bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemiluminescence from amine cured epoxy resins modified with halogenated phenylglycidyl ethers
Authors: Matisová‐Rychĺ L. , Rychlý J. , Verdu J. , Audouin L. , Tcharkhtchi A. , Janigova I. 
Published: April 2003

AbstractChemiluminescence from thermooxidized epoxide alone and that modified with phenyl glycidyl ethers has been investigated in isothermal and nonisothermal regime. Isothermal curves are characterized by a monotonous fall of chemiluminescence intensity from some initial value to very low levels of light emission. Nonisothermal curves show a maximum intensity at temperatures above 473 K. The luminescence intensity is influenced by both Tg and thermal stability of epoxide. The higher Tg or higher thermal stability brings about the higher intensity of light emission and vice versa. © 1994 John Wiley & Sons, Inc.
Copolymerization of ethylene and styrene with supported TiCl4/NdCl3 catalyst
Authors: Lu Zejian , Liao Kairong , Lin Shangan 
Published: April 2003

AbstractThe copolymerization of ethylene and styrene was carried out in the presence of TiCl4/NdCl3/MgCl2/AlEt3 catalyst. The influences of comonomer ratio, concentrations of catalyst and AlEt3, solvents, and temperature on the copolymerization were investigated. Copolymerization products containing styrene of 4–85 mol % were obtained with good yield. The results of 13C‐NMR, IR, X‐ray diffraction, and solvent extraction show that the products are mainly copolymers with various comonomer sequences and exhibit special mechanical properties. © 1994 John Wiley & Sons, Inc.
Carbon dioxide foaming of glassy polymers
Authors: Wessling M. , Borneman Z. , Van Den Boomgaard Th. , Smolders C. A. 
Published: April 2003

AbstractThe mechanism of foaming a glassy polymer using sorbed carbon dioxide is studied in detail. A glassy polymer supersaturated with nitrogen forms a microcellular foam, if the polymer is quickly heated above its glass transition temperature. A glassy polymer supersaturated with CO2 forms this foam‐like structure at much lower temperatures which indicates the Tg‐depressing effect of CO2. Having this interpretation in mind, the overall sample morphology, i.e., a porous foam enclosed by dense outer skins, can be completely explained. The dense skins, however, are not homogeneous but show a nodular structure when analyzed by SEM and AFM. Foaming experiments with samples having a different thermal history suggest that the nucleation mechanism underlying the foaming process is heterogeneous in nature. © 1994 John Wiley & Sons, Inc.
High‐temperature SEC coupled with MALLS detector for evaluating the end‐use performance of LDPE
Authors: Dayal Umendra 
Published: April 2003

AbstractLow‐density polyethylene (LDPE) is the most widely used plastic material in the film‐packaging industry. To improve its tensile strength and elongation, it is blended with linear LDPE. Three commercial samples of LDPE, which were found to give different performances in the sealing strength of films prepared from their blends, have been evaluated for their molecular weight (MW), molecular weight distribution (MWD), and long‐chain branching by high‐temperature size exclusion chromatography (SEC) and SEC coupled with a multiangle laser light‐scattering (MALLS) detector. It has been shown that the differences in MW and MWD that remain unnoticed by conventional SEC are detected by SEC/MALLS. Wide MWD and a low weight‐average MW of the resin has been found to favor film‐sealing strength. © 1994 John Wiley & Sons, Inc.
Microporous polypropylene hollow fibers containing poly(methylsilsesquioxane) fillers
Authors: Nagō Satoshi , Mizutani Yukio 
Published: April 2003

AbstractMicroporous polypropylene hollow fibers were prepared by stretching polypropylene microtubes containing poly(methylsilsesquioxane) fillers with uniform particle sizes. The properties of the resultant hollow fibers are controllable by adjusting the particle size of the filler, the filler content, and the stretching degree. Also, it is elucidated that the hollow fibers have a fine texture of split PP fibrils, in which the filler particles are dispersed. © 1994 John Wiley & Sons, Inc.
Population balance modeling for a continuous gas phase olefin polymerization reactor
Authors: Choi Kyu Yong , Zhao Xia , Tang Shihua 
Published: April 2003

