bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on graft polymerization onto glass fibers. II. Graft copolymerization of glass fiber having pendent mercaptan groups and its application
Authors: Fujisawa Takao , Kobayashi Masahiro , Hashimoto Koshiro , Yosomiya Ryutoku 
Published: April 2003

AbstractGraft polymerization of styrene using a glass fiber having pendent mercaptan groups was carried out under nitrogen in sealed tubes. The percent grafting appeared to increase with monomer concentration, and also to depend to a large extent on the initiator concentration. When CHPO was used as initiator, the percent grafting was maximum at the initiator concentration of 0.02 mol/L. The percent grafting saturation values decreased with increase in the temperature of polymerization. Chain transfer constants and grafting efficiency, both calculated from the equation of Fox et al., were compared with the experimental results. The absorption of Ag ion increased with increase in the percent grafting, and a maximum appeared at a solution pH of 4.0.
Surface protection of poly(vinyl chloride) by photografting of epoxy–acrylate coatings
Authors: Decker Christian 
Published: April 2003

AbstractUV‐curable epoxy–acrylate coatings were used to protect poly(vinyl chloride) against superficial degradation. With α‐hydroxy–acetophenone photoinitiators, the crosslinking polymerization develops in the ms time scale; 50% degree conversion is reached after irradiation times of 2.5 ms in a nitrogen atmosphere and 17 ms in air. The adhesion of the coating on to the PVC substrate can be greatly improved by inducing a photochemical grafting process. The best results are obtained by incorporating the photoinitiator into the top layer of the PVC sheet. Highly crosslinked epoxy–acrylate coatings are very stable toward UV radiations and chemical agents like organic solvents and strong acids. By their light‐screening effect they provide an excellent protection against photodegradation for light‐sensitive polymeric materials.
Aging and performance of structural film adhesives. II. Comparison of two nitrile–epoxy systems
Authors: Pearce P. J. , Davidson R. G. , Morris C. E. M. 
Published: April 2003

AbstractThe room‐temperature aging of two nitrile rubber–epoxy adhesives has been examined. Both are 121°C curing systems, based on DGEBA‐type epoxy resins, one of which has been available for about 15 years while the other is a more recent development. It has been found that hydrolysis of the epoxide and polymerization both occur slowly, reducing the epoxide content and solubility. A major reduction in honeycomb peel strength of joints made with aged material was evident in the older system and to a lesser extent in the newer adhesive. This is a result of diminished adhesive flow. Tensile strength was less affected by aging.
Immobilization of mortierella vinacea cells by radiation polymerization
Authors: Kumakura Minoru , Kaetsu Isao 
Published: April 2003

AbstractImmobilization of Mortierella vinacea cells, which contain active α‐galactosidase, by radiation polymerization at low temperatures was studied. The durability of the enzymatic activity of the immobilized cells was examined by repeating the batch enzyme reaction. The enzymatic activities of the immobilized cells obtained with hydrophilic monomers was affected by the concentrations of the cells and monomer in which optimum conditions were observed. The enzymatic activity of the immobilized cells obtained with hydrophilic monomer was compared to that of hydrophobic monomers. Michaelis constants of the immobilized cells varied with monomer concentration. The effect of addition of porous solid substances on the immobilization of the cells was studied.
Melt spinning of poly(ethylene terephthalate)—structural transitions in a range of spinning speeds
Authors: Hamidi A. , Abhiraman A. S. , Asher Pravin 
Published: April 2003

AbstractThe transitions which occur in the structural state of poly(ethylene terephthalate) filaments in the range of spinning speeds, 1600–4500m/min, have been studied. Thermal annealing of as‐spunfilaments has been shown to provide useful indirect evidence for the structural states of these filaments. The results have been explained with a simple model of orientation distributions arising from crystallization in an oriented precursor.
Precipitative polymerization for polycarbonate: A simultaneous reaction–precipitation technique
Authors: Sikdar S. K. 
Published: April 2003

AbstractA novel phenomenon, termed precipitative polymerization, is described. In it, the BPA—phosgene reaction is conducted with simultaneous precipitation of polycarbonate granules. Very low organic‐to‐aqueous phase ratio and high pH medium are primarily required to cause this in‐situ precipitation.
Structure and properties of polyethylene–polypropylene blend
Authors: Teh J. W. 
Published: April 2003

