bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unidirectional fiber–polymer composites: Swelling and modulus anisotropy
Authors: Coran A. Y. , Boustany K. , Hamed P. 
Published: April 2003

AbstractThe solvent swelling of unidirectional rubber–fiber composites was studied. The amount of matrix swelling was constrained to the extent that would be predicted from the thermodynamic theories of elasticity and polymer–solvent interaction. The geometry of swelling was found to be orthotropic in nature. A simple trigonometric function was derived to relate linear deformation due to swelling to the angle which the direction of its measurement makes with the fiber direction. The validity of the derivation was demonstrated experimentally. Considering swelling to be the imposition of tensile forces of equal magnitude in all directions, and considering a swelling‐induced linear deformation to be analogous to a tensile compliance, a simple set of relationships between elastic parameters and their direction of measurement was derived:

where Eθ, Gθ, vθ, and ηθ are Young's modulus, shear modulus, Poisson's ratio, and the shear coupling ratio measured in a longitudinal transverse plane at an angle with the fiber direction, respectively, and EL, GLT, and θLT are the longitudinal Young's modulus, the longitudinal transverse shear modulus, and the longitudinal transverse Poisson ratio, respectively. Further simplifying the case of combined transverse isotropy and special orthotropy was the conclusion that 1/GLT = 1/ET + (1 + 2vLT)/EL. The relationships for G and E were experimentally demonstrated.
Relationships between mechanical properties and relaxation processes in polymers. Nylon 6
Authors: Garbuglio C. , Ajroldi G. , Casiraghi T. , Vittadini G. 
Published: April 2003

AbstractThe dynamic‐mechanical properties as a function of temperature and frequency were measured for five samples of polycaprolactam (nylon 6) containing different amounts of hydrosoluble products. Low‐ and high‐speed tensile properties and Izod impact strength were determined between −190° and 100°C for the same samples by using autographic methods. The influence of the mechanical relaxation processes on moduli, yield strength σy, yield strain εy, tough‐brittle transition temperature, elongation at break εR, and tensile and Izod fracture energies was investigated. It has been found that some mechanical properties, such as modulus and yield properties, can be directly related to specific relaxation phenomena, whereas as far as other properties, such as the ultimate properties, are concerned, the existing correlation can be concealed by the interference of purely mechanical phenomena which depend on the testing technique used, the testing conditions, and the previous history of the material.
Aging behavior of polyarylsulfone films
Authors: Alvino William M. 
Published: April 2003

AbstractThe aging behavior of two experimental polyarylsulfone films is discussed. The mechanical and electrical properties of the films were measured as a function of time at temperatures of 300°, 275°, and 250°C. The effect of “reprocessing” the material is also reported. DTA and TGA analysis, coupled with other aging test results, point out the excellent thermal stability of the polyarylsulfones. However, some peculiar behavior is exhibited by the unrefined polymer. Free film aging of this material showed no signs of discoloration or deterioration in properties after 1000 hr at 300°C. Film aged wrapped on metal and glass rods discolors badly, is subject to stress cracking, and embrittles. The reprocessed'' film is superior to its predecessor and exhibits none of the disadvantages that characterize the unrefined polymer. Solubility studies, coupled with the other aging tests, provided some insight into the degradation phenomenon of this polymer. Resistance to ultraviolet light is extremely poor. Reprocessing of the material provided for a much superior film material with a higher level of mechanical, electrical, optical, and thermal properties.
Effects of monomer impurities on the emulsion polymerization of chloroprene and properties of polychloroprene. III. Effect of divinylacetylene
Authors: Sufčák Miloslav 
Published: April 2003

AbstractThe presence of small amounts of divinylacetylene in the monomer during the emulsion polymerization of chloroprene results in substantial increase of the molecular weight, gel formation, and in corresponding changes of physical and mechanical properties of vulcanizates. These changes appear at concentrations of divinylacetylene as low as 0.05% in chloroprene. The polymerization kinetics of chloroprene are influenced to a relatively small extent.
Measurement of the rheological properties of polymer melts with slit rheometer. I. Homopolymer systems
Authors: Han Chang Dae 
Published: April 2003