AbstractSteady‐state population balance models have been developed for a continuous flow gas phase olefin polymerization process with both uniform sized and log‐normally size distributed high activity catalyst feeds. For the calculation of polymer properties such as molecular weight averages and weight fraction of comonomers in the copolymer, a multigrain solid core model was used with an assumption that intraparticle monomer mass transfer resistance is negligibly small. The multigrain solid core model was incorporated into the population balance model and the effects of feed catalyst particle size distribution and catalyst deactivation parameters on the polymer production rate, polymer particle size distribution, and polymer properties were investigated. It is observed for deactivating catalyst that the polymer particle size distribution tends to be narrower with a reduced amount of large polymer particles. For the catalyst with nonuniform site deactivation, polymer particles of different sizes exhibit different molecular weight and copolymer composition. © 1994 John Wiley & Sons, Inc.
Dielectric normal‐mode relaxation of entangled cis‐polyisoprene melts: Effects of polydispersity
Authors: Fodor Jeffrey S. , Hill Davide A. 
Published: April 2003

AbstractThe effects of polydispersity on the dielectric normal‐mode relaxation of entangled, cis‐polyisoprene melts are considered. We use a linear mixing rule and reptation theory in conjunction with a theoretical molecular weight distribution (MWD) of variable breadth to predict loss spectra of model cis‐polyisoprene melts. The half‐widths of the predicted spectra show a nonlinear dependence on polydispersity index, with the greatest sensitivity near the monodisperse limit. The calculations are in agreement with literature data on narrowly dispersed samples. © 1994 John Wiley & Sons, Inc.
Correlation between mechanical properties and degradation processes of poly(methyl methacrylate‐co‐butyl acrylate) films
Authors: Leskovac M. , Kovac̆ević V. , Stanojević D. , Bravar M. 
Published: April 2003

AbstractCopolymer systems based on various molar ratios of methyl methacrylate (MMA)/butyl acrylate (BA) and different mass content of N‐methylolacrylamide (NMA), as a crosslinking agent, were investigated. The influence of temperature, 150°C, under conditions similar to those used in the textile industry, and effect of ultraviolet (UV) irradiation were examined. The changes of mechanical properties were found to be connected with the cross‐linking and/or degradation mechanisms. The effect of copolymer composition on the mechanical properties was established, especially during UV degradation. © 1994 John Wiley & Sons, Inc.
Mechanical properties of organic–inorganic polyurethane elastomers. I. Al(OH)3–polyurethane composites based on PPG
Authors: Furukawa Mutsuhisa , Yokoyama Tetsuo 
Published: April 2003

AbstractAluminum hydroxide was used as a reactive filler to elastomers prepared from poly(oxypropylene)glycol (PPG), 2,4‐tolylene diisocyanate (TDI), and 1,4‐butane diol (BD). Mechanical properties, dynamic mechanical properties, and thermal properties were measured. Morphologies were observed by use of X‐ray diffraction and scanning electron micrographs. The model reaction of isocyanate and aluminum was also studied. It was found that aluminum hydroxide fillers can be used for cost reduction without any detrimental effects on mechanical properties. Scanning electron micrograph studies of freshly cut surfaces of the aluminum filled elastomers showed that aluminum hydroxide is highly compatible with the elastomer. © 1994 John Wiley & Sons, Inc.
Molecular transport of organic esters into tetrafluoroethylene/propylene copolymer membranes
Authors: Aminabhavi Tejraj M. , Phayde Hemant T. S. 
Published: April 2003

AbstractDiffusion, permeation, and equilibrium sorption coefficients have been determined using a sorption gravimetric technique for methyl acetoacetate, ethyl acetoacetate, methyl benzoate, ethyl benzoate, methyl salicylate, isobutyl salicylate, and diethyl malonate into tetrafluoroethylene/propylene copolymer membranes in the temperature range 25–70°C. The sorption kinetics process has been characterized by first‐order rate constants and penetration velocities. From a temperature dependence of the transport coefficients, the activation parameters have been estimated. It is observed that the values of the transport coefficients for the systems of this study depend on the nature of the penetrant molecules rather than on their molecular sizes. On the whole, the mechanism of solvent transport into the copolymer membranes used here follows nearly the Fickian trend. © 1994 John Wiley & Sons, Inc.
In situcure monitoring of epoxy resins using fiber‐optic Raman spectroscopy
Authors: Lyon R. E. , Chike K. E. , Angel S. M. 
Published: April 2003

