bluuebunny/crossref_metadata_2025 huggingface dataset:
Photocrosslinking of azidated poly(vinyl chloride) coated onto plasticized PVC surface: Route to containing plasticizer migration
Authors: Jayakrishnan A. , Sunny M. C. , Rajan Mini N.
Published: April 2003

The migration of phthalate esters which are commonly employed for plasticizing poly(vinyl chloride) (PVC) is a significant problem in PVC‐based medical devices as well as in packaging used for food stuffs and pharmaceuticals. Medical‐grade PVC resin was treated with sodium azide in dimethylformamide (DMF) to prepare the azide polymer. The polymeric azide was coated onto the surface of plasticized PVC sheets by dipping in a solution of the polymer in tetrahydrofuran (THF). Crosslinking of the azide polymer was accomplished by irradiating the surface using a 125 W UV lamp for various lengths of time. Migration of the plasticizer di 2‐(ethylhexyl phthalate) (DEHP) from coated and uncoated samples was examined in n‐hexane at 30°C. It was found that 50–80% reduction in migration of DEHP could be effected from plasticized PVC in comparison with the controls in 72 h by this technique depending on the concentration of the coating solution, coating thickness, azide concentration, and irradiation dose. © 1995 John Wiley & Sons, Inc.
Graft copolymerization of acrylonitrile and its binary mixture with 4‐vinyl pyridine onto isotactic polypropylene powder by preirradiation method
Authors: Kaur Inderjeet , Barsola Raghuvir , Misra B. N.
Published: April 2003

Graft copolymerization of acrylonitrile (AN) and its binary mixture with 4‐vinyl pyridine (4‐VP) onto isotactic polypropylene powder in aqueous medium, using γ‐rays as an initiator, was studied. Optimum conditions for affording maximum percentage of grafting were evaluated. Rate of grafting (Rg) of AN and binary mixture (4‐VP + AN) was determined as a function of total initial monomer concentrations. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. © 1995 John Wiley & Sons, Inc.
Characterization and magnetic behavior of cobalt(II) and gadolinium(III) polyacrylates
Authors: Ünaleroğlu C. , Zümreoğlu‐Karan B. , Özcan Ş. , Firat T.
Published: April 2003

The 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

In 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

The 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

Two 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

The 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

Stress 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

Polyester (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

The 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

The 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

The 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

The 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

Polypropylene/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

In 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

Three 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

Isothermal 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

In 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

A 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

The 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

A 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

A 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.
Crystallization kinetics of PPS composites and quantification of fiber nucleation density using a computer simulation
Authors: Mehl Nathan A. , Rebenfeld Ludwig
Published: April 2003

Differential scanning calorimetry and hot‐stage optical microscopy were used to study the isothermal crystallization kinetics of unreinforced poly(phenylene sulfide) (PPS) and PPS reinforced with aramid, carbon, and glass fibers. The influence that fibers have on the crystallization kinetics of PPS was found to depend on the characteristics of the fiber as well as the type of PPS used. For one kind of PPS, fibers enhanced the crystallization rate, while for another type of PPS, reinforcing fibers had a moderate depressing effect on the polymer crystallization rate. To clarify these effects, we used a new method of quantifying the nucleation process in fiber‐reinforced composites that employs a 3‐D computer simulation of spherulitic crystallization. Using this method, the nucleation density in the bulk polymer, Nb, and the nucleation density on fiber surfaces, Nf, were calculated for PPS composites as a function of crystallization temperature. The calculated values of Nb and Nf were used to explain differences in the effectiveness of the fibers as well as differences in the nucleating characteristics of the two polymers. © 1995 John Wiley & Sons, Inc.
Synthesis and biological activities of copolymers of N‐glycinyl maleimide with methacrylic acid and vinyl acetate
Authors: Gam Gi‐Tak , Jeong Jin‐Gon , Lee Neung‐Ju , Lee Young‐Woo , Ha Chang‐Sik , Cho Won‐Jei
Published: April 2003

