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  • Chemical Engineering  (1,025)
  • 1980-1984  (1,025)
  • 1945-1949
  • 1940-1944
  • 1925-1929
  • 1983  (547)
  • 1980  (478)
Collection
Keywords
Publisher
Years
  • 1980-1984  (1,025)
  • 1945-1949
  • 1940-1944
  • 1925-1929
Year
  • 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
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    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
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    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
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    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
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    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
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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 
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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.760201411
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  • 21
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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.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.
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    URL: http://dx.doi.org/10.1002/pen.760201808
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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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    Equilibrium solubility and permeability of sulfur dioxide in epoxy resin of aliphatic diglycidyl ether (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 6-12 
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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: Equilibrium sorption isotherms were obtained for the sulfur dioxide-epoxy resin of aliphatic diglycidyl ether system over a temperature range of 1° to 45°C. The sorption isotherms indicated the presence of Langmuir sorption due to specific interaction. This is uncommon for rubbery polymers, though similar behavior was also observed previously. Zimm-Lundberg's clustering analysis indicated a slight tendency for clustering of the penetrant molecules at low temperatures and higher activities. The number of Langmuir sites for sorption was found to be independent of temperature. The mobilities of the molecules sorbed in Henry's law mode and the Langmuir mode were found to be approximately equal. Predictions of the permeability values for this system are presented and compared with other data from the literature. The temperature dependence of different sorption parameters is presented and discussed in detail.
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    URL: http://dx.doi.org/10.1002/pen.760230103
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    Tensile yield in poly(4-methyl pentene-1)Presented, in part, at the American Physical Society Meeting in Dallas, Texas, March 1982. (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 13-16 
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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: Uniaxial tension tests to the yield point were performed on a crystalline polymer, poly(4-methyl pentene-1) (PMP) as a function of temperature from 21° to 200°C at a strain rate of 2 min-1. After testing, the specimens showed considerable stress whitening as a result of microvoid formation. Yield energy was found to be a linear function of temperature extrapolating to zero at the melting point (240°C). Thus, the behavior of this crystalline polymer is similar to that of glassy polymers, but with the melting temperature, rather than the glass transition temperature, as the reference point. The ratio of thermal to mechanical energy input to produce yielding is an order of magnitude smaller for PMP than it is for glassy polymers. The ratio of yield stress to Young's modulus is about 0.02, which is typical for polymers. Yield stress is a linear function of log strain rate, which implies that yielding can be described as a segmental flow rate process in which the applied stress biases the activation energy. The activation volume is on the order of 20 monomer unit volumes and increases as the temperature increases. The activation energy is 19 kcal/mol.
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    Masthead (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983) 
    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.760230201
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    Residual stress craze and crack formation in poly(methyl methacrylate)Presented in part at the Fifth International Conference on Deformation, Yield, and Fracture of Polymers, Cambridge, U.K., 1982. (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 211-215 
    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: Samples of poly(methyl methacrylate) with a central circular hole are compressed, and crazes form on or after unloading, provided that the strain attains or exceeds a threshold value ∊t. Crazes induced in air are transformed rapidly to cracks, but environmental crazes are more stable. These residual stress crazes form at the diameter of the hole on a plane perpendicular to the applied stress direction. In contrast, during loading, crazes form on the vertical plane containing the hole axis. Unloading crazes are relatively insensitive to changes in strain rate, whereas loading erazes have a pronounced rate dependence. Environmental residual stress crazing exhibits an apparent rate sensitivity at constant time, but the critical applied strain ∊t is essentially constant, irrespective of rate, if the sample is in contact with the environment for a sufficiently long time to ensure that the minimum ∊t is obtained. Residual stress crazes appear to initiate at the equator of the hole, and the maximum tensile residual strain, indicated by a strain gauge, occurs in this position.
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    Head-to-head polymers 27: Thermal degradation of head-to-head polyisobutylene (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 226-229 
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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: Head-to-head polyisobutylene degrades at a maximum rate at 320°C, a temperature about 65°C lower than head-to-tail polyisobutylene. Under our conditions, head-to-tail (the regular polyisobutylene) degrades (as do many other disubstituted vinyl monomers) to a high yield of the monomer isobutylene. Surprisingly, head-to-head polyisobutylene also degraded, primarily to isobutylene. Liquid, low-molecular compounds, probably dimers, were also obtained from head-to-tail and head-to-head polyisobutylene. A mechanism of this degradation is proposed.
