bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas transport in glassy polymers
Authors: Vieth W. R. , Eilenberg J. A. 
Published: April 2003

AbstractSorption kinetics and equilibria for CO2 in polycarbonate were studied over a range of temperatures from 35° to 65°C and pressures from 3 to 22 atm. The dual mode sorption model of Vieth et al. was used to test the data, and a comparison was made with previous work on glassy polystyrene. Further evidence of the validity of generality of the model in providing a consistent picture of small‐molecule diffusion in glassy polymers was thereby provided. The technical feasibility of membrane separation of H2 from a H2/CO2 mixture by selective permeation through polycarbonate was examined at 50°C.
On the rheology of molten binary blends of polyolefins. X. Homogeneity and high shear (Poiseuille's) melt flow of polypropylene–polyethylene blends
Authors: Płochocki A. 
Published: April 2003

AbstractStatistical analysis of inherent viscosities (LVN), shear modulus (G*), and melting temperature (Tm) interval data for isotactic polypropylene–linear polyethylene (HDPE) blends was performed in order to verify their microheterogeneity. High shear measurements in viscometric (Poiseuille's) flow were carried out on four replicated compositions of the blends. Least‐squares treatment of the results yielded power law parameters for the blends differing in composition. The significance of differences between the blends of various HDPE content was tested using the multiple‐range (Duncan's) test, and tentative conclusions are drawn on the composition dependence of the melt flow viscosities of the blends.
Radiation‐induced graft copolymerization of styrene to cellulose
Authors: Guthrie J. T. , Huglin M. B. , Phillips G. O. 
Published: April 2003

AbstractThe radiation‐induced graft copolymerization of styrene to cellulose has been studied in vacuo at 30°C and at dose rates from (0.37 to 8.73) × 10−2 W/kg. Dioxan was used as solvent for monomer and polystyrene homopolymer, and water (2% total volume) was incorporated as swelling agent for cellulose. The concentration of styrene in the bulk medium was varied from 0.432 to 3.46 moles/l., and the rates of both grafting and homopolymerization were shown to be proportional to [monomer] · [intensity]1/2. The value of 3.3 × 10−4 l. mole−1 sec−1 derived for kp2/kt in homopolymerization is similar to that for normal free‐radical polymerization of styrene. However, reduced termination during grafting yielded a much higher value (58 l. moles−1 sec−1). Degradation of cellulose in the absence of monomer was followed viscometrically, and values of 13.5 and 24.6 were derived for G (scission) in vacuo and in air, respectively.
A thermoanalytical determination of the activation energy of the decomposition of azodiisobutyronitrile
Authors: Higgs D. A. , Manley T. R. 
Published: April 2003

AbstractThe decomposition of azodiisobutyronitrile (AZDN) has been studied in a simple, robust apparatus specially constructed for simultaneous study of differential thermal analysis and evolved gas detection (DTA/EGD). The results obtained are comparable with those of other thermoanalytic techniques. It is difficult to obtain kinetic results by the DTA technique alone, as the decomposition is confounded with a melting endotherm. This problem does not arise when EGD is used. The apparatus provides a convenient method for research on blowing agents and is being extended to studies of polymer degradation.
Ultraviolet surface‐photopolymerization from phenol, cyclohexanol, and ethylbenzene
Authors: Christopher A. , Wright A. N. 
Published: April 2003

AbstractThe formation of surface‐photopolymerized films from the vapors of phenol, cyclohexanol, and ethylbenzene is described. The structures of the films are discussed in terms of their multiple‐reflection infrared spectra.
Molecular aggregation in poly(vinyl chloride). A novel analytical technique
Authors: Abdel‐Alim Ahmed H. , Hamielec A. E. 
Published: April 2003

AbstractA novel experimental technique based on gel permeation chromatography (GPC) has been developed for the measurement of molecular aggregation in poly(vinyl chloride) (PVC). PVC having a range of syndiotacticity was synthesized using polymerization temperatures of 30–70°C. Tacticity and molecular aggregation of these PVC samples were measured by NMR and GPC, respectively. The temperature dependence of molecular aggregation was found to be much greater than that of tacticity. This GPC technique is inherently more sensitive than NMR in the temperature range normally employed for commercial production of PVC. It should find extensive use in the control of PVC reactors and in PVC processing.
Studies on heterogeneous polymeric systems. II. Polyblends containing saturated rubbers
Authors: Baer Massimo 
Published: April 2003

