it reaches an asymptotic value at large values of flow rate ratio. It was also found that viscosity ratio at the interface can be reduced by changing the initial temperatures of the liquids. It was observed in some cases that large errors in the calculation of rheological and thermal variables for this problem can be made if temperature rise due to viscous dissipation is not considered.
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    Weld line structures and properties in injection molded polypropylene (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1149-1155 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Weld regions are formed wherever polymer flow fronts meet. The present study examines the effects of melt temperature, mold temperature, mold cooling conditions, injection speed and annealing on the tensile properties and morphological structure of weld regions in four commercially available polypropylene resins. One of the resins contained nucleation particles. Scanning electron micrographs of the weld region revealed a wide range of morphologies from very strong welds which formed part of a stable neck to brittle failures at low elongation caused by the presence of large nucleation particles in the weld region. The melt temperature, mold temperature, and annealing had the greatest effect on the weld region's tensile properties.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760211706
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    The viscosity of fiber suspensions at low fiber volume fractions (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1171-1172 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The viscosities of suspensions of glass fibers in an aqueous solution of sucrose have been studied by use of a capillary viscometer. In the aligned condition in the capillary, the viscosity depends little on shear rate within the range studied or on fiber length, but increases with increasing volume fraction of the fibers. The entrance effect was found to depend strongly on fiber volume fraction and fiber length: this indicates that the suspensions are relatively resistant to flow during the initial stages while alignment takes place.
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    Masthead (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760211801
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    New model of curing process kinetics of diurethane crosslinked natural rubber (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1188-1193 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new model for the curing kinetics of diurethane crosslinked natural rubber is elaborated. On the basis of rheometric data, calculation of rate constants of both formation and degradation of the following bond types: urea-urea, urethane-urethane, and urea-urethane, was enabled and thermal activation energies of these processes were determined. Activation energy values for formation of the bonds above are: 61.5 kJ/ mole, 187.6 kJ/mole, and 28.9 kJ/mole, respectively. For degradation, activation energies are: 293.9 kJ/mole, 195.5 kJ/mole, and 163.3 kJ/mole, respectively. An algorithm for carrying out of these calculations on a computer was developed.
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    The effect of annealing on the thermal properties of reaction injection molded urethane elastomers (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1210-1217 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Reaction injection molded (RIM) polyurethanes, especially reinforced RIM polyurethanes, are promising candidates to replace metal exterior body panels on automobiles. One of the most important performance properties which these RIM parts must possess is thermal dimensional stability. Thermal dimensional stability is defined as the ability of a part to withstand distortion or change in size during thermal cycles. This property is important for two reasons. First, during paint operations parts are exposed to high paint bake temperatures. Second, parts may be exposed to relatively high temperatures in use. Thermal dimensional stability is mostly controlled by formulation and post-treatment. Formulation can change the structure of the polymer leading to different thermal properties. Posttreatment such as annealing can change (a) the degree of hard segment phase order, (b) the degree of phase separation and (c) the relative continuity of the phases. Experimental evidence is given to support all these factors.
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    Molecular weight distribution in novolac-type polymerization in homogeneous, continuous-flow stirred tank reactors (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1218-1227 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetic model for irreversible novolac type phenol formaldehyde polymerization and equations governing the molecular weight distribution (MWD) of the polymer formed in homogeneous continuous-flow stirred tank reactors (HCSTR) have been derived. The set of algebraic equations involves three reaction parameters R1, R2, and R3 and have been solved using Brown's algorithm which was found to be more efficient than the Gauss-Jordon technique of solution. A sensitivity analysis of different reaction parameters has been carried out and the reactivity of the para position was found to be an important factor affecting the MWD. In view of the fact that parameters R1 and R2 have a negligible effect on MWD, the phenomenon of molecular shielding described by Drumm et al. (1) can be neglected. The novolac formation can then be equivalently described by assuming R1 = 1 and R2 = R3 and the kinetic description so obtained is completely based on the experimentally observed different reactivities of ortho and para sites. The results for HCSTR have been compared with those for batch reactors and the former is found to give polymer of lower average molecular weights having higher polydispersity index.
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    Addition polyimide adhesives containing various end groups (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 9-14 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Addition polyimide oligomers have been synthesized from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 3,3′-methylenedianiline using a variety of latent crosslinking groups as end-caps. The nominal 1300 molecular weight imide prepolymers were isolated and characterized for solubility in amide, chlorinated and ether solvents, melt-flow and cure properties, glass transition temperature, and thermal stability on heating in an air atmosphere. Adhesive strengths of the polyimides were obtained both at ambient and elevated temperatures before and after aging at 232°C. Properties of the novel addition polyimides were compared to a known nadic end-capped adhesive, LARC-13.
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    High modulus semi-crystalline polymers by solid state rolling (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 27-33 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Solid state rolling of semi-crystalline polymers is shown to be an effective method of producing high strength, high modulus tape at acceptable production rates. High density polyethylene tape was produced having a tensile strength exceeding 300 MPa and a tensile modulus of 8.7 GPa at production rates exceeding 8 m/min. A significant factor in producing highly oriented tape by the rolling process is roll temperature. Increasing the roll temperature from 25°C to 125°C not only increases the maximum extent of orientation achievable, but increases the mechanical properties at a given degree of thickness reduction. Internal frictional heat development limited the maximum thickness reduction ratio of polypropylene to 6.6:1. This reduction was reached by rolling at 150°C. The resultant tape had a tensile modulus of 5.1 GPa and a tensile strength of 300 MPa.
