bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of transparent conducting acrylic composite and its electrical properties
Authors: Park Yun Heum , Kim Yong Kweon , Lee Doo Sung 
Published: April 2003

AbstractPolyacrylonitrile (PAN)/polythiophene (PTP) composite films were prepared by polymerizing thiophene vapor in PAN films impregnated with sulfuric acid or aluminum chloride as an initiator. After polymerization of thiophene for 1 h, the electrical conductivities of composites reach in the range of 10−7–10−3S/cm depending on the initiator and its concentration. The stability of conductivity to ambient air exposure is excellent. The transparency of composite films has been estimated by transmittance at the maximum absorption wavelength of 593 nm. The transmittance of composite film prepared with 10% of sulfuric acid on the weight of PAN reaches above 90%. The transparency has been maintained for the period of experiment, i.e., 1 month under ambient air exposure. Sulfuric acid is more effective than aluminium chloride for the preparation of transparent conducting PAN/PTP composite films.
Photodegradation of polyethylene: Factors affecting photostability
Authors: Torikai Ayako , Shirakawa Hajime , Nagaya Shigeo , Fueki Kenji 
Published: April 2003

AbstractFour kinds of annealed polyethylene (PE) films with varying densities were photo‐irradiated with a medium pressure mercury lamp. Photodegradation processes were followed by ultraviolet (UV) and Fourier transform infrared (FTIR) spectroscopic techniques and by gel and mechanical property measurements. Oxygenated products build‐up was more favored in linear low density (LLD) PE and the rate of formation increased in the reverse order of polymer density. A similar trend was seen in gel formation. Measurements of elongation at break (%) showed that the embrittlement time of photo‐irradiated PE increased with the decrease of polymer density. The experimental results on unquenched samples were compared with those of quenched samples. It was found that the density (or crystallinity) and crystal size of PE play important roles in determining photostability.
Preparation of ultra‐high modulus polyvinyl alcohol fibers by the zone‐drawing method
Authors: Kunugi Toshio , Kawasumi Tamio , Ito Takashi 
Published: April 2003

AbstractThe zone‐drawing method has been applied to prepare ultra‐high modulus polyvinyl alcohol fibers. First, the suitable temperature for zone‐drawing was decided. In the first zone drawing, when drawing temperature was as high as near melting point, the highest draw ratio and modulus were obtained. The modulus was further increased by repeating zone drawing and heat treatment. In this study, the highest dynamic moduli were 115 GPa at room temperature and 42 GPa at 200°C. The fiber has a sharp melting peak that appeared at 246°C and a small peak at 260°C in the DSC curve.
Application of UV‐curable diazoresin. I. Immobilization of glucose oxidase into PVA in the presence of UV‐sensitive diazoresin and sensitizers
Authors: Liu Jui‐Hsiang , Chen Ming‐Yi , Lin Ming‐Te 
Published: April 2003

AbstractA study of the immobilization of glucose oxidase into poly(vinyl alcohol) membrane in the presence of UV light sensitive diazcresin and benzoic acid and/or sodium benzoate sensitizers was carried out. An effective enzyme electrode by using the immobilized glucose oxidase membrane was developed. The effect of the concentration of diazoresin and sensitizers in poly(vinyl alcohol), UV nght irradiation on the degree of insolubility as well as the activity yield of the membrane were examined for the immobilized glucose oxidase using glucose as a substrate. An unstable phenomenon was found in the initial usage of the immobilized glucose oxidase membrane prepared from poly(vinyl alcohol)‐sensitizer system. Activity yields of 39.98 and 35.30 for poly(vinyl alcohol)‐diazoresin and poly(vinyl alcohol)‐sensitizer system were obtained, respectively.
Miscibility of poly(chloromethyl methacrylate) with bisphenol‐A polycarbonate
Authors: Goh S. H. , Lee S. Y. , Neo M. K. 
Published: April 2003

AbstractPoly(methyl methacrylate) (PMMA) and bisphenol‐A polycarbonate (PC) are important commerical polymers. PMMA/PC blends were once considered as immiscible blends.1–3 However, recent studies have shown that the miscibility of PMMA/PC blends depends on the method of preparation.4–8 Chiou and co‐workers4 reported that PMMA/PC blends prepared by solution casting and melt mixing were immiscible while blends prepared by precipitation from solution using n‐heptane as nonsolvent were miscible over the whole composition range. Kyu and Salhanda5 reported that PMMA/PC blends cast from tetrahydrofuran (THF) at room temperature were immiscible but those cast from THF at temperatures above 47°C were miscible. In this communication, we report the miscibility of poly(chloromethyl methacrylate) (PCMMA) with PC. It will be shown that the miscibility behavior of PCMMA/PC blends is similar to that of PMMA/PC blends.
Miscibility enhancement of polystyrene and poly(alkylene oxide) blends using specific intermolecular interactions
Authors: Weiss R. A. , Beretta C. , Sasongko S. , Garton A. 
Published: April 2003