AbstractSaturated rubbers composed of ethylene–propylene or ethylene–vinyl acetate copolymers and terpolymers were used in the mass polymerization of high‐impact styrene or styrene–acrylonitrile polyblends. Conventional polymerization procedures lead to blends of inferior mechanical properties. The cause for the poor performance was traced to the inability of the rubber‐phase particles to preserve the desired size and particularity during processing.Polymeric blends of saturated rubbers having mechanical properties comparable to those obtainable with polybutadiene rubbers are prepared by (1) controlling the rubber‐particle size during prepolymerization and (2) preserving such size by crosslinking and grafting of the rubber following phase inversion. Extensive crosslinking of the rubber in the final blend must take place prior to processing to resist rubber particle deformation and disintegration during mechanical working. Rubber vulcanization is realized by the presence of peroxides in the final stages of polymerization; pendant unsaturation in the rubber is also needed or helpful. The reactivity and number of unsaturated groups in the rubber must be controlled to avoid excessive grafting prior to phase inversion and to permit efficient crosslinking following phase inversion.
On the solubility parameter of polar polymers
Authors: Utracki Lechoslaw A. 
Published: April 2003

AbstractThe binary cluster integral, β, was computed from intrinsic viscosity data. Subtracting from β the polar contribution, βe, calculated from YRCR theory,9 the nonpolar interaction parameter, βn, was found. The calculations were performed for poly(vinylacetate) and poly(methyl methacrylate), each in 16 solvents. The correlation between βn and the solvent solubility parameter, δ1, was found to be similar to that reported8,17 for solutions of natural rubber, cis‐polybutadiene and for poly(vinyl chloride). This correlation can be crudely approximated by the formula

where E and F are functions of the ill‐defined symmetry of the solvent molecule and δm is the δ1 value for the local maximum of the function. At δ1 = constant, the more spherical is the molecule, the higher is the βn value. It was shown that for most cases separation of the solvent into two classes (linear and nonlinear) is sufficient. This βn behavior finds support in the Funk and Prausnitz6 report on aromatic–saturated hydrocarbon mixtures and in the theoretical calculations of Huggins.21,22
A scanning electron microscope study of plasma‐polymerized organosilicon films suitable for use as lightguides. A determination of the cause of signal attenuation
Authors: Thompson L. F. , Smolinsky G. 
Published: April 2003

AbstractThe scanning electron microscope was used to evaluate the optical quality of a plasma‐deposited organic film. A major source of signal attenuation in lightguide films results from scattering by microscopic embedded spheres. The spheres are produced in the gas phase, and their size and population density are a function of the substrate surface and the rate of film formation. For all systems studied, the number of spheres increase with increasing rate. High‐quality films were deposited more easily on silicon, silicon dioxide, tungsten, and glass than on Nichrome or β‐tantalum. Gold, copper, and titanium surfaces proved more difficult, while aluminum was the most intractable material encountered. The rate of film growth usually increased with an increase in power input for any ratio of total pressure‐partial pressure of monomer. Spheres were essentially eliminated or their number reduced to a tolerable level by a proper choice of reaction conditions.
A radiotracer study of durability of acrylic soil release polymers to laundering
Authors: Warburton C. E. , Flynn L. T. 
Published: April 2003

AbstractCotton/polyester fabrics were treated with 14C‐labeled acrylic soil release polymers, either alone or with a durable press reagent, dimethyloldihydroxyethyleneurea (DMDHEU). Both two‐bath and one‐bath applications were used. Rate of removal of polymer in laundering was determined experimentally by radiotracer methods. Removal was faster in the order polymer alone (no DMDHEU) > two‐bath process > one‐bath process. The difference was much more significant when high molecular weight emulsion polymer was used than partially neutralized low molecular weight solution polymer. It is concluded that condensed DMDHEU serves as a coupling agent to bind polymer to fabric, thereby retarding removal of polymer in laundering. The significance of the results with respect to soil release of treated fabrics is discussed.
The morphological consequences of annealing high‐density polyethylene in solvents
Authors: Blackadder David A. , Keniry John S. 
Published: April 2003

