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  • Chemical Engineering  (1,589)
  • 1980-1984  (1,589)
  • 1935-1939
  • 1925-1929
  • 1984  (587)
  • 1982  (524)
  • 1980  (478)
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  • 1980-1984  (1,589)
  • 1935-1939
  • 1925-1929
Year
  • 1984  (587)
  • 1982  (524)
  • 1980  (478)
  • 1983  (547)
  • 1981  (460)
  • 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
    Introductory remarks (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 237-237 
    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.760200402
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  • 6
    Electronic Resource
    Electronic Resource
    Residual stresses and aging in injection molded polypropylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 230-236 
    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 residual stresses in injection molded bars of polypropylene have been examined using a stress relaxation method and by the layer removal technique. A positive value for the internal stress parameter was obtained with newly molded specimens and was found to be retained by specimens stored at liquid nitrogen temperature. The stress relaxation parameter reduced to zero both for specimens aged at room temperature and also for those aged at -40°C. Nevertheless the relaxation behavior of specimens aged at all three temperatures was quite distinct. The layer removal technique showed that the stresses near to the surface were compressive and those in the interior tensile, in apparent contradiction to the interpretation of Kubat and Rigdahl for the meaning of a positive internal stress parameter. A marked reduction in stress levels on aging at room temperature was confirmed, however. The relevance of the relaxation spectrum of polypropylene to these observations is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200311
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  • 7
    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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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Sorption and diffusion of ionic dyes in anionic cellophane membranesPresented in part at the “Textilwissenschaftliches Forum” Elmau (West Germany) (1975) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 264-270 
    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: Experimental steady-state permeability studies have been made with non-ionic, anionic and cationic dyes using carboxy cellulose membranes as anionic substrates. The experimental results show that with increasing bulk ionic strength the diffusion velocities of anionic and cationic compounds increase and decrease, respectively. The diffusion behavior of non-ionic compounds is independent of the ionic strength. Empirical relationships have been deduced which fit the permeation data of the anionic compounds. A new concept is introduced which postulates that the diffusion behavior of colons within an anionic membrane is dependent on the basicity of the fixed ionic groups. In substrates with matrix-bound anionic groups of high basicity, such as carboxy cellulose, the permeability behavior is described in terms of a new diffusion mechanism referred to as the “fluctuating” charge mechanism. This concept can provide a semi-quantitative understanding of the different electrostatic obstruction effects which matrix-bound carboxylate and sulfonate groups have on the permeability of colons. The measured permeability of the counter ions is in qualitative agreement with the proposed diffusion model.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200407
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  • 10
    Electronic Resource
    Electronic Resource
    The glass point of elastin as a function of diluent concentration (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 290-293 
    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: Elastin shares the properties of rubberlike elasticity and its capability to form a glass with crosslinked polymers in general. The glass transition temperature of dry elastin at 200°C is strongly depressed by water, as well as by ethylene glycol. On a volume fraction basis, both diluents depress the glass point equally. This result is strong evidence against any specific binding of diluent molecules and indicates relatively high mobility of diluent molecules in glassy elastin. This deduction is in agreement with the conclusions reached on the basis of heat capacity and dielectric measurements. Proposed small sections of β turns in the elastin chain are compatible with the concept of naturally occurring elastin chains in the amorphous state. Our results, however, do not confirm the existence of proposed β spirals with periodicities of 100 Å which were suggested to be the basis for the banded filaments observed in electron micrographs.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200412
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  • 11
    Electronic Resource
    Electronic Resource
    Sorption and transport of water vapor in glassy poly(acrylonitrile) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 300-304 
    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: Sorption data for H2O in glassy poly(acrylonitrile)(PAN) are presented for a range of relative vapor pressures at temperatures from 20 to 50°C. Simple dual mode sorption, involving “hole-filling” and molecular solution appears to dominate the low activity region of sorption. Based on the clustering analysis suggested by Zimm and Lundberg, pronounced clustering of penetrant appears to occur above a relative pressure of 0.6. The form of the effective concentration-dependent diffusion coefficient for H2O in PAN, determined by analysis of steady state permeation data, suggests that water in the microvoids and clusters has a lower mobility than the molecularly dissolved water in the polymer matrix. Time lag measurements at high upstream relative water vapor pressures suggest that the transient state permeation has a non-Fickian character due to relaxations which occur slowly to accommodate the clustering process.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200414
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  • 12
    Electronic Resource
    Electronic Resource
    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.760200501
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  • 13
    Electronic Resource
    Electronic Resource
    Water vapor transport in an epoxy resin based on TGMDA and DICY (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 310-314 
    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: Water uptake has been measured in an epoxy resin based on tetraglycidylmethylenedianiline curved with dicyanidamide. The curing behavior of this system as elucidated by differential scanning calorimetry and Fourier transform infrared is complex. Based upon this information we selected curing temperatures and times in addition to the “standard” cure. The kinetics of the sorption of water by the materials which have undergone the standard cure indicate that the two modes of sorption are involved at high humidity and only a single mode at lower humidity (as seen by changes in the slope of the log Mt vs log t plots). The kinetics of the sorption in the resins which have undergone post cure at higher temperatures also indicate two or more modes of sorption at high humidities. However the slopes of the log Mt vs log t plots differ from those for the resin with standard cure. Subsequent sorption/desorption cycles on the standard cure resin showed marked increases in the initial sorption rate as well as changes in mode, suggesting that irreversible changes in the resin had occurred.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200416
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  • 14
    Electronic Resource
    Electronic Resource
    Finite element solutions for flow in a single-screw extruder, including curvature effects (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 339-348 
    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 developed flow in an extruder channel has been set up as a two-dimensional, variational problem using a helical coordinate system, thus avoiding the usual geometrical simplification. Continuity is enforced by an integral form of constraint, and solutions for isothermal, Newtonian flow are obtained by a finite element method for both shallow and deep, highly curved channels. The performance of the solution procedure as a function of Lagrangian multiplier is discussed. Convergence to correct solutions is demonstrated for the shallow channel case. Deep channel results are compared with analytic predictions, curvature corrected according to Booy. Further testing of deep channel results will be made against experimental data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760200505
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  • 15
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    Corona-discharge treatment of polymeric films, II: Chemical studies (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 330-338 
    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: Polymeric films, chiefly polyethylenes, were subjected to corona-discharge treatment in a continuous treater at commercial rates in a program covering wide ranges of the main processing factors (2). Electron-spin-resonance measurements on freshly treated films found no free radicals. Reactions of the treated surfaces with a free-radical compound, diphenyl picryl hydrazyl (DPPH) were studied, focusing mainly on the rate effects. The evidence indicates that corona treatment produces fairly stable peroxide structures of the forms RO2R and RO3R on polyethylene surfaces. RO3R reacts rapidly with DPPH alone, while RO2R undergoes a slower reaction after addition of the catalyst, triethylene diamine. DPPH is capable of detecting as few as 1013 peroxide groups per square centimeter. Activation energies were 12 kcal/mole for the uncatalyzed reaction and 16 kcal/mole for the amine-catalyzed reaction. As with the physical effects reported earlier (2), the production of peroxides is most strongly dependent on the energy delivered to the film during treatment. This energy is proportional to the quotient of corona current and web speed, I/S, Regression analysis showed that air-gap thickness, relative humidity, and number of electrodes used also were significant factors, while dielectric thickness and corona frequency were not. We found that-γSP, the polar component of surface energy of the treated film, which is nearly zero for untreated polyethylenes, is exponentially related to the concentrations of both RO2R and RO3R with a correlation coefficient for 92 specimens tested of 0.88. We believe this is the first strong evidence linking treatment factors, at commercial levels of treatment, to chemistry of the treated surface and linking both of those to changes in physical behavior of the surface.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200504
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  • 16
    Electronic Resource
    Electronic Resource
    Finite element solutions for flow in a single-screw extruder, including curvature effects (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 983-983 
    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.760201412
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  • 17
    Electronic Resource
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    Fracture mechanics of adhesive joints (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 977-981 
    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 load carrying capacity of adhesive joints is analyzed by applying the principle of fracture mechanics in which failure is assumed to initiate from sites of initial imperfections such as bubbles, cracks or unbonded portions of the interface. The cohesive and adhesive modes of failure are investigated for a butt joint under angle loading. Based on the prediction of the strain energy density criterion, the lowest failure stress for the adhesive joint occurred when the load is applied at an angle with respect to the crack plane. This is in contrast to the homogeneous material solution where the lowest failure stress corresponds to normal loading. Numerical examples are provided for a joint made of DER 332-TEPA epoxy with aluminum as the adherends. Discussed in detail are the dependencies of the strength of the joint with reference to the material properties of the constituents, geometries of the components, and direction of loading.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201410
