bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic and thermogravimetric analysis of the thermal oxidative degradation of flame‐retardant polyesters
Authors: Cooney J. D. , Day M. , Wiles D. M. 
Published: April 2003

AbstractUntreated and flame‐retarded poly(ethylene terephthalate) fabrics have been subjected to thermogravimetric analysis in air at several heating rates between 0.1°C/min and 100°C/min. The data have been analyzed using a variety of methods to obtain kinetic parameters for the sequential stages in the thermal degradation process. The data obtained reveal that the phosphorous‐only flame retardants do not significantly effect the degradation kinetics. The two bromine‐containing flame retardants, however, are capable of modifying the degradation kinetics, with the Dacron 900F material being responsible for a beneficial condensed‐phase effect while the TRIS‐treated sample is responsible for reduced activation energies and more rapid weight loss.
Grafting of poly‐β‐alanine onto carbon black: The hydrogen transfer polymerization of acrylamide catalyzed by n‐butyllithium in the presence of carbon black
Authors: Tsubokawa Norio , Nagano Yukihiro , Sone Yasuo 
Published: April 2003

AbstractThe hydrogen transfer polymerization of acrylamide (AAm) catalyzed by n‐butyllithium in the presence of carbon black was carried out at 80–100°C and the grafting of poly‐β‐alanine (nylon 3) was investigated. It was suggested that the growing polymer anion was captured by the quinonic oxygen group on the surface of carbon black. Furthermore, the growing polymer anion reacted with the phenolic hydroxyl group on the surface to give ungrafted polymer and the lithium phenolate (O−Li+) group (chain transfer to phenolic hydroxyl group). The O−Li+ group formed was considered to be capable of initiating the hydrogen transfer polymerization of AAm. Accordingly, during the hydrogen transfer polymerization in the presence of carbon black, poly‐β‐alanine was effectively grafted by the termination of growing polymer anion and the propagation of the polymer from the O−Li+ group on the surface. The grafting ratio was determined to be 60–80%. The carbon black obtained from the polymerization gave a stable colloidal dispersion in water, N,N‐dimethylformamide, and formic acid. Furthermore, it was found that the ratio of hydrogen transfer polymerization to normal vinyl polymerization (T ratio) increased with an increase in polymerization temperature.
Dynamic mechanical properties of polypropylene composites filled with ultrafine particles
Authors: Sumita Masao , Tsukihi Hidetoshi , Miyasaka Keizo , Ishikawa Kinzo 
Published: April 2003

AbstractThe dynamic moduli of isotactic polypropylene (PP) filled with ultrafine SiO2 and micron sized glass particles are measured in the temperature range 30–130°C at frequency 10 Hz. The storage moduli of PP composites, E′c, increase with filler content and decreasing filler size in the whole range of temperature. The loss moduli of PP composites, E″c, increase with filler content and decreasing filler size above 40°C. The intensity of the broad despersion which appears at ca. 60°C increases with filler content and decreasing filler size. By assuming that the energy is not dissipated in the effective volume, namely, filler volume plus that of immobilized interfacial region, the effective volume fraction is evaluated from the relative loss modulus, E″cE″0 at 60°C. The effective volume fraction increases with filler content and decreasing filler size. The effect of addition of ultrafine particles on the broad dispersion at ca. 60°C resembles the effect of increasing crystallinity of pure PP. It is concluded that the broad dispersion which appeared at ca. 60°C seemed to be assigned to the grain boundary of PP composities or crystalline boundary of pure PP.
Compatibility of polystyrene and poly(methyl methacrylate) of various molecular weights in toluene
Authors: Lau Wayne W. Y. , Burns Charles M. , Huang Robert Y. M. 
Published: April 2003

AbstractGel permeation chromatography has been successfully used to determine the compositions of the conjugate phases in the system of polystyrene and poly(methyl methacrylate) with toluene as solvent. Application of this method to equilibrated samples yields tie lines, binodal curves, and plait points. Polymer–polymer compatibility and the polymer–polymer interaction parameters at the plait points in this system were found to be strongly dependent on the molecular weights of the polymers.
Modified cellulose acetate membranes for desalination
Authors: Ghatge N. D. , Sabne M. B. , Gujar K. B. , Mahajan S. S. 
Published: April 2003