Copolymerizations of N‐glycinylmaleimide (GMI) with methacrylic acid (MA) and vinyl acetate (VAc) were carried out in 2‐butanone using lauroylperoxide as an initiator at 70°C. Synthesized GMI, poly(GMI‐co‐MA), and poly(GMI‐co‐VAc) were characterized by IR and 1H‐NMR spectroscopies, elemental analysis, and gel permeation chromatography. The in vitro cytotoxicities of poly(GMI‐co‐MA) and poly(GMI‐co‐VAc) were evaluated using K‐562 human leukemia cells and HeLa cells. From the cytotoxicity data against HeLa cells, the copolymers are less cytotoxic than monomeric GMI at dosage of 0.02, 1.0, and 5.0 mg/mL. Copolymers were very effective at any dosage tested. The in vivo antitumor activities of poly(GMI‐co‐MA) and poly(GMI‐co‐VAc) were also evaluated against mice bearing sarcoma 180. Monomeric GMI and its copolymers showed higher antitumor activity than 5‐fluorouracil (5‐FU) at any dosage tested. © 1995 John Wiley & Sons, Inc.
Modeling of transfer phenomena on heterogeneous Ziegler catalysts: Differences between theory and experiment in olefin polymerization (an introduction)
Authors: McKenna T. F. , Dupuy J. , Spitz R.
Published: April 2003

This article begins by briefly reviewing the more important contributions to the area of modeling heat and mass transfer, and particle growth during the polymerization of olefins on Ziegler–Natta catalysts. It is shown that these models are capable of identifying the critical areas involved in heat and mass transfer, and of modeling polymerizations where the observed activity is less than approximately 5,000 g of polymer per gram of catalyst per hour (g/g/h). However, it is not possible to use these models “as‐is” to model more modern catalysts whose activity levels can surpass the 50,000 g/g/h mark because they predict prohibitively large concentration gradients inside the growing particles during slurry polymerizations, and temperature gradients outside the particles during polymerization in the gas phase. An analysis of the mass and heat transfer Peclet numbers (Pe) reveals that certain simplifying assumptions may not always be valid. Pe values in the transition range suggest that convection inside the particles during polymerization in the liquid phase may help to explain why observed mass transfer rates are higher than the predicted rates. In an opposite vein, a Pe analysis shows that conductive heat transfer may play an important role at length scales characteristic of those in the early stages of polymerization. A new mechanism for heat transfer at reduced length scales is proposed. © 1995 John Wiley & Sons, Inc.
Characterization of surface‐modified polyurethane blends, poly(vinyl alcohol), and poly(4‐hydroxybutyl acrylate) for biomedical application by electron spin resonance spectroscopy
Authors: Lorenz Günter , Klee Doris , Höcker Hartwig , Mittermayer Christian
Published: April 2003

Two polyurethane blends—poly(carbonate urethane)/poly(vinyl alcohol) [PCU/PVA] and the aliphatic poly(ether urethane) (Tecoflex™)/poly(pentanedioic acid mono‐4‐(acryloyloxy)butyl ester) [Tecoflex™/COOH]—were surface‐modified. Poly(vinyl alcohol) [PVA] and poly(4‐hydroxybutyl acrylate) [PHBA] were used as model surfaces. 4‐Isocyanato butanoic acid methyl ester was coupled as a spacer molecule to PVA and the PVA‐containing polyurethane blend. Saponification of the generated ester group was verified by means of Electron Spin Resonance (ESR) spectroscopy using the nitroxyl radical 4‐amino‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (4‐amino‐TEMPO) as a reporter group. In the case of Tecoflex™ and PHBA, glutaric anhydride served as a spacer molecule. 4‐Amino‐TEMPO was coupled to this spacer as well. ESR spectroscopy as a bulk method was used together with the surface‐sensitive method X‐Ray Photoelectron Spectroscopy (XPS) verifying the modification steps by elemental composition, ESR line shapes, and determination of the rotational correlation time τc. © 1995 John Wiley & Sons, Inc.
High TC superconductor polymer composite based on YBa2Cu3O7−x. II. Conduction mechanisms and temperature effect on conductive and dielectric properties of polypropylene composites
Authors: Acosta José Luis , Jurado José Ramón
Published: April 2003

