bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induced anisotropy of thermal conductivity of polymer solids under large strains
Authors: Peng Stevens T. J. , Landel Robert F. 
Published: April 2003

AbstractA simple analytical form of induced anisotropy of heat conductivitykij(λ1,λ2λ3,T) of initially isotropic polymer solids results from employing the simplified theory of the three‐chain model of the non‐Gaussian network. The analytical form appears to be valid up to a stretch ratio of λ = 2.65, which is the limit of existing experimental data. The effect of induced anisotropy on the temperature distribution, due to the large deformations, is illustrated for a highly expanded spherical shell and a cylindrical tube under a steady‐state heat flow using the derived analytical form of the strain‐dependent heat conductivity.
Theory of reverse osmosis and some other membrane permeation operations
Authors: Lee Cheng H. 
Published: April 2003

AbstractThe general permeation equations for various transport operations using membranes were correlated according to the solution‐diffusion theory. It was shown that for some important conditions, the permeation properties for reverse osmosis can be generated from those of pervaporation. The use of reverse osmosis with pressure smaller than 2000 psi is calculated to be of limited use for the purification of water with small amounts of organic compounds.
Polymer composites through in situ matrix formation
Authors: Bless P. , Semen J. , Lando J. B. 
Published: April 2003

AbstractNylon 66 graphite composites have been prepared by the in situ polymerization of the monomer epitaxially crystallized onto the fiber surface. Nylon 66 monomer, whether oriented (crystallized from solution) or unoriented (deposited from an aqueous slurry) was found to polymerize to an oriented composite by a variety of techniques (spark discharge, resistance heating, and furnace heating). X‐ray diffraction has demonstrated that the matrix orientation corresponds to the polymer chains aligning themselves with the graphite crystal edges along the fiber axis. Scanning electron microscopy of fracture surfaces has shown excellent adherence between the fiber and matrix with fracture occurring mostly in the matrix material.
A mathematical model for polymerization of isoprene with n‐butyllithium in benzene
Authors: Magott Raymond J. , Ahmad Abu , Anthony Rayford G. 
Published: April 2003

AbstractIsoprene was polymerized in batch reactors by use of bottle polymerization techniques at 20°, 30°, and 40°C at concentrations from 1 to 5 molar. Isoprene and n‐butyllithium conversions and molecular weight distributions were determined for different reaction times. Rate equations for the initiation and propagation reactions are presented. The importance of the association reactions in obtaining a narrow molecular weight distribution is illustrated.
Reverse osmosis separation of inorganic solutes in aqueous solutions using porous cellulose acetate membranes
Authors: Matsuura Takeshi , Pageau Lucien , Sourirajan S. 
Published: April 2003

AbstractUsing a modified form of the Born expression for the free energy of ion‐solvent interaction, to both the bulk solution phase and the membrane–solution interface, a parameter is obtained to express the repulsion of the ion at the interface. This parameter, called the free energy parameter for ions, is then related to solute transport parameter obtained from reverse osmosis experiments. Numerical values of this free energy parameter have been obtained for six monovalent and four divalent cations and for 12 monovalent anions. Using the experimental data for the reverse osmosis separation of sodium chloride as reference, the utility of the above parameter for predicting solute separation in reverse osmosis is illustrated for 32 other inorganic salts.
Thixotropic behavior of gel‐like systems
Authors: Lin O. C. C. 
Published: April 2003

AbstractThe changes of shear stress with time under constant shear rate and temperature of several pigmented acrylic polymer gels were examined. This behavior, known as thixotropy, was interpreted based on a model which separates the stress into two regions. Region I covers the growth of the stress up to the yield point, represented by a peak stress, F0. Region II covers the decay of the stress from the peak to the point it attains an asymptotic value, F∞. The material in region I is assumed to be elastic and in region II is represented by a dynamic equilibrium between structure A, which is non‐Newtonian and structure B, which is Newtonian. The transitions between A and B represent structure degradation and structure recovery. The concentrations of A and B are solved explicitly. The total shear stress is then evaluated following a theory proposed by Ree and Eyring and is shown to give relationship between shear stress–shear rate–shearing time in good qualitative agreement with experimental observations. The ratio (F0 − F∞)/F∞, defined as the coefficient of thixotropy, is sensitive to the fundamental physical chemical parameters of the system and is easy to measure. It is shown to be useful in the characterization of thixotropic materials such as gels. Methods for evaluating the elastic modulus and yield stress of the material in the gel state are also illustrated.
Stabilization of poly(vinyl chloride). II. Stabilization mechanism through metal soaps by complementary color action
Authors: Iida Takeo , Nakanishi Motoharu , Gotō Kunio 
Published: April 2003