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    URL: http://dx.doi.org/10.1002/pen.760230412
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    Masthead (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983) 
    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.760230501
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    A low-energy solvent separation method (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 230-237 
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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 presents a new low-energy method to separate solvents from polymers. The method is based upon the lower critical solution temperature (LCST), a phenomenon exhibited by all nonpolar polymer-solvent systems. Three key issues concerning this new separation method are discussed for the specific system of high cis polybutadiene in a commercial grade n-hexane. The first issue, energy cost, is greatly reduced from present commercial separation processes by avoiding the liquid-vapor phase transition for more than half of the solvent. The predicted energy cost for the new method (not including inefficiencies) is about 15 percent of the present energy cost (including inefficiencies). The second issue, recycling of the dilute phase with terminator, is shown not to be a serious problem, and a solution is suggested based upon available methods. The third issue discussed, and perhaps the most difficult, is the physical separation of the two phases. This is solved by inducing spinodal decomposition, which leads to rapid gravity separation. Several alternative separation scenarios based upon this idea are presented at the end of the article.
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    URL: http://dx.doi.org/10.1002/pen.760230413
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    Masthead (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983) 
    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.760230601
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    Design of two-stage extractor screws (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 299-305 
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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 basis for design of two-stage extractor screws is developed with special focus on determining optimum design of the final pumping section in order to maximize pressure-generating capability. Departure from the conventional square-pitch helix angle of 17.7° appears justified in this section of the screw where pressure-development capability is critical to successful performance. Optimization can produce gains of 5 to 30 percent in pressure (or in corresponding length reductions), the exact benefits depending on the non-Newtonian behavior of the melt and on the optimization strategy selected.
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    URL: http://dx.doi.org/10.1002/pen.760230603
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    Properties of polyisobutylene-polyurethane block copolymers: I. Macroglycols from ozonolysis of isobutylene-isoprene copolymer (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 337-349 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The properties of a series of polyisobutylene (PIB) based polyurethanes were studied and compared to those reported in the literature for polyether, polyester, and polybutadiene-based polyurethanes. Good phase separation was reflected in the invariance of the soft segment Tn with increasing hard segment content. Increasing hard segment content resulted in larger domains, higher modulus and lower ultimate elongation. The modulus above the soft segment Tn was higher than that previously reported for polyurethanes of similar hard segment contant; improved phase separation and short contour lengths of the PIB chains were cited as possible causes of this behavior. Stress-strain data indicated a change from isolated to interconnected domain morphology with incerasing hard segment contant. Generally similar trends were seen for all types of urethanes. The overall properties of polybutadiene polyurethanes were closest to those of the polyisobutylene polyurethanes studied. The properties of both of these systems were suggested to suffer from significant synthesis problems in urethane formation due to the incompatibility of the nonpolar hydrocarbon soft segment and the polar diol chain extender. Preliminary environmental tests indicated that polyisobutylene based materials exhibit improved hydrolytic stability and reduced moisture permeability compared to polyether and polyester polyurethanes and greater oxidative stability compared to polybutadiene based materials.
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    Vulcanization shrinkage of rubber articles with rigid armoring parts (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 350-353 
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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 discusses the shrinkage characteristics of armored (reinforced) rubber articles for two types of boundary conditions: (a) cases where the armoring material is neither flexible nor thermoexpansive, and (b) cases where the armoring material has a finite thermal expansion between room and vulcanization temperature. A quantiative analysis of shrinkage strains and stresses is developed for the two boundary conditions.
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    URL: http://dx.doi.org/10.1002/pen.760230609
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    An observation on the han-villamizar critical pressure concept in thermoplastic foams (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 354-355 
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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 note draws together the Han-Villamizar experimental observations on the critical pressure at which gas bubbles became visible in flowing thermoplastic melts and a simple method of predicting the equilibrium pressure based on gas solubility. It is shown that the observed pressure is 40 to 75 percent of the calculated pressure.
