bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization and magnetic behavior of cobalt(II) and gadolinium(III) polyacrylates
Authors: Ünaleroğlu C. , Zümreoğlu‐Karan B. , Özcan Ş. , Firat T. 
Published: April 2003

AbstractThe characterization and magnetic behavior of Co(II) and Gd(III) polyacrylates prepared by organic gelation synthesis have been studied. Gd(III)‐polyacrylate shows a higher thermal stability due to stronger ionic interactions. IR spectra of both compounds reveal that carboxylate groups and water molecules exist in the coordination sphere with various forms of complexation. The samples are x‐ray amorphous and have complex structures with the randomly distributing metal atoms along the PAA chain. The a.c. susceptibility measurements between 4.2 K and 250 K indicated a low temperature magnetic ordering. Annealing the samples at 160°C for 48 h result in the appearance of a spin‐glass behavior in the in‐phase and out‐of‐phase susceptibility curves. The presence of different sizes and shapes of clusters, however, precludes the determination of effective magnetic moments and Curie temperatures. © 1995 John Wiley & Sons, Inc.
Kinetic study on the poly(methyl methacrylate) seeded soapless emulsion polymerization of styrene. I. Experimental investigation
Authors: Lee Chia‐Fen , Chiu Wen‐Yen 
Published: April 2003

AbstractIn this work, methyl methacrylate (MMA) and styrene (ST) were used as monomers in the first stage and second stage of polymerization, respectively, and potassium persulfate (K2S2O8) was used as the initiator to synthesize the poly(methyl methacrylate)‐polystyrene (PMMA/PS) composite latex by the method of two‐stage soapless emulsion polymerization, i.e., PMMA seeded soapless emulsion polymerization of styrene.The morphology of the latex particles was observed by transmission electron microscopy (TEM). It showed that the composite latex particles had a core–shell structure. The particlesize distribution of the composite latex was very uniform.The kinetic data of seeded soapless emulsion polymerization showed that the square root of polymer yield (Wp)1/2 was proportional to the reaction time in the earlier period of the reaction. The slope of the line of (Wp)1/2 vs. reaction time was independent of the content of the seed, but proportional to 0.5 power of the initiator concentration. The gel effect was apparent after monomer droplets disappeared. A glassy effect was found in the latter period of the reaction. The number‐average molecular weight of the polymers increased but the weight‐average molecular weight of the polymers decreased with decrease of the MMA/ST weight ratio. The number‐ and weight‐average molecular weight increased with decreasing the temperature significantly. © 1995 John Wiley & Sons, Inc.
Effect of gamma irradiation and irradiation temperature on hydrolytic degradation of synthetic absorbable sutures
Authors: Chu C. C. , Zhang L. , Coyne L. D. 
Published: April 2003

AbstractThe purpose of this study is to examine the effects of γ irradiation and the relative magnitude of Tirr to Tg on the physical, mechanical, thermal, morphological, and hydrolytic properties of two types of synthetic absorbable polymers. Polyglycolic acid (PGA) and glycolide‐trimethylene carbonate block copolymer fibers in the form of 2/0 size Dexon and Maxon sutures from Davis/Geck were used in this study. In addition, injection‐molded PGA disks were also used for determining how different polymer morphology affected the outcomes of γ irradiation and irradiation temperature. These two types of biomaterials were 60Co γ irradiated at two irradiation temperatures (55 and −78°C in dry ice). Both γ‐irradiated and control speciments were immersed in a phosphate buffer solution of pH 7.44 at 37°C for various durations of hydrolysis. After each predetermined duration, the specimens were removed for subsequent testing which included determinations of tensile strength, weight loss, level of crystallinity, melting temperature, intrinsic viscosity, surface morphology, and infrared spectroscopic characteristics. γ irradiation at both irradiation temperature resulted in a faster hydrolytic degradation of these two biodegradable polymers. There was no apparent irradiation temperature effect in terms of mass loss, intrinsic viscosity, level of crystallinity, and melting temperature. However, irradiation temperature effect was evident in those properties that depended on the tie‐chain segments located in the noncrystalline domains, such as tensile strength. The observed seffect of irradiation temperature was attributed to chain mobility which could facilitate cage recombination of macromolecular radical pairs at the irradiation temperature lower than the glass transition temperature of the irradiated polymers. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of soluble polyimides
Authors: Qiu Wulin , Li Can , Zeng Wenxiang , Liu Jinsong , Lu Lude , Wang Xin 
Published: April 2003

