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  • 1985-1989
  • 1970-1974  (1,970)
  • 1890-1899
  • 1970  (1,970)
  • Polymer and Materials Science  (1,970)
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Years
  • 1985-1989
  • 1970-1974  (1,970)
  • 1890-1899
Year
  • 101
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 979-990 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have measured the relaxation modulus in the temperature range 150-220°C of two samples of poly(vinyl chloride) resin with different molecular weights. The data were treated by the principle of reduced variables to yield composite curves. The shift factors (aT) when plotted against reciprocal temperature gave good straight lines from which apparent activation energies were obtained. An apparent activation energy of 50 kcal/mole was obtained for both samples. A relaxation spectrum for each resin was calculated from the relaxation modulus data. These spectra showed a marked molecular weight dependence. The spectra were in the range characteristic of the terminal zone of the entanglement plateau. Zero-shear-rate viscosities were obtained from the integration of relaxation modulus plots. From extrapolation of capillary viscosity data it is shown that the viscosity of the higher molecular weight resin used in this study does not approach its zero-shear value until shear rates less than 10-3 sec-1 are reached. The effect of supermolecular flow units is briefly discussed.
    Additional Material: 8 Ill.
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  • 102
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1015-1026 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An investigation of small-angle scattering produced by polarized light from stretched and annealed polymer systems containing spherulites yields information on the supermolecular transitions that occur during such treatment. A series of semicrystalline polymer systems (films, fibers) show that stretching leads to deformation of spherulites and subsequent transformation to an orientational supermolecular order. The size of the single element C2 of the supermolecular order in the direction of stretching, determined from the distance between the layer lines of the scattering pattern, is related to the diameter D0 of the initial spherulites by the relation C2 = KD0λs, where λ, is the draw ratio of the macrosystem and K is a parameter determining the deformability of the spherulites. For polyethylene at room temperature K is unity and for polychloroprene it is 1.2. Changes of C2 after annealing and restretching of the systems also obey this ratio.
    Additional Material: 9 Ill.
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  • 103
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1073-1087 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A convenient pressure apparatus was designed for crystallization of high polymers under hydrostatic pressure up to 5000 atm. Melt crystallization as well as heat treatment under various temperatures and pressures was carried out on several polymers, and the effects of pressure on the molecular and crystal structures of the samples are discussed. Heat treatment of syndiotactic polypropylene under high pressure yields a new crystal modification rather than the previously known helix and planar zigzag modifications. Of the three modifications of poly(vinylidene fluoride), modification III was found as a high-pressure phase for specimens in the unoriented state, while modification I was obtained as the most stable one on heat treatment of oriented specimens under high pressure. Heat treatment under high pressure converts ordinary isotactic poly-4-methylpentene-1 with a lower density than the noncrystalline value, to a new crystal modification with higher density. As is reasonable, the dense modification is stable in a high-pressure range. For these three cases, the orientation of specimens was found to remain unchanged during the transitions, which must therefore occur in the solid state.
    Additional Material: 9 Ill.
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  • 104
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1137-1157 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The scattering of light by a two-dimensional spherulite of radius R is calculated when there is disorder of optic axis orientation with respect to the radius. Special cases are considered when (1) the disorder occurs in the radial direction only, (2) the disorder occurs in the angular direction only, (3) there is combined radial and angular disorder, and (4) the optic axis makes a constant angle with the radius but there is disorder in the twist angle about the axis. In all of these calculations, a correlation function for disorder is defined and the scattering pattern depends on the ratio of the associated correlation distance to the size of the spherulite. With decreasing correlation distance, the azimuthal dependence of the scattering becomes less and there is a change in the variation of scattered intensity with scattering angles in a manner dependent upon the type of disorder.
    Additional Material: 6 Ill.
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  • 105
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1187-1194 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nonrandom orientational distribution of structural units, such as crystallites and chain segments, prevailing in an anisotropic bulk polymer sample can be represented fully by an orientation distribution function. Measurements of fluorescence polarization and wide-line NMR are, in principle, capable of yielding information on the moments of the distribution function up to the fourth order. This work presents the method of analysis required to determine these moments. For this purpose, the distribution function is expanded in a series of generalized spherical harmonies. The method is an extension of a similar technique previously proposed for analysis of x-ray diffraction data for determination of a complete crystallite orientation distribution function.
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  • 106
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1195-1209 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The strain-optical coefficient and relaxation modulus were simultaneously measured for high-density polyethylene at various temperatures ranging from 12 to 100°C. Not only horizontal but also vertical shifts were necessary to obtain smooth master curves by the application of time-temperature superposition. However, the relaxation modulus decreases with rising temperature while the strain-optical coefficient increases. This behavior indicates that the variation of the relaxation modulus and the strain-optical coefficient with time can not be explained by a decrease in crystallinity with rising temperature since a decrease in crystallinity usually causes a decrease in the strain-optical coefficient with time can not be explained by a decrease in crystallinity with rising temperature since a decrease in crystallinity usually causes a decrease in the strain-optical coefficient. It was emphasized that another explanation should be sought for the vertical shift in the time-temperature superposition of the time-dependence curves of the relaxation modulus and the strain-optical coefficient at various temperatures. The master curve of the strain-optical coefficient at various temperatures. The master curve of the strain-optical coefficient or the optical distribution function of relaxation times determined from it serve to distinguish the type and thermal history of the polyethylene.
    Additional Material: 15 Ill.
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  • 107
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1291-1302 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Changes produced in γ-irradiated polyethylene by subsequent ultraviolet irradiation have been investigated by ESR measurements, ultraviolet spectroscopy, and viscometric determination of average molecular weight. The photoinduced changes depend on the wavelength of irradiation. Upon irradiation at wave length greater than 3900 Å, main-chain scission occurs by reaction of trapped allylic radicals: A reduction in molecular weight sndicated by this reaction was verified by fractionation experiments and molecular weight determinations.
    Additional Material: 5 Ill.
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  • 108
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A mathematical representation of the transformation of an orientation function between two sets of Cartesian coordinates is discussed in terms of a series expansion of the distribution function in generalized spherical harmonics. A general procedure for calculating the mechanical anisotropy of a single-phase system (a polycrystalline material) from the orientation of its structural units and the intrinsic mechanical anisotropy of the structural unit is discussed in relation to the transformation of the orientation distribution function, i.e., mutual conversion of the coefficients in the expansion of the distribution function between the two sets of Cartesian coordinates. The procedure is extended to a two-phase systems (semicrystalline polymers) containing structural units composed of crystalline and noncrystalline materials in three different geometrical arrangements.
    Additional Material: 7 Ill.
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  • 109
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1387-1393 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(ethylene adipate), poly(ethylene suberate), and poly(ethylene sebacate) were synthesized by a modified ester interchange procedure. Polydispersity was reduced and low molecular weight material removed by fractional crystallization. Samples of 50-60% crystallinity were prepared by bulk crystallization and annealing. Melting points and amorphous densities were obtained by dilatometry. Melting points were 7-12°C higher than previously reported. Heats of fusion were measured by differential scanning calorimetry and extrapolated to 100% crystallinity by using measured amorphous densities and recently redetermined crystalline densities. Entropies of fusion were calculated and separated for the first time into volume expansion and conformational contributions.
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  • 110
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1057-1072 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric properties of poly(vinylidene fluoride) have been studied in the frequency range 10 Hz to 100 kHz at temperatures between -196 and 150°C. Three dielectric relaxations were observed: the α relaxation occurred near 130°C, the β near 0°C, and the γ near -30°C at 100 kHz. In the α relaxation the magnitude of loss peak and the relaxation times increased not only with increasing lamellar thickness, but also with decrease of crystal defects in the crystalline regions. In the light of the above results, the α relaxation was attributed to the molecular motion in the crystalline regions which was related to the lamellar thickness and crystal defects in the crystalline phase. In the β relaxation, the magnitude of the loss peak increased with the amount of amorphous material. The relaxation times were independent of the crystal structure and the degree of crystallinity, but increased slightly with orientation of the molecular chains by drawing. The β relaxation was ascribed to the micro-Brownian motions of main chains in the amorphous regions. The Arrhenius plots were of the so-called WLF type, and the “freezing point” of the molecular motion was about -80°C. The Cole-Cole distribution parameter of the relaxation time α increased almost linearly with decreasing temperature in the temperature range of the experiment. The γ relaxation was attributed to local molecular motions in the amorphous regions.
    Additional Material: 13 Ill.