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  • 18
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    Introductory remarks (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 653-653 
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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.760201002
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  • 19
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    Instrumental methods for the study of the thermal degradation of polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 668-674 
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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: After consideration of the objectives of a degradation study, product fractions, and experimental variables, an attempt is made to assess the applicability of various instrumental methods to particular objectives. The technique of thermal volatilization analysis (TVA) is discussed in greater detail. Several examples are discussed from degradation investigations to illustrate important aspects of experimental approach.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201005
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  • 20
    Electronic Resource
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    Experimental deep-channel velocity profiles and operating characteristics for a single-screw extruder (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 982-982 
    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.760201411
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  • 21
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    Electronic Resource
    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.760201501
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  • 22
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    Residence time distribution of polymer melt in the T-die (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 212-214 
    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: Theoretical or rheological calculations for crosshead die geometry were thought not worthwhile until recently, and restrictor, or choker, bars were often excessively relied upon for film uniformity. Thus, the residence time distribution of a polymer melt was infrequently calculated especially in the T-die, because it was assumed to be very wide in T-dies. This report provides a general equation expressing the residence time distribution of polymer melts in T-dies, and indicates how to take an optimum combination of the flow-path dimensions in order to obtain both a high flow uniformity and a comparatively narrow residence time distribution across the die width. Such a T-die designed by the above considerations will produce a shorter heat history and improved physical properties of the sheet or film produced.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200308
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    Co-extrusion of polymers with one single screw having a specially devised double channelPresented at the 2nd Joint Meeting of 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. 1002-1008 
    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: Co-extrusion by means of only one single screw with a double channel was studied. The effects of the operating conditions, the material properties and the screw geometries on the inter-channel flow and the output rate were determined. The flow mechanism and the application to the composites with stratified structures were discussed. The inter-channel flow rate decreased with decrease in the back pressure, the stock temperature, the screw rotational speed and the viscosity difference between polymer melts in both channels. The decrease in the compression ratios of channels, the barrier flight in the compression zone and the sealing at the flight clearance with the polyamide-packing reduced the inter-channel flow significantly without a decrease in the output rate. With this method, co-extrudates with distinctly stratified cross-sections were prepared. The single screw with double-channel could be applied effectively to the co-extrusion of composites with stratified structures such as sheath-and-core structures, and it is particularly suitable to distribute the additives heterogeneously or to enclose the waste polymer.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201504
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    Some considerations of heat-transfer problems in thermoforming (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1009-1014 
    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: Details are given below of how the heat-up process for radiation methods may be expressed mathematically. In order to fulfill practical requirements, a process must ensure calculation of necessary heating time using process-specific characteristic curves with a minimum of mathematical effort. To this end the amount of heat actually absorbed by the surface of the O product must be known when sheets are heated by radiation. This can easily be determined through measurement of sheet surface temperature. It will be shown that if certain preconditions are satisfied, then variations in the distance of the IR-heaters have no effect on the temperature profile of the sheet. With poly(methyl methacrylate) (PMMA) the nature of coloration does not play a significant role. Investigations into the cooling process centered on a number of cooling methods and tool materials. The dynamic behavior of tempered and untempered thermoforming tools showed similarities to work already carried out in the injection molding sector. Consideration was given to possible ways of using the “Thermolog” analog computer, developed at IKV, to calculate the necessary cooling times in the production of thermoformed parts. Input values and basic data on temperature-time curves, necessary for the compilation of cooling curves using the analog simulator, were derived from appropriate tests on a thermoforming machine.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201505
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    Polymer devolatilization: Theory of equipment (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1015-1022 
    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 role of surface renewal and feedback phenomena in devolatilization equipment is clearly illustrated via staged models. A continuous model for the vented, single-screw devolatilizer is developed, including barrel evaporation and bulk surface renewal as well as backmixing, which represents de-volatilization data more accurately than previous models. Numerous sample computations are included. The models are used to demonstrate the sensitivity of devolatilization equipment to certain design parameters.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201506
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    The effects of light and heat on the rubber content and impact strength of acrylonitrile-butadiene-styrene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 995-1001 
    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: DSC analysis of acrylonitrile-butadiene-styrene (ABS) samples either weathered outdoors for up to 10 years or aged at 71°C has shown that these plastics deteriorate most readily through the polybutadiene (BD) component. Oxidation of the BD in ABS leads to an increasing and broadening Tgas well as a decrease in ΔCp at Tg. The latter quantity can be used to quantitatively assay the amount of unoxidized rubber in a photo- or thermal-oxidized sample. The loss of impact strength of these resins with chemical aging can be correlated with the oxidation of the polybutadiene phase. Studies of rubber content as a function of sample thickness have revealed that an embrittled layer containing oxidized BD develops at the surface of an aged, 100 mil. ABS plaque (natural) and grows to a thickness of about 10 mils after 3 years exposure to sunlight. ABS containing carbon black is effectively screened from this photo induced degradation and consequently has much better retention of its initial impact strength values. In addition, carbon black was observed to retard thermal oxidation in some ABS samples. Lastly, it appears possible to do accelerated aging studies at elevated temperatures to evaluate the relative stabilities of various ABS formulations.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201503
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    Use of “penalty” finite elements in analysis of polymer melt processing (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1029-1034 
    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 finite element method is an approximate numerical analysis approach of great applicability to a wide variety of field problems. This paper describes the formulation of a convenient method for treating fluid-flow problems relevant to analysis of polymer processing operations, and illustrates its use by means of some linear and nonlinear problems in melt extrusion.
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    URL: http://dx.doi.org/10.1002/pen.760201508
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    Rheology of molten blends of polyoxymethylene and ethylene-vinyl acetate copolymer and the microstructure of extrudates as a function of their melt viscosities (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1023-1028 
    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 polyoxymethylene (POM) with a copolymer of ethylene and vinyl acetate (CEVAc) have been studied. The effect of viscosity ratio for melts of the components on the processes of fiber formation in extrudates and on the rheological properties of the molten blend has been tested. The viscosity ratio of the fiber-forming POM and the matrix varied in the range 0.35-27.7. POM ultrathin fibers of unlimited length can be formed in the CEVAc only at a viscosity ratio close to unity. For ratios much greater than unity, the extrudate is found to contain short fibers and a finely dispersed powder or no fibers at all. If the viscosity of the POM melt is lower than that of the matrix, films are formed in addition to fibers. The second factor that governs fiber formation is the extrusion shear stress. An optimum shear stress exists at which the amount of ultrathin fibers is a maximum.
    Additional Material: 6 Ill.
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    Rheology in polymerization processes (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1035-1044 
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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: Parameters are developed for predicting rheological changes during ionic, condensation, and free-radical polymerization. Polymerization is viewed as changes in molecular weight and concentration for polymer solutions. Polymerization data in the laboratory and in tubular reactors are shown to be consistent with the proposed rheokinetic theory. This approach is based on polymerization kinetics and the corresponding solution rheology and phase diagrams.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760201509
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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.760201601
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    Iodinated polystyrene: An ion-millable negative resist (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1054-1057 
    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: Iodinated polystyrene (IPS) is obtained by direct iodination of polystyrene and its lithographic characteristics are investigated. The sensitivity of the polymer to electron beams is increased as the result of iodination by a factor of about 10 and reaches 1 μC/cm2. Coated IPS films are very stable and no changes in exposure characteristics are observed even after pre-baking at 220°C for 10 min. It is found that crosslinking does not proceed in a vacuum after electron beam exposure. The milling rate of IPS under Ar+ bombardment is measured to be 0.25 nm/s. This is lower than that of poly(glycidyl methacrylate-co-ethyl acrylate) (0.67 nm/s) and that of permalloy (0.42 nm/s), both obtained under the same conditions. The mechanism of sensitization by iodination is discussed.