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    Residual stresses in polymers I: The effect of thermal historyThe availability of appropriate illustrations has led to publication in this journal of Part II (Vol. 21, NO. 15, page 997) p or to this Part I. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 40-47 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The distribution of residual stresses in quenched modified poly(phenylene oxide) (PPO) specimens was investigated. Quenching was carried out from temperature level above Tg to various temperatures below Tg. As expected, compressive stresses were measured at the surface layers while tensile stresses were in the inner layers. The ratio between the tensile and compressive stresses varied, depending on the thermal history. The level of residual surface stresses was found to depend on both the total temperature difference during cooling and the initial specimen temperature. At constant initial temperature the surface stresses are proportional to the total temperature difference, whereas, at constant final temperature the surface stresses are inversely proportional to the total temperature difference. An empirical correlation describing the surface stresses as a function of thermal history has been suggested. The differences between present theories and experimental data are discussed. emphasizing the apparent discrepancy regarding the influence of initial temperature above Tg on the level of residual stresses.
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    The lower critical solution temperature (LCST) of non-polar polymer solutions: An introduction (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 58-63 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The phase behavior at high temperatures of non-polar polymer solutions is discussed in a qualitative way in terms of the free volume theory of liquids developed by Prigogine, Patterson and Flory. This theory is necessary to explain the existence of a Lower Critical Solution Temperature (LCST) in non-polar polymer solutions and the related exothermic heats of mixing. The classical theory of polymer solutions and its limits is first reviewed.
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    The transesterification of bisphenol-a polycarbonate (PC) and polybutylene terephthalate (PBTP): A new route to block copolycondensates (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 229-233 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this work, the exchange reaction taking place in molten blends of bisphenol-A polycarbonate and polybutylene terephthalate was studied. A direct transesterification mechanism catalyzed by titanium residues, present in commercial PBTP, was deduced. The transesterification reaction can be -stopped at various levels by additives capable of complexing the titanium catalyst.This work enhances the possibility of a new approach in macromolecular engineering by directly combining polycondensates in a processing machine such as an extruder.
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    An analysis of thermal warpage in injection molded flat parts due to unbalanced cooling (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 241-247 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: To illustrate the potential effect of unbalanced cooling on warpage of flat parts, a simplified two-part analysis is presented. First a computational model for amorphous polymers cooling in an injection molding cavity is presented. The simulation is a finite difference solution of the one-dimensional, transient heat conduction equation with constant material properties. Plastic and mold temperature profiles are calculated through the cooling cycle and the transients from cycle to cycle are included. Temperatures are predicted for both sides of the mold allowing asymmetrical cooling to be analyzed. The model is verified analytically and is in agreement with published data. Secondly, a simplified method of predicting the thermal warpage of a fiat part from calculated temperature profiles is discussed and illustrated. The relative effects on calculated part warpage of asymmetric mold geometry and cooling fluid temperature are predicted with this analysis method. The sensitivity of warpage to these design factors is illustrated for an example part.
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    Some rheological aspects of fracture in thermoforming (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 265-268 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper focuses on several aspects of drawability, including the interactions between material parameters, operating temperatures, and frictional properties of the material. The deep draw process for a molten plastic sheet can be described by a simplified model using the characteristics of the normal stress as a lumped parameter. A rapid evaluation of the draw ratio and mold closing speed can be obtained by systematically drawing a series of three draw ratios. The fracture mode should then be examined to determine the appropriateness of molding temperatures. Therefore the maximum attainable draw ratio can be calculated from the elongational viscosity data. To support the analysis, data is provided on the formation of a cup with polystyrene sheets and using Maxwell extensional model as an example.
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220501
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    Anisotropy and dimensions of blow-molded polyethylene bottles (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 287-291 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A commercial blow-molding grade, high-density polyethylene resin was employed to produce cylindrical bottles in a commercial reciprocating screw-extrusion blow-molding machine. The distributions of thickness, crystallinity, birefringence, and impact strength were obtained at various positions. The thickness is greatest near the parting lines, while minimum thickness occurs at the top and bottom of the bottle. The thickness tends to be uniform in the middle section, in agreement with earlier studies of the parison during processing. Density and crystallinity distributions are closely associated with the distribution of thickness and its effect on the cooling rates prevailing during molding. Frozen stresses and birefringence are largest at the outer surface, where cooling rates are highest. The impact strength is lowest near the parting line. Photomicrographs suggest that this is associated with internal flow and crystallization phenomena.
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    Model of steady-state melt spinning at intermediate take-up speedsPresented at 2nd Joint Meeting of U.S. and Japanese Rheological Societies, Kona, Hawaii, April 6-9, 1979. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 292-299 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model of melt spinning has been developed for speeds above which the effects of gravity, inertia, and aerodynamic drag become significant. The model has as an upper bound the speed at which stress crystallization begins to occur on the spin line. For poly(ethylene terephthalate), these velocities are approximately 750 and 3500 meters/minute. The calculated temperature and velocity profiles are shown to agree with measured values. The stress at the freeze point is calculated and found to correlate well with the spun yarn birefringence which, in turn, is shown to predict uniquely the spun yarn physical properties on a “simple” spin line. The stress-optical coefficient derived from the calculated stress at the freeze point and measured birefringence agrees well with the literature.
