bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of molecular weight distribution on elongational viscosity of undiluted polymer fluids
Authors: Bersted B. H. 
Published: April 2003

AbstractA combination of the Bersted model, giving the relaxation spectrum in terms of the molecular weight distribution (MWD), and the rubberlike‐liquid model of I odge is used to describe the elongational viscosity for constant extensional strain rates in terms of the MWD. Predictions of this hybrid model are in reasonable agreement with experimental results for polystyrene, if one assumes a strain rate dependent truncation of the relaxation spectrum. The predicted effects of varying molecular weight and breadth of the molecular weight distribution on the extensional viscosity are presented. At constant weight average molecular weight and constant strain, a narrower MWD is predicted to yield an extensional viscosity‐strain rate curve that is essentially shifted to higher strain rates relative to a broader MWD. Furthermore, at constant weight, average molecular weight, constant strain, and high strain rates, a narrower MWD is predicted to yield a higher extensional viscosity.
Thiuram vulcanization of natural rubber in the presence of hydrofuramide and ethanolamines
Authors: Banerjee B. , Chakravarty S. N. , Kamath B. V. , Biswas A. B. 
Published: April 2003

AbstractInfluence of hydrofuramide and ethanolamines on efficient vulcanization (EV), semi‐EV, and conventional sulfur vulcanization accelerated by tetramethyl thiuram disulfide is reported. In the case of thiuram vulcanization, the amines increase the cure rate but reduce the crosslink density. The interaction of tetramethyl thiuram disulfide with amines has been studied. The amines interact with thiuram disulfide (TMTD) giving rise to the formation of gaseous products. Thermogravimetric analysis shows weight loss of about 50% in case of TMTD–ethanolamine system and 25% in case of TMTD–hydrofuramide system. Gas chromatographic studies of the gaseous products indicate that it consists mainly of H2S. The other constituents in the gaseous product are CO2 and a thiol. A possible reaction based on these observations to account for decrease in crosslink density in thiuram vulcanization caused by amines is reported.
Polybutadiene adhesive compositions
Authors: Alvino William M. 
Published: April 2003

AbstractThis paper deals with the development of adhesives that are useful for preparing flexible laminates. The adhesive compositions are based on the chemistry of 1,2‐polybutadiene polymers and their reactions via chain extension and epoxidation. The resulting materials can be suitably formulated to produce resins that can be used to impregnate fibrous reinforcements which can be B staged; when laminated to copper, these materials give products with good peel strength, solder resistance, tear strength, and flame resistance. These adhesives can also be used to bond polyimide and polyester film to themselves and to copper. Typical properties of selected laminates include peel strength values of 8 lb/in. width, tear strength of 1–2 lb, oxygen index from 29 to 37, and excellent solder resistance.
Fractography of nylon‐6 yarn
Authors: Ogata N. , Dougasaki S. , Yoshida K. 
Published: April 2003

AbstractThe breaking mechanism of nylon‐6 yarn is investigated, and the breakage of the yarn under simple tensile loading conditions is compared to that of a filament caused by the same loading. The simple model yarn consisting of seven filaments was prepared for this purpose. The yarn was ruptured at a low rate of extension, and the fracture morphologies of the filaments in the yarn were inspected by a scanning electron microscopy. These morphologies are clearly different from those of the filaments broken individually under the same testing conditions used for the yarn. Various kinds of appearances are obtained in the yarn, for example, a large V‐shaped notch is observed, the controlled ductile tearing region is developed across the filament at a large angle to its axis, and the ruptured end is expanded into a plane which is perpendicular to its axis. These causes are discussed in detail to understand the breaking mechanism of the yarn.
Preparation of a flocculant based on polyamides
Authors: Mircheva V. , Mladenov I. , Konsulov V. , Sodeva D. 
Published: April 2003

AbstractA flocculant based on waste oligomers from the polycaprolactam production was synthesized by alkaline reduction with Ni/Al alloy. Both the reduced oligoamide and the sodium aluminate are precipitated by methanol. An oligomer, absorbed by a mineral carrier, is isolated as final product. The modified oligoamide was characterized by elemental analysis, IR spectra, and was shown to contain hydroxyl groups. The prepared flocculant may be used for the clarification of natural dilute (1%) clay suspensions and wastewaters. It accelerates the precipitation 35 times, giving a compact precipitate, which favors the decanting of the clarified liquid. The optimal concentration of the flocculant is 1.8 g/liter (corresponding to 0.06 g/liter oligomer).
Physical and chemical properties of methyl trifluoroacrylate–α‐olefin copolymer and its hydrolyzed copolymer
Authors: Watanabe Terutaka , Matsuda Osamu , Tabata Yoneho , Machi Sueo 
Published: April 2003