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    Recent advances in the photodecomposition mechanisms of diazo-oxides (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1049-1053 
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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 1902, Wolff proposed a mechanism to explain the formation of carboxylic acids from diazo-oxides; Süs in 1944 invoked this same mechanism for the formation of indene carboxylic acid from diazo-oxides. Since these materials are currently used in the well known class of AZ photoresists, the Süs mechanism has been referred to many times to explain the positive working nature of the photoresists. In spite of the widespread use and industrial importance of the AZ resists, the validity of the Süs mechanism had not been unequivocally demonstrated to any degree of satisfaction. For these reasons, photochemical studies were initiated to establish the following: (1) Obtain direct spectroscopic evidence for ketene intermediates in the Wolff rearrangement of diazooxides. (2) Determine the reactivity of the ketene towards water and hydroxyl containing organic compounds. (3) Determine the reactivity of the ketene in the AZ resists. Fundamental photochemical decomposition mechanisms have been established for the AZ-type photoresists; these and recent theoretical results on the Wolff rearrangement are used to convey the technological implications of the studies.
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    Electron-beam lithography of chlorinated polystyrenes with narrow molecular weight distributions (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1058-1063 
    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: Polystyrenes with narrow molecular weight distributions have been chlorinated with only slight broadening of molecular weight distributions to yield materials that are five to six times more sensitive to electron-beam irradiation. The chlorinated polystyrenes are useful negative resists for electron-beam lithography. At molecular weights of 3-4 × 105g/mole, their threshold sensitivities to 20 keV electrons are 1-2μC/cm2. Their lithographic contrasts are ≥ 1.5; in fact, 〉 2.0 for the narrowest molecular weight distributions. They compare favorably in these regards to polystyrenes of similar molecular weight characteristics. Lithographic relief images that are 80% of the original thickness of the polymer film can be formed at three to four times the threshold dose.The degree of chlorination ranged from 0.65-0.76 Cl/monomer unit. The infrared spectra of the chlorinated materials resemble the spectrum for poly(4-chlorostyrene). Elemental analysis indicated, however that some addition of chlorine had occurred. More extensive chlorination or chlorination of the higher molecular weight starting materials broadened the molecular weight distributions.The chlorinated material, a kind of poly(4-chlorostyrene-costyrene), is less sensitive than poly(4-chlorostyrenc) prepared by addition polymerization by almost a factor of four.
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    Lithographic technique using radiation-induced grafting of acrylic acid into poly(methyl methacrylate) films (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1069-1072 
    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 lithographic process is described which increases the sensitivity of polymers to electron beam irradiation. The free radicals and peroxides produced in a film of polymer by irradiation are used to initiate the grafting of a monomer to form a graft copolymer, the solubility of which may be higher or lower than that of the initial polymer. Acrylic acid has been grafted into poly(methyl methacrylate) films to produce a copolymer which is insoluble in the solvents of PMMA. The sensitivity of this negative system depends on the conditions of grafting and on the conditions of development. A sensitivity of 2.8 10-8 C.cm-2 at 20 keV has been obtained.
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    URL: http://dx.doi.org/10.1002/pen.760201606
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    Sensitivity and contrast of some proton-beam resists (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1064-1068 
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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: Fifteen negative and four positive resists were tested to determine their proton-beam sensitivity and contrast. The ratio of the required 20-keV electron dose (QE) to the required 100-keV proton dose (QP) ranged from a low value of 7.8 to a high value of 270. In general, the most sensitive resists had the lowest values of QE/QP. This result is explained as being due to incomplete coverage by reactive species at low proton doses because the incident protons are spaced too far apart. The product of QP and the weight-average molecular weight (Mw) was almost constant for a series of narrow dispersivity polystyrenes over the Mw range of 20,000 to 2,600,000. This product was used as a figure of merit for comparing negative resists.
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    Effect of chemical composition upon the radiation and electron beam resist behaviors of vinyl polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1077-1081 
    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: Chemical composition effects upon polymer electron energy absorption and radiation chemistry have been identified to develop resist design criteria. By use of Bethe's theory for electron scattering in solids, chemical incorporation of higher atomic-numbered substituents is predicted to decrease energy absorption and increase scattering. Incorporation of chlorine or fluorine into vinyl polymers at the possible substituent sites is empirically found to have a large effect upon radiation G (scission) and G (crosslink) values. G (scission) values determined for several copolymers over a large range of compositions are found to vary linearly with composition. In contrast, G (crosslink) values are found to be generally less than those predicted from a linear extrapolation between the homopolymer values. Electron beam resist behavior is found to correlate well with the Gs/Gx ratio.
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    Sensitivity of diazoquinone resists to optical and electron-beam exposure (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1073-1076 
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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 compares the response of resists consisting of novolak resin and diazoquinone sensitizers (inhibitors) to optical and electron-beam radiation. In both cases, irradiation destroys the sensitizer leading to an increased rate of solubility in alkaline developer. For optical exposure in the near-uv region, the light is absorbed only by the chromophore sites and a unique quantum efficiency of 0.30 ± 0.03 can be measured for a range of wavelengths and sensitizers (10.5 ± 1.0 eV/bleached site). In the case of electron-beam exposure, the initial rate of bleaching in pure sensitizer implies that 7.6 ± 0.6 sites are destroyed per 100 eV absorbed (13 ± 1 eV/molecule). In mixtures of sensitizer and resin (i.e., resists), this inherent sensitivity, or G-value, based on the calculated absorption by the sensitizer only, increases by almost a factor of 2 as the proportion of resin is increased. While the electron and optical exposure both destroy the sensitizer center, absorption spectra and solubility properties show that the end products of the chemical reactions are not the same in the two cases. In addition, high doses of electrons produce cross-linking and insolubilization of the resin.
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    Electron sensitive negative resists of vinylaromatic polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1082-1086 
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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: Electron resist properties of three vinylaromatic polymers, polystyrene, polyvinylcarbazole and poly(3-bromo-N-vinylcarbazole) have been examined. Polystyrene and polyvinylcarbazole are high contrast resists of high dry etch resistance, but for adequate sensitivity (Dg0.5 ≤ ca. 10 μC/cm2 at 25 kV) high molecular weights are needed (Mw ≥ 106). Poly(3-brotno-N-vinylearbazole) has a much higher sensitivity (Dg0.5 = ca. 2 μC/cm2) than the unsubstituted polymer. The sensitivity of polystyrene and polyvinylcarbazole is increased appreciably by addition of organic bisazides as crosslinking agents, e.g. a sensitivity increase of almost an order of magnitude was found upon addition of 3% 4, 4′-diazidostilbene to polystyrene, high contrast being maintained.
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    Device processing using the trilevel technique (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1097-1101 
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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: Three front runners for the next generation of devices for fine line lithography are photo, electron, and X-ray lithography. Each of these techniques has both advantages and disadvantages when considered for direct wafer processing. This paper discusses the problems encountered using each of these techniques and how a trilevel technique can be applied to make each of these techniques more viable.
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    A trilogy on surfaces. II. On Gibb's adsorption equation and Antonow's law (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1164-1165 
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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 Gibb's adsorption equations for a multicomponent multiphase system are used to discuss the relationship between the surface tensions and interfacial tension. It is shown for binary systems that when the terms involving the surface excesses vanish, Antonow's rule is obtained.