AbstractTwo kinds of soluble polyimides from pyromellitic dianhydride with Congo red and 4‐sulfanilamide were prepared, respectively. Their structures were characterized by IR and 1H‐NMR, and the thermal properties were investigated by DSC and TG–DTA. © 1995 John Wiley & Sons, Inc.
Graft copolymerization of polyacrylonitrile (PAN) onto polyester (PET) and simultaneous homopolymerization: A kinetic study. I
Authors: Gopalan A. , Vasudevan T. , Manisankar P. , Paruthimalkalaignan C. , Ramasubramanian A. , Hariharan S. S. 
Published: April 2003

AbstractThe kinetics of graft copolymerization of polyacrylonitrile (PAN) onto polyester (PET) and the simultaneous homopolymerization initiated by the potassium penoxomonosulfate (PMS)–ascorbic acid (H2A) redox system were studied separately. Results on the graft copolymerization was adequately explained by a mechanism which also accounts for the reason for simultaneous homopolymerization. The observed homopolymerization results agreed with the proposal. Kinetic chain‐length measurements on the graft copolymer and homopolymerization were used to evaluate the kinetic parameters. © 1995 John Wiley & Sons, Inc.
Viscoelastic properties of phenolphthalein poly(ether ketone)
Authors: Han Yanchun , Yang Yuming , Li Binyao , Feng Zhiliu 
Published: April 2003

AbstractStress relaxation and dynamic mechanical behavior of phenolphthalein poly(ether ketone) (PEK‐C) have been investigated. Using Ferry's reduction method, the master curve was obtained. From the experimental results, we found that the WLF equation is not appropriate in the lower‐temperature range (T < Tg). The relaxation spectrum was calculated according to the first approximation method proposed by Schwarzl and Staverman. In addition to the α‐transition region, a second transition zone is revealed at low temperature. This transition is probably due to a restricted motion of its main chain. © 1995 John Wiley & Sons, Inc.
Optothermal properties of fibers. I. Relations between optical properties and change of the density and mechanical loss factor for annealed polyester fibers
Authors: Hamza A. A. , Fouda I. M. , El‐Tonsy M. M. , El‐Sharkawy F. M. 
Published: April 2003

AbstractPolyester (Egyptain manufacturers) fibers were annealed in the temperature range 80–190°C for time intervals from 1 to 10 h. The density of the annealed fibers was measured by a system based on the theory of vibrating strings. The fiber diameter was also determined, using the laser forward diffraction technique. Refractive indices and birefringence for annealed fibers at different temperatures and constant time, 1 h, were measured by the polarizing interference microscope. The behavior of fiber density and the mechanical loss factor at different annealing temperatures and times were discussed at different optical parameters. The results obtained clarify the effect of annealing time and temperatures on the optical, density, and mechanical loss factor behavior of polyester fibers. Microinterferograms are given for illustration. © 1995 John Wiley & Sons, Inc.
Effect of the crosslinking degree on curing kinetics of an epoxy–anhydride system
Authors: Montserrat S. , Flaqué C. , Pagès P. , Málek J. 
Published: April 2003

AbstractThe cure kinetics of a diglycidyl ether of bisphenol A (DGEBA)‐based epoxy resin with methyltetrahydrophthalic anhydride and an accelerator was studied by nonisothermal DSC data. The systems were uncured resin and partially cured with the following extents of cure measured by the residual heat method (αDSC): 0.37, 0.63, 0.81, and 0.90. The activation energy calculated by the Kissinger method increases from 63 kJ/mol for the uncured epoxy to 77 kJ/mol for the partially cured with αDSC = 0.90. Additionally, the activation energy calculated by the isoconversional method shows a dependence on the conversion degree α. The activation energy tends to decreases initially with the conversion degree, possibly due to the autocatalytic effect; then, it passes through a minimum about α = 0.4 and, finally, increases slightly due to the increase of crosslinks which reduce the mobility of the unreacted groups. A simple, consistent method of kinetic analysis was applied. This method enables one to select the most convenient model and the calculation of kinetic parameters. A two‐parameter (m, n) autocatalytic model (S̆esták–Berggren equation) was found to be the most convenient model to study the curing of epoxy systems. The results show a dependence of the kinetic parameters on the initial degree of crosslinking of the partially cured epoxy. The exponent m tends to decrease with the extent of cure, while the exponent n remains practically invariable. These results show a change of the kinetic when the initial extent of cure of the epoxy system increases. The In A data, A being the preexponenetial factor in the Arrhenius dependence of the temperature on the rate of conversion, increase with the extent of cure, showing a correlation with the calculated activation energy values. The nonisothermal DSC curves theoretically calculated show a very good agreement with the experimental data. The two‐parameter (m, n) autocatalytic model gives a good description of the curing kinetics of epoxy resins with different extents of cure. © 1995 John Wiley & Sons, Inc.
Consolidation and self‐bonding in poly(ether ether ketone) (PEEK)
Authors: Cho Bum‐Rae , Kardos John L. 
Published: April 2003