AbstractFiber‐optic Raman spectroscopy was used to monitor the curing of epoxy resinsin situfor eventual application to polymer composite processing. A 200‐μm diameter quartz fiberoptic sensor immersed in liquid resin was used to obtain Raman spectra for a concentration series of diglicidyl ether of bisphenol‐A in its own reaction product with diethylamine using an 820 nm continuous‐wave diode laser excitation. A Raman peak at 1240 cm−1was assigned to a vibrational mode of the oxirane (epoxide) ring and its normalized intensity was found to be linearly related to the concentration of epoxide groups in the resin mixtures. Raman peaks at 1112 and 1186 cm−1associated with phenyl andgem‐dimethyl resin backbone vibrations, respectively, did not change in intensity due to the curing reaction and were used as internal references to correct the Raman spectra for intensity changes due to density fluctuations and instrumental variations during the experiments. Fiber‐optic Raman spectroscopy was used to monitor the extent of reactionin situfor the room‐temperature cure of phenyl glicidyl ether with diethylamine. The extent of reaction of the epoxide groups calculated from the Raman spectra were in excellent agreement with kinetic data from Fourier transform near‐infrared absorbance measurements made under the same conditions. © 1994 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Aqueous polymerization of methyl methacrylate and characterization of the obtained polymers in the presence of N,N‐dioxalyl P‐amino benzoyl N,N‐dioxalyl urea and its Fe(II) and Fe(III) complexes
Authors: Sabbah I. A. , Elkhalek A. A. Abd , Sayyah S. M. , Mohamed S. A. , Ewais H. A. 
Published: April 2003

AbstractThe emulsifier‐free emulsion polymerization of methyl methacrylate (MMA) was studied using sodium bisulfite as initiator in the absence and presence of a new organic chelating agent, N,N‐dioxalyl p‐amino benzoyl N,N‐dioxalyl urea, and its iron (II) and (III) complexes. The organic ligand with free carboxyl groups has a retarding effect on the polymerization reaction while its iron complexes have a catalytic effect. The mechanisms of the catalytic effect of iron complexes or the inhibition mechanism of the organic ligand are discussed. The effect of pH values on the polymerization processes was also investigated. The apparent energy of activation was found to be 4.99 × 104 J/mol, 6.38 × 104 J/mol, 4.46 × 104 J/mol, and 3.72 × 104 J/mol in the absence and in the presence of 0.5 g of ligand and 0.1 g of its Fe (II) and (III) complexes, respectively. © 1994 John Wiley & Sons, Inc.
Modification of epoxy resins by hydrosilation for electronic encapsulation application
Authors: Ho Tzong‐Hann , Wang Chun‐Shan 
Published: April 2003

AbstractHydride terminated polydimethyl siloxanes were used to reduce the stress of cresol–form‐aldehyde novolac epoxy resin cured with phenolic novolac resin for electronic encapsulation application. The effects of the structure and molecular weight of the hydride terminated polydimethyl siloxane in reducing the stress of encapsulant were investigated. The mechanical and dynamic viscoelastic properties and morphologies of rubber modified epoxy networks were also studied. A “sea‐island” structure (“islands” of silicone rubber dispersed in the “sea” of an epoxy resin) was observed via SEM. The dispersed silicone rubbers effectively reduce the stress of cured epoxy resins by reducing flexural modulus and the coefficient of thermal expansion, while the glass‐transition temperature was hardly depressed. Electronic devices encapsulated with the dispersed silicone rubber modified epoxy molding compounds have exhibited excellent resistance to the thermal shock cycling test and have resulted in an extended use life for the devices. © 1994 John Wiley & Sons, Inc.
Water‐soluble polyamides as potential drug carriers. VIII. Poly(alkylene oxide)‐grafted polyaspartamides bearing ethylenediamine side‐group functions
Authors: Neuse Eberhard W. , Perlwitz Axel G. , Barbosa Anna P. 
Published: April 2003

AbstractIn continuation of previous investigations of aspartamide‐type polymers as drug carriers, polyaspartamides featuring hydrosolubilizing poly(alkylene oxide) side chains in addition to ethylenediamine side‐group functions as potential drug‐binding sites are synthesized from poly‐D,L‐succinimide by successive aminolytic ring‐opening steps. Yields are in the range of 45–55%. Depending on selected feed ratios, the target polymers contain both the poly(alkylene oxide) and the ethylenediamine groups in systematically varied proportions. Compositions are determined microanalytically and from relative band intensities of the 1H‐NMR spectra. The polymers dissolve smoothly and completely in aqueous media and thus fulfill the major design requirement of water solubility. © 1994 John Wiley & Sons, Inc.
Development of polyion complex membranes for the separation of water–alcohol mixtures. I. Synthesis and physical properties of the polycations based on 1,3‐di (4‐pyridyl) propane
Authors: Jegal Jonggeon , Kim Jeong‐Hoon , Park You‐In , Lee Kew‐Ho 
Published: April 2003