AbstractPhysical and chemical properties of alternating copolymers of methyl α,β,β‐trifluoroacrylate (MTFA; CF2CFCO2CH3) with α‐olefins such as ethylene, propylene, and isobutylene and their hydrolyzed copolymers were investigated. The original ester‐type copolymers are amorphous and hydrophobic. The copolymers, except for the MTFA–isobutylene copolymer, were found to be easily hydrolyzed in boiled NaOH–methanol aqueous solution to give hydrophilic fluoropolymers which contain nearly theoretical amounts of carboxyl groups. No chain scission takes place during the hydrolysis. The decomposition temperature of the original ester‐type copolymers is in the range of 347° to 379°C in nitrogen atmosphere, and the glass transition temperature is in the range of 21° to 76°C. Two steps of weight decrease, at around 100°C due to the removal of absorbed water and around 250°C due to the decomposition, were observed in the TGA curve of the hydrolyzed acid‐type copolymers. Both ester‐ and acid‐type copolymers were crosslinked by electron beam irradiation, while the MTFA–isobutylene copolymer was degraded. The tensile strength of the copolymers is in the range of 190 to 450 kg/cm2.
Permeability of solutes through cellophanes grafted with vinyl monomers. I. Diffusion of potassium chloride, urea, and uric acid
Authors: Takigami Shoji , Maeda Yasukatsu , Nakamura Yoshio 
Published: April 2003

AbstractThe diffusive permeability of potassium chloride, urea, and uric acid through cellophanes grafted with acrylamide, acrylic acid, styrene, and N‐vinyl‐2‐pyrrolidone by γ‐ray irradiation was studied. The diffusive permeability coefficients of the permeants through the grafted cellophanes were increased with increase in hydration of the grafted membranes, except for the permeation of potassium chloride through cellophanes grafted with acrylic acid. The permeation of potassium chloride, urea, and uric acid through the various grafted cellophanes is explained by the free volume concept of homogeneously water‐swollen membranes. However, the behavior of the permeation of potassium chloride through cellophane grafted with acrylic acid deviated from that of nonionic membranes because of the contribution of the electrical interaction between electrolyte and charge of the membrane.
Permeability of solutes through cellophanes grafted with vinyl monomers. II. Diffusion of potassium chloride through cellophanes grafted with acrylic acid
Authors: Takigami Shoji , Maeda Yasukatsu , Nakamura Yoshio 
Published: April 2003

AbstractThe permeability behavior of potassium chloride through cellophane grafted with acrylic acid by a γ‐irradiation method was studied by the theoretical equation derived from the phenomenological equation and compared with the results of Donnan membranes equilibrium. It was shown that the permeation of potassium chloride through the grafted cellophanes exhibited behavior typical of a polyionic membrane for grafts of more than 55% but depended on the permeability of both cellophane and graft regions for lower percents of grafting. It was found that the dominant factor affecting the permeation of potassium chloride was an effective concentration of fixed charge in the membrane.
A model of physical adsorption of gases
Authors: Burghoff H.‐G. , Pusch W. 
Published: April 2003

AbstractUsing the Gibbs description of surfaces, a sorption model is developed which describes sorption isotherms for such systems as water in polymers. Moreover, the Freundlich isotherm for monolayer sorption is obtained. The physical interpretation of the constants of the model and the boundary conditions required for application to sorption isotherms are discussed. On basis of the Freundlich isotherm, a multilayer model is proposed to describe the water sorption in polymers. Experimental results within the whole range of relative humidity are found to be in excellent agreement with the multilayer model. Disagreement between model isotherm and experimental data of some polymers at relative humidities above 90% might be due to capillary phenomena not considered in the present model description.
Preparation of Fresnel lenses by radiation cast polymerization
Authors: Kaetsu Isao , Yoshida Kenzo , Okubo Hiroshi 
Published: April 2003

