bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient, “one‐pot” synthesis of suspension crosslinked sulfonated polystyrene via a Friedel–Crafts reaction
Authors: Theodoropoulos A. G. , Bouranis D. L. , Valkanas G. N. 
Published: April 2003

AbstractA suspension technique leading to macronet ionic resins is described based on a single reactor process. The procedures demonstrate sulfuric acid as a polar suspending medium that can act as a sulfonating agent, a Friedel–Crafts catalyst, and a crosslinking agent. The sulfonation reaction was finally completed using sulfuric acid excess, or oleum 65%. High yields were obtained for the crosslinking and the sulfonation reaction, while the final products were characterized by using ion‐exchange capacity measurements, U.V. spectra, and determination of the degree of crosslinking. The number average molecular weight between crosslinks and the ion‐exchange capacity H+→Na+ of the resins was decreasing by increasing the nominal crosslinking ratio. © 1992 John Wiley & Sons, Inc.
Metastable solutions and interactions of decomposition products in porogen derived membranes
Authors: Eyal A. M. , Edelstein D. , Hazan B. , Hajdu K. 
Published: April 2003

AbstractSmall incompatible molecules formed on porogen decomposition were found to be metastably dissolved in Porogen Derived Membranes, confirming previous analysis. 1Degrees of metastable dissolution are determined by polymer and porogen characteristics, by porogen content, and by decomposition parameters (characteristics of reagent, its concentration, and decomposition temperature). These parameters determine the characteristics of decomposition products (DPs) formed, the rate of their formation, and the properties of the matrix through which they have to diffuse for phase separation. Extraction experiments indicated that, for many compositions, leaching out of DPs during contact with water is very slow. Porogen derived membranes are thus intermediate between polymeric membranes and supported liquid membranes, with the potential of combining high selectivity and reasonable stability. © John Wiley & Sons, Inc.
Polymeric dye receptors for disperse dyeable polypropylene fibers
Authors: Dayioglu H. 
Published: April 2003

AbstractPolypropylene fibers containing various amounts and different types of 2‐vinyl pyridine/styrene (2VP/St) copolymer in terms of molecular weight and molar ratio were prepared, and the disperse dyeability of these fibers were investigated. In addition, the disperse dyeability of 2VP/St copolymer alone was also studied. © 1992 John Wiley & Sons, Inc.
Curing of unsaturated polyester resins—effects of comonomer composition. I. Low‐temperature reactions
Authors: Huang Yan‐Jyi , Chen Chaur‐Jeng 
Published: April 2003

AbstractThe effects of comonomer composition on the curing kinetics of unsaturated polyester (UP) resins at 40°C were studied by differential scanning calorimetry (DSC) and infrared spectroscopy (IR) over the entire conversion range. Two commercial UP resins, including UP2821 and UP536B, which on the average contained 6.82 and 4.16 unsaturated CC bonds per polyester molecule, respectively, by 1H‐NMR analysis, were used. Experimental results showed that for UP536B reactions initiated by BPO (benzoyl peroxide)/DMA (N,N‐dimethyl aniline) amine accelerated system, at higher molar ratio of styrene to polyester CC bonds, the DSC rate profile at 40°C exhibited a shoulder after the peak, which could be caused by the grafting reaction of styrene on CC bonds of the polyester chain inside the microgel particles. In contrast, for UP2821 resin, no shoulder was observed presumably because UP2821 reaction systems would lead to a higher crosslinking density during the cure, and styrene molecule could not readily diffuse into the microgel structure at the later stage of the reaction for the reaction shoulder to appear. A microgel‐based reaction mechanism was thus proposed due to the experimental results. © 1992 John Wiley & Sons, Inc.
Energetic ABA and (AB)n thermoplastic elastomers
Authors: Xu Baopei , Lin Y. G. , Chien James C. W. 
Published: April 2003