AbstractThe effects of processing variables (time, temperature, and pressure) on the strength development during self‐bonding of amorphous PEEK films were studied using a modified single lap‐shear test. It was shown that the self‐bonding strength developed isothermally at different bonding temperatures exhibits a linear response with the bonding time raised to the 1/4 power in agreement with Wool's theory. DSC measurement of the crystallinity produced at different bonding conditions demonstrated that even though PEEK specimens contain the same amount of crystallinity, the resultant self‐bonding strength is sensitively dependent on bonding history. C‐mode scanning acoustic microscopy (C‐SAM) was applied to define the effect of the processing variables on wetting of the bonding area during the bonding process. It was shown that, above a threshold pressure (< 17 psi), the degree of wetting depends weakly on time, but not on temperature. SEM analysis revealed that amorphous PEEK films are self‐bonded by crystalline growth after diffusion and entanglement of the polymer chains across the interface. The crystalline growth rate across the interface is much higher at higher temperatures, leading to a higher self‐bonding strength. The shear fracture surface observations also support the above result. The PEEK specimens showing the higher self‐bonding strengths exhibit much denser striations and deeper dimplelike ductile patterns in the fracture surface, arising from much more crystalline growth across the interface. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of oxime resin of poly(4‐viny1, 2′‐carboxybenzophenone) and its metal polychelates
Authors: Kamble K. j. , Patkar D. N. 
Published: April 2003

AbstractThe synthesis and characterization of oxime resin of poly(4‐vinyl, 2′‐carboxybenzophenone) is described and its exchange properties for Cu(II), Ni(II), and Co(II) are studied. The metal poiycheiates are investigated by magnetic measurements, diffuse reflectance spectroscopy, and infrared spectroscopy. © 1995 John Wiley & Sons, Inc.
Volume changes and relaxations within the interphase domain of blendlike polymer particles
Authors: Pekcan Önder 
Published: April 2003

AbstractThe behavior of volume changes upon solvent swelling and annealing was studied within the interphase domain of poly(methyl methacrylate) (PMMA) Particles sterically stabilized with polyisobutylene (PIB). Transient fluorescence technique was applied on these micronsized particles labeled in the PMMA phase with naphthalene (N) groups. Mean decay times 〈τ〉, obtained from fluorescence decay measurements, were used to examine volume changes within the PMMA–PIB interphase domain. The mathematical model proposed by Inokuti–Hirayama for the quenching of lifetimes was employed to quantify the individual volume changes and relaxations at this particular domain. © 1995 John Wiley & Sons, Inc.
Mechanical and morphological properties of elastomer‐modified polypropylene/polyamide‐6 blends
Authors: Rösch Joachim , Mülhaupt Rolf 
Published: April 2003

AbstractPolypropylene/polyamide‐6 (70:30) blends, containing dispersed discrete polyamide‐6 microphases as matrix reinforcement, represent attractive materials for engineering applications. In order to enhance impact resistance, ethene/propene (EPM) was incorporated as a second separately dispersed microphase using reactive blending technology. Blend morphologies were controlled by adding maleic‐anhydride‐grafted‐polypropylene (PP‐g‐MA) as compatibilizer during melt processing, thus enhancing dispersion and interfacial adhesion of the polyamide‐6 phase. With PP‐g‐MA volume fractions increasing from 2.5 to 10 vol %, much finer dispersions of discrete polyamide‐6 with average domain sizes decreasing from 8 to 0.8 μm were obtained. When polyamide‐6 and ethene/propene (EPM)‐rubber are dispersed simultaneously in the polypropylene matrix, impact resistance was improved. The influence of PP‐g‐MA volume fraction and blend morphologies on mechanical properties such as Young's modulus, yield stress, notched Charpy impact resistance was investigated. The ternary polypropylene/polyamide‐6/EPM blend properties were compared with those of binary polypropylene blends containing the equivalent volume fraction of EPM. © 1995 John Wiley & Sons, Inc.
The effect of preparation process of PMDA–ODA–DR1 polyimide on its second harmonic generation characteristics
Authors: Chang Chi‐Jung , Whang Wha‐Tzong , Huang Jung‐Yaw , Liao Chueng‐Liang , Liu Jonq‐Min 
Published: April 2003