AbstractIn a previous paper, it was pointed out that the stabilization mechanism through metal soaps might be affected by an effect of complementary color. In this work, the colors of heated poly(vinyl chloride) (PVC) films mixed with various metal soaps were investigated by using a differential colorimeter and a spectrophotometer. Monochromatic coloration was observed with PVC, PVC–Ca stearate, and PVC–Ba stearate systems. On the other hand, the phenomenon of color mixing was observed with PVC–Zn stearate, PVC–Cd stearate, PVC–Zn/Ca stearate, and PVC–Cd/Ba stearate systems. In particular, achromatic color remained with PVC–Zn/Ca stearate and Cd/Ba stearate systems for longer heating periods. This means that the stabilization mechanism for PVC compounded with metal soaps should be effected finally by subtractive complementary colors situated between polyene color and the color effected with the metal complex, in addition to being subject to the usual chemical stabilization mechanisms.
A continuum of molecular weight distributions applicable to linear homopolymers
Authors: Gloor Walter E. 
Published: April 2003

AbstractAn array or continuum of molecular weight distributions was set up, based upon the numerical solutions found for the theoretical log‐normal (LN) and generalized exponential (Gex) distribution functions, for a range of Mw/Mn = H ratios. For the Gex distributions, m > 0 in the continuum, and the theoretical Schulz–Zimm and Tung–Weibull distributions, in which m ≥ 1 for H ≤ 31, are located within the continuum. The LN distribution is the broadest, and the Gex‐related distributions become narrower as the numerical value of m increases. From literature data for polystyrene, poly(vinyl chloride), linear polyethylene, and polypropylene, one can assign to these polymers specific molecular weight distributions that fall within the continuum.
Surface impregnation of concrete bridge decks with polymers
Authors: Paul D. R. , Fowler D. W. 
Published: April 2003

AbstractPolymer‐impregnated concrete has proven to be a strong and environmentally resistant material with many potential uses. One such application is to impregnate the surface of highway bridge decks to improve their durability. This paper reports on various aspects of research directed toward the objective of developing a practical and economical process for surface treating bridge decks with liquid monomers which subsequently are polymerized. This work has included (1) selection and tailoring the monomer–initiator system, (2) development of application and curing systems, and (3) evaluation of the resulting treatments by many different testing procedures. Considerable progress has been made toward increasing the durability of concrete slabs as shown by laboratory and small‐scale field tests and toward developing a practical method of application. Selected aspects of the fundamentals of surface treatments of highway bridge decks and details of the process and product as they have been developed to date will be presented here.
Studies on the biaxial stretching of polypropylene film. XI. Type II orientation during [2‐2FI]‐type stretching and its change by subsequent thermal contraction
Authors: Iwato Noboru , Tanaka Hiroshi , Okajima Saburo 
Published: April 2003

