bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of copolymeric poly(2‐vinylimidazoline)
Authors: Hurndall Margaret J. , Spies Hendrik S. C. , Sanderson Ronald D. 
Published: April 2003

AbstractCopolymeric poly(2‐vinylimidazoline), comprising the ring‐closed 2‐imidazoline and ring‐opened linear amide repeat units, was characterized by 13C‐NMR spectroscopy. This was facilitated by the 13C‐NMR analyses of the model compound forms of the copolymer's repeat units, 2‐ethylimidazoline and N‐propionylethylenediamine. Quantitative determinations were made for the percentages of ring‐opened, linear amide, repeat units and residual ethylenediamine present in different batches of the poly(2‐vinylimidazoline) copolymer. © 1995 John Wiley & Sons, Inc.
Influence of spinning velocity on mechanical and structural behavior of PET/nylon 6 fibers
Authors: Aslan S. , Laurienzo P. , Malinconico M. , Martuscelli E. , Pota F. , Bianchi R. , Di Dino G. , Giannotta G. 
Published: April 2003

AbstractInfluence of spinning velocities on the mechanical and structural properties of polyethylene terephthalate (PET)/nylon 6 blend fibers have been reported. Fibers of PET/nylon 6 containing a small percentage of nylon (5% by weight) have been melt‐spun at 3 different spinning velocities (2,900; 3,200; 3,600 m/min). The fibers have been characterized by thermal, morphological, structrual, and mechanical analysis. Various techniques such as SEM, DSC, X‐ray diffraction, hot water shrinkage (HWS), viscosity, and birefringence have been used. SEM analysis revealed that in the blend, nylon 6 is well‐dispersed as spheres in the PET matrix. The blend shows a marked decrease in the melt‐flow index, which in turn leads to a beneficial effect on the rheological properties of the PET without negatively influencing its mechanical characteristics. This finding results in a saving on energetical requirements of the processing, as both temperature and pressure of spinning can be decreased. © 1995 John Wiley & Sons, Inc.
Dependence of dynamic mechanical behavior of DGEBA/DDM stoichiometric epoxy systems on the conditions of curing process
Authors: Sanz G. , Garmendia J. , Andres M. A. , Mondragon I. 
Published: April 2003

AbstractDynamic viscoelastic properties of diglycidyl ether of bisphenol A (DGEBA) cured with diaminodiphenylemethane (DDM) have been studied. The relaxation spectra of stoichiometric mixtures have been investigated as a function of the casting procedure and the thermal history during curing. Variations on the temperatures of the loss peaks and also on their magnitude have been observed when a solvent was employed to cast the mixtures. These variations have been attributed to the existence of high crosslinked regions formed at the earlier stage of curing inside the overall matrix. The results obtained from mixtures cured with different thermal histories underline the importance of adequate selection of curing conditions in order to obtain the optimum properties for these materials. Differences in crosslink density amongst the mixtures cured at different conditions have been correlated to the extent of reaction obtained by infrared measurements. © 1995 John Wiley & Sons, Inc.
Hydrolytic aging of polycarbonate. II. Hydrolysis kinetics, effect of static stresses
Authors: Ghorbel I. , Akele N. , Thominette F. , Spiteri P. , Verdu J. 
Published: April 2003

AbstractPlaques of bisphenol A polycarbonate (PC) were exposed to a water‐saturated atmosphere at temperatures ranging from 40 to 90°C for up to 7 months. Certain samples were exposed under tensile load at 60 and 90°C, 100% RH with stresses ranging from 3.7 to 8.7 MPa. The PC molecular weight was determined by steric exclusion chromatography, and the kinetic parameters for hydrolytic chain scission were determined. It appears clearly that in the presence of tensile stresses, the hydrolysis rate is increased (at both temperatures under study) by a factor of about 10. The stress effect cannot be represented by the Eyring‐Zhurkov relationship because the activation volume appears as an increasing function of the temperature and a decreasing function of time. Some possible causes of the observed stress effects are discussed © 1995 John Wiley & Sons, Inc.
Epoxy resins based on trimethylolpropane. I. Determination of chemical structres
Authors: Pellín M. Pazos , Regueira L. Núñez , Gándara J. Simal , Losada P. Paseiro , Lamela C. Pérez , Abuín S. Paz 
Published: April 2003