AbstractResidual hydroxyl groups of commercially available cellulose acetate (39.9% acetyl) have been reacted partially with phenyl isocyanate. The characteristics of these modified polymers have been studied. Membranes have been cast from these polymers to study their potentiality as reverse osmosis membranes. The work has been further extended to investigated the stability of these modified CA under the influence of high temperature and γ irradiation.
Effects of enzymes and gamma irradiation on the tensile strength and morphology of poly(p‐dioxanone) fibers
Authors: Williams David F. , Chu C. C. , Dwyer J. 
Published: April 2003

AbstractThe objective of this study was to examine how and to what extent a new degradable polymeric fiber, poly(p‐dioxanone), used as a surgical suture material, degrades in the presence of enzymes and after γ‐irradiation. The degradation of the fiber was studied mechanically using an Instron and morphologically by SEM. Both esterase and trypsin enzymes and their corresponding buffer controls were used. The fibers were γ‐irradiated at the dosages ranging from 0 to 20 Mrad, immersed in the solution for up to 70 days, and then removed for tensile strength and morphological examinations. It was found that γ‐irradiation alone lowered the tensile strength of PDS fibers and made them more susceptible to hydrolysis. Esterase and trypsin did not accelerate the hydrolytic degradtion of this fiber to any significant level. Both γ‐irradiation and enzymes influenced the gross morphological characteristic of PDS fibers when they were subjected to hydrolysis. The most important morphological observations were the formation of surface cracks and chips on the fibers and the subsequent peeling of the chips. Enzyme‐treated PDS fibers exhibited similar morphological findings but the size of the chips was smaller. The morphological observations of PDS fibers were consistent with the tensile strength data.
Aliphatic polyester miscibility with polyepichlorohydrin
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractBased on the behavior of the glass transition for blends of polyepichlorohydrin with various aliphatic polyesters, miscible amorphous phases are formed in all cases when the ratio of aliphatic carbons to ester groups in the repeat unit is less than 10 but more than 2. This observation includes selected polyesters with branched and saturated cyclic units in their structure. Interaction parameters deduced from polyester melting point depression were all negative and showed a minimum within this range of polyester molecular structures. The composition dependence of the observed glass transitions was found to be severely influenced by the presence of polyester crystallinity in the blend when heated through the transition region.
Preparation of tri‐O‐benzylcellulose by the use of nonaqueous cellulose solvents
Authors: Isogai Akira , Ishizu Atsushi , Nakano Junzo 
Published: April 2003

AbstractA procedure has been developed for preparing tri‐O‐benzylcellulose with higher yields than 90%. In this procedure, cellulose was dissolved in a nonaqueous cellulose solvent, SO2–diethylamine (DEA)–dimethyl sulfoxide (DMSO), and then powdered sodium hydroxide was added. To the suspension thus prepared, benzyl chloride was added in four portions under heating. Chemical and physical properties of tri‐O‐benzylcellulose were studied, and tri‐O‐benzylcellulose prepared from microcrystalline cellulose powder shows the characteristic of thermotropic liquid crystal.
Curing stresses in an epoxy polymer
Authors: Srivastava A. K. , White J. R. 
Published: April 2003

AbstractCuring stresses in sheets of an epoxy polymer cured at 80°C, 120°C, and 135°C have been determined using the layer removal procedure. Tensile stresses were found to be present in the interior and compressive stresses near to the surface in all samples. Very low stresses were found to be present in material cured at 80°C, with a maximum compressive stress level close to 0.5 MN/m2 and a maximum tensile stress close to 0.25 MN/m2. Higher stress magnitudes were obtained when using higher curing temperatures, with values of more than 1 MN/m2 (compressive) and 0.6 MN/m2 (tensile) recorded for specimens cured at 135°C.
Polymer composite of rigid and flexible molecules: Blend systems of poly(p‐phenylene terephthalamide) and ABS resin
Authors: Takayanagi Motowo , Goto Kohei 
Published: April 2003