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  • 111
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1127-1136 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory for scattering of light from films in which the orientation correlation between two scattering elements depends upon the angle β between the optic axes and the vector connecting the two elements is extended. A delta-function type dependence is assumed in which the correlation is strongest when β equals some preferred value β0. Calculated results of scattered intensities are shown to be similar to experimental observations.
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  • 112
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1159-1168 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ESR and electrical conductivity measurements have been made on a recently prepared polymer, polypropiolamide. The polymer was obtained as a fine powder which exhibited a nearly Lorentzian line with a width between derivative maxima of 5.2 ± 0.1 gauss and a g value of 2.0036 ± 0.0005. The signal intensity increased with increasing molecular weight. The signal was retained in a dilute solution in formic acid with a slight narrowing of the line. Permanent changes were produced in the spectra at room temperature by heat treatments of the polymer at temperatures up to 800°K. The changes were similar for samples sealed in tubes containing air, dry nitrogen gas and a vacuum of 3 × 10-5 mm of Hg. Spectra obtained at temperatures up to 500°K showed no dependence on the presence or absence of oxygen in the ambient atmosphere. The deresistance of pressed pellets of the polymer was measured in the temperature range 450°K to 525°K, and the results were described by the relation R = R0cE/kT. The activation energy E had a value of 1.2 ± 0.2 ev and the resistivity at 500°K was approximately 1013 ohm-em. The ESR signal is attributed to an intrinsic property of the polymer which is associated with a conjugated bond system along the polymer backbone. Neither the activation energy nor the magnitude of the resistivity suggest that the delocalized electrons associated with the conjugated bond system have produced unusual electrical characteristics in the polymer.
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  • 113
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1235-1237 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 114
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Critical miscibility data obtained from measurements of phase-volume ratios have been used to calculate the concentration dependence of the pair interaction parameter for the system polystyrene-cyclohexane. The measured temperature and concentration ranges are 11-30°C and 4-18% polymer by weight, respectively. With the Gibbs free energy of mixing expressed in polymer segment mole fractions, x*, the pair interaction parameter is g(x*, T) = 0.4961 + 71.92/T + 0.2312x* + 0.0750x*2. In a polymer volume fraction formulation the parameter is g(ϕ, T) = 0.4099 + 90.65/T + 0.2064 ϕ + 0.0518 ϕ2, which approximates to χ(ϕ, T) = 0.2035 + 90.65/T + 0.3092 ϕ + 0.1554 ϕ2. Comparison of the temperature and concentration dependence with that obtained by other authors shows very good agreement, even when extensive extrapolations in temperature and concentration are applied. The present function is believed to be the most accurate. Solutions of mixtures of two narrow-distribution polystyrenes in cyclohexane show separation into three liquid phases under the exact conditions predicted by theoretical calculation with the present pair-interaction function.
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  • 115
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1279-1289 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Selenacyclobutane (trimethylene selenide) readily undergoes photochemical reaction to give polymeric products. Also, the material polymerizes rapidly when the polycrystalline solid film liquifies on a salt substrate in vacuum. Upon polymerization of the sample, infrared and Raman spectra exhibit profound changes which definitely establish ring cleavage. The Raman spectra of the polymer reveal strong C-Se stretching peaks but little or no scattering in the region of Se-Se stretching, strongly suggesting that the polymerization process proceeds in a regular head-to-tail fashion. An EPR study of the monomer exposed to ultraviolet radiation at -180°C supports this fact, since the resulting spectrum is indicative of an intermediate radical species, (CH2CH2-CH2Se)n., where n is sufficiently large that the terminal electrons do not interact. No triplet spectra were observed. Molecular oxygen apparently plays an important role in the polymerization kinetics, since it is found that degassed samples of the substance, in contrast to those which have not been degassed, polymerize rapidly even under room illumination. Freezing-point depression measurements fix a lower limit to the average molecular weight of the polymer at 2700 (n = 23 monomer units).
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  • 116
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of long-and short-chain branching in polymer molecules on gel-permeation chromatographic (GPC) separation is discussed. The calculation of calibration curves for branched polymers is developed from the universal calibration technique based on the hydrodynamic volume concept and previously established relationships for the effect of branching on molecular dimensions. Typical calibration curves are shown for different branching models and degrees of branching. As branching increases, the curves are shown to converge. Methods of characterizing branching and molecular weight distributions of franctions and whole polymers from GPC and intrinsic viscosity data are presented.
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  • 117
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 2177-2186 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Branched polyethylene, melt-crystallized in commercial fabrication processes, cleaves into two layers when exposed to a prolonged “chemical filling” treatment (i.e., formation of filler in situ by interdiffusion of two reactive permeants). Cleavage has been observed in film and blown bottles. With film, progressive changes in experimental conditions from one sample to another, shifted the cleavage plane from near the surface to deeper lying planes. Separation of a thin surface layer requires more filler deposit than does separation into layers of more equal thickness. These observations suggest that a well defined layer structure may exist in branched polyethylene and that cohesive bonding is stronger between layers near the surface of the film than it is between deeper lying layers. Linear polyethylene showed slight layer separation after prolonged chemical filling, but clean cut separation of large areas was not achieved. This behavior may indicate that the cohesive bonding between layers is much stronger in linear polyethylene than in branched polyethylene.
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  • 118
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1797-1801 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The current theoretical treatment of diffusion of gases in glassy polymers is based on the “dual sorption” model, but also includes certain other important assumptions, at least some of which cannot be fully justified a priori. They require experimental validation, which, however, is not possible by the procedures used or proposed so far. Methods suitable for this purpose are discussed here.
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  • 119
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1773-1786 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature dependence of the crystallinity of bulk polyethylene is calculated in terms of branching (methyl or ethyl side groups on the chain). In the model, the chains are approximately parallel and they pass through alternating amorphous and crystalline layers forming a periodic structure. The crystalinity and the thicknesses of the layers are determined by minimization of the free energy. The theory shows that the temperature at which the polymer begins to crystallize is lower than the melting point of pure polyethylene and that the thicknesses of the layers becomes smaller as the temperature decreases.
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  • 120
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1837-1839 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 121
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1831-1835 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Average polymer segment densities and thermodynamic properties of polymer adsorbed at liquid-solid interfaces were computed by extension of the polymer adsorption theory of Forsman and Hughes. Expressions were derived for the total free energy of adsorbed polymer chains by using the Flory-Huggins theory to represent free energy of mixing. A square-well potential was used to represent segment-surface interaction, and configurational entropy was calculated from the probability density function for the radius of gyration of random-flight chains. For each specified amount of surface coverage the free energy of the adsorbed polymer was minimized by varying the density of segments normal to the adsorbing surface and using a modified gradient search algorithm on a digital computer. Two different segment densities were considered, and they both gave qualitatively the same results. The two densities were (1) the sum of two Gaussian distributions and (2) a two-step density distribution. Isotherms were then calculated by equating the partial molal free energy of polymer at the surface to that of polymer in bulk solution for each specified amount of surface coverage. The results showed that for the initial region of the isotherms the distribution of polymer segments normal to the surface consisted of a high-density layer adjacent to the surface and a low-density “tail” extending far out into the solution. At higher amounts of adsorbed polymer, i.e., in the general concentration range of the pseudo-plateau, the tail of the polymer density distribution was predicted to thicken, and a single Gaussian distribution best described the segment density. Predicted adsorptions were in good agreement with reported experimental values.
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  • 122
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1897-1908 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of molecular weight distribution on the viscoelastic properties of “entangled” polymers has been examined with blends of narrowly distributed polystyrene and broadly distributed polydimethylsiloxane. It is shown that blending laws established for nonentangled polymers do not apply to high molecular weight systems. The steady-state shear compliance of a blend is examined as a function of its molecular weight and the molecular weight of its components, and an approximation is given for the longtime viscoelastic response of entangled blends.
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  • 123
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1927-1935 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The storage (J′) and loss (J″) shear compliances have been measured for two random copolymers of styrene and n-hexyl methacrylate with styrene contents of 18% and 30% (by weight) in the frequency range 45-4400 Hz and the temperature range 31-107°C. The data at different temperatures were combined by the method of reduced variables, and the WLF coefficients were calculated from the temperature shift factors by the method of Pierson and Kovacs. The data were compared with earlier data for the two homopolymers. The thermal expansion coefficient of the fractional free volume, and the free volume at the glass transition temperature, varied monotonically with composition, but the fractional free volume at a reference temperature of 100°C appeared to pass through a maximum as a function of concentration. Comparison of isothermal plots of J′ at 100°C, plots of the relaxation spectrum at 100°C, the monomer friction coefficient and its temperature dependence, and isochronal plots of the storage shear moduls at 100 radians/see all show that the properties of poly(n-hexyl methacrylate) are very slightly affected by incorporation of 18% styrene and only moderately affected by 30% styrene. By contrast, comparison of styrene-butadiene rubber with 1,4-polybutadiene shows a very large effect of incorporation of 23.5% styrene. These differences may be associated with local packing relations of the comonomer residues and suggest that copolymer properties cannot be readily predicted from those of the component homopolymers.