AbstractPreparation of Fresnel lenses was investigated applying radiation polymerization of methyl methacrylate prepolymer systems containing polyfunctional monomers. Line focus Fresnel lenses 75 × 75 cm could be prepared in very short time cycles with sufficient exactness by radiation cast polymerization, preferably at low temperatures. Preparation of Fresnel lenses could be carried out also very easily and efficiently by printing the soft plastic prepolymer sheet with a Fresnel lenses mold and then curing it by irradiation.
Polymerization studies of creosote bush (Larrea tridentata) phenolic resin with formaldehyde
Authors: Belmares Hector , Barrera Arnoldo 
Published: April 2003

AbstractAbout 25% of the surface area of Mexico is covered by the shrub Larrea tridentata, also known as creosote bush. Therefore, an intense study of the shrub as a source of industrial raw materials was started. Presently, we have studied the polymerization of the phenolic resin of Larrea with formaldehyde. This polymerization has been carried out in bulk and in aqueous suspension with acid catalysts such as oxalic and hydrochloric acids. The molar ratio of Larrea resin/formaldehyde was 1/1, 1/3, and 1/4 at different reaction times. Larrea resin and the formaldehyde condensation products were characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance (NMR), and vapor pressure osmometry (VPO).
Acrylic‐functional aminocarboxylic acids and derivatives as components of pressure‐sensitive adhesives
Authors: Heilmann S. M. , Smith H. K. 
Published: April 2003

AbstractHigh‐performance thermoplastic pressure‐sensitive adhesives have been prepared by copolymerization ofN‐acryloylamino acid and acid derivatives with long‐chain alkyl acrylate esters. A comparative study with equivalent copolymers made from conventional polar comonomers and long‐chain alkyl acrylate esters has shown that theN‐acryloylamino acids and derivatives impart generally higher levels of tack, adhesion, and cohesion than their conventional counterparts.
Curing reactions in plastic prepolymers and propellants. I. Polystyrene
Authors: Kishore K. , Verneker V. R. Pai , Vasanthakumari R. 
Published: April 2003

AbstractCuring reactions of the viscous PS prepolymer and PS/AP propellant slurry have been studied. The molecular weight of the binder (separated from the propellant) and the prepolymer was found to increase to a maximum value, remain constant for some time, and then fall off between 50–125°C. The molecular weight of the binder was found to be less than corresponding prepolymer between 100–150°C but at lower temperatures (50–75°C) the reverse was found to be true. The increase in the molecular weight during curing at lower temperatures has been explained on the basis of Trommsdorff effect which gets support from the estimated activation energy (9 kcal mole−1) for the curing process. Curing was recognized as chain extension where the rate of polymerization becomes diffusion controlled below 75° C.
Emulsion copolymerization of alpha‐methylstyrene and styrene
Authors: Rudin Alfred , Samanta M. C. 
Published: April 2003

AbstractFast copolymerizations of styrene and alpha‐methylstyrene can be achieved in emulsion systems where free‐radical reactions in the bulk or solution are inefficient. The Smith–Ewart–Gardon theory of emulsion polymerization was developed for homopolymerizations but should extend to this copolymerization since the particular comonomers meet the basic assumptions of this model. Sodium lauryl sulfate surfactant provided faster initial polymerization rates, but steady‐state conversions were faster with potassium laurate, especially at higher alpha‐methylstyrene contents. This is ascribed to acceleration of potassium persulfate decomposition by the former soap. Monomer concentration in the polymerizing particles was constant during steady reaction rates. The rate of volume growth of particles during this interval was generally as predicted by theory. The number of particles and particle sizes could be predicted well if allowance was made for initiator wastage reactions. The observed average number of radicals per particle appeared to be 0.5. Analysis of the composition of monomer droplets and proton NMR analyses of copolymer compositions provided independent confirmations that the present emulsion copolymerization was consistent with the terminal copolymerization model.
Synthesis of copolyamide–esters and some aspects involved in their hydrolysis by lipase
Authors: Tokiwa Y. , Suzuki T. , Ando T. 
Published: April 2003

