bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of filler particles and polymer structure on the mobility of polymer molecules
Authors: Howard Gordon J. , Shanks Robert A. 
Published: April 2003

AbstractThe presence of carbon filler has been shown to cause a change in the glass transition temperature of polymers. For poly(vinyl chloride) and two of its copolymers with 10 and 15% vinyl acetate an increase in Tg was observed when Graphon C Carbon was added. The increase was greater when the proportion of vinyl acetate was greater. Polar vinyl acetate units allow stronger adsorption of polymer onto the carbon. Brittle polymers such as polystyrene and poly(methyl methacrylate) showed scattered Tg's when filled with carbon. The changes were not a function of concentration. It is postulated that the thermal stress of these polymers is increased in the presence of filler.
Poly(n‐butyl acrylate)/polystyrene interpenetrating polymer networks and related materials. III. Effect of grafting level and molecular weight in semi‐2 IPNs
Authors: Yeo J. K. , Sperling L. H. , Thomas D. A. 
Published: April 2003

AbstractA series of poly(n‐butyl acrylate)/polystyrene IPNs and semi‐1 IPNs with deliberately controlled graft levels were synthesized via a urethane chemical coupling method. Also prepared were a series of semi‐2 IPNs with the molecular weight of polymer II as the variable. The more highly grafted IPNs displayed poorly defined morphologies in which the domain structures were irregular and phase domain boundaries were characterized by fibrillar and interphase regions. A single glass transition peak was another feature of the more highly grafted IPNs. Polymer network II formed in the presence of linear polymer I results in morphologies dependent on the molecular weight of linear polymers. In the semi‐2 IPNs, polymer I molecular weights below Mv = 20,000 caused polymer I to behave like a plasticizer or a diluent. The domain sizes of semi‐2 IPNs agree with theoretical predictions developed by the present authors.
Molecular motion of small molecules in cellulose gels studied by NMR
Authors: Nyström B. , Moseley M. E. , Brown W. , Roots J. 
Published: April 2003

AbstractMeasurements of relaxation times, T1 and T2, and self‐diffusion coefficients, D, for small molecules, viz., H2O, dioxane and t‐butanol, in the gel system cellulose/H2O are reported and compared with those for H2O in a polyacrylamide gel of the same polymer content. The temperature dependence of T1 and D can for all the penetrants be represented by Arrhenius type relations which merely are parallel shifts by the same amount, towards smaller values, of those obtained without polymer. The T2 values for H2O in both gels pass through a shallow minimum over the considered temperature interval (14°−44°C). Furthermore, relaxation times T1 of D2O in the gel system cellulose/D2O are reported; in a plot of ln T1 vs. 1/T, a plateau region is observed at higher temperatures.
Thermo‐oxidative degradation of low‐density polyethylene close to industrial processing conditions
Authors: Hoff A. , Jacobsson S. 
Published: April 2003

AbstractThermo‐oxidative degradation of low density polyetylene (LDPE) at a low degree of volatilization (about 4%) at 264–289°C was studied. Gas chromatography—mass spectrometric analysis was used to separate and identify the products of LDPE decomposition. Altogether 44 compounds representing hydrocarbons, alcohols, aldehydes, ketones, acids, cyclic ethers, cyclic ethers, cyclic esters, and hydroxycarboxylic acids were identified. Sixteen oxygen‐containing products were quantified. Among the components identified, the fatty acids and aldehydes predominated. The most abundant product was formic acid. The mechanism of formation of the degradation products is discussed.
The initial and terminating stage of glow discharge polymerization investigated by thickness monitor
Authors: Inagaki N. , Yasuda H. 
Published: April 2003

AbstractAn attempt to discuss the initial stage and terminating stage of glow discharge polymerization was made by selecting the monomer system of styrene and acetylene, which differ in their condensibility, and a certain polymerization procedure. Results indicate the important aspects of the initial and terminating stages of glow discharge polymerization. These aspects may not play a significant role in the study of bulk properties of plasma‐polymerized polymers or in the study of polymer deposition rate. However, the initial stage effect might influence the adhesion of the polymer. The terminating stage effect might influence the surface characteristics of glow discharge‐polymerized polymers. These effects are particularly important in a batch polymerization system, where the beginning and the end of process cannot be rigorously controlled with respect to the timing and sequence of the beginning and the end of monomer flow and of electric discharge. This study points to the importance of these aspects for proper utilization of glow discharge polymerization as a thin film process.
Effect of drawing on creep fracture of polypropylene fibers
Authors: Takaku Akira 
Published: April 2003