AbstractTo prepare good polymeric materials for the preparation of the polyion complex membranes useful for water–alcohol separation, polycations were synthesized by the quaternization polymerization of 1,3‐di(4‐pyridyl)propane with dibromoalkanes or with 1,8‐bis (p‐toluenesulfonyl)octane. The polycations were characterized by FTIR spectroscopy, viscometry, DSC, and X‐ray diffractometry. The polycations were in molecular weight ranges good enough to be used as membrane materials. The polycations were very hygroscopic and easily soluble in highly polar solvents such as water and these properties might be good for the membrane materials. The thermal properties and X‐ray diffraction patterns of these polycations suggested that the polycations were semicrystalline and difficult to form crystals by melt crystallization. © 1994 John Wiley & Sons, Inc.
Rubbery and rigid particle toughening of epoxy resins
Authors: Geisler B. , Kelley F. N. 
Published: April 2003

AbstractFour types of materials were evaluated in this study: neat epoxy resins of differing initial molecular mass, and their rubbery particle‐filled, rigid particle‐filled, and hybrid particle‐filled counterparts. Both rubbery and rigid particle‐filled epoxies exhibited fracture energies,GIc, greater than the neat resins. Cured resins prepared with an optimum loading of both rubbery and rigid particles gaveGIcvalues greater than those from rubbery or rigid particles alone (approximately sixteen‐fold increase over the neat resins). Rigid particle composites were toughened by means of a crack front impedance mechanism. In hybrid particle composites, rigid particles enhanced localized plastic deformation ahead of the crack front. © 1994 John Wiley & Sons, Inc.
Improvements of fiberboard properties through fiber activation and subsequent copolymerization with vinyl monomer
Authors: Rozman H. D. , Banks W. B. , Lawther M. L. 
Published: April 2003

AbstractHigh‐temperature refined thermomechanical pulp (MDF fiber) was dried, extracted with neutral organic solvent, and reacted with three types of electrophilic reagents (glycidyl methacrylate, maleic anhydride, and succinic anhydride). The adducts formed were further reacted in a hot press with a vinyl monomer in the presence of a free‐radical initiator (benzoyl peroxide). Well‐conformed boards were produced by the process. Modified boards showed significant improvement in thickness swelling as well as in strength properties compared to control phenol–formaldehyde boards. Glycidyl methacrylate modified/methyl methacrylate boards were the most stable toward the wet‐and dry‐exposure cycles, whereas succinic anhydride/methyl methacrylate boards showed the lowest water absorption. © 1994 John Wiley & Sons, Inc.
Chlorinated polyolefins for asphalt binder modification
Authors: Morrison Geoffrey R. , Lee Jin K. , Hesp Simon A. M. 
Published: April 2003

AbstractThe benefits obtained from the addition of small quantities of chlorinated polyolefins to paving grade asphalt binders were investigated. A chlorinated polyethylene plastomer, Tyrin 2552, and a chlorinated olefinic elastomer, Tyrin CM0730, were added to asphalt binders at 3 and 5 wt % and subsequently reactively processed to facilitate compatibilization. The mixtures were analyzed for rheological performance relating to fatigue and rutting as well as low‐temperature fracture performance. The addition of small quantities of these polymers to the asphalt binders resulted in significant improvements over conventional modifiers at both the high and low temperature extremes. © 1994 John Wiley & Sons, Inc.
Quantification of free ketene acetals and determination of cure kinetics of poly(ortho ester)s by a facile deuterium labeling method
Authors: Shih Chung , Waldron Niki , Deeken Rodney 
Published: April 2003