AbstractAcid–base interactions were used to enhance the miscibility of blends of polystyrene and oligomeric poly(alkylene oxide). The polystyrene was modified by sulfonation of less than 5% of the styrene rings. The poly(alkylene oxides) were low molar mass polyethylene oxide chains (M = 900 and 6000) that were end capped with propyl amine groups. Blends of the poly(alkylene oxide) diamines with polystyrene were immiscible. Blends with the sulfonated polystyrenes were miscible due to proton transfer from the sulfonic acid groups to the basic amino groups of the functionalized poly(alkylene oxide). This was confirmed by FTIR. DSC and dynamic mechanical analyses were used to verify the one‐ or two‐phase nature of the blends.
Polymérisation radicalaire du pentadiène‐1,3. IV. Détermination de la composition et du “run number” des copolymères de cis‐ ou trans‐pentadiène‐1,3 et d'acrylonitrile par pyrolyse éclair couplée à la chromatographie en phase gazeuse
Authors: Petit Alain , Néel Jean 
Published: April 2003

AbstractThis paper investigates the possibility of using the method of flash pyrolysis‐gas chromatography for the quantitative determination of the composition of free‐radically prepared cis‐ or trans‐1,3‐pentadiene–acrylonitrile copolymers and for evaluation of their comonomer sequence distributions in terms of the run numbers. The experiments (sample weight: 50 μg, pyrolysis time: 4 s) were carried out, under a flow of helium, at a thermolysis temperature ranging from 450 to 900°C with a Curie‐point pyrolyzer. After discussion of the respective thermal behaviors of the poly(1,3‐pentadiene), polyacrylonitrile, mixtures of these homopolymers, and various kinds of copolymers (radically or fully alternating samples), the pyrolysis–gas chromatographic characterization of the primary structure of copolymers was studied, between 500 and 800°C, through the quantitative treatment of the corresponding liberated monomers which appeared on the pyrograms. By applying the both‐side boundary effect theory on the molar amounts of these degradation products, which depend both upon copolymer composition and triad sequence distributions in the chain, the relative values of the monomer formation probability constants were calculated. The composition and the run number of each pyrolyzed sample were then determined using these parameters. The analytical data obtained by means of the procedure suggested are in very good agreement with those predicted, from reactivity ratios, by the usual theory of copolymerization (terminal‐unit model) and with the evaluations provided by the 13C‐NMR spectroscopy.
Characterization of radiation induced ethyl methacrylate grafted nylon‐6 fibers
Authors: Basak Anindita , Nayak Padm A. L. , Lenka S. 
Published: April 2003

AbstractEthyl methacrylate grafted nylon‐6 fibers prepared by mutual irradiation technique was characterized to determine the modifications in its properties arising as a result of grafting. Scanning electron microscopy study provides some information about the presence of grafting. Density of fibers were found to increase constantly with percentage graft. Where as alkali solubility, moisture regain decreased with percentage graft thereby decreasing the dyeability of the fiber. However the ethyl methacrylate grafted nylon‐6 fiber showed improvements in its thermal properties over the original nylon‐6 fiber.
Effect of absorbed water on undercured epoxy/amine thermosets
Authors: Johncock P. 
Published: April 2003

AbstractThe effect of water immersion at 70°C on undercured epoxy thermosets obtained from tris[4‐(2,3‐epoxypropoxy)phenyl]methane and 4,4′‐diaminodiphenylsulphone and from N,N‐bis(2,3‐epoxypropyl)aniline and 1,3‐diaminobenzene was investigated. It is concluded from water absorption studies, Tg measurements, and gravimetric data that the predominant reaction is that of additional cure induced by the plasticising and catalytic effect of the absorbed water.
Epoxy resin modified by aliphatic cyclic carbonates
Authors: Rokicki Gabriel , Wojciechowski Cezary 
Published: April 2003

