bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyacrylonitrile (PAN)‐grafted jute fibres: Some physical and chemical properties and morphology
Authors: Ghosh Premamoy , Ganguly Prasanta K. 
Published: April 2003

AbstractGrafting of polyacrylonitrile (PAN) on (dewaxed and bleached) jute fibres was done by aqueous polymerization of acrylonitrile (AN) in the presence of the fiber samples employing a sodium periodate (IO4−) and copper sulfate (Cu2+) combination as the initiator. Effect of PAN grafting to different extents on X‐ray crystallinity, tensile properties, thermal behavior, whiteness index, dyeability, light‐fastness rating, and moisture regain properties of the fiber samples were studied and analyzed. Their rot resistance, determined by a standard soil burial test, were also examined and compared. Twenty to thirty percent PAN‐grafting was found to impart a most desirable balance of physical properties including fiber strength and modulus, moisture regain, whiteness index, and light‐fastness rating. PAN grafting also makes the otherwise nonresistant jute fiber significantly rot‐resistant. Morphology of the different fiber samples as studied and compared using scanning electron microscopy indicates that PAN grafting occurs on surfaces and intercellular regions as well as within the lumens of the multicellular jute fibers. © 1994 John Wiley & Sons, Inc.
Microstructure of polyurethane ionomers derivatized with dodecylamine and polyethylene oxide in the hard segment
Authors: Santerre J. P. , Brash J. L. 
Published: April 2003

AbstractSegmented polyether‐polyurethanes containing sulfonate groups in the hard segment were modified by the grafting of polyethylene oxide and C12 hydrocarbon chains. The grafts were attached via the sulfonate groups. The physical properties of the materials, including stress–strain behavior, thermal behavior, and water uptake were studied. Grafting was found to alter material behavior significantly. Both the alkyl and polyethylene oxide grafts appear to alter the packing of the hard segments in microdomains because the grafted materials, in contrast to their sulfonated precursor, do not exhibit a melting transition. However, the polyethylene oxide chains appear to interact with the hard segments, probably through hydrogen bonding. For the C12 grafted materials, differential scanning calorimetry showed that a third microphase, consisting largely of C12 chains, may be formed by annealing. Stress–strain and water uptake data support these interpretations. The grafted materials were found to absorb more water than the sulfonated precursor. Most of the water taken up by the C12 material appears to be bulk water whereas for the PEO materials the absorbed water behaves as if it is bound. © 1994 John Wiley & Sons, Inc.
Phototackification of polymer blends
Authors: Simmons H. E. , Hertler W. R. , Sauer B. B. 
Published: April 2003

AbstractA direct single‐layer phototackification scheme is demonstrated making use of chemical amplification and photo‐induced microphase separation in an initially nontacky miscible blend of acid‐labile poly(2‐tetrahydropyranyl methacrylate) and poly(2‐tetrahydropyranyl acrylate), tacky poly(2‐phenylethyl acrylate), and a photoacid generator. The mechanism involves four process: photoacid generation, acid migration, acetal ester cleavage, and phase separation. Thin film in situ IR studies showed the rate of acid migration and acetal ester cleavage to be strongly dependent on the presence of ambient water and polymer matrix (Tg) effects. The rate of phase separation is affected by polymer molecular weight. A number of approaches to minimize humidity sensitivity are discussed. The system has been sensitized to both UV and near‐IR radiation. © 1994 John Wiley & Sons, Inc.
Fast pyrolysis of cellulose with reactive methane gas in a single‐pulse shock tube
Authors: Öztürk Zihni , Merklin Joseph F. 
Published: April 2003

AbstractA shock tube technique was employed to study the fast pyrolysis of cellulose with methane under conditions of high temperature, high heating rate, short reaction time, and rapid quenching. The effects of temperature, methane atmosphere, and reaction time are investigated. Experiments were carried out at temperatures between 700 and 2200°C in 1% methane (diluted in argon), and comparisons in the yields of major gas products are made with the results obtained in pure argon atmosphere. The total gas yield decreased about 25–30% in methane. The principal gas products—carbon monoxide, carbon dioxide, and acetylene, except ethylene—were significantly decreased in methane as compared to the yields in pure argon. An increase of about 25% in ethylene yield in methane over argon was observed. The onset of the decomposition of cellulose and the evolution of major pyrolysis products were changed with the reaction times, which also affected the amplitude and the distribution of the pyrolysis products. © 1994 John Wiley & Sons, Inc.
Strong buffering characteristics and swelling behavior of cationic copolymers
Authors: Peppas Nikolaos A. , Foster Lisa K. 
Published: April 2003