AbstractThe ultimate properties of polypropylene fibers, prepared by drawing the same undrawn fibers to different draw ratios, were determined by the creep fracture method at temperatures from 40 to 120°C. The composite curves of the engineering stress at break, the true stress at break, the ultimate extension ratio were constructed as a function of reduced time to break by assuming time–temperature superposition. The temperature dependence of the shift factor aT used in the superposition could be represented by a single equation of the Williams, Landel, and Ferry form. The composite curves of the true stress at break for the samples with different draw ratios were almost the same independently of draw ratio. The composite curves of the ultimate extension ratio for these samples could be reduced to a single curve by assuming that the ultimate extension ratio evaluated with respect to the unit length of the undrawn fibers were constant independently of draw ratio if the time to break and temperature conditions of the measurement were fixed constant. A possible fracture mechanism is discussed on the basis of the fracture mechanisms proposed by Samuels and Peterlin.
Molecular weight distribution of an unsaturated polyester
Authors: Kaštánek Alois , Zelenka Jiří , Hájek Karel 
Published: April 2003

AbstractA precipitation fractionation was carried out by the nonsolvent addition method of 60 g of an unsaturated polyester. The polyester was prepared by the generally known melt condensation of maleic anhydride, phtalic anhydride, ethylene glycol, and cyclohexanol. Number‐average molecular weights of fractions were determined by vapor pressure osmometry in acetone at 36°C. Polydispersities of fractions were evaluated by gelpermeation chromatography (GPC) measurements with tetrahydrofuran as solvent. They seem to be wider for fractions of higher molecular weights. By infrared spectroscopy the fractions were found not to have marked differences in chemical compositions. The obtained molecular weight distribution curve of the unsaturated polyester was found to be in good agreement with that expected from the theory of polycondensation kinetics. The small differences appear only in the low molecular weight range.
Effect of crystallinity of condensation polymers on platelet adhesion
Authors: Ogata Naoya , Sanui Kohei , Tanaka Hozumi , Takahashi Yoichi , Kitamura Eichi , Sakurai Yasuhisa , Okano Teruo , Kataoka Kazunori , Akaike Toshihiro 
Published: April 2003

AbstractVarious polyamides and polyesters having different numbers of methylene groups in their repeating units have been synthesized and their blood compatibilities have been evaluated in terms of the adhesion behavior of blood platelets on the surface of these condensation polymers by a micro‐sphere‐column method. The number of methylene groups in the repeating units of polyamides and polyesters influenced the adhesion behavior of platelets and there was an optimum number of methylene groups each in polyamides and polyesters. Poly(hexamethylene terephthalamide) and poly(pentamethylene terephthalate) adsorbed platelets in the smallest number in the polyamide and polyester series, respectively. Blood platelets were adsorbed on polyamides in smaller numbers than on corresponding polyesters. It was found that the platelet adhesion on the surface of polyamides and polyesters was closely related to their crystallinities and the number of the adsorbed platelets decreased linearly with increasing their relative crystallinity.
Development of automatic cross fractionation: Combination of crystallizability fractionation and molecular weight fractionation
Authors: Nakano Seikou , Goto Yukitaka 
Published: April 2003

AbstractAn automatic cross‐fractionation system is presented by combining a newly developed crystallizability fractionation device based on the principle of isothermal dissolution with a commercially available GPC. The detail design, procedure, and operation variables are described. The fractions eluted from the device are characterized by use of an infrared spectrometer and a differential scanning calorimeter for clearing the mechanism of it. As the result of the study, it is found that the system is very useful for characterizing semicrystalline polymers.
Cure kinetics of a low epoxide/hydroxyl group‐ratio bisphenol a epoxy resin–anhydride system by infrared absorption spectroscopy
Authors: Stevens Gary C. 
Published: April 2003