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220601
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    The principles of pipe-line design for molten poly(ethylene terephthalate) (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 141-146 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The flow of molten poly(ethylene terephthalate) in pipes is discussed. The considerations made are based on the results of previous investigations by the authors, concerning the rheological behavior of the melt which exhibits thermal degradation. A procedure is proposed which enables the design of a pipe-line system for the distribution of molten, spinnable poly(ethylene terephthalate) in a fiber plant to be made.
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    Shear-induced anisotropy in thermal conductivity of a polyethylene melt (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 154-157 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A rotating concentric-cylinder thermal conductivity cell for polymer liquids is described. Thermal conductivity can be measured at temperatures approaching 200°C and at strain rates up to 400 s-1, The transient heat flux probe (with inner cylinder as heat source and temperature probe) method is used to permit the separation of the viscous heating effect from the probe heating effect.A polyethylene melt was studied and showed that at 50 s-1, a 2 percent increase in thermal conductivity occurs, followed by a gradual decrease until a value 10 percent less than the no-shear thermal conductivity was found at 400 s-1. This effect is due to molecular orientation.
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    Modeling of polymeric film-blowing processesPresented at the 52nf Annual Meeting, Society of Rheology, February 1981. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 172-181 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Industrial film-blowing processes are characterized by large deformation rates, rapid changes of temperature and high stress levels. A pilot scale process was set up to simulate these variables. The pivotal element in modeling the process is a rheological constitutive equation which describes the fluid properties accurately over the entire range of conditions encountered; it was found that contributions to the stress in the material which arise out of the changing thermal history of a fluid element were a significant fraction of the total. When the deforming film is subjected to stretching but to little or no blowing, the axial stresses in the film are predicted excellently by the model under both isothermal and non-isothermal processing conditions. With rapid blowing and major deviations from uniaxial extension, the axial stresses are predicted less well, but still satisfactorily, under the conditions used. In no case are the circumferential stresses predicted accurately: i.e. unequal biaxial extensional deformations represent complications which have not been resolved.
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    Influence of molecular weight and molecular weight distribution on mechanical properties of polymers (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 205-228 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This work reviews the literature published over the last ten years on polymer mechanical properties as a function of molecular weight and molecular weight distribution, Thermal properties, stress-strain properties, impact, fracture, fatigue, creep, stress relaxation and cracking and crazing are examined for a wide variety of homopolymers and a limited number of copolymers. In general, mechanical properties increase as the molecular weight increases. However, above some limiting molecular weight the mechanical property is usually unaffected. Although much work has been done to describe the effects of molecular weight on mechanical properties, little quantitative correlation exists. The available equations to predict such properties as cracking and crazing, Tg, Tm and tensile strength from molecular characteristics are discussed in detail. However, a more quantitative description incorporating a wider range of mechanical properties would be more useful. This would facilitate use of the vast amount of information available and enable it to be applied more readily to new polymer systems.
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    Processing properties of high- and low-density polyethylenes and their blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 280-286 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of two characterized linear polyethylenes with a branched polyethylene have been prepared by melt extrusion. It has been found that the linear polyethylenes can be shear modified in a reversible manner similar to branched polymers and that this shear modification and its reversal by re-heating does not change the molecular weight distribution, thereby indicating that the shear modification is a physical rather than chemical change in structure. Because both the high- and low-density polyethylene components of the blends are capable of undergoing reversible shear modification, it is possible to produce blends with either greater or less melt elasticity than the individual components by adjusting the conditions of blending. This demonstrates that the correlation of the properties of blends with the properties of their components should not be attempted without consideration of the effect of the blending process on the properties of the individual components.
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    The limiting pressure-velocity (PV) of plastics under unlubricated sliding (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 248-253 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The limiting pressure-velocity (PV) of plastics materials under normal contacting pressure P and sliding velocity V when the sliding goes on continuously unlubricated has been discussed theoretically in this study. The sliding friction tests between the rotating edge of a hollow cylinder against a stationary metal surface were carried out in room air and when the metals were cooled with circulating water.The results obtained were as follows: The relation between PVmax and the critical temperature τbmax of the surface above which ordinary frictional conditions are not maintained may be represented by the following formula, \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm PV}_{max} = C(\tau _{bmax } - \tau _a)} & {(1)} \\ \end{array} $$\end{document} Where C = Hn/μk, and H is the mean total heat conductivity between materials and environment in cal/cm2. °C · s, n the area ratio of heat radiation surface to frictional surface, μ the kinetic frictional coefficient, k the thermal equivalent of frictional work in cal/kg · cm · s, and τa the cooling or environment temperature.The value of C ranges from 1 to 10 in cal/kg · cm s · °C, and the value of PVmax from 45 to 750 in kg/cm2 · cm/s under prevailing room temperature air cooling in this experiment, however, the value of C has been increased about 2.3 times as much as those values by circulating water of 2°C around the lower side of the test piece.