AbstractThe swelling behavior of crosslinked cationic copolymers of 2‐hydroxyethyl methacrylate with (3‐methacryloylamino propyl) trimethylammonium chloride was investigated in various buffered solutions as a function of ionic strength and pH. The equilibrium degree of swelling increased as the pH decreased or as the cationic group‐containing comonomer in the polymer increased. The water transport in such copolymers was controlled by a non‐Fickian mechanism. These results can be used in the development of physiologically sensitive controlled drug delivery systems. © 1994 John Wiley & Sons, Inc.
Preparation and structure of cross‐linked asymmetric membranes based on polystyrene and divinylbenzene
Authors: Byun H. S. , Burford R. P. 
Published: April 2003

AbstractAsymmetric polystryene‐based membranes were prepared by photocross‐linking with divinylbenzene (DVB) combined with phase‐inversion steps. The primary variables examined were original polystrene concentration in the membrance casting solution and degree of cross‐linking. The effects of these upon membrane morphology and reverse osmosis performance were determined. At higher DVB concentration, skin was formed at the top due to phase separation and at the bottom due to preferential polymer absorption at the support interface. An attempt was made to increase membrane ductility by incorporating low levels of liquid polybutadiene or styrene‐butadiene block copolymer, but no significant change was measured. © 1994 John Wiley & Sons, Inc.
Interpenetrating hydrogel networks based on gelatin and polyacrylamide: Synthesis, swelling, and drug release analysis
Authors: Ramaraj B. , Radhakrishnan Ganga 
Published: April 2003

AbstractInterpenetrating hydrogel network has been synthesized from gelatin and polyacrylamide by cross‐linking with their respective cross‐linking agents. The swelling behavior of this Interpenetrating polymer network (IPN) system was analyzed in water and in citric acid‐phosphate buffer solution at various pH. The effect of temperature on swelling behavior of these gels has been analyzed by variation from 25 to 60°C at physiological pH. The drug release behavior of these gels was also analyzed with temperature variation at physiological pH. © 1994 John Wiley & Sons, Inc.
Preparation and physical properties of polyurethane modified with poly(4,4′‐diphenylsulfone terephthalamide)
Authors: Wang Huei‐Hsiung , Shiao Kai‐Rhen 
Published: April 2003

AbstractThree conventional polyurethane (PU) elastomers were blended physically with various ratios of high molecular weight of poly(4,4′‐diphenylsulfone terephthalamide) (PSA) to form 12 PU/PSA polyblends in order to modify their physical properties. Also three new polyurethanes were synthesized with a low‐molecular‐weight PSA prepolymer as a hydrogen donor for chain extending. From dynamic properties, it showed that both the blends and the new polyurethanes (or polyurethane‐ureas) exhibited a glass transition temperature (Tg) below 0°C and had a higher modulus E′ than those of the conventional PU. Based on the analysis of X‐ray diffraction of the conventional and the new PU, it was shown that the degree of stress‐induced crystallization was dependent on the segmental composition of the soft and hard segments and also the degree of its stretching. On the morphological observation, it was revealed that both the blends and the new polyurethanes were in a dispersed phase structure, although new PU exhibited a better compatible state. For tensile properties, it was found that both tensile strength and elongation of the new polyurethanes were better than those of the blends and conventional PU. © 1994 John Wiley & Sons, Inc.
Comb‐type polymers and their interaction with wax crystals in waxy hydrocarbon fluids: Wide‐angle X‐ray diffraction studies
Authors: Chatterjee Alok K. , Phatak Sadanand D. , Murthy Pappu S. , Joshi Girish C. 
Published: April 2003