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    URL: http://dx.doi.org/10.1002/pen.760230610
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    Dynamic mechanical studies of thermal aging in poly(vinyl chloride) (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 390-393 
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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 effects of thermal aging on the dynamic mechanical properties of rigid poly(vinyl chloride) (PVC) and chlorinated poly(vinyl chloride) (CPVC) are examined in the glass transition (Tg) and β transition (Tβ) regions. PVC, when quenched through Tg and then annealed at 40°C, exhibits a sub-Tg peak in the loss modulus function. The position of the peak moves to higher temperatures with increasing annealing time. The effect is analogous to sub-Tg endothermic peaks previously observed by differential scanning calorimetry (DSC). A sub-Tβ peak in the tan δ or the loss modulus functions can be produced by quenching through Tβ. The effect of heating rate on the sub-Tβ peak is explored.
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    Effects of strain rate and temperature upon tensile properties of acetal copolymers (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 216-221 
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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 strength and elongation to break of an acetal copolymer were measured at four elongation rates, from 0.2 to 20 in./min, at temperatures from 239 K to 339 K. Both strength and elongation results could be reduced to master curves by means of time-temperature superposition. The temperature dependence of the shift factors was given by an equation of the WLF form, with parameters close to those found for most amorphous polymers, at a reference temperature equal to the γ-transition temperature of the polymer. Extrapolation to much higher testing rates and to much slower creep rates was satisfactory. Similar but less extensive tests were run on two other samples with different molecular weights. The yield stress was independent of molecular weight, but elongation increased with increasing molecular weight at all conditions.
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    The specification of orientation and its development in polymer processing (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 247-256 
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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 critical review of the specification of orientation and its development in polymer-processing operations is presented. Orientation may in general be specified by orientation distribution functions, but is most conveniently expressed in terms of orientation factors which are second moments of the distribution. The Hermans orientation factor represents polymer-chain orientation for systems with fiber symmetry (uniaxial orientation) and the Hermans-Stein orientation factors express uniaxial orientation for each of the crystallographic axes of crystalline polymers. Biaxial orientation is, however, developed in tubular film extrusion, blowmolding and, indeed, all processing operations other than fiber formation. Orientation factors developed previously by the authors express biaxial orientation in terms of the angles between the machine and transverse directions and the polymer chain axis or crystallographic axes. In flowing polymer melts, the Rheo-Optical Law, which relates birefringence and stress, represents a relationship between polymer-chain orientation and stress. In vitrified polymeric glasses (e.g. polystyrene), the orientation factors are related linearly to the stress field at vitrification. This has been shown experimentally for melt spinning and tubular film extrusion. The results of studies of blowmolding and injection molding are consistent with this. The crystalline orientation factors have also been found to be determined by the stress field at solidification in melt spinning and tubular film extrusion.
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    Super strong polymers in planar directions (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 266-270 
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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 novel approach for producing multiaxially oriented polymers with ultrahigh mechanical properties in more than one direction is discussed. According to the approach, which is adaptable to conventional commercial processes, the polymer is processed in a contained geometry at a temperature near to but below the isotropic crystalline melting point under curvilinear flow conditions generated by the combined effects of a compressive force and a rotational force perpendicular to the compressive force. The process is demonstrated with thermoplastic and thermotropic polymers using simple torsional flow. The general features of the process and the properties of the multiaxially oriented polymers are discussed in view of the different flow conditions.
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    URL: http://dx.doi.org/10.1002/pen.760230506
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    Thermal conductivity of plastic foams (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 293-298 
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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 simple equation enabling the prediction of the thermal conductivity of plastic foams, without the aid of adjustable parameters, is proposed. The equation is based on a recurrent method, previously developed, that showed reasonable agreement with experimental results. Ways of decreasing the thermal radiation contribution are shown. In particular, the influence of cell size, radiation transmission through solid membranes, and low-emissivity boundary surfaces are analyzed. Errors involved in steady techniques of measuring the thermal conductivity associated with radiation are discussed.
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    The length of a transfer unit (LTU) for polymer devolatilization processes in screw extruders (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 323-327 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this paper we introduce the concept of the length of a transfer unit (LTU) for polymer devolatilization and show that the LTU is an appropriate measure of the effectiveness of the process unit in which the devolatilization operation is conducted. The utility of the concept is demonstrated for the case when the process unit is a twin screw extruder for which values of the LTU were determined from experimentally measured values of devolatilization rates. Values of the LTU were found to depend solely on the fluid mechanics in the extruder as expected and were in good agreement with the predictions of a theoretical expression developed for the system that was studied. Finally, we discuss the implications of the LTU concept in relation to the engineering design and analysis of polymer devolatilization processes.