AbstractHomogeneous coagulant of poly(p‐phenylene terephthalamide) (PPTA) and ABS resin was obtained by pouring the dimethylsulfoxide solution of N‐sodium PPTA and ABS into acidic water. Transmission electron microscopic observation proved that PPTA was dispersed in the matrix in a form of microfibril with a diameter of 10–30 nm. The Tg of the resin component in ABS shifted to higher temperatures with increasing fraction of PPTA. Stress‐strain behavior of the polymer composite showed increased tensile modulus and strength with addition of PPTA. The transition temperature from brittle to ductile fracture, however, shifted to higher temperature resulting in lower extensibility. Incorporation of the block copolymer of PPTA and polybutadiene into ABS improved the ultimate extensibility, i.e., increased toughness was provided compared with the simple composite systems of ABS and PPTA microfibrils. Scanning electron microscopic observation showed that the polymer composite made with the block copolymer generated many crazes upon deformation, while the composite with PPTA homopolymer fractured without remarkable craze formation. Thus, a new type of thermoplastic with improved mechanical properties was obtained by use of PPTA block copolymer as compatibilizer.
Addition polyimides. IV. Effect of structure on thermal characteristics
Authors: Varma Indra K. , Sangita  , Varma D. S. 
Published: April 2003

AbstractChain extension reaction of bis(m‐maleimido phenyl) methyl phosphine oxide (BP) with 4,4′‐diaminodiphenylmethane (BP–M), 4,4′‐diaminodiphenyl ether (BP–E), 3,3′‐ and 4,4′‐diaminodiphenyl sulfone (BP–DDSm and (BP‐DDSm respectively), tris (m‐aminophenyl) phosphine oxide (BP–TAP), and 9,9‐bis(p‐aminophenyl) fluorene (BP–BAF) was carried out by refluxing 1:0.3 molar solution of BP:diamine. The melting temperature and exothermic peak associated with curing of BP decreased by such chain extension. The thermogravimetric analysis indicated more than 60% residual weight at 800°C in nitrogen atmosphere in BP–DDSm, BP–DDSp, and BP–TAP resins. These resins can be processed at low temperature and can be used for fabrication of composites with improved properties.
Preparation of spherical polymer beads of maleic anhydride–styrene–divinylbenzene and metal sorption of its derivatives
Authors: Ogawa N. , Honmyo K. , Harada K. , Sugii A. 
Published: April 2003

AbstractCompounds having acid anhydride moiety have been used for starting materials for many useful derivatives. Spherical crosslinked polymer beads of porous maleic anhydride–styrene–divinylbenzene copolymer are obtained by suspension polymerization. Glycerol is found to be a preferable dispersant to make spherical beads. The beads contained 93% of the anhydride and 7% of the free carboxyls. As one of applications, the beads were hydrolyzed or reacted with anhydrous hydrazine, and the metal sorption behavior of them was examined. The hydrolyzed beads show a similar sorption manner as a conventional cation exchange resin having carboxylic acid groups, but the hydrazide beads sorbed mercury (II) selectively over a wide pH range. This investigation suggests a simple preparative method for the insoluble spherical porous beads of the maleic anhydride copolymer.
Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. VI. Polyurethane–poly(methyl acrylate‐co‐ethyl acrylate) semi‐1‐interpenetrating polymer networks
Authors: Hourston D. J. , Zia Y. 
Published: April 2003

AbstractDynamic mechanical and longitudinal sonic velocity measurements have been made on a series of semi‐1‐IPNs in which the network component is a polyurethane and the linear constituent a copolymer of methyl acrylate and ethyl acrylate. Dynamic mechanical analysis reveals phase separation. The shifting of the polyurethane glass transition in both the tan δ− and the E″–temperature plots indicates that some mixing occurs. The longitudinal sonic velocity results indicate that the polyurethane is present as a continuous phase in all the materials investigated.
Short silk fiber‐reinforced polychloroprene rubber composites
Authors: Setua D. K. , Dutta B. 
Published: April 2003

AbstractThe reinforcement of polychloroprene rubber by short silk fiber has been studied in the presence of three different dry bonding systems, viz.: (a) “cohedur RK–cohedur A–silica”; (b) “cohedur RK–cohedur A–carbon black”; (c) “resorcinol–hexamethylenetetramine–silica.” The degree of fiber–rubber adhesion of the different bonding systems follows the order (a) > (b) > (c). Scanning electron microscopy studies of tensile, tear, abrasion, and flex failed surfaces of both unfilled and fiber–filled composites containing “cohedur–silica” bonding system have also been made in order to gain an insight to the mechanism of failure.
Characterization of ethylene‐1‐butene copolymer by differential scanning calorimetry and 13C‐NMR spectroscopy
Authors: Kimura Keiichiro , Shigemura Takeo , Yuasa Sakae 
Published: April 2003