AbstractThe structure and mechanical properties of blends of low‐density polyethylene and isotactic polypropylene were studied. The blends behaved like a simple composite obeying the rule of mixture for the modulus dependence on composition. Tensile strength of the LDPE was enhanced with the addition of PP but elongation at break was drastically reduced for all blend compositions. Studies with WAXD, hot‐stage microscope, and DSC indicated lack of interaction between the LDPE and the PP. The crystallographic structure of LDPE and PP remained unchanged. However, the spherulite size of the PP was found to be reduced in the presence of LDPE, possibly due to an increase in nucleation density.
Pyrolysis of poly(ethylene terephthalate) fibers: Characterization of involatile residues
Authors: Carlsson D. J. , Day M. , Suprunchuk T. , Wiles D. M. 
Published: April 2003

AbstractPoly(ethylene terephthalate) fabric was degraded under rapid heating conditions and the solid residue characterized by diffuse reflectance infrared spectroscopy. Fabric samples with and without flame retardant were pyrolyzed in air or nitrogen and spectra‐recorded after various percentage weight changes. Dominant species included carboxylic acid end groups and linear anhydrides, based on infrared absorbances before and after chemical treatments of the residues. Vinyl benzoate end groups were clearly precluded, as were cyclic anhydrides. Diffuse reflectance spectra were also compared with spectra obtained by transmission infrared on conventional KBr discs prepared from the same residue. The former technique was shown to be superior to the pressed disc method for the tough residues obtained by thermolysis.
Gelation and fusion profiles of PVC dispersion resins in plastisols
Authors: Nakajima N. , Ward D. W. 
Published: April 2003

AbstractPoly(vinyl chloride) (PVC) plastisols are used for coatings, films, sheets, foams, and rotational castings. In order to satisfy the requirements for the different applications, a variety of PVC dispersion resins are manufactured. The requirements for the plastisols are many: for example, good air release, viscosity stability, fine particle size, foamability, and good heat stability. Processability is another important requirement, which emphasizes the rheological behavior at room temperature and the gelation—fusion behavior. This paper documents research to fingerprint the gelation and fusion profiles of various PVC dispersion resins. The viscoelastic measurements were used to continuously monitor the changes of moduli during gelation and fusion under a heating rate which simulates the temperature profile of the processes. The effects of molecular weight, resin type, and copolymer on the gelation–fusion behavior are discussed.
Rheological properties of mixtures of molten polymer and fluorocarbon blowing agent. II. Mixtures of polystyrene and fluorocarbon blowing agent
Authors: Han Chang Dae , Ma Chin‐Yuan 
Published: April 2003

AbstractThe viscosities of mixtures of polystyrene and fluorocarbon blowing agent were determined, using the experimental technique described in Paper I of this series. For the study, three commercial grades of polystyrene were used, together with the following fluorocarbon blowing agents, trichlorofluoromethane (FC‐11), dichlorodifluoromethane (FC‐12), and blends of FC‐11 and FC‐12. For each combination of polystyrene and blowing agent, blowing agent concentration and melt temperature were varied. We have found that, for all three polystyrenes used, a single correlation exists between the viscosity reduction factor (VRF) and the blowing agent concentration, in which VRF is defined as the ratio of the viscosity of polystyrene‐blowing agent mixture to that of polystyrene homopolymer. The correlation was found to be independent of shear rate and temperature, and dependent upon only the type of fluorocarbon blowing agent. It was suggested that such a correlation be used in predicting the bulk viscosity of mixtures of polystyrene and fluorocarbon blowing agent, using information on the viscosity of polystyrene alone.
A study of tensile modulus and molecular orientation in drawn and shrunk poly(ethylene terephthalate) combining refractive index, polarized fluorescence, and X‐ray diffraction measurements
Authors: Bower D. I. , Korybut‐Daszkiewicz K. K. P. , Ward I. M. 
Published: April 2003