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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.760201801
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    Drag reduction in cocurrent horizontal natural gas-hexane pipe flow (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 485-492 
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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: Drag reduction in two-phase cocurrent horizontal natural gas-hexane pipe flow was studied experimentally. The effects of pipe diameter, gas flow rate, liquid flow rate, and additive concentration were investigated using the Dowell APE drag reducer. In the annular-mist flow regime studied, it was found that drag reduction increased with decreasing gas rate for a given liquid rate, drag reduction decreased with increasing friction velocity and it decreased with decreasing gas-liquid ratio for a given friction velocity. Although the drag reduction decreased rapidly as the liquid-gas ratio approached zero, drag reductions as high as 34 percent were obtained. Attempts to predict two-phase drag reduction were unsuccessful as it was found to depend upon friction velocity, liquid and gas rates, liquid-gas rate ratio, pipe diameter and additive concentration.
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    Polydiallylorthophthalate resist for electron-beam lithography (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1110-1114 
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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: Polydiallylorthophthalate, PDOP, of low molecular weight and low molecular weight dispersivity has been prepared and investigated as a negative resist for electron-beam, X-ray and ultraviolet lithographies. The resist polymers were prepared by a conventional fractional precipitation method. It has been found that a high resolution pattern is obtained by using a molecular weight of 1 × 104 and an Mw/Mn 〈 2. This gives a good solubility difference between the exposed and unexposed portions in the developer. Resolution is less than 1 μm without any scum. Sensitivity for 15 kV electron bourns is 4 × 106C/cm2; and for X-rays (Al Kα) it is 100 mJ/cm2. Sensitivity for UV is 10 times that of poly(methyl methacrylate), and resistance for C3F8 dry etching is comparable to AZ-1350J.
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    Flow-assisted degradation in dilute polystyrene solutions (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 517-523 
    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 flow-assisted degradation behavior of polystyrene was studied as a function of solvent, polymer concentration, molecular weight, and molecular weight distribution. To obtain data at concentrations as low as 100 parts per million by weight, turbulent drag reduction measurements were used to augment the usual analytical techniques of viscosity and gel permeation chromatography. Turbulent flow measurements were found to be a valuable technique for evaluating the effects of degradation: the drag reduction onset point provides information about the largest molecules in the sample while the flow rate dependence is related to the shape of the top part of the molecular weight distribution. For the polymers and flow conditions studied, the degradation causes a shift in the distribution to lower molecular weights with little change in the shape. This suggests a complex mechanism where the probability of bond scission is not random but varies along the polymer backbone.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200713
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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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    Modification to weld lines in extruded thermoplastic pipe using a rotating die system (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 551-554 
    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: When a polymer melt flows around the cross head or past the fins of a torpedo in a pipe die, a weld line is produced where the separated melt streams rejoin. This weld line may result in an area of weakness in the extruded pipe, although in the case of unfilled materials the effect can be reduced by using a compression section in the die. However, With fiber reinforced polymers it is unlikely that fibers will cross the weld line, and a reduction in strength is inevitable. It is shown theoretically that by rotating the core of the extrusion die the weld line can be modified to form a spiral around the pipe wall, with a large-surface area for improved strength. Experimental investigations, which employ photographs of thin sections of pipe containing carbon black particles, support these conclusions.
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    URL: http://dx.doi.org/10.1002/pen.760200807
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    Estimation of the shear deformation exerted by a roll-mill upon a rubber compoundPresented at the Jahrestagung der Deutschen Rheologischen Gesellschaft with Conference Chemical Engineering Rheology in Aachen, 5-7 March 1979 (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 585-588 
    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 shear deformation which a rubber compound undergoes when passing through a mill nip was calculated. For this purpose the pressure distribution was measured using a strain gauge mounted in the table of a RAPRA micro-mill. The method has been applied to black-loaded master batches of natural rubber and styrene-butadiene rubber, where the shear deformation was estimated as a function of the mill nip opening. Furthermore, the physical properties of a latex-mixed powder vulcanizate was measured as a function of the estimated shear deformation.
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    Manufacture of high stiffness solid rods by the hydrostatic extrusion of linear polyethylene. Part II: Effect of polymer grade (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 597-600 
    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 solid phase hydrostatic extrusion behavior of a range of linear polyethylenes, including methyl and butyl copolymer grades, has been compared in terms of processing behavior and product properties, for large diameter extrusions in the adiabatic thermal regime. The most useful improvements in both stiffness and long term creep behavior were obtained from medium melt flow index homopolymers, although such grades required higher forming pressures than the copolymers. This represents a reversal of the creep behavior trends observed for small diameter isothermal extrusions, where copolymer grades were superior. The engineering potential of hydrostatically extruded linear polyethylene is discussed.
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    URL: http://dx.doi.org/10.1002/pen.760200903
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    Evaluation for the curing characteristics of phenolic molding compounds by rockwell hardness test at an elevated temperature (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 608-616 
    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: Rockwell hardness measurement at an elevated temperature has been proposed as an evaluation method for the curing characteristics of thermosetting molding compounds. This method is convenient and has a high accuracy over a wide range of curing, Using a cone indenter, the following advantages are brought about: a good correspondence with acetone extraction test, in showing the degree of cure of the internal part of a molding rather than that of the skin layer, and a higher sensitivity in measuring higher degrees of cure. On examining curing behavior of commercial phenolic molding compounds by this method, an inflection point was observed on a plot of the hardness vs log curing time. This critical point has been called “the minimum cure time”, beyond which the molding exhibits good physical properties.
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    URL: http://dx.doi.org/10.1002/pen.760200905
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    Stepwise increase of hardness in the curing process of one-step phenolic folding compounds (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 617-621 
    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 curing behavior of one-step phenolic molding compounds was studied using results of Rockwell hardness measurements at elevated temperatures with a cone indenter. The curing process was found to advance in a stepwise manner to the final stage of cure at a specific temperature. An explanation for this phenomenon has been attempted by suggesting the alternating occurrence of two types of curing reactions - propagation and crosslinking. After proceeding to some extent of cure, only the propagation reaction can occur through the migration of low molecular resin to the reactive sites of polymer chains. The propagation facilitates the subsequent crosslinking which drastically enhances the hardness of the resin. The results of electrical resistivity measurements and acetone extraction tests were also found to support the occurrence of above phenomenon.
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    URL: http://dx.doi.org/10.1002/pen.760200906
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    The ductile-brittle transition of low-density polyethylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 622-629 
    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 impact behavior of a low-density polyethylene was studied with an instrumented Charpy tester. A change from elastic or ductile response to brittle fracture was observed over a small temperature interval, usually within 1°C. This characteristic impact transition temperature (ITT) was highly sensitive to shallow, sharp notches. Whereas an unnotched test bar had a very low impact transition temperature of -94°C, a razor cut with a depth of only 5 percent of the total thickness raised it to -4°C. The impact transition temperature was effectively reduced by increasing the cooling rate during specimen preparation and by the addition of nonpolar liquids, On the other hand, impact properties were adversely affected by aging, annealing, and adding other thermoplastics.
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    Radiation degradation behavior of chlorine-containing vinyl copolymers. Search for improved electron-beam resists (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 630-636 
    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: Vinyl copolymers with high radiation degradation sensitivity have been synthesized by copolymerizing vinylidene chloride (VDC), CH2 = CCl2, with methyl methacrylate (MMA), methacrylonitrile, methyl α-chloroacrylate, and dimethyl itaconate using emulsion techniques. In addition, copolymers of methyl α-chloroacrylate with methyl methacrylate and poly(α-chloroaerylonitrile) were studied. Introduction of vinylidene chloride into methyl methacrylate polymers caused a sharp increase in Gs even at relatively low VDC incorporation. Upon 29 percent VDC incorporation, the Gs value increased from 1.3 (homopolymer of MMA) to 3.4. Gs was found to be a linear function of copolymer content for several systems, but Gx was not. At higher VDC levels, the increase in Gs was countered by increases in Gx. At lower VDC levels, Gx was suppressed below the values predicted by a linear Gx dependence on composition for such systems as VDC/MMA, MCA/MMA, and α-chloroacrylonitrile/MMA. The VDC/MMA co-polymer(29 percent VDC) gavea sensitivity of 4.0 × 10-5C/cm2 to electron beam exposure using the 0 percent unexposed resist thickness loss criterion and is 2-3 times more sensitive than PMMA. Poly(α-chloroacrylonitrile) is a negative resist with a sensitivity of 5 × 10-5 C/cm2 using one-micron line images for testing.