AbstractThe chemical structure of an aliphatic epoxy resin was studied by using gel permeation chromatography (GPC), Fourier transform infrared (FTIR), FTIR‐TGA (thermogravimetric analysis), mass spectrometry in fast atom bombardment (FAB) mode, and wet analysis. We found that when trimethylolpropane is used as starting monomer, only two OH groups are epoxidized. The resin and its different fractions have a functionality of two. Under the conditions of synthesis used by the supplier, three main products were found with masses of 246,339, and 430. No trifunctional product was detected. © 1995 John Wiley & Sons, Inc.
Preparation of polypyrrole–polyurethane composite foam by vapor phase oxidative polymerization
Authors: He Feifeng , Omoto Mitsuru , Yamamoto Toshihiro , Kise Hideo 
Published: April 2003

AbstractConductive polypyrrole–polyurethane composite foam was prepared by vapor phase polymerization of pyrrole on polyurethane foam using mixtures of FeCl2 and FeCl3 as oxidants. With increase in the FeCl2/FeCl3 ratio, the conductivity of the composite foam increased in spite of the decrease in polypyrrole content in the composite foam. Both conductivity and polypyrrole content increased with increase in the oxidant content in polyurethane. The conductivity of the composite foam is also a function of reaction temperature, and lower reaction temperatures were preferable for higher conductivity. The composite foam exhibited tensile strength and elongation comparable to those of pristine polyurethane foam. © 1995 John Wiley & Sons, Inc.
Mechanochemical polymerization of methyl methacrylate initiated by the grinding of inorganic compounds
Authors: Hasegawa Masahiro , Akiho Yasushi , Kanda Yoshiteru 
Published: April 2003

AbstractThe polymerization of methyl methacrylate mechanochemically initiated by the grinding of several inorganic compounds was attempted using a vibrating ball mill. The inorganic compounds used were quartz, quartz glass, marble, limestone, feldspar, and talc with the particle size range of 149–210 μm. The results demonstrated that all compounds used in these experiments had the activity for mechanochemical polymerization of methyl methacrylate, and that the degree of the activity at the same grinding time remarkably differed with the kind of compound. The existence of the induction period, which is the time until the polymerization started, was also confirmed in all of the compounds. The molecular weight distributions of the polymer formed were unimodal and somewhat broad in the case of any compound, and the number‐average molecular weight was similar to that formed by ordinary radical polymerization. It was suggested that there were two types of the initiation mechanism in the mechanochemical polymerization of methyl methacrylate initiated by the grinding of inorganic compounds. © 1995 John Wiley & Sons, Inc.
Permeability control of poly(methacrylic acid)–poly(ethylenimine) complex capsule membrane responding to external pH
Authors: Yoon Nam Sik , Kono Kenji , Takagishi Toru 
Published: April 2003

AbstractPreviously, permeability of partly crosslinked poly(acrylic acid)–poly(ethylenimine) complex capsule membranes has been shown to be controlled responding to external pH [K. Kono, F. Tabata, and T. Takagishi, J. Membr. Sci., 76, 233 (1993)]. In order to improve pH‐dependent permeation behavior of the polyelectrolyte complex capsule membranes, poly(methacrylic acid), which has hydrophobic side groups, was used as a polyanion component instead of poly(acrylic acid). The polyelectrolyte complex capsules composed of poly(methacrylic acid)–poly(ethylenimine) with a diameter of 5.2 mm were prepared. Permeation of phenylethylene glycol, which was used as a permeant, through the capsule membrane was quite limited at pH between 4 and 8. The permeation of the permeant across the capsule membrane in these pH regions was much less than that of poly(acrylic acid)–poly(ethylenimine) complex capsule membrane. However, the permeability constant was drastically increased in the order of 1 or 2 above pH 8 and below pH 4, depending on temperature. The Arrhenius plot for the permeation of phenylethylene glycol through the capsule membrane showed that the activation energy for the permeation is almost constant in the pH region between 4.5 and 8, but greatly decreases below pH 4 and above pH 8.8, suggesting occurrence of a significant change of the capsule membrane structure near these pH regions due to dissociation of polyelectrolyte complex. When environmental pH of the capsule was changed, release rate of phenylethylene glycol from the capsule was altered quickly and reversibly under acidic condition. © 1995 John Wiley & Sons, Inc.
Studies on applications of natural polyphenol–phenol–formaldehyde copolymer based cation exchange resins
Authors: Mitra N. C. , Banerjee R. S. , Sarkar A. 
Published: April 2003