AbstractIn order to study the deformation mechanism of type II stretching, the change in orientation during the restretching and subsequent thermal contraction was investigated by x‐ray diffraction method. When a uniaxially oriented film is restretched, the lamellae which are stacked in the stretching direction by the stretching rotate as a whole toward the restretching axis. They rotate backward nearly reversibly during the thermal contraction, unless the restretching exceeds a balancing state, where the orientation in the film plane are equal in all directions. However, when the restretching degree is so high and the film orientation exceeds the balancing state, the lamellar rotation is accompanied by a complex phenomenon. It is considered from the wide‐angle and small‐angle x‐ray diffraction patterns that the lamellar surface becomes indented because of slippage between microfibrils composing the lamellae, and the microfibrils themselves bend at the boundary between the amorphous and crystalline regions within which the tilting of c‐axis also occurs. Upon contracting of the film; these changes recover, but even in the last stage of contraction the orientation approaches the symmetrical biaxial orientation but not the uniaxial orientation from which the biaxial orientation is started. These orientation and disorientation behaviors are not affected basically by a slight change in the restretching temperature and the degree of stretching.
Thermal properties of poly[N,N′‐(4,4′‐diphenyl ether) 4‐amidophthalimide] film
Authors: Alvino W. M. 
Published: April 2003

AbstractThe aging behavior of a polyamide–imide film was investigated. Film samples have been exposed to temperatures from 225° to 350°C for various times and the mechanical and electrical properties measured. This information was used to construct log life plots to gain an insight into the service life of this material. TGA and DTA results coupled with the information from the aging tests indicate that this film can be used at temperatures of 180° to 200°C for extended periods of time. Mechanical properties, especially elongation, of the film deteriorate faster than the electrical properties.
The preparation and physical properties of polyester–poly(methyl methacrylates) triblock copolymers
Authors: Grezlak J. H. , Wilkes G. L. 
Published: April 2003

AbstractBlock copolymers having the basic structure of PMMA–PE–PMMA were prepared by the reaction of diisocyanate‐terminated polyesters with hydroxyl‐terminated poly(methyl methacrylate). The molecular weights of these copolymers varied from 7,500 to 47,000. The formation of block copolymers by this method was confirmed by infrared and molecular weight analyses as well as by the physical behavior of these materials. Block copolymers of molecular weight less than 21,000 were extremely brittle in nature. The stronger copolymers of molecular weight greater than 29,000 were examined as to their dynamic modulus and stress–strain behavior. This included the effect of added homopolymer on the stress‐strain behavior of such materials. To better understand their physical properties, the micelle theory of Inoue et al. was applied to these copolymers to help elucidate their morphologies.
Reverse osmosis separations of some organic and inorganic solutes in aqueous solutions using aromatic polyamide membranes
Authors: Dickson J. M. , Matsuura Takeshi , Blais P. , Sourirajan S. 
Published: April 2003

AbstractThe reverse osmosis separations of some ethers, ketones, aldehydes, monocarboxylic acids, and inorganic salts in single‐solute (55–454 ppm) aqueous solution systems using aromatic polyamide membranes have been studied at 250 psig. It was found that reverse osmosis separation was essentially a function of steric parameter for ethers, and of both polar and steric parameters for ketones, aldehydes, and alcohols. Solute separations for monocarboxylic acids passed through a minimum at a pKa value of ∼4.8. The values for the free‐energy parameter for Li+, Na+, K+, Rb+, Cs+, and F−, Cl−, Br−, I−, and IO3− ions have been calculated for the polyamide membranes used. The above values for cations are negative and those for anions are positive, suggesting that the polyamide membrane surface behaves as if it is positively charged. Further, the data show that the polyamide membrane material is only about 40% as polar as that of the cellulose acetate membrane material studied earlier.
Insoluble starch xanthate: Use in heavy metal removal
Authors: Wing R. E. , Doane W. M. , Russell C. R. 
Published: April 2003

AbstractWater‐insoluble starch xanthates were prepared by xanthation of highly crosslinked starches under various conditions. After isolation of the products by solvent dehydration, freeze drying, or spray drying, their properties were determined. These products were very effective in removing heavy metals from water.
Effects of ozone and UV on tire cord adhesion
Authors: Iyengar Y. 
Published: April 2003