AbstractEarlier studies of the orientation of the crystalline and amorphous regions in drawn and shrunk PET tapes by refractive index, X‐ray, and polarized fluorescence measurements have been extended to include a study of young's modulus of such samples. The results show that for samples of low crystallinity, whether drawn or drawn and shrunk, the modulus correlates well with the overall orientation, as indicated by the birefringence. For such samples the overall orientation and modulus fall with increasing shrinkage. For samples which crystallize substantially, either on drawing or subsequent shrinkage, the behavior is more complicated. In particular, for samples originally drawn at 80°C to λ = 3.44 there is a range of shrinkage temperatures for which greater shrinkage can be accompanied by a smaller loss of overall orientation and modulus because of an increase in crystallinity for the same degree of crystalline and amorphous orientation. The modulus results are discussed in the light of current understanding of the structure of oriented PET. In the case of the samples which crystallize substantially on shrinkage it is shown that changes in modulus primarily related to changes in crystallinity.
Influence of copolymer composition on non‐fickian water transport through glassy copolymers
Authors: Franson Nancy M. , Peppas Nikolaos A. 
Published: April 2003

AbstractThe dynamic swelling behavior of poly(2‐hydroxyethyl methacrylate‐co‐methyl methacrylate) and poly(2‐hydroxyethyl methacrylate‐co‐N‐vinyl‐2‐pyrrolidone) in water was followed at 37°C. The results were analyzed in terms of a simple non‐Fickian transport equation, which expresses the fractional penetrant uptake as an exponential function of the diffusion time. The exponent n, which indicates Fickian or non‐Fickian transport mechanism, was correlated to the content of the more hydrophilic component of the copolymer. Photomicrographs obtained with polarized light offer new information about the position and movement of the penetrant front in glassy, hydrophilic polymers.
Microstructural characterization of injection‐molded articles
Authors: Kamal Musa R. , Moy Francis H. 
Published: April 2003

AbstractThe techniques of density, X‐ray diffraction, and infrared dichroism measurements were employed to study anisotropic behavior, as a result of processing, in injection‐molded parts. Data pertaining to the distributions of crystallinity and orientation indicated that significant changes occur at or near the surface of the molding. Generally, maximum density (crystallinity) is observed in the core of the molding and near the gate, while minimum density (crystallinity) is observed near the surface. X‐ray diffraction suggests a complex pattern of orientation for the three crystallographic axes. The crystallographic a‐axis tends to be oriented in the flow direction as indicated by both X‐ray diffraction and infrared dichroism measurements. Generally, raising the molding temperature has only marginal influence on crystallinity and orientation. However, the two resins included in the study exhibited substantial differences in the distribution of these properties. The distributions of crystallinity and orientation are attributable to the complex interactions between resin properties and process conditions.
Characteristic features of the matrix effect on the stokes shift of fluorescent dye molecules in pure and plasticized polymers
Authors: Eisenbach C. D. , Sah R. E. , Baur G. 
Published: April 2003

AbstractThe influence of the chemical structure, composition, and physical properties of polymers [polyacrylates and ‐methacrylates, poly(vinyl acetate), polystyrene, and polybutadiene] and plasticized polymers [poly(methyl methacrylate) and polystyrene] on the Stokes shift of fluorescent dyes has been investigated. The results indicate that the structure and overall mobility of the polymer matrix as well as the nature of the dopant all together influence the separation of the absorption and emission band of a given fluorescent dye. In general, polar and highly flexible polymers favor the band separation. The effect of both polar and apolar dopants seems to be primarily a plasticization in case of polar polymers, whereas for apolar polymers the plasticizer effect can be neglected and the increased Stokes shift upon addition of polar dopants has to be attributed to particular dopant/dye interactions. These findings open some new routes to improve the efficiency of solar collectors based on fluorescent dyes.
Effects of dry blending on morphogy of PVC powder particles
Authors: Katchy E. M. 
Published: April 2003

AbstractMass and suspension PVC were blended on a Fielder mixer and changes in powder morphology and additive distribution investigated. The techniques used to characterize and assess processing behavior have included microscopy, density, size analysis, torque, and capillary rheometry. The particulate structure of PVC remained intact, and there were no pronounced differences in the processability of blends discharged at different temperatures. In the absence of shear PVC particles are largely unchanged in character. Solid additives do not appear to enter into resin particles while liquid stabilizer readily does so.
Dynamic mechanical and vibration damping properties of polyurethane compositions
Authors: Wong Dennis T. H. , Williams H. Leverne 
Published: April 2003