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    Solid-phase backward extrusion of thermoplastics (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 269-279 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The backward extrusion process was studied as a means of forming projections and ribs on flat sections of thermoplastic parts. The simplified, open-die axisymmetric and plane-strain extrusion cases were mainly considered. The results were applied to the development of a continuous solid-phase-forming process. Commercial-grade polycarbonate (PC), polypropylene (PP), and polystyrene (PS) were used in the investigation. The projection height and extrusion loads in the unconstrained extrusion were measured as a function of the initial temperature of the material, the load hold time, and geometric variables. Cold dies were used in the experiments, and the samples were kept below their melt temperatures. The dimensional recovery of the flange section of the formed samples was also measured as a function of the hold time for given initial temperature and geometric variables. The slab and the upper-bound methods-in plasticity analysis were used to theoretically derive the projection heights and forming loads. The degree of correlation between the predictions and the experimental results depended on the estimates used for the frictional factors at the interfaces between the deforming material and the dies.
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    Effect of compaction rate during the cold forming of polymeric powders (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 300-306 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: During many plastics processing methods, both conventional and novel, plastic powders or granules are subjected to pressure. The pressure transmissibility through the powder has an important effect on the success and efficiency of the process, and so it is desirable to be able to predict the pressure at any point from a knowledge of the applied pressure and the geometry of the system. To examine this pressure transmissibility effect, poly(vinylidene chloride) powder has been compacted in a metal die under different rates using either load or displacement control. It has been found that rate effects are particularly important for loading rates greater than 8 MPa/s and displacement rates greater than 7.5 mm/s. The ratio of transmitted pressure (P2) to applied pressure (P1) has been measured for a range of compact geometries, and it has been found that the ratio is approximately constant during the latter stages of the compaction process. Various laws for predicting the transmitted pressure have been studied, but it has been found that the simplest equation that agrees with the data is of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{P_2 }}{{P_1 }} = e^{- \alpha \mu ch/D} $$\end{document}
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220701
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    Rheokinetics of polymerization of N-laurylmethacrylate (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 402-409 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The free radical polymerization of n-laurylmethacrylate has been studied using a combination of rheological and kinetic methods. In addition to classical dilatometry, the extent of reaction of a polymerization was followed in a cone and plate rheometer by measuring the change in the diffraction of a laser beam shone through the polymerizing sample parallel to the plate of the rheometer. The change in diffraction was caused by the change in index of refraction of the monomer becoming polymer, which was related to the extent of reaction. Simultaneous measurements of loss and storage moduli and dynamic viscosity at 1 Hz provided the data necessary for correlating changes in the kinetics with changes in the rheology of the polymerizing system.
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    A network flow analysis of extrusion dies and other flow systems (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 432-437 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method is presented to calculate the slow viscous flow distribution in systems of passages, for which the major velocity components are substantially parallel to the axes of those passages. That condition is generally satisfied in flat extrusion dies, disc filters, in-line filters, and other now devices. A finite difference matrix method is initially used to determine the flow distribution for an assumed viscosity distribution. That flow distribution is next used to determine a new distribution of resistances, now based on a specified rheological equation. This process is iterated until there is no significant change in the flow distribution. The passages are subdivided in this method and replaced by a network of resistances. A few unknowns are introduced at one end of the network, which are solved at the other end, using a matrix marching routine. The method is described for newtonian flow through a flat die with equalizing channel, for which the analytic solution is known. Results are shown for that die for flow of power law liquids.
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    Fracture surface features of polyethylene pipe samples (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 549-555 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Slow crack growth behavior of medium-density polyethylene pipe samples has been investigated by applying standard and nonstandard fracture mechanics test methods. Slow crack growth rate varied by several orders of magnitude among the PE2306 materials from different manufacturers. Slow crack generated surfaces exhibit fibrous textures of varying degrees of coarseness when examined under the scanning electron microscope. When the measured fiber heights, δ/2, of these samples were plotted against the applied stress intensity factor, KI, they showed a simple power law relationship (of exponent 2). Assuming that the pulled-out fibers transmit almost uniform tensile stresses across the crazed zone at the crack front, the Dugdale-Barenblatt model was introduced to predict the fiber height. Although the model needs further modification, it provides a general power law relationship between the fiber height and the applied stress intensity factor.
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    The dynamics of parison free inflation in extrusion blow molding (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 569-577 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Parison free inflation behavior, associated with the extrusion blow molding process, is considered both experimentally and theoretically. Experimental observations indicate1 that the parison assumes a rather complex shape under conditions of unrestricted inflation. In particular, the time-dependent shape is markedly ellipsoidal rather than cylindrical in nature. This nonuniform behavior, however, becomes more prominent in relation to the entire length as the parison-length-to-diameter ratio is decreased. Based on the experimental observations, a simplified analytical treatment of the free inflation of a viscoelastic parison is presented. The theoretical results illuminate the influence of material properties and process conditions on the inflation process. Expectedly, inflation is enhanced by an increase in the pressure driving force as well as by a decrease in viscosity. However, melt elasticity is also found to exert a significant influence on the inflation behavior. Moreover, the theoretical analysis suggests that the initial parison dimensions play a central role in controlling the inflation process.
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    A plasticating model for single-screw extruders (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 578-586 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: By measuring the solid-bed transfer velocity, width and thickness under various conditions, die following results are obtained. As the result of melting, the solid bed decreases in width and thickness almost with the same rate, and the solid-bed transfer velocity is constant, while a melt layer exists between the solid bed and the screw root; also, when the phenomenon of dam-up occurs, caused by the combined effect of decreasing depth of the screw channel with tin insufficient decrease of solid-bed thickness, the transfer velocity increases proportional to the rate of decrease of channel depth. Consequently, the solid bed is considered to behave us loosely packed particles. A new plasticating model is developed by making the above results an assumption and adopting finite differential calculus with the Newton-Raphson method to obtain accurately the melting velocity, melt profile, and solid-bed temperature. Calculated values are in remarkably good agreement with the experimental values Solid-bed softening point, pressure, and screw torque are also successfully estimated.