AbstractIn situ second harmonic generation (SHG) observation of PMDA–ODA–DR1 polyimide films prepared by different preparative procedures were studied to understand the effects of the residual acid and the imidization byproduct and the extent of imidization on the SHG characteristics of the PMDA–ODA–DR1 polyimides. PMDA–ODA–DR1 polyimides with or without removal of salt were also investigated to study the influence of remaining triethyl hydrogen ammonium chloride salt on the SHG characteristics and reliability of the polymers. A blue shift in the UV/vis spectrum during poling was observed for the low temperature‐baked film, but did not occur for the high‐temperature‐baked film. Both high temperature imidization and removal of the byproduct organic salt did not only improve the poling efficiency of PMDA–ODA–DR1 polyimide as a SHG material, but also slowed down the relaxation of the film and made the film more reliable. © 1995 John Wiley & Sons, Inc.
Studies on the synthesis and properties of thermotropic liquid crystalline copoly(amide–ester–imide) derived from N‐(hydroxyphenyl)phthalimide‐4‐carboxylic acid with amino acid
Authors: Li Chien‐Hui , Jung Ay , Liang Ay‐Ling , Chang Teh‐Chou 
Published: April 2003

AbstractThree series of copoly(amide–ester–imide)s were prepared from amino acid (4‐aminobenzoic acid, 3‐aminobenzoic acid, or 6‐aminohexanoic acid) and N‐(4‐hydroxyphenyl)phthalimide‐4‐carboxylic acid (M1), N‐(3‐hydroxyphenyl)phthalimide‐4‐carboxylic acid (M2), or N‐(2‐methyl‐4‐hydroxyphenyl)phthalimide‐4‐carboxylic acid (M3) in the presence of diphenylchlorophosphate (DPCP) and pyridine as direct condensation agents. The inherent viscosities of copoly(amide–ester–imide)s were in the range of 0.13–0.95 dL/g. Thermotropic liquid crystalline (LC) behavior of these polymers was examined by differential scanning calorimetry (DSC) and optical polarizing microscopy. These copoly(amide–ester–imide)s (IIa, IIe, IIIa, and IIIc) polymerized from 3‐aminobenzoic acid or 6‐aminohexanoic acid with M1 or M3, respectively, showed thermotropic liquid crystalline behavior in the range of 190–426°C. © 1995 John Wiley & Sons, Inc.
Anomalous behavior of thermosetting systems after cure vs. chemical conversion: A normalized conversion–temperature–property diagram
Authors: Venditti R. A. , Gillham J. K. 
Published: April 2003

AbstractIsothermal properties of thermosetting materials after cure, such as density and modulus, pass through maximum and minimum values with increasing chemical conversion. In this report observed decreases in modulus and density at isothermal temperatures below the glass‐transition temperature, Tg, are termed “anomalous.” Four diepoxide (diglycidyl ether of bisphenol A) and tetrafunctional diamine (trimethylene glycol di‐p‐aminobenzoate) high Tg thermosetting systems with different ratios of amine to epoxy were investigated for the purpose of analyzing the evolution of the isothermal properties with increasing conversion. The density, Tg, and modulus of the materials with increasing conversion were measured by a combination of dilatometric, differential scanning calorimetry, and torsional braid analysis techniques. The results are presented in the form of conversion–temperature–property (TgTP) diagrams with modulus and density as the properties. Tg is used as a direct measure of conversion based on the one‐to‐one relationship between Tg and conversion. The property‐conversion behavior of the systems with different ratios of amine to epoxy show similar behavior if Tg is used as the measure of conversion and the data are normalized with respect to Tg at a conversion corresponding to the lower limit of the conversion range at which a maximum in the isothermal modulus occurs. The conversion corresponding to molecular gelation, gelTg, correlates with the lower limit of the conversion range at which the maximum in isothermal modulus occurs; gelTg also marks a change in the behavior of the sub‐Tg mechanical relaxations vs. conversion. The conversion corresponding to the maximum in isothermal modulus vs. conversion correlates with the conversion corresponding to the maximum in isothermal density vs. conversion. © 1995 John Wiley & Sons, Inc.
Quantitative measurement of dispersion of carbon black in rubber by an image processing technique
Authors: Ganesan L. , Bhattacharyya Pritimoy , Bhowmick Anil K. 
Published: April 2003