AbstractTwo kinds of ethylene‐1‐butene copolymers that were produced by the different procedures, that is, the slurry and the high‐pressure polymerizations, were characterized by differential scanning calorimetry (DSC) and carbon‐13 nuclear magnetic resonance (13C‐NMR) spectroscopy. The melting points of both copolymers were found to be different in spite of the same 1‐butene content. It was deduced that this phenomenon depended upon the subtly different chain structures between these two copolymers from the tetrad monomer sequence analysis by 13C‐NMR method. In addition, the behavior of the composition fractionation by temperature rising elution technique was also considered to be affected by the chain structures.
Polymerization of methyl acrylate in the presence of 2‐mercaptobenzothiazole
Authors: Dwivedi U. N. , Mitra B. C. 
Published: April 2003

AbstractAzobisisobutylronitrile‐initiated polymerization of methyl acrylate was carried out in a dilatometer at 60°C for 180 min in the presence of 2‐mercaptobenzothiazole. The 2‐mercaptobenzothiazole acts as a retarder. The values of various kinetic parameters such as rate of polymerization, average degree of polymerization, inhibition constant, and Schulz's constant have been calculated for the present system.
Simulation of ARB type reversible step growth polymerization in semibatch reactors
Authors: Gupta Santosh K. , Mohan D. , Kumar Anil 
Published: April 2003

AbstractThe polymerization of ARB type reversible step growth polymerization in semibatch reactors has been simulated. It is assumed that the condensation byproduct W and the monomer P1 both can vaporize, but P1 is refluxed back to the reactor. Raoults law as well as Flory–Huggins theory have been used to account for vapor–liquid equilibrium. The degree of polymerization, μn, and the polydispersity index DN have been computed for various situations. The results are found to be most sensitive to the total pressure and the equilibrium constant. A limiting total pressure history PT(T) has been obtained, going below which does not help to increase μn. The final set of equations incorporate both equalities as well as inequalities, and a simple and efficient computational scheme has been suggested to solve them.
The unfolding model for the representation of the mesophase layer in composites
Authors: Theocaris P. S. 
Published: April 2003

AbstractThe adhesion between matrix and inclusions (fibers or particulates) in a composite material is one of principal factors characterizing the mechanical and physical behavior of the modern composite materials. All theoretical models describing these substances neglect to consider the influence of the boundary layer developed between phases during the preparation of the composite. In this paper, two versions of a theoretical model were introduced for the evaluation of this mesophase layer. It had been shown that this thin layer influences considerably the physical properties of the composite. It was assumed that the physical properties of the mesophase unfold from those of the hard‐core fibers to those of the softer matrix. Thus, a multicylinder model was assumed, improving the classical two‐cylinder model introduced by Hashin and Rosen for the representative volume element of the composite. Based on thermodynamic phenomena appearing at the glass transition temperatures of the composite and concerning the positions and the sizes of the heat‐capacity jumps there, as well as on the experimental values of the longitudinal elastic modulus of the composite, the extent of the mesophase and the mechanical properties of the composite may be accurately evaluated. These versions of model are based on a previous one concerning a multilayer model, but they are considerably improved, in order to take into consideration, in a realistic manner, the physical phenomena developed in fiber‐reinforced composites.
The effect of alkali salt on solvent–polyacrylonitrile interaction
Authors: Padhye M. R. , Karandikar A. V. 
Published: April 2003

AbstractIn solvent spinning of polyacrylonitrile from DMF or DMSO, it is observed that complete removal of solvent is rather difficult. It is shown that addition of Lithium salt, e.g., lithium bromide to the solution before casting a film helps in removing the solvent easily. The probable mechanism of the action of lithium salt in solvent removal is investigated, and it has been shown that the formation of coordinate linkage with the ion stops solvent bonding.
Transport and related properties of paint films. I. Composition and structure
Authors: Newey Herbert A. , Busso Charles J. , Wedgewood Alan R. , Beck Theodore R. 
Published: April 2003