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    Modeling of poly(ethylene terephthalate) reactors: 5. A continuous prepolymerization process (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 619-627 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A mathematical model for the continuous prepolymerization of BHET to PET, carried out in a series of stirred tank reactors, has been developed. The influence of process and operational variables on productivity, as well as the side-product formation (which controls the product quality), have been studied in a range as close to industrial practice as possible. The overall conclusions concerning the productivity profile, as well as some side products, appear to be substantiated from the available data in the open literature. The results of the mathematical model have been used to highlight the key process and operational variables that are likely to give the best productivity and product quality in industrial practice.
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    Modeling of poly(ethylene terephthalate) reactors: 4. A continuous esterification process (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 610-618 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A mathematical model has been developed for the direct, continuous esterification process. Influence of process and operational variables, including temperature distribution, residence time distribution, bis(hydroxyethyl)terephthalate recycle, pressure, and ethylene glycol (EG) to terephthalic acid ratio on the reactor performance have been investigated in a range as close to industrial practice as possible. The variables influencing the amount of EG reflux (which governs the energy economy) and side products (which govern the product quality) have been discussed. This investigation provides an analysis of a continuous, direct esterification process, and the results indicate strategies for optimizing productivity and product quality.
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    Mechanistic studies of adhesion promotion by γ-aminopropyl triethoxy silane in α-Al2O3/polyethylene joint (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 637-644 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to understand the mechanism of adhesion promotion by organo silane in joints where its chemical reaction with a polymer matrix may be negligible, we studied the role of γ-aminopropyl triethoxy silane (γ-APS) in α-Al2O3/ polyethylene joints. When adsorbed or deposited on α-A12O3/ and moderately dried, γ-APS forms a multimolecular film that is not fully cured. Drying at elevated temperatures for an extended time leads to further curing, resulting in a glassy silane film with a Tg around 108°C, while prolonged dry may cause some degradation. Joint strength is markedly improved by the application of a γ-APS film with a maximum peel strength of 2.3 kg/cm when the silane is applied from a 2 percent aqueous solution. Drying the silane at an elevated temperature prior to joint formation reduces joint strength and also changes the failure mode from cohesive failure through the polyethylene to a mixed mode. Evidence of interdiffusion between γ-APS film and polyethylene at a temperature (149°C) that is above the melting point of polyethylene and the Tg of the silane film was obtained by measuring the Si concentration profile across the interface of the laminate of polyethylene/γ-APS/polyethylene. Diffusion constants in the order of 10-12 cm2/s were obtained, with a teridency toward reduced diffusion as a consequence of extensive drying. DSC results indicate at least partial miscibility of the silane polymer in the amorphous region of polyethylene. It is proposed that the interdiffusion between γ-APS silane film and polyethylene is an important mechanism for adhesion promotion of the joints investigated in this study.
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    Correction (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 697-697 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221108
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    The mechanical properties of styrene-butadiene-styrene (SBS) triblock copolymer blends with polystyrene (PS) and styrene-butadiene copolymer (SBR) (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 673-683 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurements were made of linear viscoelastic properties and nonlinear stress-strain properties of phase-separated styrene-butadiene-styrene (SBS) copolymers and their blends with several homopolymer polystyrenes (PS) and one random copolymer (SBR). Torsion pendulum testing yielded shear moduli G′, G″, and Rheovibron experiments produced tensile moduli E′, E″, over a 220°K range of temperature, both at low frequencies. For pure copolymers and their PS blends, G′ and E′ correlated quite well with the total PS content, but G″ and E″ were more sensitive to how the additive was distributed. Results suggest that a PS additive whose molecular weight (M) is less than that of the copolymer PS-block (Ms) causes expansion of both the interphase and the homogeneous PS-rich phase, while an additive with M 〉 Ms mixes less well with these phases (probably forming separate domains of pure PS) and is less effective in enhancing the linear moduli. The blending with SBB produced reduction in G′ but a broad midrange peak in G″, suggesting that SBR was localized almost entirely within an expanded interphase. Tensile stress-strain data were obtained with an Material Testing System at room temperature. For PS blends, properties did not correlate well with the total PS content, the blends being always weaker than the SBS of the same overall composition. The amount of set also increased with PS content in the blends. Cyclic tests to increasing strain showed progressive structural alterations (as for the host SBS), with blend behavior resembling host properties more closely with each new cycle. When SBR was the additive, amounts as small as 1 percent reduced the curves by 15 percent. The yield stress was eliminated entirely with an addition of 10 percent SBR, but for all cases the set was the same. Results are discussed in terms of interphase force barriers to chain flow.
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    Analytical melting model for extrusion: Melting rate of fully compacted solid polymers (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 729-737 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The melting mechanism inside screw extruders is presently analyzed using numerical, iterative methods that are too complex to be used widely by practicing engineers. Our theoretical and experimental investigations of the melting mechanism have produced simple, analytical equations for predicting the melting rate of fully compacted solid polymers without iterative calculations. The accuracy of these equations was found to be satisfactory. Consideration of the temperature and shear dependencies of the melt viscosity was found to be essential for the accurate prediction of the melting rate.