AbstractWe report the results of our wide‐angle X‐ray diffraction (WAXD) studies on the interaction of various comb‐type acrylate polymers, synthesized in our laboratories, with waxes crystallizing out below the cloud point of an indigenously available high‐wax commercial diesel fuel. These copolymers were made from monomers from C8 to C24 carbon numbers, which covers the average carbon number, viz., C16–C22, of most of the commercial diesel fuels. The influence of the pendant chain on the crystallization process of n‐alkanes below the cloud point of the fuel has been assessed, for the first time, to the best of our knowledge, by this method. Wax crystals, isolated by this procedure, are basically hexagonal, with some features relating to mal‐structures and have similarity to the comb‐type polymers with more than eight carbon atoms in their side chains. Effective pour‐point depressants showed distinctive changes in the diffraction pattern of the low‐angle, i.e., larger than van der Waals (LVDW) peaks, usually a general shift to higher angles, and in some cases, a distinct split. © 1994 John Wiley & Sons, Inc.
Permeability through cellulose membranes grafted with vinyl monomers in a homogeneous system. VIII. N‐vinylpyrrolidone‐grafted cellulose membranes
Authors: Nishioka Noboru , Tsuetaki Motoji , Kato Ryoichi , Uno Masakuni 
Published: April 2003

AbstractThe homogeneous grafting of N‐vinylpyrrolidone (NVP) onto cellulose was carried out in a dimethyl sulfoxide/paraformaldehyde (DMSO/PF) solvent system. The diffusive permeabilities of solutes through the NVP‐grafted cellulose membranes, apparent activation energy for solute permeation through them, states of water in them, and their microphaseseparated structures were investigated. The solute permeability through the grafted membranes was superior to that through the cellulose membrane cast from the DMSO/PF solution of cellulose. The total water and nonfreezing water contents of the grafted membranes were larger than those of the cellulose membrane. The difference in permeability through the membranes was not correlated quantitatively with the amount of each state of water in them. Activation energies for permeation of solutes through the grafted membranes were similar to those through the cellulose membrane. © 1994 John Wiley & Sons, Inc.
Effect of polymeric steric stabilizers on the settling of alumina
Authors: Armstrong G. H. , Johnson L. , Parker A. A. 
Published: April 2003

AbstractThe effect of polymeric steric stabilizers on the dispersion stability of alumina was determined by settling experiments. The theoretical settling density was determined for alumina in a 90:10 wt% toluene‐ethanol mixed solvent. Polymers evaluated were sulfonated polystyrenes, Shell's functionalized Kraton block polymers (styrene‐hydrogenated diene), ICI's polymeric surfactants, homopolystyrene, a nonfunctionalized Kraton block polymer, and two Union Carbide Corporation silwet surfactants. The high‐molecular‐weight sulfonated polystyrene (60,000) containing a low level of sulfonation, functionalized Kraton block polymers, and one ICI polymeric surfactant were effective in improving the dispersion stability of the alumina. The percent of theoretical settling density for the “good” polymeric steric stabilizers ranged from 45 to 50%. The low‐molecular‐weight sulfonated polystyrene (10,000 MW), homopolystyrene, unfunctionalized Kraton block polymer, one ICI polymeric surfactant, and the silwet surfactants were ineffective in improving the dispersion stability of the alumina in the mixed solvent. © 1994 John Wiley & Sons, Inc.
Effect of antioxidants on properties and morphology of poly(acrylonitrile–butadiene–styrene)/polycarbonate blends
Authors: Yan Rong Jiang , Yang Bingxin 
Published: April 2003

AbstractPoly(acrylonitrile–butadiene–styrene), polycarbonate (PC), and two types of antioxidants have been blended by an extruder twin screw. Notched Izod impact strength, tensile property, and melting flow index (MFI) were measured for the blends including different amounts of antioxidants, and morphology of the blends was investigated by scanning electron microscopy (SEM). The antioxidant action, especially on mechanical properties and the phase structure of the blends, has been studied for the undergraded samples. It was found that the phenolic antioxidant, tetrakis (3,5‐di‐tert‐butyl‐4‐hydroxyhydrocinnamoyloxy‐methyl) methane, C73H108O12, whose commercial name is KY‐7910, and phosphite antioxidant, triphenyl phosphite (TPP), (C6H5O)3P, all decrease the Izod impact strength and tensile modulus of the blends and increase the elongation at break if a small amount of the antioxidants (such as less than 0.7%) was mixed into the blends. When the content of the antioxidants is increased, surpassing 0.7%, KY‐7910 has little effect on impact property of the blends, but TPP made the Izod impact strength decrease and the MFI increase to a great degree. SEM results show that the two phases of ABS/PC with a weight ratio of 30/70 is cocontinuous; this structure is destroyed by addition of the two antioxidants, and in ABS/PC/antioxidants blends, the size of the ABS phase, as dispersion, does not change not much with increasing KY‐7910 content, but becomes more scattered and greater with increasing content of TPP. These results are consistent with the mechanical tests. © 1994 John Wiley & Sons, Inc.
Effect of moisture and orientation on the fracture of nylon 6,6 fibers
Authors: Michielsen S. 
Published: April 2003