AbstractOzone exposure of resorcinol‐formaldehyde‐latex (RFL) dipped tire cords reduces adhesion because ozone attacks the double bonds in the butadiene component of the rubber latex in RFL and impairs its cocuring with the solid rubber compound. This mechanism also explains: (a) the ineffectiveness of chemical antiozonants or chloroprene latex as RFL additives, (b) the increased ozone sensitivity of RFL adhesion with progressive curing of RFL dip, and (c) the insensitivity to ozone of adhesion with RF‐EPDM adhesives. A major reduction in the rate of adhesion loss in either ozone (50 pphm, 50% RH) or UV (carbon arc, 4 hr) was demonstrated when small amounts of waxes (3% solids basis) were added to the RFL dip. The waxes protect the RFL adhesive by blooming to the surface of the adhesive treated cord.
Bis(diisopropyl) thiophosphoryl disulfide in cis‐1,4‐polyisoprene vulcanization reactions. I. As a sulfur donor
Authors: Pimblott J. G. , Scott G. , Stuckey J. E. 
Published: April 2003

AbstractBis(diisopropyl)thiophosphoryl disulfide (DIPDIS) is used as a sulfur donor vulcanizing system for cis‐1,4‐polyisoprene. It is shown that the network structure consists of poly‐ and disulfidic crosslinks at early stages of cure, simplifying at optimum cure to monosulfidic crosslinks. It is thought that pendent accelerator groups are bound to the rubber molecule at early stages of cure, but are subsequently replaced by cyclic sulfidic groups. The good thermal and thermal oxidative aging behaviour of the vulcanizate is due to the formation of zinc diisopropyldithiophosphate (ZDP) in situ.
The effects of fillers, crosslinking agents, and domain size on the physical properties of PE–PCV blends
Authors: McGill W. J. , Fourie J. 
Published: April 2003

AbstractBlends of polyethylene and poly(vinyl chloride) were prepared on a Brabender Plasticorder, and attempts were made to improve the very inferior physical properties of the product. The blends were found to have domain structures, and it was shown that their physical properties could be improved very considerably if the domain sizes could be reduced drastically. However, in melt blending, there was a limit to the reduction of domain sizes. A noticeable improvement in properties was achieved through the use of various fillers and crosslinking agents. Small changes in crystallite size and percentage crystallinity were observed where certain additives were used. It appeared that the additives that were most effective in enhancing physical properties acted by improving load transfer at the interface between the two polymer phases.
Photodegradable polyethylene
Authors: Pozzi Vittorio , Silvers Arthur E. , Giuffrè L. , Cernia E. 
Published: April 2003

AbstractPolymer photodegradation can be achieved by introducing carbonyl groups which absorb radiations above the 300 mμ wavelength and thus are sensitized by solar or atmospheric radiations.We introduced these groups in polyethylene by oximation of aliphatic chain with photoactivated NOCI and hydrolysis of the oxime.Modified polymers show, during accelerated aging in Weather‐O‐Meter, a constant molecular weight decrease, which is directly proportional to the concentration of carbonyl groups.
Behavior of unstretched nylon 6 fibers subjected to longitudinal and transverse impact
Authors: Cernia E. , Conti W. 
Published: April 2003

AbstractThe impact resistance of unstretched fibers of nylon 6 has been measured at impact velocities in the range of 10–20 m/sec by means of a freely falling dart of variable weight. The analysis was made on fibers with a high moisture content, since samples with low moisture content were brittle, as were unstretched fibers of poly(ethylene terephthalate). The observed impact behavior is in line with that predicted by the stress–strain curves obtained on a dynamometer, although it deviates somewhat in the ultimate properties and when the extent of deformation is small. The behavior for small deformation is discussed and a model is proposed.
Thermal degradation of polymers. VII. Ablation studies on a series of composite specimens containing asbestos fiber with various high‐temperature resin binders
Authors: Kershaw D. , Still R. H. , Bashford V. G. 
Published: April 2003

AbstractThe use of a laboratory ablation test ring for the assessment of tubular asbestos‐reinforced composites is described. Ablation resistance, char depth, smoke, and flash measurements have been made on a series of composites produced using asbestos fiber with a variety of commercially available high‐temperature resin binders. The results have been compared with those obtained from a standard asbestos/phenolic composite and are discussed in terms of the properties of the composite and its components.
Thermal degradation of polymers. VIII. Ablation studies on a series of fiber‐reinforced phenolic resin composites
Authors: Kershaw D. , Still R. H. , Bashford V. G. 
Published: April 2003