AbstractA series of polyurethane compositions with varying comonomer ratio and structure, polyblends with epoxy resin, and filled systems with mica and calcium carbonate were prepared. The dynamic mechanical properties of the compositions were measured at 110 Hz using a Rheovibron. The vibration damping properties were measured using a Brüel and Kjaer damping modulus apparatus with steel strips as substrate, the polyurethane compositions as coatings, and, when used, a constraining layer of aluminum or epoxy. The damping curves by the two techniques were similar in shape. Furthermore, the damping properties of the compositions in both extensional and constrained layer configurations could be estimated from the dynamic mechanical properties. The width of the damping region in terms of the temperature range was used as a criterion for effectiveness. Very wide ranges of temperature, and hence frequency, fell within the damping region which was broadened to as much as −40–60°C by the use of bulky backbone chain polymers, by polyblending with epoxy, and by filling with mica. Mica in an extensional mode configuration could be considered as equivalent to a constraining layer for purposes of calculation. The data agree well with the general view that extensional mode damping requires a high loss modulus and constrined mode damping a high loss factor, in both cases being more effective if the storage modulus were also high.
Chemorheology of thermosetting resins. II. Effect of particulates on the chemorheology and curing kinetics of unsaturated polyester resin
Authors: Lem Kwok‐Wai , Han Chang Dae 
Published: April 2003

AbstractThe effect of particulates on both the rheological properties during cure and the curing kinetics of unsaturated resin has been investigated. For the investigation, a general‐purpose unsaturated polyester resin was used, with calcium carbonate and clay as inorganic particulates and high‐density polyethylene powder as organic particulates. It has been found that, as the particulate content increases, the resin/particulate mixture gives rise to shear‐thinning behavior and the rate of cure increases. It has also been found that the CaCO3 particles helped control shrinkage during cure when the material was subjected to steady shear deformation and that the gel time tη∞ is shorter for mixtures of resin and particulates than for the neat resin alone. Differential scanning calorimetry (DSC) is found useful for determining the curing kinetics of resin/particulate mixtures. We have combined rheological and DSC measurements to obtain a correlation between viscosity and the degree of cure during isothermal curing operations.
Permeant saturation and regulation of membrane transport
Authors: Wirbrant Anita , Sundelöf Lars‐Olof 
Published: April 2003

AbstractStudies have been made on the equilibrium sorption of p ‐toluene sulfonic acid by nylon 66. The sorption was found to vary strongly with concentration of sulfonic acid in aqueous phase, approaching a saturation concentration in nylon for high concentration in aqueous phase, similar to a Langmuir adsorption isotherm. It was also found to vary strongly with pH. These findings have been used to give simple conditions for the establishment of almost constant permeation rates through nylon film over extended periods of time.
Distribution of molecular weights and branching of high‐density polyethylene
Authors: Agarwal Ram Kumar , Horská Jitka , Stejskal Jaroslav , Quadrat Otakar , Kratochvíl Pavel , Hudec Pavel 
Published: April 2003

AbstractSamples of industrial high‐density polyethylenes (Liten Macro, Liten FB 29, and Hostalen GM 9255 F) were divided into fractions by precipitation fractionation. The original samples and their fractions were characterized by light scattering, GPC, and viscometry. For all samples the molecular weight distribution is of logarithmic‐normal type. High‐density polyethylenes under investigation contain also high‐molecular‐weight fractions of pronouncedly branched structure, the content of branched molecules being, of course, considerably smaller than that in low‐density polyethylenes.
Tire cord adhesion—A TEM study
Authors: Gillberg Gunilla , Sawyer Linda C. , Promislow A. L. 
Published: April 2003