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    Rapid response of a growing environmental craze to a stress pulsePresented in part at the March 1979 meeting of the American Physical Society, Chicago, Ill. (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 637-641 
    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: Double exposure holographic interferometry has been used to measure the response of a growing craze to a pulsed stress. The craze was grown in situ by application of methanol to a crack in a poly (methyl methacrylate) (PMMA) strip under tension (K1 = 0.4 MN/m3/2). An incremental stress, approximating 15 percent of the overall crazing stress, is applied to the growing craze in a 1 s pulse. Incremental strain and stress profiles are measured along a line parallel to, but displaced 1.0 mm from, the growing craze, from a double exposure hologram triggered just before and during the pulse. The craze deforms rapidly, relieving the incremental stress concentration that can be shown to exist before craze growth. In a second set of experiments one holographic exposure is triggered during the incremental stress pulse, and a second exposure is triggered afterward. The results of such experiments indicate that the craze deformation is primarily plastic, and corresponds to a plastic strain rate of not less than 0.2 s-1. Consideration of the diffusion limitation of the rate of craze thickening leads to the conclusion that this plastic deformation is attributable to fibril creep rather than a surface drawing mechanism.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760200909
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    Some problems of chemical kinetics in polymer aging and stabilization (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 662-667 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Some problems related to polymer aging and stabilization are discussed. Several experimental and theoretical procedures are outlined and their use demonstrated for a number of polymers. Thermal, photochemical as well as mechanical degradation is considered.
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    URL: http://dx.doi.org/10.1002/pen.760201004
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    Structure vs stability in polymer degradation (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 654-661 
    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: All materials are subject to aging, a process of long-term degradation, but not at the same rate or affected in the same manner. The wide variation in susceptibility (or resistance) of polymers to various degradative agents, e.g., oxidative, thermal, mechanical, chemical, biological, depend on their chemical composition and structure. Accordingly, the chemical, physical, and energy considerations inherent in the pure polymer are discussed in relation to degradative stability.
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    Degradation kinetics applied to lifetime predictions of polymers (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 675-677 
    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 prediction of the lifetime of a polymer by extrapolation from weight-loss data requires a thorough analysis of degradation kinetics over a wide temperature range. Techniques are described in which entire kinetic spectra are compared among experiments performed at heating rates from 6 deg/min to 9 deg/day. These comparisons permit diagnosing shifts in reaction mechanism, uncoupling of competing processes and more reliably predicting the rate-limiting process at service conditions. These techniques and a method for obtaining initial X kinetic parameters are illustrated for several polymers.
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    Investigations on thermal and hydrolytic degradation of poly(ethylene terephthalate) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 680-683 
    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: The thermal properties of poly(ethylene terephthalate) (PET) are sensitively affected by polycondensation catalysts and temperature. The kinetics of thermal degradation were investigated by determining the rates of formation of carboxyl groups on isothermal heating. Carboxyl groups in PET were not only a result of thermal exposure but they were also an influence on hydrolytic stability. The hydrolytic cleavage of polyester chains, i.e., the formation of carboxyl groups, was found to be an autocatalytic reaction.
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    Photodegradation of polymers in solution as studied by laser flash photolysis (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 688-691 
    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 applying the light scattering detection method during flash photolysis experiments, causing main chain degradation of polymers, it is possible to study disentanglement diffusion of coiled macromolecules or the kinetics of the chemistry of main chain breakage. Results of typical experiments are presented. Poly(phenylvinylketone) was degraded at 347 nm in various solvents (disentanglement diffusion). Polystyrene was degraded at 265 nm in CHCl3 containing O2 (chemical reaction).
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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.760201101
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    Degradation of polycarbonate during recycling in a capillary rheometer (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 703-707 
    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: Polycarbonate was recycled in a capillary rheometer at high constant shear stresses (0.15-0.95 MPa) and at temperatures between 275 and 320°C. Changes in melt viscosity and molecular weight were evaluated. Significant polymer degradation was observed on repetitive extrusion. An activation energy of 113 kJ/mol was determined for the initial stages of the process. The degradation kinetics were in agreement with a non-random chain scission. It was concluded that bonds were more susceptible to scission the closer they were to the middle of the polymer molecule and that the extent of degradation increased with an increase in molecular weight.
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    Direct evidence for the existence of a craze at the crack tip in environmental stress cracking of polyethylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 720-724 
    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: Liquid nitrogen fracture tests have been carried out to produce direct evidence of the existence of a voided region, the craze, ahead of the crack in environmental stress cracking of polyethylene. Evidence of crazing is presented for both low and high density polyethylenes.
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    Calendering poly(vinyl chloride): Theory and experimentsPaper presented at the 2nd Joint Meeting U.S. & Japan Soc. Rheology, Kona, Hawaii, April 1979. (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 725-731 
    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 isothermal model for the calendering of power-law fluids which exhibit a slip boundary condition is presented. This model is based on lubrication approximation and Gaskell's theorxy. It Predicts sheet thickness, pressure distribution, velocity profiles, torque and power from rheological data for the melt and machine parameters. The predictions (sheet thickness, pressure distribution and torque) are compared with a set of experimental data for rigid poly(vinyl chloride)(PVC) provided to the authors by Solvay & Cie S.A.
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    Cold compaction molding and sintering of ultra high molecular weight polyethylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 747-755 
    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: Cold Compaction Molding and Sintering of Ultra High Molecular Weight Polyethylene (UHMWPE) has been examined as a function of particle size, sintering time and temperature, and cooling rate. Properties nearly equivalent to those obtained by compression molding can be obtained from samples with a fibrous particle morphology, sintered just above the melting point, with further improvement possible by control of particle size and addition of fine particles of normal molecular weight linear polyethylene. UHMWPE with a nodular particle morphology sintered poorly.
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    High stiffness polymers by die-drawing (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1229-1235 
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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 application of die-drawing to the production of highly oriented polymers is considered, ft is shown that a variety of useful products can be obtained including not only rod and multifilament, but also tube and filled polymer. The investigations under discussion include the processing of several grades of linear polyethylene, polypropylene homopolymer and co-polymer. In favorable cases, products of very high stiffness were obtained, reaching modulus values of 50 GPa for linear polyethylene and 20 GPa for polypropylene.
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    Isothermal flow of viscous liquids in corotating twin screw devices (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1220-1228 
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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 derived for isothermal flow of a Newtonian liquid through corotating twin screw equipment. Two different flow regimes are studied. In the first, channels of twin screw equipment are completely filled with liquid, generate a pressure gradient, and provide a discharge pressure at the end of the pump. Equations are given for drag flow rate, pressure backflow rate, and flow rate through the nip zone. It is shown how the analysis of single screw pumps can be modified for twin-screw pumps. In the second regime channels are partly full, which is the case with extraction equipment. Equations show how the degree of fill in the equipment changes with flow rate, speed, and dimensions.
    Additional Material: 14 Ill.
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    Molten poly(methyl methacrylate) under electron irradiation: Studies of depropagation and chain scissionThis work is based on the D.Sc. Thesis of H. Ficke, Submitted to M.I.T. July 1977 entitled, “Depolymerization of Vinyl Polymers Under Conditions of Moderate Temperature and Ionizing Radiatation.” (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1236-1241 
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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 degradation rates of free radical polymerized and syn-diotactic poly(methyl methacrylate) (PMMA) under electron radiation were explored at temperatures ranging from 225 to 325°C and at electron dose rates from 10,000 rads/min to 100,000 rads/min. Scission of bonds between main-chain atoms resulted in pairs of radical chain ends, of which some disportionated, thereby reducing polymer molecular weight without loss of volatile, while others proceeded to depropagate via the usual radical transfer, causing complete volatilization of the chain without significant change of molecular weight of the residual polymer. Electron irradiation at a dose rate of 100,000 rads/min produced a significant enhancement in the reaction, rate, and reduced the overall activation energy from 140 KJ/g-mole observed for thermally induced depropagation to a value of 75 KJ/g-mole observed during simultaneous irradiation and/thermal depropagation.