AbstractNaturally occurring polyphenol(condensed tannin)‐phenol‐formaldehyde copolymer matrix based cation exchange resins have been successfully used as a solid catalyst (in H+ ion form) in the inversion of sucrose and hydrolysis of methyl acetate. Apart from the normal advantages of the solid catalyst over the acid catalysts in the solution phase, the values of the activation energy, entropy, and enthalpy of activation of the reactions involved reveal that the resins prepared acted as a catalyst with characteristics comparable to those of the commercially available resins based on a styrene–DVB matrix. The resins have also been successfully used for softening of hard water and enrichment of metal ion concentration from very dilute solutions. © 1995 John Wiley & Sons, Inc.
Investigations into the micellization and conductance behavior of cerium soaps in a benzene–DMF Mixture
Authors: Mehrotra K. N. , Chauhan Mithlesh , Shukla R. K. 
Published: April 2003

AbstractConductivity measurements were employed to determine the critical micelle concentration (CMC), degree of dissociation and dissociation constant of dilute solutions of cerium soaps in 50% benzene and 50% N‐N‐dimethyl formanide (DMF) mixture (v/v). The results show that the soaps behave as weak electrolytes below the CMC. The various thermodynamic parameters were also evaluated for both dissociation and association process. © 1995 John Wiley & Sons, Inc.
Concentration effect of stearic acid on scorch behavior of epoxidized natural rubber
Authors: Poh B. T. , Tang W. L. 
Published: April 2003

AbstractThe effect of stearic acid on Mooney scorch time of epoxidized natural rubber (ENR 25 and ENR 50) and one grade of unmodified natural rubber (SMR L) was investigated in the concentration range of 0.5 to 14.5 phr. Other parameters, namely accelerator systems, temperature, and fillers (carbon black and silica), on the scorch property of ENR 25 in the presence of excess loading of stearic acid were also studied. Results indicate that scorch time increases with stearic acid loading for all the rubbers investigated, the rate of increase being fastest in ENR 50, followed by ENR 25 and SMR L. Mooney scorch time of ENR shows strong dependence on stearic acid loading for delay‐action accelerators and at lower temperature of vulcanization. For a fixed filler loading, the dependence of scorch time on stearic acid concentration is similar to that of gum stock. The retardation effect exhibited by excess stearic acid on the vulcanization of ENR may be attributed to complex formation of chelates and the reduction in activation of adjacent double bonds in ENR resulting from interaction between stearic acid and the epoxide group of ENR. © 1995 John Wiley & Sons, Inc.
Functionalization and metallization of fluoropolymer surfaces through reduction1,2
Authors: Hung Ming‐H. , Burch Robert R. 
Published: April 2003

AbstractFluoropolymer films, such as Teflon™‐TFE [poly(tetrafluoroethylene)], Teflon™‐FEP [copolymer of tetrafluoroethylene and hexafluoropropylene], Teflon™‐PFA [copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether)], and PCTFE [poly(chlorotrifluoroethylene)], are reduced by the mild reducing agent benzoin dianion/DMSO, while Teflon™‐AF [copolymer of tetrafluoroethylene and perfluoro‐2,2‐dimethyl‐1,3‐dioxole] is unreactive. The reduction makes the films adherable toward epoxy resins, the adhesive strength decreasing in the order PCTFE>PFA≥FEP>PTFE. Surprisingly, Teflon™‐AF films are totally inert except when the TFE content is high, and in these cases the adhesive strength of Teflon™‐AF is close to that of PTFE. The surfaces of PTFE, FEP and PFA films are further modified by first treating these films with the benzoin dianion/DMSO reagent and then with an excess of sodium salts of mercaptans. Reactive PTFE films that are light colored with a metallic luster are formed rather than the dark, metallic color typical of PTFE surface reduction without mercaptan treatment. These films have poor adhesion toward epoxy resins but good adhesion toward gold applied by sputtering. FEP and PFA films behaved similarly. These results are attributed to the incorporation of sulfur onto the reduced surface. Unreduced fluoropolymer films reacted with only sodium mercaptan fail to show C—S bond incorporation. This newly developed method can be used to selectively metallize the fluoropolymer film surface with gold layers and affords very high conductivity of the metallized regions. © 1995 John Wiley & Sons, Inc.
The morphology and mechanical properties of phenoxy/liquid crystalline polymer blends and the effect of transesterification
Authors: Choi Gi Dae , Kim Seung Hyun , Jo Won Ho , Rhim Moo San 
Published: April 2003