AbstractCopolyamide–esters (CPAEs) were synthesized by the amide–ester interchange reaction. The change of intrinsic viscosity during CPAE synthesis was negligible. Polyamide blocks were shortened with increasing reaction time and polyester content. The polymerization degree of nylon 12 blocks on CPAE was smaller than that of nylon 6 blocks. CPAEs were hydrolyzed by Rhizopus delemar lipase. The biodegradability decreased with the shortening of the polyamide blocks and with increasing polyamide content. It was concluded that the amount and distribution of the hydrogen bonds, based on the amide group, in the CPAE chains strongly influenced their biodegradation by this lipase.
Synthesis of cationic flocculant by radiation‐induced copolymerization of methyl chloride salt of N,N‐dimethylaminoethyl methacrylate with acrylamide in aqueous solution
Authors: Okada Toshimi , Ishigaki Isao , Suwa Takeshi , Machi Sueo 
Published: April 2003

AbstractThe radiation‐induced copolymerization of the methyl chloride salt of N,N‐dimethylaminoethyl methacrylate (DMAEM·MC) with acrylamide (AAm) was used to prepare a cationic polymer flocculant. The polymerization rate increased with increasing dose rate, polymerization temperature, monomer concentration and mole fraction of AAm in the monomer mixture. The molecular weight of the copolymer was also found to increase with monomer concentration and mole fraction of AAm, but at high concentration and fraction of AAm, intermolecular crosslinking tends to occur during the polymerization to form water‐insoluble copolymer. A water‐soluble copolymer having various molecular weights and cationic strengths can be synthesized by selecting suitable reaction conditions; i.e., this radiation process can provide a much higher molecular weight copolymer with a wide range of cationic strength. The flocculation effect was evaluated using sludge from wastewater of sugar manufacture. It was found that the radiation‐polymerized copolymer DMAEM·MC–AAm has an excellent flocculation effect.
Effect of uniaxial stretching on the tensile impact test for poly(ethylene terephthalate)
Authors: Yokouchi Mitsuru , Hiromoto Yasuyuki , Kobayashi Yasuji 
Published: April 2003

AbstractIn order to correlate impact strength with the structure of polymeric materials, a tensile impact test was carried out using a uniaxially stretched poly(ethylene terephthalate) (PET) sheet. The structural factors were the draw ratio (λ) and the cut‐out angle (θ) under the conditions of constant impacting speed (10.5 m/sec = 1.8 × 104%/sec) and temperature (20° ± 1°C). The occurrence of structural anisotropy by stretching of isotropic amorphous quench‐rolled PET was classified into three drawing stages: λ = −1.5 or 2.0, −3.5, and over 3.5. This is related to a deformation mechanism of masses with dimensions a few tenths of a μm and their boundaries. The boundaries are not clear until adiabatic deformation (mechanical impact) is applied. The area supporting the mechanical strength was limited to just a small section. Its character was affected by macroscopic deformation only in the direction parallel or near to the stretching direction, since the mechanical properties were not changed for the range of the cut‐out angle θ = 45–90°.
Polyester–polycarbonate blends. V. Linear aliphatic polyesters
Authors: Cruz C. A. , Paul D. R. , Barlow J. W. 
Published: April 2003

AbstractPolycarbonate blends with the linear aliphatic polyesters poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(1,4‐butylene adipate) (PBA), and poly(hexamethylene sebacate) (PHS) were prepared by solution casting. Blends containing PES, PEA, and PBA exhibited a single Tg by DSC and thus form a single, miscible amorphous phase with polycarbonate. However, blends containing PHS exhibited only partial miscibility. Crystallinity of the polyesters was reduced by mixing with polycarbonate; however, plasticization by the polyesters induced crystallization of the polycarbonate. Miscibility in these systems is the result of an exothermic heat of mixing stemming from an interaction of the carbonyl dipole of the ester group with the aromatic carbonate. The effect of polyester structure on miscibility with polycarbonate is interpreted by and correlated with heats of mixing obtained by direct calorimetry of low molecular weight liquid analogs of the polymers.
Mechanism of solvent crazing in unmodified and rubber‐modified polystyrenes
Authors: Iisaka K. , Shibayama K. 
Published: April 2003