AbstractThe use of a laboratory ablation test rig for the assessment of tubular fiber‐reinforced composites is described. Ablation resistance, char depth, smoke, and flash measurements have been made on a series of composites based on a standard phenol–formaldehyde resin incorporating various fibrous reinforcing agents. The results have been compared with those obtained from a standard asbestos‐reinforced composite prepared from the same resin. Results are discussed in terms of the properties of the composite and of the fibrous reinforcing agent.
Thermal degradation of polymers. IX. Ablation studies on composites: Comparison of laboratory test methods with tethered rocket motor firings
Authors: Kershaw D. , Still R. H. , Bashford V. G. 
Published: April 2003

AbstractThe use of a novel laboratory ablation test rig for material selection is described. The results obtained are compared with those obtained from differential thermal analysis, thermogravimetry, and tethered rocket motor test firings.
The influence of gum on the crystalline structure in ramie fiber
Authors: Ray P. K. , Bag S. C. , Chakravarty A. C. 
Published: April 2003

AbstractThe fine structure of decorticated and degummed ramie fibers was studied by x‐ray and optical methods. It has been found that while crystallinity increases, crystallite orientation deteriorates with gradual removal of gum. Optical orientation falls at a more rapid rate, indicating that the major part of the gum resides in the amorphous regions and these regions are more sensitive to the process of extraction of gum.
Contribution to the mechanism of the thiuram vulcanization. I. Polymerization of styrene in the presence of tetramethylthiuram disulfide and natural rubber
Authors: Beniska J. , Kyselá G. , Štaudner E. 
Published: April 2003

AbstractThe influence of the concentration of tetramethylthiuram disulfide (TMTD) on grafting of natural rubber by styrene at 80°, 95°, 115°, and 130°C and constant molar ratio of rubber and styrene was studied. It was found that the dependence Rp = f([TMTD]½) at all followed temperatures goes through a maximum and that TMTD substantially decreases the amount of bound rubber in the graft copolymer. The analysis of the kinetic data and the results of separation of polymer mixtures showed the significant role in the process of the termination reactions of the growing polymer and the rubber radicals with the RS radicals. The derived kinetic relation is in good agreement with the experimental, results and allows calculation of the transfer rate constants of RS radical on rubber.
Studies on physical properties and structure of silk. Glass transition and crystallization of silk fibroin
Authors: Magoshi Jun , Nakamura Shigeo 
Published: April 2003

AbstractAmorphous silk fibroin with random coil conformation shows endothermic and exothermic peaks and endothermic shift on the DSC (differential scanning calorimetry) curve. The endothermic shift observed at 175°C was due to the glass transition. The exothermic peak at 212°C is recognized to be the crystallization, which later was confirmed by x‐ray diffraction pattern. The endothermic peak at 280°C is shown to be the degradation.
The water curing of a polyurethane resin used as a wool fiber coating
Authors: Beevers R. B. 
Published: April 2003

AbstractIn the industrial application of polyurethane resins to form surface coatings on wool fabrics, the prepolymer resin Synthappret is curred by reaction with water, either as steam or as atmoshpheric water vapor, to form the rubber network. This paper examines changes in the mechanical properties of the resin with cure conditions. It is shown for steam‐cured resin that the initial modulus, the equilibrium swelling in tetrachloroethylene, the Mooney‐Rivlin constant C1, and the average molecular weight of chain segments between crosslinks all reach constant values after 1 hr. However, the resin density and the Mooney‐Rivlin constant C2 show a linear dependence on cure time with no indication of reaching an equilibrium value. It is concluded that although the network is substantially complete after 1 hr of steam cure, there is a continuing pattern of reorganization. The mechanical properties of resin produced by air curing, a much slower process, are consistent with those of a network which has had a longer period of reorganization. The density of air‐cured resin is significantly higher than that of resin prepared by steam curing. Stereoscan electron micrographs of the resin surface reveal a texture which coarsens with prolongation of cure time and also reveal a difference for the two methods of cure.