To improve the connectivity of YBaCuO particles in a polypropylene matrix, different amounts of carbon black (N) or copper (C) were incorporated into the binary base system. In this research the effects of these conductor fillers on the conduction mechanism of the experimental composites were studied using complex impedance spectroscopy as the analytical technique. In addition the effects of temperature on certain electrical properties were examined in the synthesized materials. © 1995 John Wiley & Sons, Inc.
Exploration of the difference of reaction rates for polyester and polyether urethane prepolymers with 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane
Authors: Xiaolie Luo , Jin Liu , Dezhu Ma
Published: April 2003

Polyester (PEPA) and polyether (PTMO) prepolymers with NCO end groups were synthesized. The chain extension reaction of these prepolymers with MOCA diamine was studied by FTIR spectrometry and found to be a second‐order reaction. Data on chain extension reaction rate constants and activation energy showed that the chain extension reaction rate of the PEPA prepolyme with MOCA was faster than that of PTMO prepolymer with MOCA. Such a difference of chain extension reaction rate for PEPA and PTMO prepolymers with MOCA can be explained by hydrogen bonding interaction and miscibility between hard and soft segments in the cast polyurethane elastomer. The hydrogen bonding interactions of MOCA with PEPA prepolymer and PTMO prepolymer without chain extension reaction convincingly demonstrated the difference of chain extension reaction in the polyurethane‐urea systems. © 1995 John Wiley & Sons, Inc.
Effects of cholesteric order on mechanical properties of (E‐CE)C/PAA composites
Authors: Jiang S. H. , Huang Y. , Shen J. R.
Published: April 2003

The ethyl‐cyanoethyl cellulose [(E‐CE)C]/poly(acrylic acid) [PAA] composites were prepared via in situ photopolymerization of the (E‐CE)C/acrylic acid (AA) solutions, in which the morphology and structure of (E‐CE)C was retained as the same as that in the solution. The strength and the modulus of the composites depended on their morphology and structure. The strength of the composites with a completely amorphous state or with a completely cholesteric order did not significantly change with increasing (E‐CE)C content, although the strength of the composites with completely cholesteric order is much higher than with the completely amorphous state. However, when the (E‐CE)C content changed from 33.8% to 42.5%, in which the composites had both cholesteric order and amorphous phases, the strength of the composites greatly increased with increasing (E‐CE)C. The elastic modulus of the composites with completely isotropic structure decreases with increasing (E‐CE)C content but abruptly increases with increasing the fraction of cholesteric phase in the composites. The (E‐CE)C with cholesteric order had a significant enhancing effect on the strength of the composites. The stress–strain curves indicated that the composites with completely amorphous or completely cholesteric order were breakable, while they were tough in the case when they had both cholesteric and amorphous phases. © 1995 John Wiley & Sons, Inc.
Morphological and rheological properties of PS melts filled with grafted and ungrafted glass beads
Authors: Friedrich Chr. , Scheuchenpflug W. , Neuhäusler S. , Rösch J.
Published: April 2003