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    URL: http://dx.doi.org/10.1002/pen.760230606
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    Studies on whitening phenomena induced by some non-solvents on highly oriented glassy polymers (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 328-336 
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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: Whitening phenomena, characterized by optically opaque regions when a highly oriented glassy polymer is immersed in some liquids, were investigated as a function of temperature, extent of molecular orientation, different solvent and molecular weight, using oriented polymethyl methacrylate (PMMA) obtained by hot-stretching and cold drawn polycarbonate (PC). Whitened PMMA is highly porous resembling foamed plastics and shows the same Tg as in unwhitened PMMA, while whitened PC is denser with much smaller pores and exhibits melting behavior characteristic of solvent-induced crystallinity. Whitening progresses with a sharp boundary between whitened and unwhitened layers, which advanced at a constant velocity. This feature is similar to Case II transport. However, whitening differs from Case II sorption in that it only occurs in highly oriented polymers in contact with liquids of negligible sorption. Activation enthalpy of 44.1 and 39.7 kcal/mol has been found in a certain temperature range for PMMA/N-methyl formamide (N-MF) and PC/di-isopropyl amine (DIPA) respectively. At a given temperature, a higher extent of orientation leads to faster whitening process. Entropy correlation theory, in which the decrease in the configurational entropy (ΔSc) due to orientation is assumed to approximate an inerease in the activation entropy, was employed to correlate the dependency of the whitening rate on orientation. For hotstretched PMMA, where ΔSc is proportionl to \documentclass{article}\pagestyle{empty}\begin{document}$ (\alpha ^2 + 2/\alpha - 3) $\end{document} since affine deformation applies, a good correlation is observed. For cold drawn PC, correlation was poor, probably because ΔSc cannot be expressed to be proportational to \documentclass{article}\pagestyle{empty}\begin{document}$ (\alpha ^2 + 2/\alpha - 3) $\end{document}. In PMMA, when the molecular weight is in the same order as the average molecular weight between entanglements, the orientation and the whitening rate are both lower than higher molecular weight speciments. This may be due to a smaller number of chain entanglements and consequent chain slippage. In PMMA, whitening induced liquids seem to have a solubility parameter somewhat greater (2.5 ∼ 5.0) than that of PMMA. For PC, no consistent tendency is found.
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    Polyurethane-poly(methyl methacrylate) interpenetrating polymer networks: Some mechanical properties (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 394-398 
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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 mechanical behavior of polyurethane-poly(methyl methacrylate) interpenetrating polymer networks (PUR/PAc IPN's) was investigated. Stress-strain and impact resistance measurements were made on IPN's with a variable PUR content. The effect of the degree of crosslinking of each network on the mechanical properties was also studied. It appears that only the ultimate elongation varies largely upon changing the crosslink degree. The results are interpreted in terms of the contribution of each network to the mechanical behavior, but also by the interpenetration of both components and by the phase continuity of the PAc network.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230705
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    Plane strain fracture toughness of polyethylene pipe materials (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 404-411 
    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 plane strain fracture toughness of medium density polyethylene pipe materials has been investigated over a range of test temperatures and rates. Conditions are defined under which valid fracture toughness values can be obtained; at higher temperatures the material is notch-insensitive. Fracture surface morphology is described, and features are compared with predictions from the Dugdale model. The toughness derives from a band of fibrillar, drawn morphology associated with crack initiation or slow growth. The plane strain fracture toughness correlates with percent crystallinity according to the same relationship whether the crystallinity is varied by thermal treatment, comonomer content, or molecular weight.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230707
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  • 89
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    Properties of phenolic fiber-reinforced polymers (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 776-778 
    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: Fibers made of phenol formaldehyde are relatively new to the market place and are currently manufactured in Japan. They have certain characteristics which make them attractive as a reinforcement for rubber, thermoplastics, and thermosets. This paper will discuss the properties of molded polypropylene thermoplastics as a function of fiber weight percent and surface treatment. It is shown that the elevated temperature properties are improved without sacrifice of low-temperature brittleness.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231405
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  • 90
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    Phase relationships of rigid rod polymer/flexible coil polymer/solvent ternary systems (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 789-791 