AbstractTwo slit dies have been designed, having aspect ratios of 10 and 20. Three melt pressure transducers were flush‐mounted on the long side of the rectangular slot, along the longitudinal centerline of each die. The dies were then used to measure wall normal stresses along the longitudinal direction of polymer melts flowing through the thin slit. The polymeric materials investigated were high‐density polyethylene, low‐density polyethylene, polypropylene, and polystyrene. The measurement of wall normal stresses were used to determine the rheological properties of melts, namely, the melt viscosity from the slope of axial pressure profiles and the melt elasticity from exit pressures. The present study shows that the rheological properties determined from the slit rheometer are in good agreement with those from the capillary rheometer reported in the author's earlier papers. Therefore it may be concluded that a slit die also may be used as a means of characterizing polymeric materials by their viscous and elastic properties in the molten state.
Aminimides. XI. Modified polystyrenes containing pendent aminimide or isocyanate residues
Authors: Culbertson B. M. , Randen N. A. 
Published: April 2003

AbstractThe hydrochloride salt of 1,1‐dimethyl‐1‐(2‐hydroxypropyl)amine methacrylimide (DHA) was synthesized and shown to readily homo‐ and copolymerize with styrene to produce soluble polymers containing pendent quaternary ammonium groups. These polymers may be treated with base to provide modified polystyrenes containing pendent aminimide residues. The latter polymers may be thermolyzed in solution or in the solid phase to produce modified polystyrenes containing pendent isocyanate groups. If the thermolysis is carried out in the presence of “isocyanate reactive” moieties, high molecular weight, crosslinked polymers may be synthesized. The reactivity ratios of DHA · HCl with styrene were determined: r1 = 0.33 and r2 = 0.35. The Alfrey‐Price Q and e values were also calculated: Q = 0.88 and e = 0.67.
The drag reduction of dilute polymer solutions as a function of solvent power, viscosity, and temperature
Authors: Peyser Paul , Little R. C. 
Published: April 2003

AbstractThe frictional drag reduction of high molecular weight poly(ethylene oxide) and polystyrene solutions under turbulent flow conditions has been studied as a function of temperature, solvent power, and solvent viscosity. A rotating‐disc apparatus was used to make the drag reduction measurements. For aqueous poly(ethylene oxide) solutions, at concentrations well above that needed to produce maximum drag reduction, all drag reduction data reduced to a common curve when per cent drag reduction was plotted against the Reynolds number for the flow. However, for poly(ethylene oxide) solutions below this optimum concentration, the drag reduction‐versus‐Reynolds number curves showed decreasing drag reduction with increasing temperature. The data are explained primarily in terms of the inverse temperature solubility characteristics of poly(ethylene oxide) in water. The per cent drag reduction of polystyrene in nonaqueous liquids was found to be greater in good solvents than in poor ones. It was also found that increases in solvent viscosity and decreases in temperature increased the per cent drag reduction. The results are discussed in relation to the current drag reduction theories and are shown to be in opposition to Virk's theory. It is concluded from the data that drag reduction is very likely a function of a relaxation time phenomenon involving the polymer molecules and the flow system. The results also emphasize the importance of considering solvent power, viscosity, and temperature in the design of an efficient drag reduction system.
New method for MWD determination in branched polymers
Authors: Ram Arie , Miltz Joseph 
Published: April 2003

AbstractGPC data for long‐chain branched polymers (low‐density polyethylene) are interpreted with the aid of a polynomial expression for intrinsic viscosity in terms of the molecular weight. The resulting molecular weight distribution curves agree well with those derived in an earlier work based on certain assumptions regarding the degree of long‐chain branching.
Heat‐resistant polymers containing the low molecular weight closo‐carboranes. III. The preparation of polycarboranesiloxane polymers by alcoholysis
Authors: Kesting R. E. , Jackson K. F. , Newman J. M. 
Published: April 2003

AbstractA new synthesis for carboranesiloxane polymers has been discovered. It involves the alcoholysis of the bischlorodimethylsilylcarborane monomers and the generation of the HCl catalyst in situ. Alcoholysis is applicable to the synthesis of most carborane‐siloxane polymers, with the probable exception of the SiB‐1 homopolymers of the larger carboranes. The attack of the BH moieties in the carborane cage can be minimized both by the utilization of a tertiary alcohol and by the addition of excess acid when a primary alcohol is employed.
Influence of starch granule swelling on graft copolymer composition. A comparison of monomers
Authors: Fanta George F. , Burr Robert C. , Doane W. M. , Russell C. R. 
Published: April 2003