AbstractLinear ABA triblock and (AB)n segmented block copolymers of energetic monomers have been synthesized. The rigid and soft blocks are prepared from 3,3‐bis(azidomethyl)oxetane (BAMO) and 3‐nitratomethyl‐3‐methyloxetane (NMMO), respectively. Polymerization of BAMO initiated by triethyloxonium tetrafluoroborate and by spiro(benzoxasilole)/propanediol produced α,ω‐monohydroxy‐PBAMO (3) and α,ω‐dihydroxy‐PBAMO (4) of M̄n 16,000 and 2,000, respectively, and α,ω‐dihydroxy‐PNMMO (5) of M̄n = 13,000 was synthesized by the latter method. The block copolymers were prepared from the appropriate telechelic polymers and toluene diisocyanate. The PBAMO—PNMMO—PBAMO copolymer 6 has Tm = 82°C, Tg = −3°C, and is strongly phase separated even in the melt. It decomposes sharply within 1°C at 224°C evolving 0.69 kJ/g of heat. Copolymer 6 has excellent mechanical properties with elongation of 683% at break, 5.25 MPa stress, and 82% recovery. The (PBAMO—PNMMO)n copolymer 7 has similar thermal properties and spectroscopic characteristic, but is inferior to copolymer 6 in all rheological and mechanical properties. © 1992 John Wiley & Sons, Inc.
Synthesis and evaluation of methyl methacrylate copolymers and terpolymers as electron beam resists. II. Methyl methacrylate copolymers and terpolymers containing aromatic rings
Authors: Gitsov Ivan , Todorova Olga G. 
Published: April 2003

AbstractTerpolymers of methyl methacrylate and methacrylic acid with vinyl monomers, styrene, 4‐(α, α‐dimethylbenzyl) phenyl methacrylate and 2‐naphthyl methacrylate, were synthesized by radical terpolymerization. The molecular weights of the polymers obtained cover the range of 40,000 to 120,000. It was established that the molecular weight characteristics of the terpolymers are influenced by the content of methacrylic acid in the initial polymerization mixtures, by the chemical nature of the aromatic vinyl comonomer, and by the nature of the solvent and the concentration of the initiator. The sensitivity of the polymers towards radiation was estimated by the G‐values obtained after the products were subjected to γ‐ray treatment. The influence of the chemical composition of the terpolymers on their sensitivity is discussed in detail. © John Wiley & Sons, Inc.
Studies on the preparation and properties of conductive polymers. V. Analysis of metallized polyamide complex metal chelate films and precipitates in metal chelate solution
Authors: Yen Chih‐Chao , Huang Chueh‐Jung , Chang Teh‐Chou 
Published: April 2003

AbstractMetallized films were obtained by the reduction of polyamide metal chelate films with reducing agents. In the preparation of polyamide metal chelate solution, a small amount of precipitate forms when a certain stoichiometric ratio of formic acid, polyamide, and metal salts was mixed. The precipitate formation rate was affected by kinds and concentrations of metal salts, kinds and molecular weight of polyamide, and solution temperature. In addition, the precipitate formation rate affects the conducting surface metallic substance of reduced nylon/CuCl2/NiCl2 complex metal chelate film. The conducting surface is metallic Ni for low‐molecular‐weight nylon 4/CuCl2/NiCl2 film and metallic Cu for high‐molecular‐weight nylon 4/CuCl2/NiCl2 film reduced by NaBH4 aqueous solution. The precipitate consists of polyamide, metal salt, and formic acid. The interaction among the polyamide, metal salt, and formic acid appears to be by means of hydrogen bonds and ionic bonds. The proposed structure of precipitate was also studied. © 1992 John Wiley & Sons, Inc.
Carboxymethyl starch: A rheological study
Authors: Lapasin Romano , Pricl Sabrina , Tracanelli Paolo 
Published: April 2003

AbstractThe rheological behavior of carboxymethyl starch aqueous systems has been studied under continuous and oscillatory shear conditions. The systems examined exhibited shear‐dependent properties, typical of dispersions having a weak degree of particle aggregation. A transition in the rheological properties was observed with increasing concentration and/or decreasing temperature, as a consequence of formation of a three‐dimensional continuous network in the disperse phase under rest conditions. The shear‐dependent behavior changed from shear‐thinning to plastic and a finite plateau appeared in the low frequency region of mechanical spectra. A rheological model was proposed for the correlation of both shear‐thinning and plastic data, thus making possible an objective definition of the rheological transition. Oscillatory flow data confirmed the results obtained in continuous shear conditions, that is, the frequency dependence of the complex viscosity was almost parallel to the dependence of the steady shear viscosity on the rate of shear. Moreover, the high strain sensitivity of the viscoelastic quantities and their analysis in terms of relaxation spectra clearly indicated the moderate degree of connectivity of the structural network. © 1992 John Wiley & Sons, Inc.
Development of AAS resin by the emulsion–suspension polymerization method
Authors: Kohkame Hisashi , Shitara Masashi , Tanno Seikichi , Muroi Tadashi 
Published: April 2003