    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: Phase diagrams of two types of rigid rod polymer/flexible coil polymer/methanesulfonic acid (MSA) ternary systems were determined by polarized optical microscopy at ambient conditions. The rigid rod polymer is a wholly aromatic high temperature resistant (no measurable Tg) poly (p-phenylenebenzobisthiazole) (PPBT). One of the flexible coil polymers is a wholly aromatic high temperature resistant poly (2,5′(6′) benzimidazole) (ABPBI), the other is a thermoplastic poly[2,2′ -(1-4-phenylene)-6,6′ -bis (3-phenyl-quinoxaline)] (PPQ) with Tg of 359°C. The solvent is methane-sulfonic acid (MSA). The experimentally determined critical concentration points, Ccr, are in excellent agreement with Flory's recent theory. Total phase segregation between the polymer pair in ternary solution was predicted and observed at C 〉 Ccr. Different decomposition mechanisms of phase separation were observed as a function of concentration.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231408
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  • 91
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    Injection molding of thermotropic liquid crystal polymers (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 792-796 
    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: Thermotropic liquid crystal polymers consist of rod-like molecules and are often called “self reinforcing thermoplastics.” Their rheological behaviors as well as orientation development during processing are often very similar to those of short fiber-filled composites. Without reinforcement, the polymer shows superior mechanical properties to conventional glass fiber-reinforced engineering resins. The orientation distribution in the crosssection as well as flow patterns in the molded thermotropic polymers are clearly visible to the naked eye due to color differences. This makes it particularly convenient to study the orientation distribution as well as the flow patterns of packing, back flow, jetting, flow instabilities, and weld line formation in injection molding. This paper discusses physical properties of a typical ther motropic polymer and their relationship to mold filling process in the injection molding.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231409
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  • 92
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    Effect of a diamine additive on the structure-property relationships of rim polyurethane elastomers (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 816-819 
    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: Structural and mechanical data have been compared for reaction injection molding (RIM) polyurethanes prepared from uretonimine-modified diphenylmethane 4,4′-diisocyanate (MDI), ethylene glycol (EG), and a polyol (a polyether; Mn ≃ 5000), in order to investigate the effect of addition of a small amount of a polyetherdiamine (PEDA; Mn ≃ 400) to the reaction mixture, A series of specimens containing 18 parts and 30 parts EG, with and without the diamine additive, were examined both as-prepared and after thermal annealing. The specimens were compared in terms of their x-ray crystallinity, elongation, flexural modulus, impact strength, and heat-sag behavior. All of the specimens showed evidence for crystalline hard segments, which are more abundant in the series containing 30 parts EG. The crystallinity is lowest in the as-prepared specimens without the PEDA additive, and is increased by annealing for 1 hour at 120°C. The as-prepared specimen with additive has a hard segment crystallinity similar to that of the annealed specimen without additive. These results correlate with the mechanical property data, which improve as a result of annealing and/or the use of a PEDA additive. It is argued that the use of the polyetherdiamine enhances the phase separation and facilitates hard segment crystallization, leading to better heat-sag behavior. It is significant that the unannealed/with PEDA and annealed/without PEDA specimens have similar properties. Use of PEDA additive improves the green strength and impact strength of molded parts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231505
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    Masthead (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983) 
    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.760231601
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  • 94
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    Deformation studies of polystyrene/poly(vinyl methyl ether) blends by mechanical-vibrational spectroscopy (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 861-868 
    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 have analyzed the deformation behavior of compatible and incompatible polystyrene (PS) and poly(vinyl methyl ether) (PVME) blends by a combination of mechanical and vibrational spectroscopy. Macroscopic properties and segmental orientation were found to be sensitive to molecular weight, strain rate, and temperature of measurement above the glass-transition temperature. Considerably different orientation functions were found for the PS and PVME components. For the experiments carried out above the Tg of the blends, the deformation behavior measured was consistent with expectations of a rubbery network.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231602
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  • 95
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    Thermal, mechanical, and rheological behavior of blends of ultrahigh and normal-molecular-weight linear polyethylenes (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 888-894 
    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: Physical Blends of ultrahigh-molecular-weight linear polyethylene (UHMW LPE) and normal-molecular-weight linear polyethylene (NMW LPE) have been evaluated in terms of melt flow rate, tensile stress-strain behavior, heat of fusion, melting temperature, and crystallinity. The behavior of the blends is intermediate between that of the parent polymers; no synergistic effects are observed. The addition of small quantities of NMW LPE does not improve the flow behavior of UHMW LPE sufficiently to render it amenable to conventional melt processing.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231606