AbstractWhen a semicrystalline polymer imbibes solvent molecules at near‐ambient temperatures it is very probable that the crystalline regions are not affected. The noncrystalline regions swell to accommodate the solvent and may also undergo structural changes which are not reversed on removing the solvent. If this happens, the sorptive capacity of the polymer is permanently changed. Pretreating a polymer membrane with liquid solvent has the same effect on sorption measurements as pretreatment with the corresponding saturated vapor only when special precautions are observed. High‐density polyethylene films were used throughout the investigation, and p‐xylene was the organic permeant. Numerous measurements of sorption and permeation rates were made, and the results are discussed in terms of a new model for the behavior of noncrystalline chains in a semicrystalline polymer. The shorter tie molecules running between the crystalline lamellae appear to be of crucial importance, and slight modification of these may have a large effect on the sorptive capacity of the sample as a whole. The possibility of solvent molecules clustering in the swollen polymer is considered in an Appendix.
Estimation of viscosities of mixed polymer solutions
Authors: Rudin Alfred , Hoegy Howard L. W. , Johnston H. Kirk 
Published: April 2003

AbstractA semiempirical model for estimation of viscosities of concentrated polymer solutions1 can be applied to mixtures of polymers in a common solvent. The data required for estimation of mixture viscosity are: solvent viscosity, polymer molecular weight, density, concentration, and intrinsic viscosity in the particular solvent. Calculated and experimental viscosities agree to within a few per cent for the relatively nonpolar systems for which comparative data are available. The model does not appear to be adequate for mixtures in which there are extensive hydrogen‐bonding interactions.Results of the new model are equivalent to those of an empirical equation2 reported to be effective for fairly concentrated binary polymer mixtures.Specific interactions between polymeric solutes can be conveniently assessed by comparing measured mixture viscosity to that calculated from the model presented. It is not clear, however, that such assessments have any fundamental significance, since the interactions which are calculated depend on the assumptions inherent in the estimation of the “ideal” mixture viscosity. The same reservations apply to other models which have been proposed for this purpose.
Freezing and nonfreezing water in cellulose acetate membranes
Authors: Frommer Moshe A. , Lancet Doron 
Published: April 2003

AbstractThe relative amounts of freezing and nonfreezing water in various cellulose acetate (CA) membranes were determined by differential scanning calorimetry. It was found that: (1) A significant fraction (17–40%) of the water (1.0–3.1 g H2O per gram dry CA) in any membrane does not freeze at temperatures as low as −60°C. (2) The amount of nonfreezing bound water (0.4–0.7 g nonfreezing water per gram dry CA) depends upon the nature of the membrane and is significantly higher than the total amount of water (all of which is nonfreezing) absorbed from liquid water by a dense film of the same polymer (∼0.18 g water per gram dry CA). The structures of the membranes were studied by scanning electron microscopy. The results suggest that the amounts of nonfreezing water in cellulose acetate membranes decrease with the increase in the packing density (compactness) of the polymer within the membrane. In dense films, the extent of polymer–polymer interactions within the polymeric matrix is high, and therefore the macromolecular chains are less accessible to bind water.
Chain conformations in cellulose I and cellulose II
Authors: Manjunath B. R. , Peacock N. 
Published: April 2003

AbstractThere is strong evidence in the literature that cellulose chains have different conformations, as well as forming different crystalline lattices, in cellulose I and cellulose II. New data on the birefringence of amine‐treated fibers (cellulose III) support this view.
Radiation‐induced copolymerization of vinylphosphonic dichloride with methyl methacrylate and styrene
Authors: Fujii Shigetada , Maeda Katsuaki 
Published: April 2003

AbstractThe γ‐ray‐induced copolymerization of vinylphosphonic dichloride (VPDC) with methyl methacrylate (MMA) and styrene (St) was studied at 25°C (liquid phase) and −78°C (Solid phase). The reaction mechanisms are discussed. The reactivity ratios for the copolymerization of the VPDC–MMA system were determined as follows:

The difference between the reactivity between the liquid‐phase (25°C) and solid‐phase (−78°C) copolymerization is mainly attributable to the r2 value. The behavior of the liquid‐phase copolymerization of the VPDC–St system was anomalous, the r1 value being negative in the range from 0 to 80 mole‐% of VPDC monomer. In the solid‐phase (−78°C) copolymerization for the VPDC–St system, the reactivity ratios r1 and r2 were 0.097 and 1.6, respectively. The rate of copolymerization (Rp) at 25°C, for both the VPDC–MMA and VPDC–St systems, passes a maximum point at a certain monomer concentration, suggesting that the composition of copolymer is considerably affected by Rp. This phenomenon was interpreted by the assumption that an energy transfer reaction from VPDC monomer to the other vinyl compound can easily occur.
Radiation‐induced graft copolymerization of mixtures of styrene and n‐butyl acrylate onto cellulose and cellulose triacetate
Authors: Matsuzaki Kei , Nakamura Shigeo , Shindo Shuichi 
Published: April 2003

AbstractMixtures of styrene and n‐butyl acrylate of various compositions were grafted onto cellulose and cellulose triacetate fibers preirradiated with γ‐rays at 0°C in air. Monomer reactivity ratios of the grafted copolymers were found to be different from those of the nongrafted copolymers or those of AIBN‐initiated copolymers. The active species initiating the graft copolymerization were trapped radicals for cellulose and peroxides for cellulose triacetate. Kinetic investigations of the graft copolymerization of styrene onto preirradiated cellulose triacetate fibers were also carried out, and it was found that the kinetic scheme for radical polymerization is also applicable to graft copolymerization in a heterogeneous system.
Bond rupture during ozone cracking of torsional loaded styrene–butadiene
Authors: Devries K. L. , Moore N. B. , Williams M. L. 
Published: April 2003

AbstractThe molecular bond rupture rate during ozone attack of torsionally loaded rubber was determined from electron paramagnetic resonance (EPR) measurements. The rupture rate was successfully correlated by a Griffith‐type energy balance to the strain‐energy release rate in the samples. These observations substantiate the results from a similar study on tensile loading previously reported. In both cases there is a one‐to‐one correspondence between the rate of bond rupture (or crack growth) and the rate of energy release from the strain field and external work. A fracture energy, γn, of approximately 5×10−12 (±20%) ergs per free radical formed during the cracking was experimentally determined.
Polyurethane foam process development. A systems engineering approach
Authors: Campbell Gregory A. 
Published: April 2003

AbstractA seven‐step systems engineering approach is described and applied to the integral‐skin foam system. Through the use of a hybrid computer simulation of a dynamic mathematical model, the two process variables with the greatest lever on the skin‐forming process are determined. These data are then utilized to develop a new foam concept which makes it possible to control skin thickness and core foam density independently.
A new physicochemical technique for studying native and modified structures of polymer fibers: The continuous measurement of length variations, under tension, in a swelling medium of continuously variable concentration
Authors: Hagege R. , Tung Do Mau 
Published: April 2003

AbstractA device for linear variation of the concentration of a binary mixture in function of time is described. This device is used to study the dimensional variations of cotton yarns immersed in an aqueous caustic soda solution under a fixed tension while the concentration is increased from 0 to 10N. This method is very sensitive and seems of particular interest for the study of fibrous polymer structures.
Effect and analysis of induced thermal stresses in a plotted cylindrical inductor
Authors: Vlastaras A. S. 
Published: April 2003

AbstractThermal stresses developed during the cooling of a cured potted inductor from higher processing temperatures, resulting from the difference in the thermal expansion coefficients of the ferrite core and the epoxy polymer, cause a drop in inductance. The inductance drop was followed with time and temperature under various conditions. An attempt is made to explain the inductance drop based on experimental observations and theoretical considerations. A mathematical model was constructed to aid the thermal stress analysis at the ferrite core–polymer interface. It is shown that lower‐temperature epoxy curing results in greater stresses (inductance drop) than higher‐temperature curing.
Composite permselective membrane by desposition of an ultrathin coating from a plasma
Authors: Stancell A. F. , Spencer A. T. 
Published: April 2003