AbstractIn order to improve the weatherability of acryonitrile—styrene—butadiene rubber graft polymer (ABS resin), an attempt was made to develop a resin (AAS resin) in which acrylic rubber of good weatherability was used instead of butadiene rubber. First, by copolymerizing dicyclopentenyl‐methacrylate (DCP‐MA,3%) with butyl acrylate, crosslinked acrylic rubber was obtained. This also introduced grafting sites into the rubber. Next, methods of graft copolymerizing styrene and acrylonitrile with this rubber were examined. An emulsion–suspension polymerization method was developed in which the initial stage of the polymerization, emulsion polymerization, changed into suspension polymerization during the process. By this method of polymerization, rubber particles were combined and enlarged, bringing about a graft‐type resin with high impact resistance. This polymerization method is industrially useful because particle‐shaped resins are obtained without the need of a salting‐out process. The AAS resin, obtained in this way, has much improved weatherability over ABS resin and shows strength equal to that of ABS resin. © 1992 John Wiley & Sons, Inc.
Pervaporation through membranes made from acyl derivatives of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Schauer J. , Bleha M. 
Published: April 2003

AbstractSeveral acyl derivatives of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were obtained by Friedel—Crafts acylation, and the products were used to prepare membranes. During the pervaporation of 10% aqueous solutions of ethanol, acetone, 1‐propanol, or dioxan, membranes made from unmodified, benzoylated, or propionylated PPO (glassy polymers, Tg > 200°C) were preferentially permeable to water, and their separation factors were mainly dependent on the molecular weight of the solvent. Membranes made from palmitoylated PPO (nonglassy polymer, Tg = 34.9°C) were preferentially permeable to organic solvents, and their separation factors correlated with the solubility parameters of the solvents under investigation. As regards membranes made from caproylated PPO (Tg = 130.6°C), there was no unambiguous relation to molecular weights of the solvents or to their solubility parameters. © 1992 John Wiley & Sons, Inc.
Numerical examination of the dual‐mode model for permeation, sorption, and desorption rate curves
Authors: Toi Keio , Saito Koichi , Suganuma Yasushi , Ito Tomoyasu , Ikemoto Isao 
Published: April 2003

AbstractNumerical solutions were applied to the dual‐mode sorption and transport model for gas permeation, sorption, and desorption rate curves allowing for mobility of the Langmuir component. Satisfactory agreement is obtained between integral diffusion coefficient from sorption and desorption rate curves and apparent diffusion coefficient from permeation rate curves (time lag method). These rate curves were also compared to the curves predicted by Fickian‐type diffusion equations. © 1992 John Wiley & Sons, Inc.
Hydrogen‐peroxide‐initiated polymerization of isoprene in alcohol solutions
Authors: Grishchenko Vladimir K. , Boiko Vitaly P. , Svistova Elena I. , Yatsimirskaya Tatiana S. , Valuev Valery I. , Dmitrieva Tamara S. 
Published: April 2003

AbstractThe radical polymerization of isoprene in alcohol solutions initiated by hydrogen peroxide was studied. It was found that alcohols were components of the initiated system and that their fragments with hydroxyl groups were included in every second molecule of an oligomer irrespective of the type of alcohol, of the monomer conversion, and of the oligomer molecular weight. The oligomer yields and its molecular weight were determined by alcohols through their effect upon the phase state of polymerization systems. © 1992 John Wiley & Sons, Inc.
Crosslinked epoxies: Network structure characterization and physical–mechanical properties
Authors: Vakil U. M. , Martin G. C. 
Published: April 2003

AbstractA homologous series of epoxy resins, based on the digylcidyl ether of bisphenol‐A, were reacted with stoichiometric quantities of m‐phenylenediamine (mPDA) to form networks with varying crosslink densities. Infrared spectroscopic analyses revealed that the networks were formed predominantly by the epoxy—amine addition reactions with little or no OH‐etherification. The ultimate glass transition temperatures were inversely proportional to the epoxy chain mol wt, as predicted by a model based on the assumptions of additivity and redistributivity of free volume. The average mol wt between crosslinks, M̄c, determined from the dynamic mechanical shear moduli, agreed to within 15 to 18% with the values predicted by the reaction stoichiometry. The glassy‐state modulus did not exhibit any M̄c dependence above room temperature, however, the modulus—temperature plot for all the networks exhibited a discontinuity near −50°C with a steeper slope below −50°C than above it. The change in slope occurred over the same temperature interval as the β‐transition temperature of the networks. The discontinuity in the modulus—temperature plot can be attributed to the freezing of the localized motions of the molecular groups responsible for the β‐transition. © 1992 John Wiley & Sons, Inc.
Effect of the temperature on the drawing behavior of poly(ether ether ketone)
Authors: Russo R. 
Published: April 2003