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  • 124
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 401-410 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The free radicals formed on irradiation of nylon 6 have been studied by means of electron spin resonance (ESR). The irradiation was performed at liquid nitrogen temperature with wavelengths in the region of solar radiation. The spectrum so obtained could best be fitted by assuming —CH2—ĊH—CH2— and —CH2—Ċ=O to be the trapped radicals. The assignment of the spectrum supports the idea that the first step in photodegradation is the breaking of the amide bond. The splitting constant of the α proton of the alkyl radical has been found to be nearly the same for drawn and undrawn yarn. This strongly suggests that the low-energy radiation is capable of breaking bonds only in the unoriented amorphous regions.
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  • 125
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 455-465 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of branched polyethylenes in the molten state were determined in the frequency range 10-3-10 radians/sec. The materials tested have remarkably similar rheological properties even though they vary greatly in molecular weight and molecular weight distribution. The similarity in properties is attributed to the influence of long chain branching on the relaxation spectra. A mechanistic argument is proposed to relate the observed behavior to molecular entanglement coupling. The concept of entanglement coupling involving long-chain branching leads to the expectation that the quasi-Newtonian and non-Newtonian viscosities of branched polymers may be either greater or less than those of linear polymers of the same species, which have comparable molecular weights. This is borne out by experiment.
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  • 126
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 483-484 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 127
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 799-806 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The tensile stress relaxation master curve for polyvinylcyclohexane (completely hydrogenated polystyrene) has been measured. Direct relaxation experiments were carried out at several temperatures above the glass transition temperature over the rather long time range of four orders of magnitude. This long time span was realized by calculating the modulus during the period when a constant small strain rate was applied to the sample as well as during the usual constant strain interval. A computer solution to the Boltzmann superposition equation allowed data from these two regions to be joined into a smooth curve representing E(t), a parameter indicative of an instantaneous strain experiment. The measured Ti was found to be 143°C; Tg is expected to fall within several degrees of this temperature. This result is apparently at odds with a previously reported Tg value of 120°C. More importantly, the maximum value of the negative slope of the stress relaxation master curve of polyvinylcyclohexane in the primary transition region was only slightly different from that for polystyrene. This observation clearly indicates that the molecular factors which result in the highly coupled nature of the primary transition in polystyrene are not strongly dependent upon any side-chain π-π interactions which might be present in polystyrene.
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  • 128
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 791-797 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR second moment of a uniaxially oriented mat of single crystals of n-C32H66 (in the orthorhombic form) was measured at temperatures from -170°C to 70°C and at various alignment angles γ between the orientation axis (preferential direction of the molecular chains) and the NMR magnetic field. Accurate expressions are given for the NMR second moment of an orthorhombic normal paraffin CnH2n+2 of arbitrary molecular chain length n for n ≥ 10, in the following states of molecular motion: no motion (a rigid lattice), rotation of CH3 groups, and rotation of the chains around their axes with superimposed rotation of CH3 groups. In addition to these well-known motions, n-C32H66 is found to exhibit an α process. The corresponding decrease of the NMR second moment shows the dependence on γ predicted for “flip-flop” motion, i.e., rotational jumps of the chain molecules around their axes through 180° and a simultaneous translation along these axes by one CH2 group. The overall decrease in second moment occuring at the transition to the hexagonal rotator phase in n-C32H66 can be quantitatively accounted for. The dependence of this decrease on the alignment angle γ, however, is in disagreement with calculations based on a simple rotation of the chains around their axes. Considerable torsion of the chains superimposed on the rotation would improve agreement between theory and experiment.
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  • 129
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 869-882 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization kinetics of a high molecular weight fraction of linear polyethylene was studied in dilute solutions of p-xylene, n-hexadecane, and decalin by dilatometric methods. For all solvents and temperatures, the experimental isotherms could be quantitatively described by the Avrami formulation for the complete transformation. This result is unique in the realm of polymer crystallization, since marked deviations from this theory are usually observed in more concentrated systems. The Avrami exponent is found to be n = 4 in all cases. The temperature coefficients of the rate constants are indicative of a nucleation controlled process. The data fit either a two-dimensional or three-dimensional nucleation mode, and a discrimination can not be made between these two cases. The interfacial free energies are found to be independent of the solvent medium. It is also shown that, irrespective of the type of nucleation control governing the kinetics, the same type governs the crystallite thickness of the lamella-like crystals that are formed.
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  • 130
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanical properties of four kinds of natural rubber vulcanizates differing in vulcanization conditions, and consequently in degree of crosslinking (having values of the Mooney-Rivlin constant C1 ranging from 0.68 to 1.98) were observed under orthogonal biaxial stretching in a range of strain invariants Ii from 3.4 to 9.0 (extension ratios λi from 0.7 to 3.0). The results obtained were analyzed by two methods. One method employed the Valanis-Landel postulate that the strain-energy function W(λ1, λ2, λ3) is a separable symmetric function of the principal extension ratios, i.e., W(λ1,λ2,λ3) = w(λ1) + w(λ2) + w(λ3); the other utilized the contour plots of ∂W(I1, I2)/∂I1 and ∂W(I1, I2)/∂I2 surface within the (I1, I2) domain. The postulate for W was examined in detail with good agreement with experimental results. The dependences of ∂W(I1, I2)/∂I1 and ∂W(I1, I2)/∂I2 surfaces on the degree of crosslinking and temperature were further investigated, with the following conclusions. The surfaces have fairly steep slopes for the region of relatively small deformation (i.e., I1 〈 5) and become flat with increasing Ii for all the test specimens. The slope becomes less steep with decreasing degree of crosslinking. The values of ∂W/∂I1 increase linearly and the ∂W(I1,I2)/∂I2 surface becomes flat, both with increasing temperature: i.e., the temperature dependence of ∂W/∂I1 further depends on Ii. The ∂W(I1,I2)/∂I2 surface has a maximum near 40°C.
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  • 131
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1395-1409 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational contribution to the entropy of fusion was calculated for poly(ethylene adipate), poly(ethylene suberate), and poly(ethylene sebacate) from consideration of rotational potentials and steric interactions in model systems. An enumeration scheme similar to that applied to polyethylene was used. Comparison of the observed and calculated conformational entropies indicated the importance of a high-energy chain twist in the crystalline polyesters in reducing their measured conformational entropies. The rigidity of the polyester chains in the melt is discussed in comparison to polyethylene. The contribution of the polar ester groups to the heats of fusion of the polyesters is evaluated semiempirically.
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  • 132
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1425-1441 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The angular position of the extrema of the vertically polarized scattering intensity has previously been utilized for a method of particle size analysis for systems of monodisperse, spherical, isotropic particles which conform to the Rayleigh-Gans-Debye theory. The consequences of a finite polydispersity, which is always present in real systems, was not assessed and the application of the method has resulted in erroneous characterization of some latex systems. This work is concerned with (1) reporting the effects of finite polydispersity on the method of analysis, (2) pointing out previous misuse of the method, and (3) introducing a method of analysis which is based on the position of the extrema but which also considers polydispersity and the exact Mie calculation. This method enables one to characterize a scattering system in terms of a modal diameter and a distribution-width parameter by utilizing prepared diagrams for a particular relative refractive index.
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  • 133
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1467-1490 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was established that polyethylene and polyoxymethylene crystallize epitaxially on NaCl cleavage faces over a temperature range in which the usual polymer single crystals dissolve but a crystallization memory remains due to very small quantities of self-seeding nuclei persisting in the solution. By performing this epitaxial crystallization in the presence of self-seeding nuclei, it could be established that epitaxial crystallization at these elevated temperatures involves only the very largest molecules in the distribution. Further, the self-seeding nuclei themselves could be isolated for observation, and these results were found consistent with previous predictions. By utilizing both the adhesion of these nuclei to NaCl and the selective nature of the epitaxial crystallization, the largest molecules could be extracted and reintroduced again to the same or different solutions. This opens up the possibility of a novel kind of chromatography for the separation and characterization of the highest molecular weight end of a distribution to a sensitivity which cannot be approached by other methods. The epitaxy phenomenon itself, under the circumstances involved, provides a new decoration method for the study of the surface topography of alkali halides. The origin of such as epitaxy occurring at low supercoolings and terminating at a limiting thickness raises important questions regarding long-range forces and some unsettled features in the theory of chain-folded crystal growth in polymers.