AbstractPermselectivity was vastly improved when ultrathin crosslinked coatings, of the order of 0.5 microns thick, were deposited from a plasma onto relatively permeable film substrates. In one example, the hydrogen‐to‐methane permeability ratio was increased from 0.87 to 33, and the hydrogen permeability was decreased by just 20% when benzonitrile was plasma deposited onto a silicone–carbonate copolymer film. In another example, the hydrogen‐to‐methane permeability ratio was increased to 297 when cyanogen bromide was plasma deposited onto a poly(phenylene oxide) film. Such coatings, while effective for the hydrogen/methane pair, had little effect on modifying film permselectivity for isobutene/butene‐1, a pair nearly identical in molecular size and solubility. It appears therefore that the coatings can very effectively distinguish between molecules differing significantly in size. Also, since the coatings are so thin, the overall permeability of the coating–substrate composite can be high.
Viscosity slope constants for solutions of nylon 6 and polytetrahydrofuran
Authors: Howard N. , Huglin M. B. , Richards R. W. 
Published: April 2003

AbstractMeasurements of the viscosity slope constant k were made on solutions of nylon 6 and polytetrahydrofuran under different conditions of temperature, solvent, and molecular weight of polymer; θ‐conditions were included so that the expansion factor α could be determined in each case. The value of k was influenced somewhat by the particular equation employed to derive it, and generally the Schulz‐Blaschke equation (yielding kSB) was the most reliable. Slope constants (kcalc) calculated according to an expression of Sakai were plotted as a function of α3 and were compared with the corresponding curves in terms of experimental values of k. The agreement was moderately good for PTHF but poor in the case of nylon 6. An expression (due to Imai) involving experimental values of k and α was examined in order to establish a unique value of the slope constant kθ under θ‐conditions by an extrapolation procedure. Although individual value of kθ for nylon 6 measured under θ‐conditions were dependent on molecular weight, the Imai plot yielded a unique value of 0.50 and a slope similar in magnitude to that found for other polymer/solvent systems.
Cross‐checking between dielectric measurements, DTA, and other methods of thermal analysis in research and production
Authors: Yalof S. , Wrasidlo W. 
Published: April 2003

AbstractDifferential thermal analysis, or DTA, is a technique for determining the properties of materials from the thermodynamic and kinetic points of view. Dielectric measurement is also a powerful tool for probing the structure of materials, but from another direction. Dielectric analysis is a measure of the dipole response within dielectric materials to an applied electric field. This response is controlled by the spatial arrangement and viscoelastic properties of dielectric materials. Dielectric thermal analysis is being increasingly used in research and process control, offering the advantages of being nonobtrusive and easily instrumented and having a broad theoretical basis which can be correlated with results from other methods such as dynamic mechanical relaxation measurements, NMR, neutron relaxation, birefringence, and, of course, DTA. Because of the nonobtrusive nature of dielectric measurement, it can be run concurrently with other analytical techniques without disturbing their results. When dielectric analysis is run concurrently with other methods of analysis such as DTA, we often receive fresh insights and cross‐checking on such behavior as polymeric crosslinking, molecular weight increase, and Tg—viscoelastic behavior in general. The results and conclusions drawn for such investigations are described.
Effect of entrance geometry on the capillary flow of cellulose acetate–acetone solution
Authors: Chen F. C. 
Published: April 2003

AbstractCapillary flow data were obtained for a 27.5% solution of cellulose acetate in acetone. The solution temperature was 50°C, and the range of apparent shear rates investigated was 1.7 × 105 to 1.7 × 106 sec−1. Capillaries having tapered entrance angles of 37.88° to 120.63° were used. A power‐law model was adequate to describe the shear stress at the wall (τw) and the corrected shear rate \documentclass{article}\pagestyle{empty}\begin{document}$(\dot \gamma )$\end{document} relationship. Entrance angle affected the entrance pressure drop corrected for kinetic energy, (ΔP0,c); ΔP0,c increased as the angle widened. Treating the entrance flow as an elongational flow situation facilitated superposition of the Delta;P0,c data on a single curve. Estimated elongational viscosities decreased with increasing applied stress.