AbstractThe effect of relative humidity on the fracture of single nylon 6,6 fibers is determined using fracture mechanics. The fracture energy release rate, GIc, of these fibers is shown to be 8× that for injection‐molded nylon 6,6 at 0% RH. GIc varies from 31.3 kJ/m2 at 0% RH to 15.6 kJ/m2 at 100% RH. The dependence of GIc on RH is in agreement with previous studies indicating two types of water in nylon: a tightly bound and a loosely bound type. In addition, GIc is shown to be 10× greater for transverse fiber breaks than for axial splitting of the fiber due to the high degree of orientation in these fibers. These studies are the first of their kind for organic fibers. © 1994 John Wiley & Sons, Inc.
Glycidyl‐terminated polyurethane modified epoxy resins: Mechanical properties, adhesion properties, and morphology
Authors: Hsia Hung‐Chung , Ma Chen‐Chi M. , Li Ming‐Shiu , Li Ye‐Shiu , Chen Der‐Shyang 
Published: April 2003

AbstractGlycidol was used to convert the isocyanate‐terminated polyurethane prepolymer to glycidyl‐terminated polyurethane prepolymer. The modified polyurethane not only offers some distinct advantages over the commercial polyurethane prepolymer, but also enhances the properties of the epoxy resins. The glycidyl‐terminated polyurethane modified epoxy resin proved to be superior to conventional epoxy resins in improving impact strength, fracture energy, and adhesion properties. The compatibility of the compounds in this glycidyl‐terminated PU/epoxy system was investigated using different preparation procedures. It was found that the synthesized glycidyl‐terminated polyurethane prereacted with curing agents, exhibited a lesser degree of phase separation, and can influence the mechanical properties of polymer blends. The results coincide with the phenomena observed in dynamic mechanical analysis and scanning election microscopy. © 1994 John Wiley & Sons, Inc.
Solid‐state NMR characterization of motion in flexible polyurethane foams
Authors: Moreland J. C. , Wilkes G. L. , Moreland C. G. , Sankar S. S. , Stejskal E. O. , Turner R. B. 
Published: April 2003

AbstractHigh‐resolution solid‐state 13C‐NMR has been used to study the phase separation and molecular motion in two series of polyurethane foams. These two series differ by one possessing the additive of lithium chloride, LiCl. NMR relaxation times can map the motion throughout the polymer molecule and detect changes in that motion arising from either microseparation or phase mixing between the different segments. There are only slight changes in the soft segment T1p(13C) values as well as an increase in the hard segment T1p(1H) values with increase in the hard segment content for the foams studied. The T1p(1H) and T1p(13C) values do indicate that the phase separation of the hard and soft segments is similar for all foams. A decrease in the T1p(1H) and T1p(13C) values with increasing LiCl content indicates that the motion of the soft segments is restricted more by the hard segments. This is explained by more phase mixing in the foams containing the LiCl additive. © 1994 John Wiley & Sons, Inc.
Catalytic transesterification in polycarbonate–polycaprolactone systems
Authors: Shuster M. , Narkis M. , Siegmann A. 
Published: April 2003

AbstractBisphenol A polycarbonate (PC)–poly‐ε‐caprolactone (PCL) blends have been prepared by melt mixing in the presence of different catalysts using a Brabender plastograph and single‐screw extruder at 240–260°C. Increased crystallizability [detected by differential scanning calorimetry (DSC)] of the PC component was observed in the blends obtained in the presence of p‐toluenesulfonic acid. Acceleration of carbonate‐carbonate exchange reactions is suggested as the main reason for the crystallizability enhancement. Results of solubility tests, DSC, and infrared (IR) spectroscopy evidence ester‐carbonate transesterification taking place during PC–PCL blending in the presence of tetrabutoxy titanium and dibutyltin dilaurate. © 1994 John Wiley & Sons, Inc.
The effects of soft segments on the physical properties and water vapor permeability of H12MDI‐PU cast films
Authors: Yen M. S. , Cheng K. L. 
Published: April 2003