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  • 134
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polypropylene film was biaxially stretched in one step in air at 140°C or 152°C, and the deformation was studied optically. A linear relation held between Δnss and vA-½ for vA 〉 10, at both temperatures, where Δnss is the birefringence with respect to the normal to the film and vA is the degree of stretching expressed as the factor by which the area of the film is increased. Extrapolation of data in this linear region yielded a value of 20 × 10-3 for -Δnss at infinite vA. Since it is presumed that the polypropylene molecules lie completely parallel to the film surface when the film is stretched infinitely, -Δnss at vA-½ = 0 must be just half Δn°, the intrinsic birefringence in the case of completely parallel orientation. Thus, Δn° must be 40 × 10-3. This value was obtained experimentally in uniaxial stretching when the birefringence with respect to the direction of drawing was extrapolated to infinite extension. Similar relations held between np, the average of the refractive indices in the two stretching directions, and vA, and between nss, the index normal to the film, and vA. By similar extrapolations, (1/2)(n′γ + n′β) and n′β = n*α′ were estimated, and thence nα′ was obtained. Here, n′α and n′β are the refractive indices along the c axis (molecular chain axis) and b axis. All these optical parameters refer to a density of 0.900 g/cm3. Hence by applying a density correction to those values, the principal refractive indices and the intrinsic birefringence of polypropylene crystal were evaluated as follows: nα = 1.5522, nβ = n*α = 1.5106 and Δnc° = 4.16 × 10-3, where n*α is the refractive index prependicular to the b and c axes of the crystal.
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  • 135
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1617-1626 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The swelling curves of 6μ films of low conversion homopolymers and copolymers of acrylamide (AM) and N-isopropylacrylamide (NIPAM) were obtained in water by an optical microscope technique. Poly(AM) swelled appreciably faster than poly(NIPAM) but there was no apparent correlation between overall swelling rate and copolymer composition. A 57/43 (mole %) AM-NIPAM copolymer swelled fastest. Sequence distribution calculations indicated that its backbone structure tended toward comonomer alternation, which might reduce the extent of hydrogen bonding in the film. The amount of water sorbed during swelling, as approximated from increasing film thickness, was proportional to the square root of time and agreed well with previous work in the literature. Homopolymer films from runs of ca. 50% conversion consistently swelled slower than their low conversion counterparts, probably due to branching and increased entanglements. Heating also promoted slower film swelling due to a tightening of the film structure and/or a low degree of imidization. Monomer reactivity ratios and Alfrey-Price Q and e values for NIPAM were calculated. Cloud points of 5% aqueous solutions of the copolymers were measured and found to decrease with increasing NIPAM content.
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  • 136
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1637-1637 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 137
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1661-1678 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The orientation of crystals in spherulites of modifications I and II of polybutene-1 was studied by micro-x-ray diffraction. Changes in such micro-x-ray diffraction patterns were measured in various regions of the spherulites as a function of strain and time. The relationship between micro-x-ray diffraction from parts of spherulites and macro-x-ray diffraction from entire spherulites is discussed. Changes are resolved into contributions arising from (1) deformation of spherulites with change in crystal orientation and (2) transformation of crystals from modification II to modification I.
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  • 138
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of nylon 3 was studied, and four crystalline modifications were observed. Modification I, as determined from the x-ray diffraction pattern of drawn fibers, is similar to the α crystal structure of nylon 6. The unit cell is monoclinic; a = 9.33 Å, b = 4.78 Å, (fiber identity period), c = 8.73 Å, and β = 60°. The theoretical density for nylon 3 with four monomeric units in the unit cell is 1.39 g/cm3, and the observed density is 1.33 g/cm3. The space group is P21. The nylon 3 chains are in the extended planar zigzag conformation. Although other odd-numbered nylon form triclinic or pseudohexagonal crystals when oriented, drawn nylon 3 crystals are monoclinic. In addition to modification I, modifications II, III, and IV were studied. Lattice spacings of modifications II and III are equal to those of modification I. However x-ray diffraction intensities are different. Infrared spectra of those forms indicate an extended planar zigzag conformation of the chains. Modification IV is thought to correspond to the so-called smectic hexagonal form. No γ crystals were found, and it appears that polyamide chains with short sequences of methylene groups cannot form crystals of this type.
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  • 139
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 991-998 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diffusion of 1,1-diphenylethane in trace amounts through eight rubbery polymers has been studied by radioactive tagging of this penetrant with 14C. For several polymers, the dependence on temperature and on dilution (swelling) by untagged diphenylethane was investigated. In the diluted systems, tagged n-hexadecane was also used as a trace penetrant. The temperature and concentration dependences were interpreted rather successfully in terms of the free volume. In comparing different polymers, with a 4000-fold range of diffusion coefficients, the translatory friction coefficient of 1,1-diphenylethane was found to be proportional to that of n-hexadecane to the power 1.06. This is interpreted qualitatively by the free volume concept to indicate a slightly less efficient mobility mechanism for the diphenylethane.
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  • 140
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1415-1424 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mutual diffusion of pairs of polymers has been studied at 160°C for two systems: isotactic polypropylene with polyethylene and poly(vinyl chloride) with polyethylene. From the assumption that Fick's law is valid and with a rhombohedral lattice model for the microheterogeneous system, it was possible to obtain from volume changes the thickness of the interphase layer after various diffusion times. It was found that the values so calculated differ considerably from the experimental values, the greatest deviations occuring after 20 min diffusion. From this it follows that non-Fickian diffusion strongly influences the distribution of concentrations in the diffuse interface, and thus affects the calculated value of the interphase layer thickness. For both polymer pairs Fickian behavior was confirmed for up to about 10 min diffusion time, in good agreement with experimental data.
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  • 141
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1503-1519 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A statistical theory for the scattering of light from oriented polymer films is developed in terms of angularly dependent generalized correlation functions. Numerical calculations of scattering patterns are carried out for special cases. The scattering depends upon two types of distributions describing (1) the orientation distribution of optical axes of scattering elements and (2) the angular dependence of correlation in orientation between pairs of optic axes. These distributions are expanded in Fourier series (in a two-dimensional treatment), the coefficients of which are functions of elongation and describe the elongation dependence of the scattering patterns.
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  • 142
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1845-1845 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 143
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1885-1896 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new light scattering photometer has been designed in order to perform light-scattering measurements at various temperatures and under pressures of 1-1000 atm. Since the scattering angle is constant (90°C), the dimensions of the dissolved molecules are determined by measuring the intensity at different wavelengths. The method of measurement, the calibration of the instrument, and the treatment of data are described. By a series of test measurements on polystyrene in trans-decalin solutions it is shown that one obtains reliable results and finds considerable effects of pressure on the radius of gyration and the fundamental thermodynamic properties of the system.
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  • 144
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Insertion poly(methyl methacrylate) (PMMA) formed within a monolayer of monomer adsorbed on montmorillonite was studied by means of NMR spectroscopy and shown to be composed of short stereosequences with a predominant isotactic component. The stereospecificity of the insertion PMMA can be understood in terms of the organization of the monomer adsorbed on the surface of the mineral. The monolayer of monomer is assumed to be composed of monads and isotactic diads due to dipole-ion interactions between the molecules of methyl methacrylate and exchangeable cations. Results of experiments relating factors such as temperature, density of ion population of the surface, and the nature of ions are discussed. It is shown that the populations of isotactic and syndiotactic triads Pi and Ps determined experimentally in the insertion PMMA are in a reasonable agreement with values calculated from the model. It is shown, furthermore, that Pi increases with increase in the density of the ion population, in agreement with the equations derived from the model.
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  • 145
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1637-1637 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 146
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1443-1456 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of varying molecular weight distribution on the self-seeding phenomenon was investigated by using high molecular weight polyethylene fractions prepared by the stirring-induced crystallization method of Pennings. The numbers of self-seeding nuclei per gram were determined by measuring crystal dimensions, and were found to increase with increasing molecular weight of the polymer, in accord with previous findings. In another experiment, self-seeded single crystals were grown from materials of various molecular weights, prepared by blending two samples of differing molecular weight in various proportions. The concentration of nuclei varies linearly with the weight fraction of high molecular weight polymer in the mixture. This result is shown to be consistent with the proposition that each nucleus contains on the average an identical number (most plausibly one) of molecules of very high molecular weight. The application of this finding to the determination of molecular weights is discussed, and it is shown that the technique provides a method of unprecedented sensitivity for the characterization of the very high end of the molecular weight spectrum. Some morphological results are also presented. In particular, direct observations of the nuclei were found to be consistent with the loosely connected multiple nucleus structure, which had been proposed previously to account for certain light-scattering results.