AbstractSeven monomers, which varied widely in water solubility and ionic charge, were graft polymerized onto both unswollen starch and starch that had been swollen by heating in water to 60°C. Polymerizations were initiated with ferrous ammonium sulfate hexahydrate–hydrogen peroxide and, where applicable, with ceric ammonium nitrate. Graft copolymers were freed of ungrafted homopolymer by solvent extraction and were characterized by weight percentage of synthetic polymer incorporated in the graft copolymer, molecular weight of grafted branches, and grafting frequency. The influence of starch granule swelling on graft copolymer structure varied with the monomer used and could not be predicted on the basis of water solubility of monomer or its resulting polymer. With acrylonitrile and acrylamide, swollen starch gave higher molecular weight and less frequent grafts than unswollen starch. However, methyl methacrylate, N,N‐dimethylaminoethyl methacrylate · HNO3, N‐t‐butylaminoethyl methacrylate. HNO3, and 2‐hydroxy‐3‐methacryloyloxypropyltrimethylammonium chloride produced less frequent graft of higher molecular weight when starch was unswollen. With acrylic acid, graft molecular weight was independent of starch granule swelling, although grafting was less frequent when swollen starch was used.
Glass transition phenomenon in vinylidene chloride–acrylonitrile copolymers
Authors: Kryszewski M. , Mucha M. 
Published: April 2003

AbstractInvestigations of glass transition phenomena were carried out on vinylidene chloride—acrylonitrile copolymers, purified commercial samples of known composition. With a view to analyzing this effect, the following physical parameters were investigated: specific volume Vs,25, Tg, and volume expansion coefficients αL, αg, and Δα. The experimental results were analyzed on the basis of semiempirical and theoretical equations describing transitions to the glassy state. It was found that Tg dependence on weight fraction C2 of acrylonitrile may be described by Wood's equation, with k = 5.88. Applying Gibb's and Kanig's theories as well as relations given by Hirai and Small, the energies associated with intermolecular interactions (A*AB, E0, Eh, CED), and intramolecular interactions (stiffness energy ε) were calculated for copolymers of different composition. The copolymer Tg was found, above all, to depend on the stiffness energy ε, which increases with increasing acrylonitrile content in the copolymer.
Grafting of wool with vinyl monomers by using trichloroacetic acid–bis(acetonylacetonato)‐copper(II) cocatalyst
Authors: Hebeish A. , Bendak A. , Kantouch A. 
Published: April 2003

AbstractGraft copolymerization of wool with methyl methacrylate (MMA) and acrylonitrile (AN) was effected under the catalytic influence of trichloroacetic acid (TCA) together with bis(acetonylacetonato)copper(II). Investigation of the action of the cocatalyst on wool in the absence of monomer revealed that the treated wool is completely soluble in dilute alkali. The effect of storage on the catalyzed wool was also studied. Increasing the period of storage, before adding the monomer, causes a significant decrease in the graft yields, indicating vitiation of some of the free radicals on the wool backbone. Based on these studies, a mechanism for the grafting reaction was proposed. Moreover, grafting of wool modified through its disulfide bonds and amino and hydroxyl groups suggests that the thiol, hydroxyl, and amino groups participate in the grafting reaction as sites for graft attachment. Wool—graft copolymers show excellent antifelt properties, particularly at higher levels of grafting.
Solutions of drag‐reducing polymers—diameter effect and rheological properties
Authors: Elliott J. H. , Stow F. S. 
Published: April 2003

AbstractSolutions (0.5% by weight) of two high molecular weight drag‐reducing polymers, a polyethylene oxide and an acrylamide copolymer having anionic functionality, were prepared under low and high shear conditions. Rheological measurements demonstrated that high shear preparation causes a decrease in the size of the polymer units, the effect being markedly greater for the polyethylene oxide.These solutions were diluted to 25 ppm and drag reduction measured in 0.047‐in. and 0.93‐in. diameter test sections. The method of solution preparation showed no significant effect in the small tube measurements. In the large tube, however, low shear solution preparation led to drag reductions comparable to those found in the small tube, while high shear preparation gave markedly lower drag reductions. These results are discussed in terms of polymer supermolecular structure.
Morphology of fabric finishes consisting of acrylic soil release polymers and durable press reagents
Authors: Warburton C. E. , Schindler A. T. 
Published: April 2003