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    URL: http://dx.doi.org/10.1002/pen.760221202
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    Fracture analysis of acrylonitrile-butadiene-styrene resins (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 760-765 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fracture properties of three grades of acrylonitrile-buta-diene-styrene(ABS) were evaluated and compared. In preliminary studies, J1c (J integral) results obtained using the Begley and Landes procedure for single-edge-notched tension specimens and compact tension specimens were compared to establish the validity of the J1c criterion. It is shown that the Rice single-specimen approximation can be applied for this material, resulting in considerable simplification of the testing procedure. The J1c values for two of the grades were evaluated at two or more rates using the compact tension geometry and the single-specimen procedure over a temperature range of-60° to + 75°C. The results are analyzed in terms of a modified Eyring model, and the activation energies for the two grades of ABS were found to be 13.7 and 36.7 Kcals/mole, respectively.
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221301
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    A criterion for craze formation (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 766-776 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A general criterion for craze formation is presented. Crazes are deformation zones that are common to both glassy and semicrystalline polymers. Crazes are composed primarily of fibrils. This paper attempts to describe the process that transforms unoriented glassy and semicrystalline polymeric solids into a fibrous state. The criterion for crazing discussed is a local phase transition. The transition occurs at the draw temperature. Unoriented solid-phase macromolecules, at local high-stress regions, undergo a transition to the elastomeric phase. Rapid extension and accompanying resolidification produce the fibrous morphology of craze fibrils. Cavitation of the deforming rubber phase ocurs because the local length increase is riot compensated for by an overall area decrease. Craze formation in glassy polymers has long been suspected to involve a local solid-to-rubber phase change. To relate crazes in glassy and semicrystalline polymers, one can assume that a solid-to-rubber phase change is required to produce craze fibrils in semicrystalline polymers. The transient melt phase would undergo rapid elongation, causing the formation of extended chain crystallites. These subsequently nucleate the remaining melt, which then crystallizes epitaxially as lamellae. Crystallization during flow would, therefore, be the mechanism of fiber formation.
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    Characterization of plastics in fire (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 793-797 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fire is a complex process in which temperature and oxygen concentration vary considerably. The methods of characterizing the flammability of plastics materials advocated in this paper use simple test procedures in a series of different fire environments; i.e., at different temperatures and oxygen concentrations. The limits of both flaming and smouldering combustion, flame spread, and burning define the burning behavior of materials as dynamic multivariable parameters and not as single-point data characteristics of the majority of current fire tests. The feasibility studies were based on modified oxygen index (ASTM D2863, NES 715) and Setchkin furnaces (ASTM D1929). The burning behavior of plastics may also be directly affected by their softening and viscosity characteristics, and this has been explored with relation to suspended ceilings and stacking chairs. The techniques used showed major differences between materials that may not always be seen in standard single-point tests but which have been correlated with full-scale ad hoc tests; e.g., room and corner tests, and actual product tests.
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    Dependence of mechanical properties in polyolefin blends on shear and thermal history (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 433-438 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Variously dispersed two-component blends of linear polyethylene and a thermoplastic rubber were subjected to different thermal histories after compression molding and their properties were evaluated. It has been shown that ultimate properties of the blends are not defined by the composition, but vary greatly with degree of dispersion and thermal history. Stronger materials failing in a ductile manner were produced under shock cool conditions and in, finely-dispersed blends. Brittle failures and weaker materials were favored by annealing procedures and in blends subjected to brief and/or lowshear dispersion procedures. Time and temperature dependent changes in properties of blends prepared under standard conditions have been observed and activation energies for the aging process calculated. Data interpretation was based on a hypothesis of domain morphology in the blends, and on the existence of “tie molecules” which help to determine the cohesive strength of domain boundaries.
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    The development of C-10 phthalocyanine for composite matrix applications (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 441-448 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermomechanical analysis was carried out for various phthalocyanine resins. The polymer based on the C-10 diamide resin was then chosen for evaluation as a potential composite matrix material. Prepregs with Thornel 300 graphite reinforcements were successfully prepared using a hot-melt technique. The processability of this material was studied by employing instrumental techniques including differential scanning calorimetry, thermal gravimetric analysis and dynamic dielectric analysis. A cure cycle was developed for the fabrication of angle-ply laminate using the conventional vacuum-bag technique in a hydraulic press. Laminate mechanical properties both in tension and in flexure were determined. The results for the C-10/T-300 samples were shown to be similar to those of an epoxy/graphite and a polyimide/graphite composite system.
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    The effect of molecular orientation on the mechanical properties of fiber-filled amorphous polymers (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 449-456 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The technology of using glass fibers to increase the modulus and the strength of polymeric systems is well-developed. Much less widely exploited has been the enhancement of properties by orienting the molecules of the polymer itself. The purpose here was to look for a synergistic combination of these two strategies: using glass fiber-filled polystyrene and introducing molecular orientation into the polystyrene matrix. For rheological reasons it is not possible to introduce large stretch ratios in the rubbery state and thus the amount of molecular orientation that can be frozen into the quenched glassy composite is small. Even so, however, the rubbery elongation (which we associate with subsequent molecular orientation) has a very significant effect on the final (room temperature) mechanical properties. Analysis of these properties was made in terms of various theoretical models (those of Brody and Ward, Smallwood-Guth, and Russel and Acrivos for the Young's modulus; and that of Kelly and Tyson, as modified by Lees, for the tensile strength). These comparisons showed that the brittleness of unoriented polystyrene is such that the matrix does not effectively distribute the stress along the length of the fiber and thus the benefit of the length is not realized; whereas the higher ductility of oriented polystyrene allows such transfer and a consequent improvement of properties.