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  • 147
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1575-1584 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The resonance frequencies of unidirectional carbon fiber reinforced/epoxy composite beams were studied over the temperature range 24-225°C. Longitudinal Young's moduli E11 and longitudinal-transverse shear moduli G12 were computed from the experimental data by the use of Timoshenko beam theory. The effects of transverse shear deformation (a function of E11/G12) were found to increase in importance with increasing temperature. Values of G12 were found to be approximately proportional to the shear modulus Gm of matrix material but were about 30% lower than predicted by the theory of Hashin and Rosen. The anisotropy of the carbon filaments and voids in the composite samples were proposed to account for the discrepancy between theory and experiment.
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  • 148
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1635-1635 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 149
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1639-1649 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The general problems presented by the determination of the optical activity of polymers in the crystalline state are considered. The necessity of using unoriented samples, if the polarimetric data are to be compared with analogous data measured in solution, is emphasized. The optical activity in the crystalline state of a number of stereoregular vinyl polymers has been measured by employing either suspensions of fine powders or thin plates with no detectable orientation. The results of optical rotatory dispersion studies in the crystalline state suggest that, at least in the case of the poly-α-olefins investigated, the same chromophores are responsible for the optical activity in the crystalline state and in solution.
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  • 150
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1697-1701 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Middle range fractions of mimusops balata, a natural trans-1,4-polyisoprene, exhibit transcrystallinity when crystallized in the 35-40°C range. The presence of transcrystallinity was established by x-ray diffraction and optical microscopy. Diffraction peak intensities change due to transcrystallinity, suggesting x-rays be used to detect transcrystallinity and that caution be exercised in using x-ray diffraction techniques to determine the phases present in bulk material and in calculating the degree of crystallinity. The tendency toward transcrystallinity may depend upon molecular weight.
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  • 151
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    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1723-1740 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The transformation of microspherulitic quenched and annealed polyethylene film into highly oriented drawn material with the characteristic fiber structure was investigated by small-angle and wide-angle x-ray measurements and by a study of the thermograms after the fuming nitric acid treatment. With the details of deformation depending slightly on the crystallinity, one observes generally a preferential tilt of the platelets against draw direction at draw ratios below 2. At least in annealed material, an increasing tilt of the molecule within the lamella is also observed, which leads at higher draw ratios to slipping of blocks in the crystallites. With further drawing a new fiber structure appears, which is practically independent of the thermal history of the original film. This fact is established by investigation of the crystal thickness by three different methods; investigations of small-angle scattering, study of the width of the (002) reflection, and investigation of the debris after treatment with fuming nitric acid.
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  • 152
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    Journal of Applied Polymer Science 14 (1970), S. 35-43 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 scheme of qualitative analysis is presented for the identification of the constituents of polyurethane foam products, or indeed polyurethane-type materials in general. Elastomeric and cellular polyurethanes are analyzed by hydrolysis to simpler compounds which are then separated and identified. The methods of identification employed include infrared and nuclear magnetic resonance spectroscopy, gas chromatography, and thin-layer chromatography.
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  • 153
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    Journal of Applied Polymer Science 14 (1970), S. 17-34 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 solutions for unsteady flow of a three constant Oldroyd fluid and a second order fluid under several different flow conditions of practical interest are obtained. The response of these fluids to suddenly applied external force is investigated in each case. Without using the stick-slip boundary condition at the wall, it is possible to show that pressure oscillation occurs with both fluids under a certain case.
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  • 154
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    Journal of Applied Polymer Science 14 (1970), S. 53-64 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Antioxidants such as bisphenol A (BPA) have long been recommended for retention of physical properties on oven-aging of PVC plasticized with certain plasticizers. We have shown how BPA inhibits oxidative fragmentation of plasticizers such as diisodecyl adipate (DIDA) and thus decreases apparent volatility, and how it improves retention of modulus, elongation, and low temperature flexibility. Low concentrations are more beneficial than either zero or high concentrations, especially on longer aging. At higher concentrations, although the plasticizer is retained in the PVC, it becomes less efficient at low temperature, and low-temperature flex is impaired while elongation is preserved. DIDA exudes during oven-aging unless oxidation occurs to prevent it. When BPA is present, exudation is worst at the most efficient concentrations of antioxidant. This appears to be the normal incompatibility of DIDA at 105°C which is permitted by the antioxidant. On oxidation, the dielectric constant of DIDA rises into the 4-8 range, signifying compatibility with PVC, and the DIDA does not exude.
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  • 155
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    Journal of Applied Polymer Science 14 (1970), S. 79-88 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurements of melt viscosity on samples of polytetrafluoroethylene of different molecular weight were carried out at 360°C by means of tensile creep tests in the linear viscoelasticity range. The apparent activation energy for viscous flow in the range between 330° and 380°C was estimated to be 20 kcal/mole. A value of about 7,500 was also determined for the average molecular weight between entanglement points (Me), from the equilibrium compliance (De). Melt viscosity data were compared with zero strength time (ZST) values and a linear correlation was found on a bilogarithmic scale. The dependence of ZST on the applied stress and temperature was also studied and the results are discussed on the basis of Bueche's theory on the creep at rupture above the glass transition temperature.
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  • 156
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    Journal of Applied Polymer Science 14 (1970), S. 141-146 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 mechanism by which TiO2 exerts a phototendering effect on nylon 66 photodegradation has not been previously explained. To aid in the elucidation of this mechanism, the wavelength dependence curves of photodegradation of nylon 66 both with and without TiO2 have been accurately determined. These data, in conjunction with reflectance and phosphorescence measurements, indicate that the phototendering effect of TiO2 proceeds by a chemical rather than an energy transfer mechanism.
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  • 157
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    Journal of Applied Polymer Science 14 (1970), S. 161-173 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It was the aim of this paper to study the influence of the solvent residues in PVC compounds on physical and mechanical properties of samples prepared from them as well as the rheologic properties of their melts. Besides tetrahydrofuran other solvents are also partly retained in PVC even after processing at higher temperatures. The properties of samples prepared from PVC compounds containing solvents depend on the solubility parameter of the solvent used. Solvents with a solubility close to that of PVC have the same effect as plasticizers. Solvents with very high solubility parameters, e.g., water, influence the flow and dynamic properties in just the opposite way than plasticizers and behave rather like fillers. A mechanism for influencing the properties of PVC by the presence of solvent residues is suggested.
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  • 158
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermal degradation of a bisphenol A-based epoxy resin (EP 274) cured with 4,4′-diaminodiphenyl methane (DDM) and with phthalic anhydride (PA) was studied using a radiochemical pyrolysis gas chromatography technique. Conclusive evidence for some of the degradation mechanisms of these resins was obtained by pyrolyzing samples containing various 14C-labelled groups and analyzing the products using this method.
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  • 159
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    Journal of Applied Polymer Science 14 (1970), S. 241-243 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Ill.
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  • 160
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    Journal of Applied Polymer Science 14 (1970), S. 253-253 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 161
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Polytetrafluoroethylene surfaces have been treated to reduce thrombogenicity in order to make them suitable for use in prosthetic devices that come in contact with blood. This was done by first etching the surface with potassium in liquid ammonia to produce double bonds and then using these double bonds as sites for grafting on polyacids or as sites for chemical reactions. Tubes so treated were tested for thrombo-genetic activity by implantation in the thoracic aorta or inferior vena cava of dogs. These tests showed that the thrombogenicity of a polytetrafluoroethylene surface can be reduced by attaching negatively charged groups provided the surface concentration of these groups is not too high (order of 1-2 × 10-6 equivalent per cm2 geometric area) and provided the distribution of these groups is uniform. Sulfonic acid groups obtained by chlorosulfonation and carboxyl groups attached by grafting tert-butyl crotonate and hydrolyzing to crotonic acid were effective. Long chains of poly(acrylic acid), poly-(ethylenesulfonic acid), and poly(vinyl alcohol) sulfate were less effective.
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  • 162
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    Journal of Applied Polymer Science 14 (1970), S. 303-309 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 widths at half-value of high-resolution NMR spectra of bound water of cellulose were studied in relation to the temperature change. Two points were made clear: First, the amount of bound water of the cellulose sample can be pointed out with higher accuracy the lower the temperature of the measurement. Second, it is possible to determine in a simple manner the boundary temperature Tc at which water molecules become bound by the cellulose. Tc is characteristic of the cellulose sample of a given water content and corresponds to the glass transition temperature of the water-containing sample. The measurements appear to be readily applicable to other hydrophilic polymers.