    Additional Material: 12 Ill.
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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 
    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 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.
    Additional Material: 18 Ill.
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    A dynamic mechanical study of the curing reaction of an unsaturated polyester (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 254-259 
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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 curing process of an unsaturated polyester was followed by employing the dynamic spring analysis (DSA) technique attached to the Rheovibron viscoelastometer. The storage and loss moduli and the gel times of the resin with various concentrations of initiator (methyl ethyl ketone peroxide) were determined at several temperatures. The activation energy for the curing process studied was about 40 kJ/mol. Temperature effects on films partially cured below the ultimate glassy transition temperature (Tg) were studied similarly using the tensile mode on the Rheovibron from room temperature to 120°C. Two modulus peaks were observed upon heating and these were independent of precure conditions. The lower temperature peak was the result of continued curing and the higher temperature peak was attributed to the glassy relaxation of the cured product. The DSA technique were found to be useful for characterization of the curing process and the results showed good qualitative agreement with those obtained by tensile measurements using cast films when the shapes of the curves were compared.
    Additional Material: 13 Ill.
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    Property-morphology relationships of polymethylmethacrylate/polyvinylidenefluoride blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 234-240 
    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 investigation was conducted to establish property-morphology relationships in polymethylmethacrylate/polyvinylidenefluoride (PMMA/PVDF) blends. All blends were compounded in a twin-screw extruder and then processed by injection molding Mechanical properties of blends of various compositions were studied by dynamic mechanical and impact strength measurements. The presence of crystalline regions in blends was determined by Differential Scanning Calorimetry (DSC). Morphology of fracture surfaces of blends was studied by Spinning Electron Microscopy (SEM). PMMA/PVDF blends were found to form compatible mixtures over a wide range of blend composition. Changes in dynamic mechanical properties upon annealing were found to be a direct function of blond morphology. Electron microscopic evidence showed no signs of phase separation. DSC measurements detected crystalline regions in all blends containing 40 percent or more (by weight) PVDF.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760220404
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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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    URL: http://dx.doi.org/10.1002/pen.760220406
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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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    Molecular weight distribution of polyethylene terephthalate in homogeneous, continuous-flow-stirred tank reactors (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 314-323 
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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: Poly(ethylene terephthalate) (PET) formation in homogeneous, continuous-flow-stirred tank reactors (HCSTRs) operating at steady state has been simulated. The feed to the reactor is assumed to consist of the monomer bis-(hydroxyethyl) terephthalate and monofunctional compound (MF1) cetyl alcohol. The overall polymerization is assumed to consist of the polycondensation, reaction with monofunctional compounds, redistribution, and cyclization reactions. At a given time, the reaction mass consists of polyester molecules (Pn), polyester molecules with an ending of molecules of monofunctional compound (MFn), and cyclic polymers (Cn). A mass balance for each of these species in the reactor gives rise to a set of algebraic equations to be solved simultaneously. The MWD calculations show that the redistribution reaction plays a major role and cannot be ignored, This result is in contrast lo the observation for semi-batch reactors, for which redistribution becomes important when the cyclization reaction is included. For the same residence times of semi-batch and HCSTRs, the latter gives considerably lower-number average molecular weight, Nav, and polydispersity index, ρ. However, for the same conversions, the ρ for CSTR is higher. The concentration of the monofurctional compound, [MF1]0, in the feed and the reactor temperature both influence ρ, but the effect is small within the range studied.
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    An improved lattice-fluid equation of state for pure component polymeric fluids (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 345-348 
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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 Fluid-Lattice Theory (Ising Fluid), recently tested by Lacombe and Sanchez, has been modified by introducing the typical Flory's surface-to-volume ratio of the characteristic-segment of a polymeric liquid. This surface-to-volume ratio is not an adjustable parameter. It is obtained from Bondi's tabulations. The resulting new equation of state has three adjustable parameters per component and it represents a definite improvement for the fitting of P-V-T data for polymeric liquids. Extension to mixtures is not tested in this work but, in principle, it can be done by well-established methods.
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    URL: http://dx.doi.org/10.1002/pen.760220603
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    Capillary and slit flow behavior of concentrated solutions of a rod-like polymer (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 521-527 
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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 is concerned with the flow behavior of isotropic solutions of the rod-like polymer, poly(p-phenyleneterephthalamide) (PPT), in 100 percent sulfuric acid. Studies include entry flow visualization in a slit die and solution fracture, and die swell in capillaries and a slit die. It was observed that solutions of PPT exhibit nearly negligible die swell, a slip-stick type of fracture that disappears at high shear rates, and radial entry flow patterns similar to Newtonian fluids. Fracture was associated with the plateau in the shear stress vs shear rate curve. Because values of the wall shear stress (τw.) obtained from capillary measurements were in good agreement with those obtained from a cone-and-plate rheometer and values of the loss modulus (G″) obtained from small-strain dynamic oscillatory measurements, it is believed that the rheological properties lead to the flow instability. These results are in agreement with the predictions of a recent theory by Doi and Edwards for concentrated solutions of rod-like molecules. Data are also presented for a flexible chain polyamide, nylon 6,6, in 100 percent H2SO4 for the purpose of comparing the flow characteristics of rigid and flexible chain polymers.
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    URL: http://dx.doi.org/10.1002/pen.760220902
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    The elastic change of volume in pressurized bottles made from polymeric materials (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 472-477 
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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 relations describing the elastic change of volume of thermoplastic cylindrical pressurized containers are presented. Discussions have been made on various cases including isotropic (i.e., un-oriented), uniaxially, and biaxially oriented materials. These relations are expected to be helpful for selecting the optimum processing conditions (i.e., draw ratio) in order to achieve the desired properties of polymeric pressurized containers.
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    URL: http://dx.doi.org/10.1002/pen.760220804
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    The hydrolytic stability of some commercially available polycarbonates (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 370-375 
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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 number of commercially available polycarbonates, including formulations made flame retardant by two different modifications, have been exposed to conditions producing moderately rapid hydrolysis. Hydrolysis rates were calculated from molecular weight data determined by gel permeation chromatography and, in some cases, from melt flow rate data. The rates calculated by the two methods are in good agreement. In general, the standard formulations containing minimal additive packages are the most hydrolytically stable. Although one relatively new flame retardant polycarbonate demonstrates generally good resistance to hydrolysis, most of the flame retardant formulations appear to be quite susceptible to hydrolytic degradation. For these materials, hydrolysis under conditions encountered in use could cause significant decreases in impact strength within a few years.
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    URL: http://dx.doi.org/10.1002/pen.760220608
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    Low temperature thermal aging of ethylene vinyl alcohol copolymers (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 382-387 
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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 crystallites of semicrystalline polymers formed at low temperatures are subject to partial partial melting and recrystallization resulting in a systematic increase in the size and perfection of the nascent crystallites. Differential scanning calorimetry (DSC) and x-ray studies suggest that ethylene-vinyl alcohol copolymers (EVOH), in particular, may undergo these secondary crystallization processes upon storage at temperatures far below Tm. DSC scans have been run on “as received” and quenched samples; the mole percent of vinyl alcohol in the copolymers studied was 0, 62, 70, 72, 82 and 100 percent. Tests on secondary crystallization kinetics, performed at different temperatures, further confirm the hypothesis of an increased degree of perfection (lamellar thickening) of the bulk crystallites achieved upon long term storage at temperature between Tg and Tm.