AbstractBidentate and tridentate cyclic carbonates obtained from the reaction of aliphatic epoxy compounds with carbon dioxide were used for the modification of an epoxy resin. The compositions obtained exhibited low viscosity, short gel time, and low exothermic effect accompanying the crosslinking. On the basis of model reactions, a mutually accelerating effect of epoxy and cyclic carbonate groups on the crosslinking of the studied systems by triethylenetetramine was found (synergistic effect). The cured epoxide–cyclic carbonate compositions exhibited considerably higher impact resistance and tensile strength in comparsion with epoxy resins.
Efficient syntheses of the triblock copolymer styrene‐b‐tetrahydrofuran‐b‐styrene by coupling of preformed blocks
Authors: Chien James C. W. , Hong Jin‐Long , Lillya C. Peter 
Published: April 2003

AbstractThe triblock copolymer styrene‐b‐tetrahydrofuran‐b‐styrene was prepared from commercially available hydroxyl‐terminated poly(tetrahydrofuran), Mn = 1,650 and mono‐hydroxyl‐terminated polystyrene, Mn = 7,600. Poly(tetrahydrofuran) blocks were first chain extended by reaction by with 1.1 equivalents 4,4′‐diphenylmethane diisocyanate (MDI) and subsequently end capped with 20% excess of hydroxyl‐terminated polystyrene. Gel permeation chromatography revealed clearly the success of the end capping step to give triblock copolymer mixed with a small amount of excess polystyrene. 1H NMR revealed a gross composition by weight of 50% styrene, 41% tetrahydrofuran, and 9% MDI. DSC revealed a 5°C elevation of the PTHF glass transition and a 15°C lowering of PS glass transition temperature as compared with those of the individual component blocks. These values along with behavior of films as a tough elastomer are consistent with triblock structure and microphase separated morphology. The polymer does not flow readily below 125°C which is well above Tg of the polystyrene domains.
Water sorption in styrene crosslinked polyesters
Authors: Bellenger V. , Mortaigne B. , Verdu J. 
Published: April 2003

AbstractVarious polyester samples differing essentially by the diol nature, the proportion of unsaturated diacid, or the prepolymer chain length were studied by gravimetry at 30, 40, or 50°C, 95% RH. The water equilibrium concentration increases with the test temperature and with the polar group concentration: esters, ethers and alcoholic or acidic chain ends. The diffusivity appears as an increasing function of the crosslink density which can be due to the “bonding” effect of chain ends through strong hydrogen bonds and/or to the fact that local motions are as favoured as the chain end concentration decreases.
Changes of structure and morphology of regenerated cellulose caused by acid and enzymatic hydrolysis
Authors: Lenz J. , Esterbauer H. , Sattler W. , Schurz J. , Wrentschur E. 
Published: April 2003

AbstractThe kinetics of the enzymatic hydrolysis of regenerated cellulose fibers before and after acid prehydrolysis has been investigated. This pretreatment changes the kinetics from a monophasic to a biphasic first order reaction. Prolonged acid prehydrolysis increases the proportion of the enzymatically easily hydrolyzable cellulose form. The kinetics were correlated with corresponding changes of the degree of polymerization, crystallinity and crystallite size.
Cathodically depositable systems based on epoxy resin and blocked isocyanates with cardanol
Authors: Balakrishna R. S. , Sathyanarayana M. N. , Vishwanath B. Balaji , Shirsalkar M. M. 
Published: April 2003

AbstractCathodically electrodepositable binders based on the reaction products of epoxy amine adduct and various proportions of partially blocked isocyanates with cardanol were prepared. Paints were formulated from the above binders using rutile titanium dioxide as pigment in the pigment volume concentration, ranging from 0–50%. A comparative study has been made on the physicochemical properties and electrodepositable characteristics of binders and the paints.
Synthetic resin. IX. Preparation and characterization of resins prepared from resacetophenone, quinacetophenone/aromatic hydroxy, amino and chloro compounds/formaldehyde
Authors: Nayak Pramod K. , Lenka Subasini , Nayak Padma L. 
Published: April 2003

AbstractA number of new resins were synthesized from 2,4‐dihydroxyacetophenone and 2,5‐dihydroxyacetophenone by reaction with substituted hydroxy, amino, and chloro compounds and formaldehyde in presence of various acids and bases as catalyst. The resins were characterized by IR spectra. The solution and chemical properties of the resins were investigated. The solubility parameter was calculated from Small's and Hoy's group contribution methods. The fungicidal properties of the resins synthesized have been evaluated.
Heat setting of oriented poly(ethylene terephthalate): Effects of deformation mode, strain level, and heating medium
Authors: Buckley C. P. , Salem D. R. 
Published: April 2003