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  • 163
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    Journal of Applied Polymer Science 14 (1970), S. 317-328 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Isotactic polypropylene hot-pressed film was subjected to uniaxial and biaxial stretching. The orientation behavior was investigated by means of x-ray pole figure technique, birefringence, electron microscope, and tensile tester. From the x-ray pole figure results it was confirmed that three kinds of crystal orientations, i.e., c-axis along the stretching direction, b-axis normal to the plane of the film, and [110] vector weakly normal to the film, accompany the biaxial stretching of the film. Electron micrographs of the surface of biaxially stretched polypropylene film revealed that, as the elongation increased, fibrillar structures became oriented to the stretching directions. From this orientation behavior a new deformation mechanism based on the woven structure presented by Khoury et al. was proposed. In this mechanism the orientation of the crystals is explained as a phenomenon accompanying the rotation and splitting of the woven structure presumed to be the structural element of polypropylene film.
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  • 164
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    Journal of Applied Polymer Science 14 (1970), S. 365-372 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 reactivity of mercerized, ethanol-washed, never-dried cotton, as indicated by acetylation, is higher than that of mercerized, water-washed, never-dried cotton. Hygroscopicity measurements indicate that the ethanol-washed cotton is not fully amorphous. They also reveal that the accessibility of cotton treated with caustic soda solution of mercerizing strength will be higher than that of cotton treated with ethylamine regardless of whether water or a solvent of lower hydrogen-bonding capacity is used to extract the swelling agent. Based on microscopic examination, acetylation of mercerized, ethanol-washed fibers apparently takes place relatively uniformly. The breaking load of cotton fibers is similar to that of mercerized, ethanol-washed cotton fibers of about 8% acetyl content. However, the crystallinity of these materials, as shown by hygroscopicity studies, is markedly different. This indicates that the fine structure of the cotton fiber can be modified considerably without causing a loss in strength. Yarn tensile tests indicate that mercerized, ethanol-washed cotton yarn with acetyl content between 10% and 30% has a breaking load which is about 12% lower than that of cotton.
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  • 165
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    Journal of Applied Polymer Science 14 (1970), S. 409-419 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 turbulence has been detected in dilute aqueous solutions of Polyox Coagulant (also known to be a highly effective drag-reducing agent). The flow line which characterizes structural turbulence from its onset in the laminar region passes well into the fully turbulent region (Reynolds turbulence) with virtually no change in slope, implying that the same molecular oscillations or segmental motions responsible for structural turbulence are now operative in drag reduction. The persistence of structural turbulence at very low concentrations is rationalized on the basis of Busse's explanation of the role of polymer entanglements in viscosity and elastic turbulence.
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  • 166
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    Journal of Applied Polymer Science 14 (1970), S. 244-247 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 167
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    Journal of Applied Polymer Science 14 (1970), S. 509-509 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 168
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    Journal of Applied Polymer Science 14 (1970), S. 254-254 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 169
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    Journal of Applied Polymer Science 14 (1970), S. 537-550 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 grafting styrene onto low-density polyethylene on the diffusion and solubility of benzene and n-hexane in the graft copolymer has been investigated. The diffusion coefficient at zero concentration Dc = 0 for both benzene and n-hexane decreased with the amount of styrene grafting in the polyethylene-styrene graft copolymer membrane. The free volume parameters of the polyethylene-styrene graft copolymer were calculated using benzene and n-hexane as the diffusing species. Results show that there is a large decrease in free volume as grafting proceeds and the effect is more pronounced at low levels of grafting. Solubility was found to be a function of the per cent grafting, there being a 50%-90% increase in benzene solubility in a 26% graft compared to polyethylene. The increase in solubility for n-hexane was considerably lower. The effect of crystallinity on the free volume parameters has also been calculated.
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  • 170
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    Journal of Applied Polymer Science 14 (1970), S. 599-610 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Just how far reactions can go after gelation during the cure of telechelic prepolymers has been a debatable point for some time. Utilizing a recently devised method,7 the curing reactions of some telechelic prepolymers were followed after the gel point. Extents of reaction above 90% occurred only in systems of average functionality close to two, functionality being the average number of reactive groups per molecule. Among systems of higher functionality, maximum extents of reaction of about 70% were most common. The final extent of reaction was only a few per cent above the extent of reaction at the gel point. The maximum extent of reaction varied with the concentration of reactive species and the relationship was a linear one at each functionality of the system. The data were consistent with PA2/r = {0.88/[(h - 1)(j - 1)]} + 0.10 where PA is the fraction of prepolymer reactive groups initially present which have reacted, r is the ratio of the initial number of crosslinking groups to prepolymer reactive groups, and h and j are weighted average functionalities of the two reactants. It is suggested that the limiting factor in defining the final extent of reaction in these systems is the accessibility of reactive groups as determined by solid geometry rather than thermodynamics or reaction kinetics. The final extent of cure is regularly dependent on functionality and one cannot regard functionality and maximum extent of reaction as independent variables.
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  • 171
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    Journal of Applied Polymer Science 14 (1970), S. 611-632 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 stress relaxation technique was used to study the kinetics of the photo-oxidation of plasticized poly(vinyl chloride) film. The effects of ultraviolet irradiation were characterized by the slope of a difference line between the stress relaxation curve of an irradiated test sample and that of a nonirradiated control. An activation energy of 12 kcal/-mole was obtained for the rate-controlling reaction, which was postulated to be hydrogen abstraction from the substrate by peroxy radicals. The rate of relaxation was dependent on the radiation energy, being greater at lower energies. It was also independent of oxygen pressure at “high” pressures and dependent at “low” pressure. The nature of the plasticizer and the presence of stabilizer and ultraviolet absorbers all affected the relaxation behavior.
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  • 172
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    Journal of Applied Polymer Science 14 (1970), S. 765-776 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Previous work has shown that a polymeric phenyl salicylate and a polymeric dihydroxybenzophenone are formed during the irradiation of polycarbonate with nonspectrally dispersed ultraviolet light. In the present studies the photodegradation of polycarbonate film has been investigated as a function of irradiating wavelength using spectrally dispersed light from a xenon are between 2300 and 6300 Å. Maximum changes in absorbance at 3200, 3600, and 4000 Å were induced in the sample by irradiating wavelengths between 2800 and 2900 Å. The wavelength sensitivity of an extruded sample of polycarbonate is compared with results obtained for a solution-cast thin film of the material. The results of the present study support the stepwise photodegradation mechanism of polycarbonate previously reported and suggest the possibility of an additional photodegradation process.
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  • 173
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    Journal of Applied Polymer Science 14 (1970), S. 789-797 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ethyl acrylate was graft-copolymerized from acetone-water systems with γ-irradiated, purified cotton cellulose. The scavenging of the free radicals in the irradiated cellulose by water, acetone, and water-acetone systems was determined by electron spin resonance spectroscopy. The ESR spectra of free radicals, scavenged by water and acetone, were recorded by the use of a time-averaging computer attached to the ESR spectrometer, in which the ESR spectrum of the irradiated cellulose, which had been immersed in water and/or acetone, was electronically subtracted from the ESR spectrum of the irradiated cellulose control. For both water and acetone, the ESR spectra of the scavenged free radicals were singlets. This indicated that free radical sites formed on carbon C1 or C4 on radiation-initiated depolymerization, which would generate singlet ESR spectra, were readily accessible to these solvents. The maximum scavenging of the radicals was observed when irradiated cellulose was immersed in acetone-water solution which had a composition of 25/75 vol-%. The scavenging of the free radicals in irradiated cellulose when immersed in acetone-water solutions was less than when immersed in methanol-water solutions. Also, the extent of graft copolymerization of ethyl acrylate from acetone solutions with irradiated cellulose was less than that of ethyl acrylate from methanol solutions. These differences were probably due to differences in the diffusion rates of acetone and methanol into the cellulosie structure. The Trommsdorff-type effect in the acetone solutions would be less than in the methanol solutions, since acetone is a better solvent for poly(ethyl acrylate) than methanol.
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  • 174
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    Journal of Applied Polymer Science 14 (1970), S. 852-858 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 9 Ill.