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    URL: http://dx.doi.org/10.1002/pen.760210803
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    Characterization of the interlaminar shear fatigue properties of SMC R-50Owens Corning Fiberglas. (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 461-466 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The interlaminar shear fatigue behavior of the sheet molding compound SMC-R50 has been studied. A thick-laminate, short beam shear test was employed to characterize S-N behavior for the material at 21 and 90°C. The shear modulus (Gxy) was determined at 21 and 90°C and the effect of fatigue on modulus at both test temperatures is discussed. Scanning electron microscope (SEM) and optical photomicrographs of pristine and post test specimens were studied to assess the relationship between material microstructure and the observed fatigue results for strength and modulus. The experimental evidence suggests that the fatigue life for this material is determined by a single flaw growth mechanism, rather than a global “wear out” process.
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    URL: http://dx.doi.org/10.1002/pen.760210805
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    Flow, pressure distributions, and internal forces in stacked-disc filters (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 895-901 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A mathematical model is described for isothermal flow of Newtonian liquids through stacked-disc filters. Dimension-less flow rates, velocities through filter media, pressure distributions, and internal forces are shown as functions of resistance ratios and reduced dimensions. The distribution of velocities through the media is a strong function of the ratios of the resistances to flow through the gaps between discs and through the spaces inside the discs to the resistance to flow through the filter media. Internal forces compress the discs and can, in exceptional cases, impair the media and open up leakage passages.
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    URL: http://dx.doi.org/10.1002/pen.760221408
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    A comparison of impact tests for assessment of fiberglass reinforced plastic toughnessPresented at the 35th Annual Technical Conference, Reinforced Plastics/Composites Institute, The Society of the Plastics Industry, Inc., New Orleans (1980). (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 467-473 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: All measures of impact resistance have shortcomings. The ASTM tests, Izod, Charpy, and drop-dart, measure impact at a single velocity. Furthermore, the Izod and Charpy tests impose an unrealistic unidimensional stress on the test specimen. Indirect gauges of impact toughness, such as the area under the tensile stress-strain curve (tensile work), flexural modulus, or resin cracking in mandrel bend tests, are normally conducted at unrealistically low straining rates. Variable-rate impact testers have been developed to overcome these shortcomings. In this paper, results obtained from a variable-rate tester are compared with those from other methods for assessing composite toughness. Data are reported for flexible and brittle low profile press molding resins, tested as SMC (sheet molding compound) moldings by Izod, drop-dart and variable-rate impact. Indirect measures of impact resistance, mandrel bend and flexural modulus, are also discussed. The effects of resin flexibility and the composite glass content are demonstrated. The glass content affects the ultimate failure strength of the composite but not the failure of the resin matrix. The resin flexibility affects the initial stages of failure.
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    Effect of aging and moisture on the reactivity of a graphite epoxy prepreg (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 474-482 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of moisture on the curing reaction of Hercules 3501-6/AS graphite-epoxy prepreg was investigated. Test samples of prepreg were aged under humid conditions, while control samples were aged under identical temperature conditions but with negligible humidity. Determinations of the amounts of moisture absorbed and desorbed fom the samples were accomplished gravimetrically. Dielectric analysis was used to monitor the relative reaction rates and overall activation energies of the prepreg after various aging periods. Changes taking place in monomer concentrations were observed using high performance liquid chromatography (HPLC). As aging continued, samples aged under humid conditions displayed, significant decrease in the overall activation energy accompanied by increased reaction rates. This change did not occur in the control samples. Samples aged in high humidity showed increased conversion of monomers to polymer when compared to dry aged samples. The aging time required before the above changes became apparent was temperature dependent; the higher the aging temperature, the sooner the changes in reactivity occurred.