AbstractWe continue a previous study of the α and α′ mechanical relaxation processes in oriented poly(ethylene terephthalate) by means of heat‐setting experiments on drawn filaments between room temperature and the melting region. Both processes were exhibited in both torsion and bending deformations, but heat setting was found consistently to be greater in bending than in torsion: this was accounted for by the known anisotropy of the α relaxation. In both modes of deformation, increasing strain level gave reduced recovery, and results suggested this arose from high stresses activating at room temperature the stress relaxation mechanisms, which at low stresses occurred only at elevated temperatures (α if as‐drawn, α′ if preset). Results were found to be independent of whether blown air or stirred oil was used as heat transfer medium, in contrast to some previous reports in the literature; the reason lay in differences in the precise sequences of deformation and temperature employed.
Controlling photoimaging of epoxies by blending to a specific molecular weight
Authors: Russell David J. 
Published: April 2003

AbstractAn epoxy formulation developed for a photoimaging application was found to exhibit poor clean‐out in the developing solvent depending on the lot of one of the base resins. Size exclusion chromatographic (SEC) analysis of the residual material showed it to be a high molecular weight (Mw) fraction of the base resin EpiRez SU‐8. The resin was fractionated, and it was demonstrated that removing the high Mw fraction from the formulation enhanced its developability. Lower Mw versions of this resin were evaluated and found to be unsuitable. However, blending one of these resins (EpiRez SU‐6) with the SU‐8 resulted in a formulation that exhibited excellent developability. Mathematical relationships were calculated that enabled blends to be made, resulting in a defined molecular weight regardless of the lots of resins used.
Miscibility of poly(acrylonitrile‐co‐methyl acrylate) with some thermoplastic polymers
Authors: Percec Simona , Melamud Lucy 
Published: April 2003

AbstractThe phase behavior of binary mixtures of poly(acrylonitrile‐co‐methyl acrylate) (70 : 30) copolymer (B200) with various polymers including poly(N,N‐dimethyl acrylamide) (PNNDA), poly(maleic anhydride) (PMA), poly(vinyl pyrrolidone) (PVP), poly(2‐ethyl‐2‐oxazoline) (PEOX), poly(styrene‐co‐maleic anhydride) (50 : 50) copolymer (SMA), and poly(ϵ‐caprolactone) (PCL) was examined by differential scanning calorimetry (DSC). Miscibility of B200 with some of these polymers was observed over a limited range of composition. Several equations existing in the literature (Fox, Gordon—Taylor, and Kwei) have been employed to describe the dependence of glass transition temperature of the miscible blends as a function of the blend composition. In most cases a deviation from the weight‐average values of the experimental glass transition temperatures and of the values predicted by various equations was found. This has been attributed to specific interactions between the molecular constituents of the polymer pair.
Preparation of polystyrene‐block‐(ethylene oxide)s and characterization of the products
Authors: Uyanik Nurseli , Baysal Bahattin M. 
Published: April 2003

AbstractBlock copolymers containing segments of poly(ethylene oxide) and polystyrene were synthesized. Dihydroxyl‐terminated polyethers (PEG‐4000 and PEG‐20,000) were reacted with an aliphatic diisocyanate (3‐isocyanatomethyl‐3,5,5‐trimethyl‐cyclohexyl‐isocyanate) and with an aliphatic hydroperoxide (t‐butyl hydroperoxide). The resulting polymeric peroxycarbamates were used as free radical initiators for vinyl polymerization. Formation of block copolymers was illustrated by several characterization methods such as chemical and UV analysis, infrared spectroscopy, and DSC thermograms. Mechanical characterization of the copolymers was made on the basis of the stress—strain curves obtained from a mechanical testing instrument (Tensilon).
Grafting onto polypropylene. V. Graft copolymerization of 4‐vinyl pyridine and binary mixture of 4‐vinyl pyridine with acrylonitrile by preirradiation method
Authors: Kaur Inderjeet , Barsola Raghuvir 
Published: April 2003

AbstractRadiation‐induced graft copolymerization of 4‐vinyl pyridine (4‐VP) and its binary mixture with acrylonitrile (AN) onto isotactic polypropylene has been studied in aqueous medium. Percentage of grafting has been studied as a function of different reaction parameters and the optimum conditions for affording maximum percentage of grafting have been evaluated. It was observed that there exists an optimum composition of the binary mixture at which percentage of grafting is maximum. The maximum percentage of grafting is obtained at the total monomer concentration of [AN + 4VP] = 0.009 moles. The graft copolymers were characterized by IR spectroscopic methods. An attempt has been made to discuss the effect of acceptor monomer (AN) on percentage of grafting of donor monomer (4‐VP).
Thermal behavior of carbon black filled polymers
Authors: Gandhi Khushroo , Salovey R. 
Published: April 2003