AbstractThis is the first of a series of articles on ionic and molecular transport processes and related properties of paint films. The intention is to correlate adhesion and initiation of corrosion to these relevant physical and chemical properties. Chemical formulas and structure of three vinyl–three epoxy– and one polyurethane–paint system are given in this article. Each paint has been formulated to meet appropriate military specifications. Subsequent articles will deal with dynamic mechanical properties, small angle x‐ray scattering measurements of porosity, and transport properties.
Particle structure of PVC based on cellulosic suspension system. III. Effect of monomer refluxing
Authors: Cheng John T. , Langsam Michael 
Published: April 2003

AbstractThe effects of monomer refluxing on both resin properties and reactor fouling of suspension PVC have been studied in a laboratory‐scale 14‐L reactor. Process control equations were developed which related the particle properties to the reflux condenser operation by controlling the parameters of (1) the time at which refluxing is begun and (2) the rate profile of heat removal from the condenser. An operating envelope has been developed for laboratory scale operations which optimizes the cycle time of polymerization while minimizing the adverse effects on particle properties. These operating conditions may have application to production scale operations when the proper scaling factors are employed.
Novel methods for efficient estimate of intrinsic viscosity
Authors: Chee K. K. 
Published: April 2003

AbstractTwo novel procedures have been established to estimate the intrinsic viscosity and the Huggins constant accurately. It is shown that these numerical methods are superior to the existing models, namely the Huggins, Nagy–Kelven–Tudos, and Reilly–Van Der Hoff–Ziogas equations. This finding is attributed to the more even distribution of errors in the dependent variables of the present analyses. The viscometic data of a poly(vinyl chloride) sample in tetrahydrofuran are analyzed by the foregoing five approaches whose accuracies are compared in terms of their variances of estimates.
A rationale for the preparation of asymmetric pervaporation membranes
Authors: Mulder M. H. V. , Hendrikman J. Oude , Wijmans J. G. , Smolders C. A. 
Published: April 2003

AbstractPervaporation is carried out primarily with homogeneous membranes. An improvement in permeation rate can be achieved by using asymmetric or composite membranes. In order to maintain a high selectivity, very dense top layers are needed. The formation of asymmetric pervaporation membranes will be discussed in terms of the model proposed by our group: formation of the top layer by gelation; formation of the porous sublayer by liquid–liquid phase separation followed by gelation of the concentrated polymer phase. To obtain very dense top layers the following factors are important: the ratio of nonsolvent inflow and solvent outflow, polymer concentration, location of the liquid–liquid demixing gap, and location of the gel region. Asymmetric membranes have been prepared by varying these factors, and the obtained membranes have been tested on ethanol/water mixtures.
Studies on selective adsorption resins. XXI. Preparation and properties of macroreticular chelating ion exchange resins containing phosphoric acid groups
Authors: Egawa Hiroaki , Nonaka Takamasa , Maeda Hironori 
Published: April 2003

AbstractMacroreticular cation exchange resins containing phosphoric acid groups (RGP) were prepared by the reaction of glycidyl methacrylate–divinylbenzene copolymer [or poly(glycidyl methacrylate)]beads (RG) with phosphoric acid or phosphorous oxychloride, and the adsorption behavior of metal ions on the RGP was investigated. The phosphorylation of the polymer beads could be effectively carried out by treatment of the polymer beads with 85% phosphoric acid at 80°C for 3 h. The RGP obtained from glycidyl methacrylate–divinylbenzene (2 mol %) copolymer beads showed high cation exchange capacity, salt splitting capacity, and adsorption capacity for Cu2+, Zn2+, Cd2+, Ca2+, and Ag+. On the other hand, the RGP obtained from poly(glycidyl methacrylate)beads had high adsorption capacity for Al3+, Fe3+, and UO22+. The RGP prepared by treating the RG with phosphoric acid had a higher selective adsorption for Li+ than for Na+.
Mechanisms of antioxidant action: the antioxidant activity of nitrones in polypropylene
Authors: Chakraborty Khirud B. , Scott Gerald , Yaghmour Hassan 
Published: April 2003

AbstractAldonitrones are effective melt stabilizers for polypropylene, the most effective being benzaldonitrones containing a partially hindered 4‐hydroxy group in the aromatic ring. They form nitroxyl radicals in the polymer during processing, and these and the related hydroxylamines are believed to be involved in a catalytic CBA/CBD antioxidant cycle during mechano‐ and photooxidation. During thermal oxidation (oven aging) they behave as stoichiometric CB‐D antioxidants.