Glass beads carrying different amounts of polystyrene (PS) grafted to their surface were prepared by solution and melt‐mixing processes. These beads are mixed with a nearly mono‐disperse PS. The morphology of polymers filled with different volume amounts, ϕ, of modified and unmodified glass beads was investigated by scanning electron microscopy (SEM). In the case of PS‐grafted glass beads, the fracture surfaces show cohesive failure. The rheological properties of these filled polymers were investigated by mechanical spectroscopy. The material functions, the storage modulus G″ and the loss modulus G″, for PS melts filled with unmodified beads can be presented in an invariant from, e.g., independent of temperature and concentration. The temperature‐shift factors follow WLF behavior, and the concentration shift factors a generalized Maron Pierce equation. The rheological material functions of melts filled with modified glass beads can be superposed for different temperatures. However, a concentration invariant representation is only possible in the frequency range belonging to the plateau region. For small frequencies, a systematic deviation occurs whose strength depends on the amount of polymer grafted to the filler surface. It is argued that this behavior may be attributed to an additional relaxation process originating from the hindered flow of the modified glass beads. This process has to be investigated in more detail in the future. © 1995 John Wiley & Sons, Inc.
Polymeric systems bearing side‐chain 2,6‐dimethylbenzoyldiphenylphosphinoxide moieties for UV curable coatings: Synthesis and photoinitiation activity
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo
Published: April 2003

Polymeric photoinitiators with pendant 2,6‐dimethylbenzoyldiphenylphosphinoxide moieties were prepared by reacting the hompolymer of 4‐acryloyloxy‐2,6‐dimethyl benzoic acid, and its copolymers with n‐butyl acrylate with thionyl chloride followed by methoxydiphenylphosphine. These polymeric systems were characterized and their photoinitiation activity checked in the UV curing of a standard acrylic mixture, by irradiation both at 330 and over 380 nm, the latter conditions being applied to simulate a TiO2‐pigmented coating formulation. The results were compared with those obtained by using the low molecular weight analog 2,4,6‐trimethylbenzoyldiphenylphosphinoxide and previously prepared polymeric systems based on the benzoyldiphenylphosphinoxide moiety. The stability to light and to hydrolytic conditions of the polymeric photoinitiators with respect to the model compound was also tested. The results obtained are discussed and related to the structural requirements of these systems. © 1995 John Wiley & Sons, Inc.
Stereoblock polypropylene/isotactic polypropylene blends. III. Isothermal crystallization kinetics of iPP component
Authors: Canevarolo S. , De Candia F.
Published: April 2003

The isothermal crystallization of blends of stereoblock polypropylene and isotactic polypropylene were analyzed. The main interest in this phenomenon is related to the steric affinity between the two components. The composition of the blend was changed over a wide range. The obtained results demonstrate the incompatibility of the two components both in the liquid phase and the solid state. © 1995 John Wiley & Sons, Inc.
Kinetic study on the poly(methyl methacrylate) seeded soapless emulsion polymerization of styrene. II. Kinetic model
Authors: Lee Chia‐Fen , Chiu Wen‐Yen , Chern Yuan‐Chen
Published: April 2003

A seeded soapless emulsion polymerization was carried out with poly(methyl methacrylate) (PMMA) as seeds, styrene as monomers, and potassium persulfate (K2S2O8) as the initiator to synthesize the PMMA/polystyrene (PS) composite latex. The morphology of the latex particles was observed by transmission electron microscopy (TEM). It showed a core‐shell structure. A core‐shell kinetic model was proposed for the seeded emusion polymerization, in which the thickness of the shell was not constant. An increase of the conversion would increase the thickness of the shell. The entire course of polymerization could be divided into three regions: In the first region, the propagation rate constant (Kp) and termination rate constant (Kt) were kept constant at constant temperature. The kinetic data showed that the square root of polymer yield (W) was proportional to the reaction time. In the second region, the gel effect was considered and the termination rate constant (Kt) was empirically modified. The Kt would decrease with increasing the conversion. In the third region, both the gel effect and the glassy effect were considered; the propagation rate constant was also empirically modified. The prediction on the conversion and the number‐average molecular weight of polymers during the seeded emusion of polymerization on the basis of our core‐shell kinetic model fitted well with the experimental data. © 1995 John Wiley & Sons, Inc.
Investigation on the simulation of the reactive extrusion of nylon 6
Authors: Yang Zhen‐Guo , Lauke Bernd
Published: April 2003