AbstractWhen acrylic emulsion copolymers containing a substantial proportion of methacrylic acid are mixed with durable press reagents such as dimethyloldihydroxyethyleneurea (DMDHEU) or dimethylolethyleneurea (DMEU) and applied to fabric in a one‐bath application, there is minimal coalescence of polymer dispersion particles. Polymer is embedded in a matrix of condensed methylol reagent which limits swelling of the polymer, in some cases to such an extent that its usefulness as a soil release agent is impaired. The degree of restricted swelling depends upon the soil release polymer and durable press reagents used. Nevertheless, in cases where swelling is severely restricted, excellent soil release is obtained if the matrix is removed sufficiently rapidly in washing. This is more so the case with DMEU than DMDHEU. Some polymer is insolubilized by zinc nitrate used to accelerate reaction of durable press reagent with cotton. Conclusions are based upon electron‐microscopic examination of film surfaces of durable press and soil release finishing agents as well as of surfaces of treated fabrics. Further conclusions are drawn from quantitative determination of film solubilities and chemical analysis of insoluble film residues.
Changes in mixing states of styrene–butadiene copolymer rubber and general‐purpose polystyrene resin mill blend by heat treatment
Authors: Satake K. , Shinki K. , Teraoka T. , Ibe S. 
Published: April 2003

AbstractThe effect of heat treatment in the so‐called phase inversion region was studied using uncured mill blends of various commercial styrene—butadiene copolymer rubbers (styrene content, 23.5 to 48 wt‐%; styrene block, 0 to 18 wt‐%) with general‐purpose polystyrene resin (blend ratio, 80–40: 20–60, in wt‐%). It was found that the effect of heat treatment on the hardening or softening phenomenon of blends is different in the random type from that in the block‐type styrene—butadiene copolymer rubber. A thorough discussion led us to conclude that this difference is caused by the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of general‐purpose polystyrene resin.
The rheology of filled polymers
Authors: Mills N. J. 
Published: April 2003

AbstractThe flow properties of polymer melts containing fillers of various shapes and sizes have been examined. If there is no failure of either the filler or polymer in the solid state, then the modulus enhancement for randomly distributed filler is equal to the melt viscosity enhancement under medium shear stress conditions (104 Nm−2) in simple shear flow or in oscillatory shear flow. Submicron‐size fillers, in particular, can form weak structures in the melt that greatly increase the low shear rate viscosity without changing the modulus of the solid proportionately. The highly pseudo‐plastic nature of polymer melts at shear stresses of 106 Nm−2 means that, even without orientation of filler particles toward the flow direction, the viscosity enhancement is less than at lower shear stresses.
Softening phenomenon by remilling of styrene–butadiene copolymer rubber–general‐purpose polystyrene resin blend
Authors: Satake K. , Shinki K. , Teraoka T. , Ibe S. 
Published: April 2003

AbstractThe softening phenomenon by remilling of uncured blends of various commercia styrene—butadiene copolymer rubber (styrene content, 23.5 to 48 wt‐%, styrene block 0 to 18 wt‐%) with general‐purpose polystyrene resin was mainly studied by examining the blend ratio dependence of hardness and compression modulus (in logarithmic form), with special attention to the state of dispersion of the polymers. It was found that the blend of styrene—butadiene copolymer rubber with general‐purpose polystyrene resin forms a microheterogeneous polymer blend system and that the hardness and the compression modulus change in S‐shaped curves versus blend ratio. However, the degree of softening phenomenon by remilling (roll surface temperature, 70°–90°C) was found to be different for the two blend systems, i.e., random styrene—butadiene copolymer rubber and block styrene—butadiene copolymer rubber. The softening phenomenon is more pronounced in random‐type rubbers; and in some block‐type rubbers, no softening phenomenon was observed. The influence of the styrene content of the polymer is small. Further discussions have shown us that the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of the general‐purpose polystyrene resin controls the state of dispersion of polymers thereby causing this difference in the softening phenomena among the different kinds of styrene—butadiene copolymer rubbers.
The effects of reaction temperature and hydrolysis on polyamic acids and polyimides
Authors: Johnson E. L. 
Published: April 2003