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    Rheology of polymer blends: Simultaneous slippage and entrance pressure loss in the ethylene-propylene-diene (EPDM)/viton system (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 507-511 
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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: Because the exact nature of the mechanism governing the marked viscosity reduction in the highly incompatible EPDM/“Viton” fluoroelastomer system is not fully understood, a study was undertaken to shed more light on the phenomenon. Interracial. Slippage in the blend has been suggested as the mechanism by which a substantial reduction in the melt viscosities of either component takes place upon addition of a small amount of the other, In the present investigation, a Mooney slip analysis demonstrated wall slippage in the EPDM/Viton system over the shear stress range of 40 kPa to 160 kPa. The capillary surface was examined for evidence of coating by the minor component of the blend (Viton), and 9-fold enrichment was found by elemental analysis. However, on no occasion was pure Viton found. In other experiments, the dynamic linear viscoelastic properties and the transient squeezing flow response of the blend were found to be no different from those of the neat elastomer. In addition, the slip velocity in a capillary (and consequently, the viscosity-lowering effect) was reduced by a factor of 2 to 3 in capillaries with a 90° included entrance angle. It is postulated that the reduction in the flow resistance for the blend is unique to the sharp-entry capillary geometry and results from removal of Viton from the melt in the recirculating flow at the entrance. This material then feeds along the capillary wall, disrupting the already tenuous adhesion of the elastomer to the metal surface.
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    Unsaturated polyesters from 2,2-dimethyl-1,3-propanediol (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 556-559 
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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 series unsaturated polyesters were made from 2,2-di-methyl-l,3-propanediol, propylene glycol, fumaric acid, and isophthalic acid by a two-step fusion process. The effect of catalyst, conversion, composition, unsaturation, and styrene content were studied, and the relationship between composition and properties was established.
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    Effect of the addition of ethylene-propylene random copolymers on the properties of high-density polyethylene/isotactic polypropylene blends: Part 1 - morphology and impact behavior of molded samples (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 536-544 
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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: Two random commercial ethylene-propylene copolymers (EPM) with different ethylene content have been added to binary isotactic polypropylene (iPP)/high density polyethylene (HDPE) blends by melt mixing in a Brabender-like apparatus. Impact Izod tests and a morphological analysis on the fractured surfaces of broken specimens have been performed and discussed, in order to improve the deficiency in toughness of the binary HDPE/iPP mixtures. The results show that the impact performance of both homopolymers and HDPE/iPP binary blends is strongly improved by the addition of the EPM copolymers. Such an effect is related to the fact that the overall morphology, as well as the mechanism and mode of fracture, are greatly modified by the presence of such additives. The extent is dependent on factors such as the nature of the matrix (HDPE or iPP), the composition, and the chemical structure and/or the molecular mass of the added copolymer.
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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.760221001
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    Estimation of injection pressure during mold fillingPresented in part at the “Second World Congress of Chemical Engineering,” Montreal, Canada, Oct, 4-9, 1981.This paper is a corrected reprint of the paper that originally appeared in POLYMER ENGINEERING AND SCIENCE, Mid-April, 1982, Vol, 22, No. 5. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 589-593 
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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: Dimensionless diagrams for estimating the bulk temperature of the flow front and injection pressure in the limit of small viscous generation are obtained. Also, a criterion for neglecting viscous generation is identified, The diagrams, based on the Lord and Williams model, refer to rectangular geometry and amorphous materials. A satisfactory comparison is obtained with literature data taken on polystyrene. A reasonable estimate of polyethylene injection pressure was obtained by roughly accounting for latent heat of crystallization through modified thermal diffusivity.
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    The relationship of carbon black dispersion to electrical resistivity and vulcanizate physical properties (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 601-609 
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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 degree of dispersion of carbon black in rubber is known to be a determining factor in the physical properties of the composite. It is important, therefore, to have a reliable, quantitative technique for assessing carbon black dispersion. It has been known for some time that the degree of dispersion of carbon black is reflected in its electrical resistivity. A resistivity instrument, developed by B. Boonstra, has been redesigned and constructed for use in this study. Factors that influence resistivity (i.e., black type, volume loading, and mixing time) are examined. Physical property and dynamic mechanical measurements are made, and their relationship to black dispersion is investigated. Light microscopy is also used to evaluate dispersion, and these data are compared to the resistivity results.
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    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221004
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    On the dynamics and control of a plasticating extruder (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1095-1106 
    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 recent years, there have been many papers published on the application of process control to plasticating extruders. Much of the literature concentrates on the more classical control techniques. However, recent research has studied the application of stochastic identification techniques for building transfer function models for the extruder. In particular, the relationship of screw speed to die pressure and temperature has been studied. In the present work, both step tests and pseudorandom binary sequence tests were used to study the process dynamics of a 38 mm Killion extruder having a Iength-to-diameter ratio of 24:1. This study concentrates on the regulation of the extruder pressure in the face of its inherent surging characteristics. Variations in the quality of the feed plastic were studied through pulse and step changes in input polymer composition. Significant control problems resulted from measurement noise, which appeared at the same frequency as the screw rotation speed. Various mathematical filters to reduce the effect of this noise on the control variables were studied.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221707
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    Siloxane-poly(Methylmethacrylate) amphoteric blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1123-1126 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly([4-(methacryloyloxy) butyl]pentamethyldisiloxane), PMBPD, has been prepared for the first time. At the weight average molecular weight of 55,900, it is a clear, viscous liquid with a glass transition temperature, Tg, of 236K. Copolymers with methylmethacrylate have also been prepared. The homo-and copolymers, all of which have methacrylate backbones with pendant siloxane groups, were blended with poly(methyl-methacrylate), PMMA. Using the existence of a single Tg as a definition of miscibility, it was found that blends of either PMMA or PMBPD with random copolymers are miscible. However, in spite of a clear appearance, the blend of the two horriopolymers were found to have two distinct Tgs.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221712
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  • 88
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    Recent advances in interpenetrating polymer networks (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1143-1152 
    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: We review the synthesis, morphology, and physical and mechanical properties of IFNs as well as the related pseudo-IPNs, in which only one of the polymers is crossliriked. Recent studies have shown that the degree of phase separation achieved in these materials is strongly dependent on the compatibility of blends of the linear polymer constituents of the IPN components as well as the kinetics of chain extension and the presence of grafting between component polymers. We illustrate this by a series of IPNs consisting of a polyurethane and an acrylic copolymer. The acrylic is a typical automotive enamel. An enhancement in properties results, which is dependent on the amount of grafting and the kinetics of polymerization. Also discussed are IPNs of a polyurethane and an epoxy, which exhibit a synergism in adhesive properties, and IPNs of a RIM polyurethane with several epoxies and unsaturated polyesters. In addition, also reported are the preliminary studies on the first successful preparation of a three-component IPN, consisting of a polyurethane, an epoxy, and an acrylic.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221715
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  • 89
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    Development of industrial polyolefin blends using melt rheology data (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1153-1165 
    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 review of current knowledge of the composition dependence of polymer-blend processability and morphology shows that development of industrial blends requires use of a semiempirical approach, based on the particular rheological composition (PRC) concept. Selecting blend composition in the close proximity to PRC and employing factorial experiments for the mixing process allows the development of successful industrial polyethylene/polypropylene blends designed for film and blow-molding applications.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221716
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    Composition and processing effects on the properties of one-component polyurethanesPresented at Second World Congress of Chemical Engineering, Montral, Canada, October 4-9, 1981. (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1177-1183 