AbstractIn this article, the quantification of dispersion of carbon black in rubber is done by an image‐processing technique. Surfaces, having different dispersion ratings, are mostly textured. These textured surfaces are digitized and the images are analyzed for quantification. Textured images are suitably represented by a closed set of orthogonal polynomials. The presence of texture has been identified by suitably measuring the orthogonal effects. The textured surfaces are described locally by pronum and globally by prospectrum. Mean, variance, and Fisher distance were computed from the prospectrums and are correlated to various dispersion ratings. There is a linear relationship between the calculated mean and the dispersion rating. © 1995 John Wiley & Sons, Inc.
Determination of the composition of ethylene–propylene–rubbers using 13C‐NMR spectroscopy
Authors: Di Martino S. , Kelchtermans M. 
Published: April 2003

AbstractA detailed 13C‐NMR procedure has been developed to analyze ethylene–propylene–rubbers (EPM). Special attention has been paid to instrumental and spectral parameters and calculation methods. By applying this procedure, it is possible to obtain consistent and reproducible molecular composition results on EPM, independent of the measuring laboratory and the calculation method. The procedure has been tested in eight industrial laboratories. Using this procedure, the composition of a set of 10 EPM standards has been defined. These standards will be used for worldwide infrared calibration purposes (ASTM D‐3900). © 1995 John Wiley & Sons, Inc.
Gamma preirradiation and grafting of 2N‐morpholino ethyl methacrylate onto polypropylene fabric
Authors: Gawish S. M. , Kantouch A. , El‐Naggar A. M. , Mosleh S. 
Published: April 2003

AbstractThe radiation‐induced grafting of 2N‐morpholino ethyl methacrylate (MEMA) in aqueous solution onto polypropylene fabric by a preirradiation technique has been investigated. Among the most important factors affecting the graft yield are monomer concentration, irradiation dose, reaction temperature, and time. It was found that the graft yield increased with increasing monomer concentration, grafting temperature, and preirradiation dose. The kinetic studies showed that the dependence of the grafting rate on monomer concentration is of 1.1 order. Moreover, the calculated overall activation energy was 14.2 kcal/mol. The grafted PP fabric shows an increase in moisture regain with increasing graft yield. Also, the dyeability with acid dye was significantly increased due to grafting with MEMA. © 1995 John Wiley & Sons, Inc.
Modeling intercomponent mixing effects in rubber‐modified glassy polymers
Authors: Taylor‐Smith Ralph E. , Register Richard A. 
Published: April 2003

AbstractA phenomenological model is presented to assess the effects of phase mixing on storage modulus vs. temperature data in polymer blends comprising a continuous glassy matrix and discrete rubbery inclusions. An extension of the Kerner–Dickie model, it is developed for systems of low‐dispersed phase content with a moderate degree of intermixing, and compared with experimental data for six blends of polystyrene or lightly hydroxylated polystyrene with poly(ethyl acrylate) at 90/10 and 70/30 w/w compositions. Phase mixing is induced in this system through intercomponent hydrogen bonding. The model successfully represents data for the four blends of lowest interphase content, but fails for the other two. The model can evidently provide a good description of blends where the bulk of each component resides in a pure phase, but fails when the mixed interphase constitutes the majority of the material. © 1995 John Wiley & Sons, Inc.
Miscibility between components of acrylic pressure‐sensitive adhesives: Phase diagrams of poly(butyl acrylate‐co‐acrylic acid) and esterified rosins
Authors: Kim Hyun‐Joong , Mizumachi Hiroshi 
Published: April 2003

AbstractA series of acrylic copolymers, poly(butyl acrylate‐co‐acrylic acid), were blended with tackifiers and dehydroabietic acid esters, and the miscibility between the components was investigated. The phase diagram of the blends changed from an LCST type to a UCST type as acrylic acid content increased, and the miscibility region in the phase diagrams decreased as the tackifier became bulkier. It was found that some of the trends can be accounted for on the basis of mean field approximation. © 1995 John Wiley & Sons, Inc.