In this article, a novel simulation of the processing conditions of the anionic ring‐opening polymerization of nylon 6 in a counterrotating twin‐screw extruder by use of a modified Haake Rheometer run at elevated temperatures is described. Experimental results for several combinations of processing parameters are presented. General relations between processing parameters, conversion ratio, and molecular weight of the product are observed. These observations can be used in the eventual scaling up of investigation to an actual twinscrew extruder. © 1995 John Wiley & Sons, Inc.
Perfluoropolyethers with acid end groups: Amphiphilicity and emulsification
Authors: Kasai Paul H.
Published: April 2003

Interactions of PFPE‐acids (perfluoropolyethers with carboxylic end groups) with a metal oxide surface and with aqueous systems were examined. The study revealed that (1) PFPE‐acids are preferentially adsorbed on metal oxide (ZrO2) surfaces over PFPE of nonfunctionalized form, (2) PFPE‐acids of shorter chain length are preferentially adsorbed over PFPE‐acids of longer dimension, and (3) the low molecular weight fraction (MW = 1300) of Demnum‐SH is abundant in molecular chains terminated with the acid end group at both ends. The study also revealed that PFPE‐acids, if agitated with aqueous solution of electrolyte, form an extremely stable macroemulsion of the water‐in‐oil type. The emulsion is extremely viscoelastic and may contain 50% by weight (hence, 65% by volume) of water. Water is occluded as droplets of diameter of 1–100 microns. A mechanism exists whereby aqueous protons are transported between droplets with the transfer rate ≥ 50 Hz at room temperature. Relevance of these observations in the lubricant application of PFPEs in magnetic recording media is discussed. © 1995 John Wiley & Sons, Inc.
Temperature and frequency effects on fatigue crack growth in acrylonitrile–butadiene–styrene (ABS)
Authors: Kim Ho Sung , Wang Xiang Ming
Published: April 2003

Fatigue crack growth (FCG) in a commercial‐grade acrylonitrile–butadiene–styrene (ABS) over the temperature and frequency ranges of 10–70°C and 0.01–10 Hz was studied. A model for the effects of temperature and frequency on the FCG rate was refined. The refined model is shown to accurately predict FCG rates in ABS. Three different types of fatigue fracture surfaces have been found. The first type is characterized by discontinuous growth bands; the second, by a rather smooth surface; and the last, by a rough surface relative to the second. The transition between the first and second types was found to be dependent on temperature and frequency as well, whereas the transition between the second and last types was found to be only dependent on temperature. These findings are discussed in relation to crazing. The apparent activation energy (ΔHth) was evaluated for both the first and second types to be 19.22 kJ/mol. © 1995 John Wiley & Sons, Inc.
Toughening of aromatic diamine‐cured trifunctional epoxy resins by modification with N‐phenylmaleimide–styrene copolymers containing pendant p‐hydroxyphenyl groups
Authors: Iijima Takao , Miura Satoru , Fukuda Wakichi , Tomoi Masao
Published: April 2003

N‐Phenylmaleimide (PMI)–N‐(p‐hydroxy)phenylmaleimide (HPMI)–styrene (St) terpolymers (HPMS), containing pendant p‐hydroxyphenyl (HP) groups, were prepared and used to improve the toughness of triglycidyl aminocresol epoxy resin cured with p,p′‐diaminodiphenyl sulfone. HPMS was effective as a modifier for the toughening of the epoxy resin. When using 15 wt % of HPMS (1.0 mol % HP unit, Mw 129,000), the fracture toughness (KIC) for the modified resin increased 190% with a medium loss of flexural strength. The toughening of epoxies could be attained because of the cocontinuous phase structure of the modified resins. The decrease in flexural strength was suppressed to some extent by introducing a functional group into the modifier. The toughening mechanism was discussed in terms of the morphological behavior of the modified epoxy resin system. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of porous polysulfone membranes with spacer‐bonded N‐containing groups
Authors: Rodemann Klaus , Staude Eberhard
Published: April 2003