AbstractThis study examines the drawing behavior of amorphous films of poly(ether ether ketone) (PEEK) and the effect of the drawing and the drawing temperature on some physical properties of the drawn samples. The thermal analysis shows that the amorphous films drawn at 200% of deformation and at temperatures of 80, 120, and 140°C crystallize by heating and the crystallization occurs at lower temperature with a lower crystallization enthalpy. The first effect can be related to the influence of orientation on the crystallization rate and the second to strain‐induced crystallization. The dynamic—mechanical behavior of the drawn samples is in good agreement with the thermal analysis and confirms the presence of strain‐induced crystallization at drawing temperatures well below 180°C. © 1992 John Wiley & Sons, Inc.
Decrystallization of jute by cyanoethylation
Authors: Reddy S. S. , Bhaduri S. K. , Pandey S. N. 
Published: April 2003

AbstractThe cyanoethylation of jute fiber was studied at different reaction conditions. Moisture regain decreased significantly on cyanoethylation. Introduction of 5–6% nitrogen content on the fiber minimized the moisture regain capacity to 2.8%. A further increase in the nitrogen content increased the moisture regain. The effect of cyanoethylation on infrared absorption was studied. The absorbance curves of OH and CH stretching frequencies are parabolic in nature, whereas β‐glycosidic and CH bending absorption curves are almost linear with an increase in the degree of substitution. The cellulosic transition was indicated by the lattice conversion ratio, which showed an increase along with the degree of cyanoethylation. © 1993 John Wiley & Sons, Inc.
Properties of copolymer‐type polyacetal/ethylene–propylene–diene terpolymer blends
Authors: Chiang Wen‐Yen , Huang Chi‐Yuan 
Published: April 2003

AbstractTwo kinds of polymer blends, polyacetals (POMs) and ethylene–propylene–diene terpolymer (EPDM), have been prepared by mechanical blending. The rubbery EPDM was added to the rigid POM matrix to increase toughness. The mechanical, physical, thermal, dynamic mechanical, and morphological properties of these samples have been measured. The notched Izod impact strength and the elongation of the blends reaches a maximum at 7.5 wt % EPDM content. Scanning electron micrographs (SEM) showed that the domain sizes of EPDM vary from 0.25 to 1.0 μm and were independent of the composition. The POM/EPDM blends were determined to be immiscible by SEM, but showed single Tg behavior as determined by differential scanning calorimetry (DSC) and dynamic mechanical analyses up to 7.5 wt % EPDM. Because of that, the Tg's of POM and EPDM were very similar in value. © 1993 John Wiley & Sons, Inc.
Unsaturated polyesters. V. Polyester from maleic anhydride and 1,6‐hexanediol
Authors: Larez V. , Cristobal J. , Mendoza Gilberto A. Perdomo 
Published: April 2003

AbstractThe polycondensation reaction between maleic anhydride and 1,6‐hexanediol, with p‐toluenesulfonic acid as catalyst has been carried out. The product has been analyzed spectroscopically and the molecular weight determined by endgroup analysis and gel permeation chromatography. The influence of spatial interactions between condensed groups on the isomerization of maleate into fumarate is discussed, as well as the effects of even‐ and odd‐ numbered carbon atom glycols. © 1993 John Wiley & Sons, Inc.
Effect of processing conditions on the structural gradients developed in injection‐molded poly(aryl ether ketone) (PAEK) parts. I. Characterization by microbeam X‐ray diffraction technique
Authors: Hsiung C. M. , Cakmak M. 
Published: April 2003

AbstractDepending on the processing conditions, poly(arylene ether ketone) exhibits unique structural gradients as a result of its thermomechanical history when it is injection‐molded. Gapwise structure gradients change from a fully amorphous to multilayer amorphous–semicrystalline–amorphous and, finally, to a uniformly semicrystalline one when mold temperature is increased. When injection speed is decreased, the crystallized layers become thicker, and at very slow injection speeds, the crystalline layers developed near the two surfaces of the parts approach each other at the core. These structure variations were characterized by differential scanning calorimetry, optical microscopy, and a matrixing microbeam X‐ray diffraction (MMBX) technique developed in our laboratories. The relationship between the structure gradients developed and the processing variables and the cavity geometry are discussed. © 1993 John Wiley & Sons, Inc.
Novel polyetherurethaneurea elastomers based on α,α,α′,α′‐tetramethyl‐m‐xylenediisocyanate: Synthesis, characterization, processability, and hydrolytic stability
Authors: Gunatillake Pathiraja A. , Meijs Gordon F. , Rizzardo Ezio , McCarthy Simon J. , Chatelier Ronald C. , Brandwood Arthur , Schindhelm Klaus 
Published: April 2003