AbstractA facile method was developed to quantify unreacted ketene acetals during polymerization of poly(ortho ester)s. The method was based on isotopic (deuterium) labeling of the unreacted ketene acetal groups arising from the diketene acetal monomer, 3,9‐diethylidene‐2,4,8,10‐tetraoxaspiro[5,5]undecane (DETOSU). In deuterium oxide, free ketene acetals are hydrolyzed to an α‐deuterated ester; ortho ester bonds are hydrolyzed to the nondeuterated analog. The relative abundance of the deuterated ester side chain can be quantified by gas chromatography‐mass spectrometry (GC‐MS). In the current method, aliquots of a diketene acetal/polyol(s) reaction mixture were dissolved (crosslinked polymers swollen) in methylene chloride and excess D2O. The diketene acetal/polyol(s) reaction mixture was hydrolyzed under mildly acidic conditions to yield pentaerythritol dipropionate (PDP; hydrolysis product of DETOSU). PDP was extracted into an organic phase, silylated, and analyzed by GC‐MS. Fragments corresponding to the C2H5CO+ ion (57 a.m.u.) and C2H4DCO+ ion (58 a. m. u.) were monitored and the quantity of free ketene acetal groups were calculated from the peak areas of the chromatograms. The precision of the method was ±0.1%. The accuracy, as compared to a parallel 1H‐NMR study, was within 5%. This method permits determination of the cure end‐point of a poly(ortho ester) polymerization reaction to within ±0.25%. The curing kinetics agreed well with DSC branching/crosslinking measurements. © 1994 John Wiley & Sons, Inc.
A study of microwave transmission, reflection, absorption, and shielding effectiveness of conducting polypyrrole films
Authors: Kaynak Akif , Unsworth Joe , Clout Ray , Mohan Ananda S. , Beard Geoffrey E. 
Published: April 2003

AbstractMicrowave transmission, reflection, and absorption behavior and the shielding effectiveness of electrochemically synthesized polypyrrole films with dc conductivities ranging from 0.001 to 50 S/cm are presented. Results show that the electrical conductivity of the doped polypyrrole films has a significant effect on transmission, reflection, and absorption of microwaves. Heavily doped, conducting films were highly reflective, whereas lightly doped, semiconducting films had very high transmission. Intermediate conductivity polypyrrole samples were highly absorptive. The agreement between experimental data and theoretical modeling provided confidence to extend the modeling to include the effect of sample thickness on the transmission, reflection, and absorption properties of films with a wide range of conductivity values, hence, providing valuable information for the design of microwave devices and fundamental understanding of the material properties. A method of measuring the far‐field sheilding effectiveness of polypyrrole films is also presented. Results of shielding experiments indicated the potential for such applications. © 1994 John Wiley & Sons, Inc.
Amidoxime resins based on poly(acrylonitrile‐co‐vinylidene chloride‐co‐divinylbenzene) and their behavior in uptake of uranium from sea water
Authors: Kabay Nalan , Hayashi Terumi , Jyo Akinori , Egawa Hiroaki 
Published: April 2003

AbstractAmidoxime resins were derived from poly(acrylonitrile‐co‐vinylidene chloride‐co‐divinyl‐benzene) beads, which were prepared by suspension polymerization of the ternary monomeric mixtures in the presence of 4‐methyl‐2‐pentanone (MIBK) or 1,2‐dichloroethane (DCE) as the diluent (porogen), in order to clarify the effect of copolymerized vinylidene chloride on properties of the resulting amidoxime resins. Pore structure analyses of the copolymers as well as of their amidoximated derivatives clarified that MIBK yields larger pores than does DCE and then the latter gives larger specific surface areas than does the former. On the other hand, chemical properties of the amidoximated resins, such as anionexchange capacities and uranyl ion uptake, were not eseentially affected by the diluent species, indicating that both MIBK and DCE as the porogen lead to the amidoxime resins with almost the same ability in recovery of uranium from sea water. The uranium recovery decreased with increase in the vinylidene chloride content, but the decrease in the recovery was minor up to the 10 mol % of vinylidene chloride. It was also clarified that the uranium recovery by the amidoxime resins containing vinylidene chloride is greatly enhanced by the alkali treatment. © 1994 John Wiley & Sons, Inc.
Immobilization of glucose oxidase onto membranes of modified acrylonitrile copolymer
Authors: Godjevargova T. S. , Dimov A. R. , Vasileva N. 
Published: April 2003

AbstractAcrylonitrile copolymer was modified with sodium hydroxide and 1,6‐hexamethylen diamine (1) and with hydroxylamine (2). The amount of amine and carboxylic groups was studied as a function of the modification conditions. Membranes were prepared from the modified copolymer by the phase‐inversion method. They were used as matrix for covalent immobilization of glucose oxidase by using glutaraldehyde. The amount of bound protein, relative activity, and storage of the activity fo the immobilized enzyme were determined. The results were compared with those obtained with glucose oxidase immobilized onto the surface‐modified membrane of acrylonitrile copolymer with sodium hydroxide and 1,6‐hexamethylendiamine and with hydroxylamine. The results were proved by scanning electron microscopy. © 1994 John Wiley & Sons, Inc.