AbstractThe dependence of critical strain on time was determined at −20° and 20°C with a Bergen elliptical strain device for unmodified and rubber‐modified polystyrenes immersed in n‐alcohols. Critical strain ϵc decreased with time and attained a lower limiting value ϵcl at long times. The value of ϵcl decreased with increasing chain length of the n‐alcohol and with increasing temperature, while it increased with increasing rubber content. In order to elucidate the mechanism of solvent crazing at longer times, the degree of equilibrium swelling Sveq and the diffusion coefficient D were also determined by sorption experiment. The lower limiting value of critical stress σcl was correlated to the value of Sveq, irrespective of the rubber content. The At, the time necessary to attain ϵcl, was regarded as the time needed for the thin layer of polymer surface to absorb the liquid to equilibrium for craze formation. The thickness of such a layer was estimated to be about 0.1 μm by using the experimental data of At and D. The predominant mechanism of solvent crazing at longer times appears to be a flow process of absorbed polymer at the craze tip.
Anion exchange resins prepared from polystyrene crosslinked via a Friedel–Crafts reaction
Authors: Belfer Sofia , Glozman Raisa 
Published: April 2003

AbstractThe preparation of anion exchange resins from polystyrene crosslinked via a Friedel–Crafts reaction is investigated. Chloromethylation of a highly swollen styrene–hexahydrotriacrylolyl‐s‐triazine copolymer with a mixture of chlorosulfonic acid and methylal is accompanied by the crosslinking of the initially flexible copolymer. The crosslinking efficiency is dependent on the conditions (temperature, nature of solvent) of chloromethylation and can be explained by cationic postpolymerization of polystyrene or poly(benzylchloride), which takes place concurrently with the chloromethylation.
Relation between dynamic mechanical properties and dye diffusion behavior in acrylic fibers from polymer blends
Authors: Bryant Y. G. , Murayama T. 
Published: April 2003

AbstractThe extension of the relation between the dynamic viscoelastic parameters (“E” and tan δ) and diffusion coefficient (D) to modified acrylic blend fibers indicates that the dependence of dye diffusion on polymer chain mobility is a general phenomenon not limited to a single component system. The relationship of D to mechanical properties permits one to “tailor” fibers with good mechanical properties while maintaining adequate dye‐diffusion behavior.
Diels–Alder adducts as epoxy resin hardeners
Authors: Matynia Tadeusz 
Published: April 2003

AbstractThe influence of hydroxyl modifiers on the properties of Diels–Alder adducts–terpene hydrocarbons with maleic anhydride—was studied. The mechanical, thermal, and dielectric properties of the composition of Epidian 5 epoxy resin hardened with an adduct modified by ethylene glycol, propylene glycol, dipropylene glycol, glycerin, or hexanetriol are described.
Phthalic anhydride‐based cation exchange resin from N‐vinylcarbazole
Authors: Biswas Mukul , Packirisamy S. 
Published: April 2003

AbstractA condensation product based on phthalic anhydride and N‐vinylcarbazole has been prepared and processed into a sulfonic acid cation exchange resin. The resin produced has been characterized by measuring its total and salt splitting capacities and by studying its thermal characteristics, rate of exchange, and behavior to pH metric titration.
Strain effects in the mass flux of methanol in poly(methyl methacrylate)
Authors: Ware Robert A. , Cohen Claude 
Published: April 2003

AbstractDiffusion of organic solvents into glassy polymers often results in a phase transformation of the hard, solid polymer into a swollen, rubbery material. During the sorption, internal stresses exist in the swollen and glassy parts of the polymer and are thought to contribute significantly to the “anomalous” diffusion observed in many penetrant–polymer systems. In this investigation, isothermal sorption data for the methanol–poly(methyl methacrylate) system have been obtained on plates ranging in thickness from 1/32 to ¼ in. The results show features characteristic of both a strain‐dependent diffusion coefficient and of a stress gradient contribution to the mass flux. An attempt to reproduce these results by combining a strain‐dependent diffusion coefficient model with a stress‐induced contribution to the flux is presented.
Functional monomers and polymers. LXX. On the adsorption of iodine onto chitosan
Authors: Shigeno Y. , Kondo K. , Takemoto K. 
Published: April 2003

AbstractThe ability of adsorbing iodine in different organic solutions by chitosan was studied by sorption isotherm measurements. The ability was found to be larger in polar solvents than in nonpolar solvents. The form of the chitosan samples, such as film, powder, and flake, had no influence on the adsorption behavior. On the other hand, chitin had only small adsorbing ability of iodine. It is concluded that the adsorption of iodine is caused by charge—transfer complexes between aminogroups of chitosan and iodine molecules, but their structure differs from that of inclusion compounds as seen in amylose–iodine complexes. The adsorption was also studied on chitosan films with different degrees of acetylation.