AbstractA series of novel polyetherurethaneurea elastomers based on m‐TMXDI, polyether macrodiols containing 4, 6, 8, or 10 methylene groups between the ether linkages, and aliphatic and aromatic diamines was prepared by two‐step solution polymerization. All the materials were thermally processable at 120–160°C except one that was solvent‐castable. Mechanical properties and hydrolytic stability (at neutral pH) were found to depend on the macrodiol and chain extender. Poly(tetramethylene oxide)‐based polyetherurethaneureas that were chain‐extended with primary aliphatic diamines, other than 1,3‐propanediamine, exhibited significantly better mechanical properties than those chain‐extended with secondary aliphatic or aromatic diamines. The mechanical properties and hydrolytic stability of polyetherurethaneureas containing poly(hexa‐, octa‐, or decamethylene oxide) and 1,6‐hexamethylenediamine were considerably better than those containing 1,2‐ethylenediamine. The hydrolytic stability increased with the increasing C/O ratio of the macrodiol. With poly(hexamethylene oxide)‐based materials, the phase separation between soft and hard domains was higher than that of the other materials as determined by DSC. © 1993 John Wiley & Sons, Inc.
Stress–relaxation in three‐element and four‐element mechanical models of viscoelastic materials
Authors: Joye Donald D. 
Published: April 2003

AbstractThree‐ and four‐element mechanical analogues are commonly used to describe viscoelastic behavior in creep (deformation under constant force or stress) but not in stress relaxation (stress response after a suddenly imposed, constant strain). Mathematical models of the mechanical analogues in stress–relaxation are re‐derived in this work, keeping notation familiar to polymer scientists. The relationship is shown to meet consistency tests and predicts, with very good accuracy, the behavior of a polyisobutylene sample in stress relaxation when the equation constants were derived from creep experiments. In experiments on an actual mechanical analog, the motion of the Voigt element is shown to exhibit a maximum stress. Implications for the interpretation of creep and stress–relaxation data on the same material are discussed. © 1993 John Wiley & Sons, Inc.
A comparison of the tetramethylthiuram disulphide accelerated sulfur vulcanization of polybutadiene and polyisoprene
Authors: Cassem A. , McGill W. J. 
Published: April 2003

AbstractA detailed study of the vulcanization of polybutadiene with various combinations of sulphur, tetramethylthiuram disuphide, ZnO, stearic acid, and zinc dimethyldithiocarbamate is reported. Vulcanization was conducted by heating samples at 2.5°C/min in a differential scanning calorimeter. The reaction was stopped at various points along the vulcanization exotherm, the soluble reaction products and residual curatives were extracted and analyzed, and the crosslink density and percentage polysulphidic crosslinks were determined. The overall reaction mechanism was found to be similar to that for polyisoprene, but the reaction, once initiated, was faster than in polyisoprene, the crosslink density was higher, and the percentage polysulphidic crosslinks was lower. These differences are discussed. © 1993 John Wiley & Sons, Inc.
Ternary phase equilibria of polystyrene with a second polymer and a solvent
Authors: Geveke David J. , Danner Ronald P. 
Published: April 2003

AbstractPhase diagrams including tie lines for nine ternary solvent–polymer–polymer systems have been obtained using size exclusion chromatography. The systems studied were toluene–polystyrene (PS)–isoprene rubber (IR), toluene–PS–butadiene rubber (BR), cyclohexane–PS–BR, tetrahydrofuran(THF)–PS–poly(methyl methacrylate) (PMMA), and THF–PS–poly(butyl methacrylate) (PBMA) at temperatures between 30 and 75°C. The results indicate PS‐PMMA is less compatible than PS‐PBMA in the presence of THF. Also, the combination of trans‐ and 3,4–IR‐PS is less compatible than cis–IR‐PS in the presence of toluene. The original Flory–Huggins model for ternary systems has been modified to account for the concentration dependence of the interaction parameters. The modified Flory–Huggins model consists of two interaction parameters per binary. Using this model, six parameters have been regressed for each of the experimental systems studied. Although the parameters are not physically meaningful, the model and the parameters obtained using it are useful for correlating the experimental phase diagrams. The results obtained using the modified six parameter model are shown to be superior to those obtained using the original three parameter model. © 1993 John Wiley & Sons, Inc.