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  • 175
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    Journal of Applied Polymer Science 14 (1970), S. 1093-1101 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 reaction of phenyl isocyanate with phthalic anhydride to form N-phenylphthalimide is strongly solvent dependent and catalyzed by tertiary amines. Water and alcohol promote imide formation, but Lewis acids and organometallic compounds are ineffective. In DMSO solvent, benzophenone tetracarboxylic dianhydride (BTDA) and polymethylene polyphenol isocyanate (PAPI) polymerize with the evolution of carbon dioxide to yield a foamed polyimide. The solvent-freed open-celled foams exhibit exceptional fire resistance and thermal stability.
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  • 176
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    Journal of Applied Polymer Science 14 (1970), S. 1103-1113 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The free-radical emulsion polymerization of chloroprene containing monovinylacetylene in concentrations from 0% to 10% has been studied. It was found that in the presence of monovinylacetylene, a polymer with a great gel content, increased values of plasticity, and deteriorated physical and mechanical properties is formed. Monovinylacetylene has been proved to copolymerize with chloroprene under the conditions used. Acetylenic groups remain unchanged in the copolymer; they cause the crosslinking of polychloroprene macromolecules and corresponding changes in polymer properties. Copolymerization reactions of monovinylacetylene with chloroprene together with the crosslinking effect of monovinylacetylene cause a substantial lowering of the crystallization rate of polychloroprene.
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  • 177
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    Journal of Applied Polymer Science 14 (1970), S. 1127-1141 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 physical creep of unfilled natural rubber vulcanizates, prepared with different vulcanizing systems, has been studied. For each of the three vulcanizing systems chosen there is a strong dependence of creep rate on crosslink density, but the rates for accelerated sulfur vulcanizates are two or three times higher than those of peroxide vulcanizates of similar crosslink density. Supplementary experiments, in which the crosslink structure of sulfur vulcanizates is modified either by chemical treatment or by variations in the vulcanizing conditions, show that the nature of the crosslink itself is not a determining factor in the type of vulcanizate. Other features, such as the type and quantity of extranetwork material arising from the vulcanizing process, contribute significantly to the viscoelastic behavior of accelerated sulfur vulcanizates.
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  • 178
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    Journal of Applied Polymer Science 14 (1970), S. 1183-1187 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As a model for the vulcanizates of block copolymers, mixtures of polyisoprene and polyethylene vulcanized both with a peroxide and with sulfur were investigated by stress birefringence. It was found that the polyethylene dispersion showed a reinforcing effect only in the peroxide vulcanizates. On the other hand, the stress birefringence was decreased with increased polyethylene content except at high polyethylene content. In the latter case, the slope of the line in the birefringence-stress plot was almost equal to that for the pure polyisoprene vulcanizate at high stress levels. However, at lower stresses significant optical creep was observed, i.e., the stress increased without bire-fringence. Such an optical creep as this exists also in styrene-butadiene block copolymer. These facts are interpreted by the assumption that polyethylene dispersion, when it is linked chemically with polyisoprene matrix, acts as a reinforcing agent by forming physical crosslinks similar to the hard domains in block copolymers. Such physical crosslinks can slip during elongation, resulting in the observed optical creep. These phenomena disappear at the elevated temperature.
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  • 179
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    Journal of Applied Polymer Science 14 (1970), S. 1235-1242 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new, graphic method of the resolution of a chromatogram into its component peaks is presented. From a mathematical description of the chromatogram of a monodispersed sample, a practical method of peak resolution of a multicomponent sample is derived. From this, the constituents may be characterized as to size and their weight fractions determined. As an example the final product in the synthesis of N,N-diglycidyl tribromoaniline is analyzed graphically and compared with results obtained using the du Pont 310 Curve Resolver. The agreement appears to be quite satisfactory.
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    Journal of Applied Polymer Science 14 (1970), S. 1227-1233 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new technique for the anionic polymerization of α-methylstyrene has been developed. By using an aliphatic hydrocarbon as the diluent, hexamethylphosphoramide as promoter, and a poly(vinyl alkyl ether) as interfacial agent, the high molecular weight polymer is obtained as a uniform dispersion. The advantages of the method are high conversions at low viscosities and an economical isolation procedure.
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  • 181
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    Journal of Applied Polymer Science 14 (1970), S. 1263-1276 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Quantitative relationships between the load-compression behavior and the physical characteristics of the foam matrix, previously reported for flexible systems, have now been extended to brittle foams. The shape of the compression curve is expressed in terms of ψ(ε), a dimensionless function of the compressive strain, while the stiffness, or load-bearing capacity, is defined by Ef, the apparent Young's modulus. Because the brittle matrix breaks-rather than flexes-when compressed, a brittle foam exhibits a flatter and wider plateau in the load-compression curve than a rigid (but ductile) foam of equivalent density, cell geometry, and Ef. These differences are expressed quantitatively by ψ(ε). It is important to distinguish between brittle foams and rigid, but ductile, foams. Since both types may exhibit the same stiffness, this distinction, particularly significant in energy absorbing applications, often is not considered in designing foam structures. Using the relationships established in this report, it is now possible to delineate precisely the characteristics a brittle foam must possess to meet a given load-compression specification.
    Additional Material: 13 Ill.
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  • 182
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    Journal of Applied Polymer Science 14 (1970), S. 1323-1337 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 degradation of samples of cellulose, hemicellulose, and lignin have been investigated using the techniques of thermogravimetric analysis (TGA) and differential thermal analysis (DTA) between room temperature and 600°C. The results calculated from static and dynamic TGA indicated that the activation energy E for thermal degradation for different cellulosic, hemicellulose, and lignin samples is in the range 36-60, 15-26, and 13-19 kcal/mole, respectively. DTA of all the wood components studied showed an endothermic tendency around 100°C in an atmosphere of flowing nitrogen and stationary air. However, in the presence of flowing oxygen this endothermic effect was absent. In the active pyrolysis temperature range in flowing nitrogen and stationary air atmospheres, thermal degradation of Avicel cellulose occurred via a sharp endothermic and a sharp exothermic process, the endothermic nadir and exothermic peak being at 320° and 360°C, respectively. In the presence of oxygen, combustion of Avicel cellulose occurred via two sharp exothermic processes. DTA studies of different cellulose samples in the presence of air showed that the shape of the curve depends on the sources from which the samples were prepared as well as on the presence of noncellulosic impurities. Potassium xylan recorded a sharp exothermic peak at 290°C in a nitrogen atmosphere, and in a stationary air atmosphere it yielded an additional peak at 410°C, while in the presence of oxygen the curve showed two sharp exothermic peaks. DTA traces of periodate lignin in flowing nitrogen and air were the same and showed two exothermic peaks at 320° and 410°C, while in the presence of oxygen there were two exothermic peaks in the temperature range 200°-500°C.
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  • 183
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    Journal of Applied Polymer Science 14 (1970), S. 1385-1386 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 184
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    Journal of Applied Polymer Science 14 (1970), S. 1390-1393 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 6 Ill.
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  • 185
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    Journal of Applied Polymer Science 14 (1970), S. 1400-1400 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 186
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    Journal of Applied Polymer Science 14 (1970), S. 1407-1407 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 187
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    Journal of Applied Polymer Science 14 (1970), S. 1473-1475 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
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  • 188
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 study of the mechanism of polyethylene crosslinking is realized by a kinetic analysis of the α,α-bis(tert-butylperoxy)-p-diisopropylbenzene decomposition, as well as by the determination of its decomposition products and crosslink formation in the polymer. The experiments were carried out in a temperature range of 118°-148°C in both polyethylene and its low-molecular model, n-octane. From the results obtained it follows that the peroxide decomposition in both hydrocarbon media is kinetically a unimolecular reaction with an activation energy of 36 ± 2 kcal/mole and with an equivalent participation of both peroxidic groups, whereby a biradical formation is improbable. Macroradicals arise by a dehydrogenization reaction in which mainly primary oxyradicals of various types take part and methyl radicals are also formed by a transformation process of the former. Both types of radicals decay exclusively in a substitution reaction with polymer chains. The whole process is terminated by macroradical recombination so leading to crosslink formation in polyethylene.
    Additional Material: 2 Ill.
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  • 189
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    Journal of Applied Polymer Science 14 (1970), S. 1507-1513 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 dilatometer was developed for studying the compressibility of polymers in their melting range at pressures to 8500 atm and temperatures to 370°C. Temperature was controlled to ±0.01°C and pressures were maintained and controlled by means of a hydraulic deadweight gauge system. The device was sensitive to volume changes of 1 part in 30,000.
    Additional Material: 3 Ill.