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    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760210807
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    Time and temperature effects on the fracture toughness of rigid poly(vinylchloride) pipe materials (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 826-831 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fracture toughness of rigid poly(vinylchloride) pipe materials has been investigated over a range of temperatures and rates. Conditions are described for valid fracture toughness (KIC) tests and notch insensitive (ductile) behavior; time-temperature effects on transitions in KIC are defined. The modes of crack extension are characterized over a range of temperatures, and the mechanisms of crack resistance are discussed, including some quantitative data for the yielded zone at the crack tip.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221307
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    Devolatilization of polymer melts in single-screw extruders (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 832-835 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer melt devolatilization (DV) was studied using a single-screw extruder with extruder RPM and polymer flow-rate as the key parameters varied. DV efficiency was studied at atmospheric pressure under nitrogen and also at reduced pressure. Preliminary results are applied to current mathematical models.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221308
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221401
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  • 89
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    Fracture toughness and fatigue of polystyrene, polyphenylene oxide and their blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 946-949 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of atactic polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) represent a compatible system that exhibits a transition from a crazing to a shear bending mode of deformation as a function of composition. PS (Mw = 30,000; Mw/Mn = 1.06) exhibited a value of \documentclass{article}\pagestyle{empty}\begin{document}$ K_{IC} = 1.00 \pm 0.20{\rm }MPa\sqrt m $\end{document}. Blends of up to 60 wt.% PPO exhibited \documentclass{article}\pagestyle{empty}\begin{document}$ K_{IC} \sim 1.00{\rm }MPa\sqrt m $\end{document}. However, there is a very rapid increase in KIC with increasing PPO content in the vicinity of 75 percent PPO. Fatigue behavior of the blends parallels that under static loading.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221507
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    Anisotropic hygroelastic behavior of poly(methyl methacrylate) under case II diffusion (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 870-877 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The hygroelastic behavior of polymers, in which the diffusion mechanism is characterized by a sharp advancing boundary between the swollen shell and the core, was studied. A highly anisotropic swelling response was observed. The an-isotropy of the swelling strains was caused by the mechanical constraints exerted by the stiff core on the penetrated shell. The swollen systems were viewed as analogous to a composite material comprising a stiff fiber embedded hi a soft matrix. The size and relative dimensions of the core were found to be the crucial factor determining the antsotropic response en-countered. The experimental system employed was of poly(methyl methacrylate).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221404
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221501
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    Introductory remarks (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 921-921 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221502
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    An electrical method of measuring crack length during crack propagation tests of polymers (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 934-936 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurement of fatigue crack propagation rate (da/dn) in polymers is normally done optically with a travelling microscope. Electrical methods have not been very successful due to lack of sensitivity and to inaccuracies caused by factors such as plastic deformation and temperature variation. Use of electrically conductive surface grids eliminates these problems. An electrically conductive grid pattern is vapor-deposited onto the surface of a compact tension specimen. The electrically conductive grid pattern is vapor-deposited onto the surface of a compact tension specimen. The electrically conductive grid lines run across the expected path of the crack. With crack advancement, the grid lines are successively torn apart. Proper interpretation of the discontinuous steps that result when electrical current is plotted against time directly generates da/dn data.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221505
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    Fatigue fracture of polycarbonate (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 937-945 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fatigue fracture process in polycarbonate can be different for cracks grown from notches and from surface crazes. During the discontinuous crack growth process (which occurs during the very slow crack growth regime), full-width cracks grown from notches have a very different crack tip plastic zone when compared to that observed in localized cracks grown from surface crazes. These localized surface cracks have a pair of sharply defined shear bands at the crack tip (forming the “epsilon” plastic zone) that are absent from notched-grown cracks, The presence of the shear band pair in this plastic zone produces two major modifications. The discontinuous crack growth is extended to higher stress intensity ranges due to the (crack tip) craze stabilization by the shear band pair. Moreover, a shear fatigue fracture mode, absent in the notched specimens, occurs upon termination of the discontinuous growth process. The implications of this comparison are that estimates of fatigue lifetimes of smooth samples based on fatigue crack growth data (on notched specimens) may be erroneous.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221506
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    Prediction of extrusion pressure loss of polymer melts flowing through noncircular dies (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1049-1051 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The geometric parameter method proposed earlier by Kozicki and coworkers for prediction of pressure losses of non-Newtonian fluids flowing in ducts of arbitrary cross-section is shown to be applicable for polymer melt flow through complex dies. Good agreement is obtained between the predicted and the published theoretical and experimental results for polystyrene and polypropylene melts flowing in rectangular and trapezoidal dies. The method is simple to use and requires only the knowledge of two geometric parameters to characterize the flow geometry.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221607
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    Degradation of polyurethane containing phosphorus (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1057-1061 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fire hazard associated with the use of polymeric materials is partly the destruction of property and partly the hazard to life by toxic fumes. Phosphorus compounds are commonly used as fire retardants. They seem to act principally by modifying the mode of thermal decomposition of the polymer. This results in changes in the pattern of volatile inflammable and potentially toxic products and also in the production of a protective layer on the surface of the burning material. Insight into these processes has been sought by comparing the mechanisms of degradation of a simple polyurethane, pure and in presence of the fire-retardant ammonium polyphosphate, and of a comparable polyurethane with similar phosphorus structures built into the polymer structure.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221609
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    Observation of molecular chain scission during crazing of polystyrene (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1046-1048 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of gel permeation chromatographic (GPC) separations has been performed on polystyrene specimens in an attempt to discern whether or not mechanical crazing is accompanied by significant covalent bond scission. It was found that the extent of scission is not large but is indeed present in concentrations that are detectable by GPC. This suggests that molecular-slippage-only models of the crazing process are perhaps overly idealized and that crazing cannot take place in highly entangled polymer solids without some bond rupture.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221606
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    Masthead (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221701
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    Editor's note (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1065-1065 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221703
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    Compatibilization of the polystyrene/poly(ethyl acrylate) and polystyrene/polysoprene systems through ionic interactionsThis article is a review of work recently reported in the Journal of Polymer Science. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1117-1122 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interactions between anions on one polymer chain with cations on another can lead to compatibilization of otherwise incompatible materials. Thus, if 5 mol% of ∼SO3H groups are attached to polystyrene, and 5 mol% of vinyl pyridine is copolymerized with ethyl acrylate, proton transfer occurs upon mixing, and the pairwise attractive interactions between the resultant ions compatibilize the blend. The same has been observed for the styrene-vinyl pyridine and sulfonated polyisoprene polymer pair. Dynamic mechanical and optical properties are used as a measure of compatibilization.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221711
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