AbstractDSC measurements suggest that polybutyl methacrylate interacts more strongly with carbon black than polystyrenes and corresponding random copolymers do, showing an increase in Tg of 8.6°C, compared to 2–3°C, by the inclusion of 20% carbon black of surface area 625 m2/g, in agreement with rheological studies. Enthalpy relaxation in the vicinity of Tg is increased by annealing at Tg – 10°C, attaining a maximum of 1.65 kJ/kg for polybutyl methacrylate and 2.6 kJ/kg for polystyrene. At constant annealing temperature, the rate of enthalpy relaxation in polybutyl methacrylate was reduced by a factor of about two by the addition of carbon black. However, both pure polystyrene and polybutyl methacrylate show the same rate of enthalpy relaxation as the corresponding filled polymers, following annealing at the appropriate Tg – 10°C.
Preparation and application of semiconductor–polymer composites
Authors: Miyama Hajime , Yokoyama Hidekuni , Nosaka Yoshio 
Published: April 2003

AbstractCopper sulfide–polymer composite was prepared by depositing copper into porous polyolefine film with a method of electroless plating and sulfurizing the copper. The composite was an n‐type semiconductor and useful as a component of p–n junction device and as a gas detector. The method was also useful for the preparation of silver sulfide–, nickel sulfide–, and cobalt sulfide–polymer composites.
A new method for rapid evaluation of long‐chain branching in polymers
Authors: Chunshan Jin , Qipeng Guo 
Published: April 2003

AbstractA new method for rapid evaluation of long‐chain branching (LCB) in polymers was developed. The crude GPC chromatogram and the measured value of intrinsic viscosity of the whole polymer are the only data required. By using trial and error in combination with graphic analysis, the threshold value M0 and average molecular weights M̄w and M̄n, as well as LCB can be simultaneously evaluated. The advantage of this method lies in avoiding predetermination of the M0 for a given resin. The results obtained by this method for NBS Branched Polyethylene Standard Reference Material SRM 1476 and for a branched cis‐1,4‐polybutadiene sample were in good agreement with those given by the conventional Ram–Miltz method.
The inhibition of spontaneous ignition by flame‐retarding cotton fabrics
Authors: Khattab M. A. , Price D. , Horrocks A. R. 
Published: April 2003

AbstractThe spontaneous ignition behavior of flame‐retarded cotton cellulose has been investigated using differential thermal analysis (DTA). One durable, phosphonium salt‐urea‐ammonia polycondensate (Proban CC), and one nondurable, ammonium polyphosphate (Amgard TR) commercially flame‐retardant‐treated fabrics have been studied. The information obtained is compared to that previously reported for untreated cotton cellulose. The onset of spontaneous ignition, temperature Ti, was determined as a function of [O2] in the flowing O2/N2 atmosphere to which samples were exposed in the DTA furnace, whose temperature was raised at a known linear heating rate. The activation energy Ep for the rate‐determining pyrolysis reaction was calculated. In the case of the Amgard TR fabric, Ep increased from 145 kJ mol−1 at 21% O2 to 261 kJ mol−1 at 50% O2, whereas that for the Proban fabric increased from 230 to 400 kJ mol−1.A plot of 1/Ti vs. In [O2] shows two linear regions that interact at about 40% O2, which is just above the limiting oxygen index values for these two flame‐retarded samples. This intersection is interpreted as indicating that the combustion mechanism of these flame‐retarded fabrics changes as [O2] passes through this 40% level. Below this value, significant amounts of char remained after the DTA experiment, suggesting that volatiles only were ignited, whereas above this value, both volatiles and char were burnt away. This is supported by evidence from the DTA traces. The difference in slopes of the two regions of the 1/Ti vs. [O2] plots is used to obtain a value for Eox, the activation energy for gaseous oxidation. Values for Eox of 270 and 536 kJ mol−1 were obtained for the Amgard TR and Proban CC fabrics, respectively. These are considerably higher than is the value of 215 kJ mol−1 previously reported for untreated cotton. Thus, one of the ways in which these flame retardants reduce the ease of combustion of the cotton is by increasing the activation energy for the oxidation of the evolved organic species.