AbstractFor some time, polyimides have enjoyed a significant degree of superiority over the other classes of thermo‐oxidatively stable polymers. This superiority is, however, offset by the tremendous difficulty associated with the processing of polyimides. In an effort to understand these difficulties and their causes, several experiments were performed which reflect the roles that reaction temperature and hydrolysis (caused by the presence of water) play during amidization and imidization. Temperatures between 0° and 120°C were found to result in progressively lower‐viscosity polyamic acids whose equivalent weights varied only slightly with increasing reaction temperatures. The presence of hydroxide ions from water were shown to cause degradation of the polymer, and the combination of temperatures above 120°C and hydroxide ions results in the rapid degradation of the polymer and lower molecular weight polyimides.
Permeabilities of coagulated cellulose acetate dialysis membranes
Authors: Yasuda H. , Ikenberry L. D. 
Published: April 2003

AbstractThe diffusive flux of NaCl and the hydraulic flux of pure water through coagulated cellulose acetate membranes are examined. Coagulated cellulose acetate membranes (without densification by heat treatment or drying) possess higher permeability than what may be expected from the permeabilities of the dry polymer. Their overall hydraulic permeability (ultrafiltration rate of water) is greatly dependent upon the membrane casting conditions and the resulting asymmetry of the membrane. On the other hand, the asymmetry of a membrane does not play as great a role in the diffusive permeability of a solute. With homogeneous membranes, higher diffusive flux is always accompanied by higher hydraulic permeability. With asymmetric membranes, this is not always true. The diffusive permeability of NaCl and the hydraulic permeability of water through coagulated cellulose acetate membranes can be controlled nearly independently. Consequently, high diffusive (NaCl) permeability with low hydraulic water permeability and vice versa can be obtained by varying the casting conditions and also by partially saponifying the denser portion of the membrane.
Measurement of molecular weight of poly(vinyl chloride)
Authors: Rudin Alfred , Benschop‐Hendrychova Ivana 
Published: April 2003

AbstractMolecular weights of six bulk‐process and five suspension‐process PVC samples have been measured as part of a study aimed at developing a technique for gel permeation‐chromatographic analysis of this polymer in tetrahydrofuran at room temperature. Osmometric M̄n values measured in cyclohexanone appear to be valid; the results are insensitive to thermal history or ultrasonic irradiation of the solution. Corresponding measurements in tetrahydrofuran changed with measurement temperature and indicated the presence of stable supermolecular PVC aggregates in this solvent. Such aggregates can be dispersed by ultrasonic treatment of the solution for brief periods. Simultaneous degradation of PVC molecules appears to be prevented by addition of small concentrations of nonionic surfactant to the tetrahydrofuran solutions. Treated solutions are suitable for GPC analyses at ambient temperatures. The results of osmometry, light scattering, and GPC agreed well.
Barrier coatings on cellulose fiber mat
Authors: Liepins R. , Yasuda H. 
Published: April 2003

AbstractTwo techniques were used in the deposition of thin, pinhole‐free vapor barriers upon a Kraft fiber mat without affecting its combustibility properties. One technique involved a collodion spray precoating followed by low pressure styrene plasma coating, and the other involved a collodion spray coating. In the formation of the above coatings, two functional steps are essential: (1) surface pore covering, and (2) nonporous barrier formation.
Degradation of drag‐reducing polymers
Authors: Fisher Dennis H. , Rodriguez Ferdinand 
Published: April 2003

AbstractA simple, fixed‐head flow device was used to characterize drag reduction by polymers in water. Using a parallel flow of water as a reference system, the Reynolds numbers ranged from 8600 to 12,000. The degradation of poly(ethylene oxide) and polyacrylamide during turbulent flow of dilute solutions (1 to 50 g/kl) was measured in terms of friction‐reducing effectiveness. Poly(ethylene oxide) decreases in effectiveness more rapidly than polyacrylamide in a recycling test.