    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 polyurethane consisting of a poly(propylene oxide) soft segment and a diphenylmethane diisocyanate - hydroquinone di-(b̃-hydroxyethyl) ether (HQEE) hard block has been characterized over the composition range of 30 to 60 percent hard block. The flexural modulus varied from 60 to 900 MPa over this composition range. The elongation was approximately 250 percent at the lower hard block contents but fell below 100 percent at 60 percent hard block. Differential scanning calorirnetric measurements showed that the crystallinity associated with the hard phase increased with increasing hard block content but decreased with increasing cure temperature. The heat sag was found to decrease with increasing hardblock and increase with increasing cure temperature. A material with properties comparable to current fascia materials had a significantly better heat sag resistance than a current RIM (reaction injection molding) polyurethane. The combination of the solid chain extender, HQEE, and a solid catalyst, zinc stearate, lowing it to be processed as a one-component resin having a pot life of greater than 8 h at 20°C al-injection molding machines. The one-component nature of the resin has made it possible to use a continuous in-line mexer and to reduce the amount of scrap by using cold runner molds. In addition, any scrap that is generated can be used as regrind in the system.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221802
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    Fractography of polyethylene glycol dimethacrylate doped with polymethyl methacrylate (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1199-1204 
    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 presence of polymethyl methacrylate (PMMA) can greatly affect the properties of materials made by polymerization of ethylene glycol dimethacrylate (EGDM). Fracture surfaces, examined by scanning electron microscopy, show a much wider range of morphologies in mist regions than observed in previous work on PEGDM alone. These morphologies are attributed to the moderation of brittle fracture by localized plastic deformation. It is suggested that the effect of PMMA is due to its segregation around clusters of highly cross-linked particles of PEGDM that, as a result, become more discrete and, hence, more susceptible to interparticle displacements during fracture. In agreement With this suggestion, the mist regions usually exhibit a particulate microstructure.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221805
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    Studies of epoxy resin systems: Part D: Fracture toughness of an epoxy resin: A study of the effect of crosslinking and sub-Tg aging (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1228-1236 
    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 an epoxy resin system, diglycidyl ether of butanediol, DGEB, cured with 4-4′ diaminodiphenyl sulphone, DDS, has been studied by varying the crosslinking density and state of aging. A stable, but rough, crack propagation was observed with specimens that were 99 percent cured and quenched. When the extent of curing was less than 99 percent or the material was aged for more than 20 min at 62°C, crack propagation was of the unstable stick-slip nature. Aging was found to decrease the initiation fracture toughness dramatically, but the arrest fracture toughness was almost unchanged. This result was associated with a change of relaxation strength of the primary, a, transition with aging. An increase of crosslinking density was found initially to reduce the fracture toughness of this epoxy resin, but the fracture toughness increased after 87 percent of curing. The initial decrease of the fracture toughness was attributed to a decrease of relaxation strength of the primary transition (i.e., the area under the α-relaxation peak), while the increase of the fracture toughness after 87 percent curing was explained by the onset of the stablerough crack propagation, Micrographs taken by scanning electron microscopy-showed possible existence of blunting during crack propagation and a decrease of blunting with the extent of aging.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760221809
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    The properties of mica-filled polypropylenes (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 169-174 
    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: Water-ground Phlogopite micas were classified into narrow particle-size distributions containing flakes with well-defined diameters and thicknesses in order to evaluate the influence of particle size and flake aspect ratio on the mechanical properties of mica-filled polypropylenes, For the purposes of comparison, most of the injection-molded specimens contained 40 percent (by weight) mica. As expected, the flexural and tensile modulus values increased in proportion to the aspect ratio over the range from 30 to 60 to a maximum of 8 GPa. The measured tensile strengths of the mica-filled polypropylenes increased substantially as the flake diameter became smaller, but did not correlate with the flake aspect ratio. The attainable properties were frequently dependent upon the method of mixing, and considerable care was necessary to ensure proper dispersion and adequate coupling. Intensive mixing, as in a Gelimat Mixer, may cause in situ delamination and particle-size reduction of the mica filler particles, leading to a marked increase in tensile strength of the resulting composite. The mica-filled compounds could be reprocessed many times without significant loss of properties, particularly compounds having mica particles less than 40 μm in diameter. The fracture energies (notched Izod) and the heat-distortion temperatures were not appreciably influenced by the size or aspect ratios of the mica within this range. Increased fracture toughness could be achieved by reducing the mica concentration or employing a polypropylene copolymer. Guidelines are presented to indicate the preferred characteristics of mica fillers and the influence of mixing conditions on performance.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240303
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    Modeling of polyethylene terephthalate reactors: 7. MWD considerations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 30-41 
    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 to compute the molecular weight distribution (MWD) in the polyethylene terephthalate (PET) manufacturing process. Unlike the previous efforts, this model takes into account the influence of side reactions and various interchange reactions on MWD. The process of blending of molten polyester chips has also been simulated with a view to calculate the equilibrium MWD as well as the time required to reach the equilibrium MWD. The1 significance of the results has been discussed in terms of industrial operations involving PET polymerization and PET blending.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240104
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    The form and origin of some non-equilibrium morphologies in multicomponent polymer blends-a brief report (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 541-543 
    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.760240806
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    Interactions in polymer blends-relationship between thermodynamic and scattering measurements (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 555-562 
    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: Methods of preparation and of determining miscibility limits for partially miscible binary polymer blends are described. An equation-of-state, theoretical description of this behavior is introduced and the terms describing interactions within the system discussed, Values of these interaction terms are obtained by fitting the models to measured cloud point curves, heats of mixing data, etc. The use of neutron scattering experiments to obtain molecular conformation and interaction parameters is described and a comparison made with values extracted from the thermodynamic measurements.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240808
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    Water-soluble copolymers VIII. Synthesis and dilute solution rheological studies of dextran-g-poly(acrylamide-co-sodium acrylates) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 163-168 
    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: Dextran-g-poly(acrylamide-co-sodium acrylates) were prepared by partial hydrolysis of dextran-g-poly(acrylamides) with controlled numbers and lengths of grafted chains. This hydrolysis route proved to be more effective than Ce(IV)-induced cografting of acrylamide and sodium acrylate comonomers onto dextran in producing the desired graft-copolymer structures. The resulting copolymers were characterized and the effects of composition, temperature, ionic strength, and shear rate on dilute solution rheological properties were studied.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240302
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    Solution of final stages of polyethylene terephthalate reactors using orthogonal collocation technique (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 194-204 
    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 formation of polyethylene terephthalate (PET) has been modeled to have reactions with monofunctional compounds, redistribution, and cyclization reactions in addition to the usual polycondensation step. In the final stages, the overall polymerization is mass-transfer controlled and solution of the reactor performance equations have been determined through the orthogonal collocation technique. This technique is found to be considerably more efficient for PET reactors compared to the finite difference method; the use of ten collocation points gives results which are close to the exact solution.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240306
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    Theoretical investigations on some rigid-rod polymers used as high-performance materials (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 218-225 
    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 review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include cis and transpoly(p-phenylene benzobisoxazole) (PBO), and the cis and trans forms of the corresponding poly(p-phenylene benzobis-thiazole)(PBT). The purpose of this paper is to summarize the authors' theoretical work on the structures, conformational energies, intermolecular interactions, and electronic properties of PBO and PBT chains, including the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240309
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    Poly(p-phenylene terephthalamide) films formed from extrusion and coagulation of liquid crystalline sulphuric acid solutions: Characterization of orientation and void structure, annealing, and upgrading of film mechanical properties (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 242-251 
    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: Poly(p-phenylene terephthalamide) (PPD-T) films have been prepared by continuous extrusion of liquid crystalline 17 percent PPD-T/sulphuric acid solutions through an annular die followed by coagulation, Films extruded without drawdown exhibit some polymer chain orientation in the machine direction. This is increased by uniaxially drawing down films. Films produced with a lubricated conical mandrel sitting between the die and the coagulation bath exhibit an equal biaxial orientation. The uniaxially oriented films exhibit highly anisotropic mechanical properties, while the mandrel-produced film exhibits balanced properties. Heat treatment at 350°C results in significant enhancement of the tensile strength of the mandrel film. Void structures in the films have been investigated by mass density, scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS). Density measurement indicate a void content decreasing with decreasing film thickness and heat treatment. SEM locates micron-size voids in the thickest films, apparently caused by rapid coagulation. SAXS indicates much smaller void sixes which are roughly prolate ellipsoids (long axis in machine direction) for uniaxial films and oblate ellipsoids (short axis in thickness direction) for the mandrel produced films. Various techniques are used to estimate mean void size.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240403
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