AbstractTire cords are commonly bonded to the rubber by means of resorcinol–formaldehyde–latex (RFL) adhesives. Modified systems involving compatible first dip resins or RFL additives are required for standard polyester (PET) cords. The tire composite contains several interfaces at which adhesive failure can be initiated. However, very little is known about the interfaces between the various materials. This paper describes a method which allows ultrathin sectioning and thereby TEM studies of cord sections embedded in rubber. The studies were performed on model samples produced in the laboratory as well as cord sections cut from commercial tires. The TEM micrographs clearly demonstrate the pronounced capillary flow of the RFL solution from outer fiber surfaces to fiber interstices. This flow leads to either no RFL or very thin RFL layers at the outer filament surfaces of the cord even in the case of high RFL levels (6%) and double dipping of the RFL. A qualitative relationship between adhesion and RFL surface coverage has been demonstrated. The RFL interface to rubber, to a second RFL dip, or to predips of other adhesives is generally very distinct and its texture similar to that of the bulk RFL. Also, no evidence for diffusion of either the predip or RFL components into the fiber surface could be found. This indicates that only limited interdiffusion of the polymeric materials of RFL and rubber phases takes place. Texture differences in the RFL and rubber phases between the various tires can be used to characterize the type of system used.
Immobilization of microbial cells on cellulose–polymer surfaces by radiation polymerization
Authors: Kumakura Minoru , Kaetsu Isao 
Published: April 2003

AbstractStreptomyces phaeochromogenes cells were immobilized on cellulose–polymer surfaces by radiation polymerization using hydrophilic monomers and paper. The enzyme activity of immobilized cell sheets was higher than that of immobilized cell composites obtained by the usual radiation polymerization technique. The enzyme activity of the sheets was affected by monomer concentration, the thickness of paper, and the degree of polymerization of paper. The copolymerization of hydroxyethyl methacrylate and methoxytetraethyleneglycol methacrylate in the sheets led to a further increase of the enzyme activity due to the increase of the hydrophilicity of the polymer matrix. The Michaelis constant of the sheets from low monomer concentration was close to that of intact cells.
Surface photografting of hydrophilic vinyl monomers onto diethyldithiocarbamated polydimethylsiloxane
Authors: Inoue Hiroshi , Kohama Shigemi 
Published: April 2003

AbstractPhotografting of vinyl monomers has been studied to make hydrophilic polydimethylsiloxane (PDMS) surfaces. A chlorine‐containing polydimethylsiloxane (C‐PDMS) prepared by polymerization of chloromethylheptamethylcyclotetrasiloxane was photocured on a glass plate. The crosslinked C‐PDMA was subjected to a reaction with sodium diethyldithiocarbamate. The diethyldithiocarbamated PDMS was then photoirradiated in the presence of hydrophilic vinyl monomers such as 2‐hydroxyethylmethacrylate and acrylamide to afford surface‐grafted PDMS. Several vinyl monomers were found to graft onto the PDMS surface, as revealed by their attenuated total reflectance infrared and ESCA spectra. Hydrophilicity of the grafted PDMS surfaces was confirmed by the decrease in their water contact angle.
The adsorption of dyes onto chitin in fixed bed columns and batch adsorbers
Authors: McKay G. , Blair H. S. , Gardner J. R. 
Published: April 2003

AbstractChitin has the ability to adsorb substantial quantities of dyestuffs from aqueous solutions. Consequently, it may be a useful adsorbent for effluent treatment from textile mills. The design procedures for batch and continuous fixed bed adsorption columns have been investigated for four dyestuffs, namely, CI Acid Blue 25 (Telon Blue Anl, Bayer), CI Acid Blue 158 (Neolan Blue 29, Ciba Geigy) CI Mordant Yellow 5 (Eriochrome Flavine A, Ciba Geigy), and CI Dirert Red 84 (Solophenyl Brown 3RL, Ciba Geigy). The main fixed bed system variables studied are bed height, dye flow rate, and chitin particle size, and these effects have been incorporated into a simplified design model.
A kinetic study of the polymerization of aliphatic imides
Authors: Galanti Anthony V. 
Published: April 2003

AbstractThermal polymerization of a homologous series of aliphatic poly(methylene) citra‐itaconimides was investigated by differential scanning calorimetry. Enthalpic analysis indicated that, at least to a major extent, the conversion reactions followed pseudo‐first‐order kinetics. A reasonably linear correlation between the number of sequential methylene groups (6, 8, 10, and 12), between the imide ring structures of the monomers, and the activation energy was observed. Reaction rates and initial temperatures of polymerization as well as thermal stability are compared to those of related poly(methylene)–biscitraconimides and –bismaleimides.