AbstractThis research was based on the study of the effects of H12MDI‐1, 4BD PU soft segments on the physical properties and water vapor permeability of films cast from solvent evaporation or wet coagulation method. The soft segments studied included polyether, polyester, and polycaprolactone polydiols. The NCO/OH mol ratios of prepolymer were prepared by 2, 3, 4, 5, and 8, respectively. The chain lengths of the soft segments used were: PTMG of molecular weights 650, 1000, 2000, and 2900; PBA of 1000, 2000, and 3000. The results revealed that the polyether‐based PU cast films had lower Tgs than the polyester‐based PU films. In general, the polyether‐based PU films shows the characters of higher water vapor permeability, lower breaking elongation, and higher breaking strength. Films with higher molecular weight soft segments in the polymer chains exhibited lower Tgs, lower breaking strength, higher breaking elongation, and higher water vapor permeability. As the hard segment contents were increased, the films exhibited higher Tgs. Films with higher hard‐segment ratios had the highest breaking strength but the water vapor permeability, on the other hand, became lower. Films cast from the solvent evaporation method had higher breaking strength and higher breaking elongation but lower water vapor permeability than films cast from the wet coagulation method. © 1994 John Wiley & Sons, Inc.
The effect of fillers on relaxation phenomena of vulcanized styrene–butadiene elastomers
Authors: Čvorkov Ljubomir , Vlatković Biljana , Veličković Jovan 
Published: April 2003

AbstractStandard recipe mixtures, based on styrene/butadiene rubber SBR 1500 and oil‐extended SBR 1712, with varying amounts of carbon black, silica, or kaoline fillers were prepared and the stress relaxation curves of vulcanized samples were determined. The measurements were restricted to slow relaxation phenomena, observed after 50% initial elongation. Three λ‐processes and a fourth ϕ‐process, existing only in filled rubbers, were observed. The relaxation times and activation energies, determined graphically, reflect the amount and activity of the fillers. All relaxation times are lower for filled vulcanizates and decrease with increasing temperature; however, the type of filler does not affect the activation energy. The higher parameters observed for the ϕ‐processes are discussed in terms of filler particle mobilities and rearrangements and of filler/rubber contact layer phenomena. © 1994 John Wiley & Sons, Inc.
Analysis of ultrasonically induced free radicals in the emulsion polymerization system by GC–MS
Authors: Liu Youbang , Chou Hsin‐Chieh , Stoffer James O. 
Published: April 2003

AbstractA specially designed gas chromatography–mass spectrometry (GC–MS) analytical method has been developed and applied to identify the source of free radicals that served as initiators in a new ultrasonically induced emulsion polymerization system with monomer methyl mathacrylate (MMA), surfactant sodium dodecylsulfate (SDS) and water. The results showed the radicals came from the dissociation of SDS under ultrasonic irradiation. A quantitative determination procedure has been also developed and utilized to investigate the effects of the polymerization parameters, such as the surfactant concentration, the acoustic intensity of ultrasound, and the argon flow rate on the concentration of the generated free radicals in the emulsion system under ultrasonic irradiation. The results were helpful to understand the mechanism and kinetics of the system. © 1994 John Wiley & Sons, Inc.
A squeeze film flow processibility tester
Authors: Pham Hoang T. , Meinecke Eberhard A. 
Published: April 2003

AbstractThe applicability of the squeeze film flow geometry in a processibility tester is investigated in this study. A prototype processibility tester has been built by retrofitting it to a servohydraulic load frame. Several processibility parameters such as viscosity and the elastic component in the melt have been investigated. With the concept of equivalent elastic strain, the extrudate swell can be semi‐quantitatively predicted from the squeeze film flow experiment. © 1994 John Wiley & Sons, Inc.
EVA–EPDM blends as cable insulant
Authors: Ray I. , Khastgir D. 
Published: April 2003

AbstractBase materials for heat‐resistant cable insulant have been developed from blends of ethylene vinyl acetate (EVA) copolymer containing 28% VA and ethylene propylene diene (EPDM) rubber. Different electrical, mechanical, and thermal properties of these blends have been studied extensively. Aging under different conditions has also been studied. The chemical and mechanical stability of these compositions has been assessed at the actual temperature range of application. Dielectric properties have been determined against varying temperature. These blends may be used as insulating materials having a temperature rating around 90–130°C, which is above the temperature rating (85–90°C) of heat‐resistant insulation based on EPDM. © 1994 John Wiley & Sons, Inc.