AbstractMorphological, rheological, and mechanical properties of poly(hydroxy ether of bisphenol A) (phenoxy) and a Vectra liquid crystalline copolyester (LCP) blends were investigated. Scanning electron micrographs of fracture surfaces of injection‐molded samples show that the LCP forms an elongated fibrous dispersion in the phenoxy matrix. As the mixing time increases, the tensile strength and modulus increase while the elongation at break remains almost constant. These improvements are attributed to the formation of LCP‐grafted phenoxy by the interchange reaction between phenoxy and LCP. The interchange reaction was identified by DSC, a rheometer, and a FTIR spectrometer. The graft copolymer gives better adhesion between the two phases and thus improves mechanical properties of the blends. © 1995 John Wiley & Sons, Inc.
Semibatch emulsion copolymerization of methyl methacrylate and butyl acrylate
Authors: Chern C. S. , Hsu H. 
Published: April 2003

AbstractThe concentration of sodium lauryl sulfate (SLS) in the initial reactor charge is the most important parameter in determining the particle size of a semibatch emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). The number of particles formed is proportional to the concentration of SLS to the 0.5–1.2 power and it is proportional to the concentration of the nonyl phenol–40 mol ethylene oxide adduct to the 0.014–0.72 power. The number of particles is almost independent of the concentration of the initiator. The solubility of monomer in water has an important effect on the nucleation mechanism according to the literature. However, the ratio of MMA to BA does not show any significant effect on the latex particle size in our laboratory. The particle size also increases with increasing ionic strength or agitation speed. Experimental data of particle‐size distribution and molecular weight distribution support the coagulative nucleation mechanism when the concentration of SLS is way below its critical micelle concentration (CMC). © 1995 John Wiley & Sons, Inc.
Hydrogels based on hydrophilic side‐chain siloxanes
Authors: Künzler J. , Ozark R. 
Published: April 2003

AbstractMethacrylate end‐capped diethylene glycol propyl methyl ether, 5‐hexyl‐1,2‐diol, and 3‐propyloxy‐1,2‐propane diol side‐chain siloxanes were evaluated for potential use as hydrogels for contact lens application. The preparation of the methacrylate end‐capped ether, hexane diol, and propane diol side‐chain siloxanes was accomplished in two relatively simple synthetic steps: The first step consisted of the acid‐catalyzed co‐ring opening polymerization of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, and 1‐3‐bis‐methacryloyl‐butyltetramethyldisiloxane, followed by a platinum‐catalyzed hydrosilation with (in separate experiments) diethylene glycol allyl methyl ether, trimethylsilyl protected 3‐allyloxy‐1,2‐propane diol, and trimethylsilyl protected 5‐hexene‐1,2‐diol. The trimethylsilyl protecting groups was removed using a 10% 0.1N HCl solution in 2‐propanol. Radical polymerization of the methacrylate end‐capped ether, hexane, and propane diol side‐chain siloxanes with hydrophilic monomers, such as dimethylacrylamide, and a strengthening agent, isobornylmethacrylate, resulted in transparent hydrogels possessing a wide range of water contents, high oxygen permeability, and a low modulus of elasticity and, for the propane diol side‐chain siloxanes, excellent hydrolytic stability. The ether side‐chain siloxane‐based hydrogels exhibited poor hydrolytic stability. © 1995 John Wiley & Sons, Inc.
Performance improvement of MgCl2/dioctylphthalate/TiCl4 catalyst in propene polymerization by employing external base pair
Authors: Yang C. B. , Hsu C. C. 
Published: April 2003

AbstractThe individual roles of three different types of external Lewis bases, namely t‐butylmethyl ether (TBME), 2,2,6,6,‐tetramethyl piperidine (TMPIP), and dimethoxydiphenyl silane (DMDPS), in propene polymerization using MgCl2/dioctylphthalate (DOP)/TlCl4 catalyst were studied. The role of TBME was found to be distinctly different from others. More active sites were believed to be activated in the presence of TBME, whereas the others seemed to play a role of converting atactic sites into isotactic ones. That difference made it possible to improve both catalyst activity and isotacticity by employing TBME together with one of the others as the external base pair. Due to the differences in the coordination strength of these bases with the catalyst, the order of addition of the two bases became important in achieving good results. © 1995 John Wiley & Sons, Inc.
A new copolymerization equation
Authors: Zhou Changren , Lin Shangan 
Published: April 2003

AbstractA new copolymerization equation is suggested for the calculation of copolymer composition. The new equation is independent of reactivity ratios, so we can obtain the copolymer composition from experimental data when the reactivity ratios are unknown. The new equation has been verified by experimental data (styrene/methyl methacrylate, methyl methacrylate/vinyl chloride, and styrene/acrylonitrile systems). The results of the comparisons suggest that the new equation is satisfactory. © 1995 John Wiley & Sons, Inc.
Water‐based polymers as pressure‐sensitive adhesives—viscoelastic guidelines
Authors: Yang Henry W. H. 
Published: April 2003