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  • 190
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    Journal of Applied Polymer Science 14 (1970), S. 1491-1505 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Styrene was copolymerized in bulk with a number of esters of benzylidenecyanoacetic acid. The kinetic scheme of all pairs fitted the improved scheme of copolymerization, taking into account the effect of the penultimate unit. The Alfrey-Price Q and e values were calculated. Using the modified Taft equation, log (1/r1) = ρ*σ* + δEs, it was found that the relative reactivities of the ester monomers toward the polystyryl radical were correlated by the polar substituent constants σ* of the ester alkyl groups (ρ* = 0.14) and not by their steric substituent constants Es (δ = 0.008).
    Additional Material: 11 Ill.
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  • 191
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    Journal of Applied Polymer Science 14 (1970), S. 1553-1561 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 diffusion behavior of nonionic penetrants in aqueous solution into nylon 6 was examined in the temperature range 5°-95°C. The Arrhenius plot of the diffusion coefficients is linear and its slope changes at 30-40°C higher than the glass transition temperature in water, as determined by dilatometry and viscoelastic measurements. The results are discussed in relation to the molecular size of the penetrant and the segmental motion of polymer chains.
    Additional Material: 7 Ill.
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  • 192
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    Journal of Applied Polymer Science 14 (1970), S. 1591-1596 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 substitution of 2-furoyl, 5-methyl-2-furoyl, 2-furanacryloyl, or 5-bromo-2-furoyl groups on fibrous cotton cellulose increased the radiation rsistance of cellulose, as indicated by the retention of strength of the modified fibrous cellulose at high dosages of γ-radiation compared with that of irradiated, unmodified fibrous cellulose. The presence of electropositive or electronegative substituents on the furan groups did not significantly change their radioprotective effects for cellulose. Electron spin resonance (ESR) spectra of irradiated celluloses indicated that the long-lived free radical sites were similar, if not the same, in both irradiated, unmodified, and modified celluloses. The radio protective effects of furan groups for cellulose were attributed to absorption of energy from the secondary radiations, primarily the secondary electrons, by the groups due to their π-electron-type structures. The absorption of energy by the groups apparently decreased the localization of energy on carbon C1 or C4 on the cellulose molecule which would result in depolymerization and loss in breaking strength of the fibrous cellulose. The radioprotective effects of furan groups for cellulose were similar to those of benzenoid groups.
    Additional Material: 1 Ill.
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  • 193
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    Journal of Applied Polymer Science 14 (1970), S. 2279-2293 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Commercial PVC was fractionated into five fractions by the incremental addition of a nonsolvent to the polymer solution. The number-average molecular weights of the original sample and fractions were determined by osmometry. The weight-average molecular weights of the sample and fractions were also determined by means of viscosity measurements and by the application of a Mark-Houwink type of equation. From a knowledge of the polydispersity of each fraction and the assumption that the number distribution of molecular weights was Gaussian, the molecular weight distribution for the composite sample was determined. The block osmometer used incorporated most of the features found useful in earlier work to facilitate rapid and reliable osmotic pressure measurements. In addition, microvolume-regulating valves were utilized in the capillary tube lines to permit an independent precise positioning of the interface level in either capillary.
    Additional Material: 4 Ill.
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  • 194
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    Journal of Applied Polymer Science 14 (1970), S. 2183-2200 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 failure criterion for amorphous polymers relating hysteresis at break with energy input to failure in tensile stress-strain tests was found to be obeyed only at very high or very low temperatures in natural rubber. Tensile results between about 80°C and 130°C show a high degree of scatter, and this behavior is attributed to the ability of natural rubber to crystallize at high strains. The modification of tensile properties by the addition of carbon black in natural rubber is also discussed and compared with published results from SBR. The effect of changing the degree of crosslinking on the failure properties in both dicumyl peroxide and sulfur-cured vulcanizates of natural rubber is also considered. It is found that differences in failure properties can be accounted for by the use of a crosslinking parameter from simple rubber elasticity theory in some of the failure equations.
    Additional Material: 13 Ill.
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  • 195
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    Journal of Applied Polymer Science 14 (1970), S. 2249-2262 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 brittle fracture properties of polyphenylene oxide, polysulfone, polycarbonate, and poly(methyl methacrylate) thermoplastic polymers were investigated over a wide range of temperatures. Fracture energy measurements were made using double edge-notched tensile samples. Tensile strength, tensile strain, and initial elastic modulus were measured for calculation of the fracture energy and further analysis of the polymer behavior. It was found that mechanical transitions in the tensile properties corresponded reasonably well with transitions in the fracture energy in the temperature range investigated. Fracture surface photographs permitted visual analysis of the fracture process. It was found that the roughest fracture surface corresponded to the maximum in the fracture energy for a given polymer. A theory for prediction of polymer tensile yield strain is presented, based on the volume dilation concept. The implications of this theory are discussed in terms of the crack tip flow process leading to brittle fracture.
    Additional Material: 13 Ill.
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  • 196
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    Journal of Applied Polymer Science 14 (1970), S. 2333-2340 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 tertiary amino groups of 2-diethylaminoethyl substituents in cotton cellulose have been found to be effective catalysts for reactions of activated vinyl compounds with cellulosic hydroxyl groups. These reactions proceed more slowly and to lesser extents at equilibrium than the corresponding reactions catalyzed by quaternary ammonium substituents. The crosslinking of cotton cellulose with divinyl sulfone is catalyzed by (C2H5)2NCH2CH2— substituents and by (C2H5)2NCH2CH(OH)CH2— substituents, with the development of moderate levels of wrinkle recovery. On the other hand, only the former substituents catalyze the reorganization of the crosslinkages during recure (160°C, 10 min), with substantial increases (40°) in wrinkle recovery angles. These same 2-diethylaminoethyl substituents are effective in catalyzing the reorganization of crosslinkages from divinyl sulfone which are introduced into the cotton by conventional external catalysis (i.e., NaOH); this effectiveness can be overcome by the introduction of excessive crosslinkages into the cellulosic composition.
    Additional Material: 2 Ill.
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  • 197
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    Journal of Applied Polymer Science 14 (1970), S. 2385-2398 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two series of copolymers containing imidazopyrrolone (pyrrone) and imide groups were prepared by solution polymerization. Thin films of the copolymers showed a general increase in the tangent modulus and a decrease in elongation with increasing pyrrone content. The copolymers were more resistant to degradation by strong acids and bases than the corresponding polyimides. The thermal stabilities of the copolymers in air improved with increasing imide content, while the thermal stabilities in a vacuum improved with increasing pyrrone content. These copolymers represent a way to combine the desirable properties of both classes of homopolymers.
    Additional Material: 9 Ill.
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  • 198
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    Journal of Applied Polymer Science 14 (1970), S. 1939-1947 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley 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 resonant frequencies of unidirectional graphite fiber-reinforced polyimide (Skybond 703) and polyquinoxaline resin composite beams were determined. The Timoshenko beam theory was employed to compute both the longitudinal Young's modulus (E11) and the effective transverse-longitudinal shear modulus (G12) from the set of resonant frequencies of the beams. E11, E22, and G12 were determined for a 64% by volume Modmor II-reinforced polyimide (Skybound 703) composite, and E11 and G12 were determined for cured and postcured Modmor II-reinforced polyquinoxaline (PQ) composites. Dynamic E11 and E22 results were found to agree with experimentally determined static flexural moduli. Voids present in these high-temperature resin composites to an extent of 5-13% by volume appeared to lower the effective shear and longitudinal moduli of the composites.
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  • 199
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    Journal of Applied Polymer Science 14 (1970), S. 2025-2037 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An investigation has been made into the effect of mixing by a screw extruder upon the molecular characteristics and the melt flow properties of high-density polyethylene. The crosslinking between molecules predominates over the scission of a molecule at an early stage of mixing, but with further increase in the degree of mixing, this situation reverses itself to bring about the formation of branched polymers. Static flow and dynamic viscoelastic properties of molten high-density polyethylene change considerably with increase in the degree of mixing. The apparent viscosity drops rather sharply after mixing. The dynamic properties for the original resin show smaller frequency dependence of the viscosity and larger dependence of the rigidity than those for extrudates. The relaxation spectra become broader with increase in mixing. These may mainly be due to the change of the molecular characteristics of high-density polyethylene with mixing by an extruder.
    Additional Material: 12 Ill.
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  • 200
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sintering of poly(methyl metacrylate) spheres to the blocks of the same material was studied at temperatures ranging from 127° to 207°C. The analysis of the data based on the empirical Ostwald relation indicates that the predominant mechanism responsible for this process is non-Newtonian viscous flow. The type of the flow changes with temperature of sintering, being pseudo-plastic at lower temperatures and tending to dilatancy at higher ones.
    Additional Material: 5 Ill.
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