Ultrafiltration membranes were prepared from epoxidized polysulfone by the conventional phase separation procedure. For epoxidizing, the polymer was first lithiated and a reaction followed with glycidyl‐4‐oxohexylether providing an eight atomic spacer. The reaction of the epoxy group with N‐containing substituents was performed heterogeneously using the ready membranes. The stability of the substituted membranes is visible by the fact that they are reacted under reflux conditions for 24 h. The reagents were trimethyl amine, diethylamine, n‐butyl amine, and tauric acid. Thus, positively charged, negatively charged, and neutral membranes were obtained. The membranes were characterized via ultrafiltation using dextran solution as well as human albumin solutions. In addition, the streaming potential was measured in the presence and absence of the protein. By these measurements the obviously neutral membranes were surprisingly identified to be positively charged. This is related to subsequent reactions of the spacer‐bonded epoxy groups with the amino groups. © 1995 John Wiley & Sons, Inc.
Codiluent effect on the properties of UV‐cured films
Authors: Khan Mubarak A. , Ali K. M. Idriss , Zaman M. M. , Hossain M. A.
Published: April 2003

Different formulations were developed with an urethane oligomer combined with a number of reactive diluents with different functionalities such as N‐vinylpyrrolidone (monofunctional), butanediol diacrylate (difunctional), tripropylene glycol diacrylate (difunctional), and trimethylolpropane triacrylate (trifunctional). The films were prepared with these formulations and cured under UV radiation in the presence of the photoinitiator Irgacura 184. Their properties were characterized. The effect of codiluents of low glass transition temperatures like ethyl hexyl acrylate and methoxyethyl acrylate on the properties of these films was studied. These formulations were then applied as thin coatings on the leather surface in order to study the improvement of the leather substrate. Both tensile strength and elongation of the treated leather increased. The gloss of the coated leather was also enhanced. Incorporation of a plasticizer into these systems substantially improved the rheological properties of the coated leather. © 1995 John Wiley & Sons, Inc.
Physical aging of high‐performance thermoplastics: Enthalpy relaxation in PEK‐C and PES‐C
Authors: Di Yingwei , D'Amore Alberto , Marino Giuliano , Nicolais Luigi , Li Binyao
Published: April 2003

The developments of physical aging in phenolphthalein poly(aryl‐ether‐ketone) (PEK‐C) and poly(aryl‐ether‐sulfone) (PES‐C) with time at two aging temperatures up to 20 K below their respective glass transition temperatures (Tg = 495 and 520 K) have been studied using differential scanning calorimetry (DSC). Substantial relaxation within the aging course of several hours were observed by detecting (Tg) decreasing during physical aging process at the two aging temperatures. The relaxation processes of both polymers are extremely nonlinear and self‐retarding. The time dependencies of their enthalpies during the initial stages of annealing were approximately modeled using the Narayanaswamy‐Tool model. The structure relaxation parameters obtained from this fitting were used to predict the possibility of physical aging occurring at their respective using temperatures. © 1995 John Wiley & Sons, Inc.
Effect of the concentration of dye on the physical property of dye‐based polyurethane ionomer
Authors: Lee J. J. , Chi Z. K. , Kuo Y. M. , Chao D. Y.
Published: April 2003

We have successfully prepared Congo Red‐based polyurethane ionomers at our lab, and these ionomer structures have been proven by infrared (IR) spectra. For a dye‐based polyurethane ionomer molecule solution, the surface tension was found to decrease, but the number‐average particle size was found to increase with increasing concentration of Congo Red employed to prepare this ionomer molecule. Interestingly, the number‐average particle size of dye‐based polyurethane ionomer molecules decreases with increasing concentration of Congo Red in the presence of other dyes (i.e., Remajol Brilliant Blue R and Amaranth), as a result of Congo Red intramolecular interaction. It is important to point out that the addition of a fixed concentration of Amaranth to prepare Congo Red‐based polyurethane ionomer molecules will significantly enhance the tensile strength but will decrease the elongation of this ionomer molecule. © 1995 John Wiley & Sons, Inc.