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    Failure of rubber-modified plastic liners (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 560-566 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to analyze the failure phenomenon of plastic liners in freezers and refrigerators the mechanical properties of the freon blown polyurethane (PU) foam insulator material and the acrylonitrile-butadiene-styrene (ABS) plastic liner are determined. The properties considered essential for this problem are the elastic modulus, the tensile strength and the fracture toughness over the temperature range -40 to 20°C. By laminating a layer of the polyurethane foam to the ABS liner and depending on the test temperature brittle to semi-brittle fractures are promoted and the maximum load fracture toughness of the liner material is reduced. The reduction is more severe for notched bend than for single-edge notched tension specimens. Based on these mechanical properties plausible reasons for liner fractures are discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231006
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    Determination of time independent component of the complex modulus during cure of thermosetting systems (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 586-590 
    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 recent development suggests an approach to measure the equilibrium modulus through an impulse method. This paper is to report an attempt to apply such methods in measuring the changes of the equilibrium modulus of a thermosetting system during isothermal cures. Dynamic modulus changes were also measured and the results were correlated with that from the impulse method. At two different temperatures of cure, the equilibrium modulus values measured were very similar when the dynamic measurements showed tan δ = 1. At this point, it is not certain if the measured modulus is the real time independent portion of the elastic modulus, or contains the long relaxation time constant portion of the relaxation spectrum which appears to be pseudo-time independent at the time scale and the instrumental sensitivity of the present experimental set-up. This paper demonstrates the ease with which the impulse technique can be applied and suggests possible limitations or refinements.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231010
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    Melt flow of polymer blends (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 602-609 
    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 production of polymer blends increases at a rate of about 13 percent/y. Most of the commercial blends are multiphase systems of complex morphology, determined by the thermodynamic properties of the components and the rheology. Since the diffusion rates are relatively low, the blends are seldom at equilibrium. In most cases, the blend products have properties imposed by the morphology, created by a particular combination of the thermal and deformational history. There are three main reasons for studying the melt flow of blends: optimization of the processing conditions, search for the appropriate means to generate the desired morphology, and the interest in the basic study of the rheology of these complex systems.In this paper the results published during the last five years are reviewed. The data for polymer blends are compared with those obtained for simpler model systems: liquid mixtures, emulsions, and polymer blends. From the rheological point of view, the blends are divided into three groups: those where viscosity shows positive deviation from the log-additivity rule, PDB, those where the opposite effect is observed, NDB, and the remaining mixed-behavior systems, PNDB. To PDB belong the miscible blends and those with strong inter-domain interactions. To NDB belong those where the interactions are weak. To PNDB belong the blends in which there is a concentration-dependent transition of structure. The shear dependent properties of blends are also discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231103
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    Engineering and molding properties of poly(vinyl chloride), acrylonitrile-butadiene-styrene and polyester blends (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 627-631 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer blends with varying amounts of poly(vinyl chloride) (PVC), acrylonitrile-butadiene-styrene (ABS) and polyester have been developed to produce parts with highly flexible, good impact strength, and flame retardant hinge properties. In the present work, the rheological and dynamic mechanical properties are balanced by changing the blend formulations. It is shown that blends morphology and rheology have greater impact on the dimensional stability and delamination at the surface of the molded hinge parts.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231107
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  • 100
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    A comparison of miscible binary blend interaction parameters measured by different methods (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 676-681 
    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: Miscible blends of the polyhydroxy ether of bisphenol-A, Phenoxy, with a series of aliphatic polyesters were studied using melting point depression analysis and sorption to obtain the Flory-Huggins polymer-polymer interaction parameter, B. The B values obtained from these measurements were found to agree well in sign, magnitude, and variation with ester repeat structure and to also agree well with B values measured calorimetrically for mixtures of low molecular weight compounds with structures which are analogous to those of the polymers. These comparisons suggest that the same mechanisms are responsible for the exothermic heats of mixing measured directly for the analog compounds and indirectly for the miscible polymer blends. For this general system, evidence is provided which suggests that hydrogen bond formation between the hydroxyl group on Phenoxy and the ester moiety is probably responsible for the exothermic interactions and polymer blend miscibility observed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231207
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