AbstractWater‐based polymers have been widely used as pressure‐sensitive adhesives (PSAs). This article addresses the fundamental viscoelastic parameters that govern PSA performance. The viscoelastic behavior of polymers before and after resin tackification is investigated. Commercial acrylic, CSBR, natural rubber emulsion polymers, and low MW petroleum‐based hydrocarbon resins with various softening points are used to demonstrate the tackification effects. Basic guidelines for selecting the appropriate polymer/resin system to achieve the target performance are given. © 1995 John Wiley & Sons, Inc.
The effect of extruder temperature and maleated polypropylene on polypropylene/nylon‐6,6 blend: A small angle X‐ray scattering study
Authors: Lin J. S. , Sheu Eric Y. , Jois Y. H. R. 
Published: April 2003

AbstractA series of small‐angle X‐ray scattering measurements were performed to study the polypropylene/nylon‐6,6 polymer blends with or without the compatibilizer: maleated polypropylene. The blends were made at various temperatures using a venting conical twin‐screw extruder with a constant extruding flow rate. The X‐ray scattering results show that the dispersion of nylon‐6,6 in polypropylene is improved for temperature above the melting point of nylon‐6,6 (265°C) when the compatibilizer involved is not used. As the compatibilizer is incorporated, the dispersion is significantly improved, even at the temperature below 265°C. With the compatibilizer, the dispersed nylon‐6,6 particle size and shape in the blends are independent of blending temperature, suggesting that the temperature effect is overwhelmed by the effect of the compatibilizer. © 1995 John Wiley & Sons, Inc.
Decrease in fluorescence and phosphorescence intensity of nylon 66 impurities by exposure to ultraviolet radiation
Authors: Brasington Chandis R. , Gadala‐Maria F. 
Published: April 2003

AbstractThe effects of exposure to ultraviolet radiation on the fluorescence and phosphorescence intensity of impurities in nylon 66, sometimes called gel, were measured using color image processing. The fluorescence intensity of the gel particles and of the polymer showed an approximately exponential decay with the time of exposure to ultraviolet radiation, with decay constants in the range 0.5 to 1.0 h−1. Analysis of images that were acquired over several hours also indicated a decrease in the phosphorescence intensity of the gel particles. Image processing provides a simpler and less expensive method of luminescence analysis than the spectroscopic techniques used previously to examine the effects of exposure to ultraviolet radiation on the phosphorescence properties of nylon 66 impurities. © 1995 John Wiley & Sons, Inc.
Flow properties of thermally depolymerized liquid natural rubber
Authors: Nair N. Radhakrishnan , Claramma N. M. , Mathew N. M. , Thomas Sabu , Rao S. Someswara 
Published: April 2003

AbstractThe flow behavior of liquid natural rubber (LNR) with reference to the effect of molecular weight, shear rate, and temperature has been studied. LNR samples were prepared by thermal depolymerization of rubber (NR) through the combined effect of mechanical, chemical, and thermal energies. High molecular weight samples, especially at lower temperatures, showed pseudoplastic behavior, whereas the low molecular weight samples were Newtonian at all temperatures. The viscosity of LNR considerably decreases with increase in temperature. The activation energy of flow was also calculated. © 1995 John Wiley & Sons, Inc.
Studies on the synthesis and properties of soluble homo‐ and copolyester–imide derived from imide–diacid
Authors: Li Chien‐Hui , Chen Chih‐Chiang , Chen Ker‐Ming , Chang Teh‐Chen 
Published: April 2003

AbstractA series of polyester–imides was prepared from diacid (imid–diacid [M1–M4] or a mixture of imide–diacid and terephthalic acid [TPA]) and bisphenol A in the presence of diphenyl chlorophosphate (DPCP) and pyridine as a direct condensation agent. The inherent viscosites of homo‐ and copolyester–imides were in the range of 0.39–0.58 dL/g. Almost all these homo‐ and copolyester–imides were completely soluble in N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAC), dimethylformamide (DMF), and m‐cresol. The thermal properties of homo‐ and copolyester–imides were examined by DSC and TGA. These copolyester–imides had glass transition temperatures in the range of 95–240°C and a 5% weight loss was observed in the range of 354–465°C. © 1995 John Wiley & Sons, Inc.