AbstractAn infrared absorption spectroscopy study of the curing kinetics of a low (1.12) epoxide/hydroxyl‐group ratio bisphenol A epoxy resin—phthalic anhydride system is reported. A full infrared peak assignment to molecular vibrational modes is given for the range 400 to 4000 cm−1, and the optical density behavior of all peaks during reaction is discussed in detail. Proposed rival reaction mechanisms are considered and their respective kinetic behavior discussed. The reaction was found to follow consecutive‐step addition esterification and simultaneous addition etherification, and epoxide—hydroxyl group and carboxylic acid dimer hydrogen bonding was found to occur. The reaction behavior supports a proposed hydroxyl group‐limited inhomogeneous bulk reaction mechanism of a colloid type.
Cure kinetics of a high epoxide/hydroxyl group‐ratio bisphenol a epoxy resin—anhydride system by infrared absorption spectroscopy
Authors: Stevens Gary C. 
Published: April 2003

AbstractAn infrared absorption spectroscopy study of the curing (gelation and postcure) kinetics of a high (4.7) epoxide/hydroxyl group‐ratio diglycidyl ether of bisphenol A (DGEBA)–mixed anhydride epoxy resin system is reported. Peak assignments to molecular vibrational modes are given for the range 400–4000 cm−1, and the optical density behavior of all peaks during reaction is discussed in detail. Chemical reaction was found to follow consecutive‐step addition esterification and simultaneous addition etherification. Epoxide hydroxyl‐group and carboxylic acid dimer hydrogen bonding was found to occur. The gelation phase of reaction is complex, exhibiting rapid initial hydroxyl–anhydride reactions followed by S‐shaped kinetics approaching an incompletely reacted limit. Postcure exhibits functional group kinetic behavior similar to that occurring in low epoxide/hydroxyl group‐ratio bisphenol A epoxy resin–phthalic anhydride systems and produces similar final chemical structures. The reaction behavior of low and high epoxide/hydroxyl group‐ratio bisphenol A epoxy resin–anhydride systems arises from an hydroxyl group‐limited inhomogeneous reaction mechanism involving bisphenol A epoxy resin molecular aggregates. The importance of free hydroxyl group content is discussed.
The simulation of hydrolytic polymerization of ϵ‐caprolactam in various reactors
Authors: Tai Kazuo , Arai Yoshihiro , Tagawa Takashi 
Published: April 2003

AbstractThe concrete simulation models dealing with the kinetic behavior of the hydrolytic polymerization of ϵ‐caprolactam (CL) in various polymerization reactors used in the industry were described, and the method for their numerical solutions was presented. The characteristic data of the polymerization such as the concentrations of CL, end group, water, ϵ‐aminocaproic acid, cyclic dimer, and the hot‐water‐soluble component, conversion, number average, and weight average molecular weights, and solution and melt viscosities can be calculated at every stage of the polymerization reaction, at every part of the reactors, and/or at the outlet of the reactors. The calculated values based upon the models were found to be quite compatible with the observed values for the reactors. The applicability of the technique was well confirmed for the quality control, process control, modification of existing plants, and development of new chemical process plants.
On the crystallinity of poly(alkylbenzimidazole) salts
Authors: Aharoni Shaul M. 
Published: April 2003

AbstractPoly(alkyldibenzimidazole) and poly(alkylbisbenzimidazole) having five, six, seven, and eight methylene groups in each repeat unit were synthesized. Salts of these polymers with strong acids, whose pK is 4.00 or less, were prepared. Weaker acids do not form salts with the poly(alkylbenzimidazole)s. It was found that polymers having an even number of methylene groups per repeat unit tend to form crystalline salts while those polymers having an odd number of methylene groups from only amorphous salts. From among the crystalline salts, those containing poly(bisbenzimidazole)s are more crystalline than their analogous poly(dibenzimidazole)s.
The effect of casting solvent and water on gas permeability of poly(γ‐methyl L‐glutamate) membrane
Authors: Minoura Norihiko 
Published: April 2003

AbstractGas permeability of poly(γ‐methyl L‐glutamate) (PMLG) membranes prepared by using dichlorethane, trifluoroacetic acid, and formic acid as solvents was studied. The membranes prepared by casting dichloroethane and trifluoroacetic acid solutions of the polymer, designated as PMLG—DCE and PMLG—TFA, respectively, had α‐helical structures according to infrared absorption spectra, while the membranes prepared by allowing the PMLG—TFA membranes to swell in formic acid, designated as PMLG—FA, had mainly a β‐sheet structure. The diffusion coefficients of each gas studied for PMLG—DCE, PMLG—TFA, and PMLG—FA decreased in that order, and the apparent activation energies of diffusion increased in that order. The apparent heats of solution for Ne,O2, N2, and CO2 were negative in PMLG—FA. These results were discussed in connection with the molecular conformations of PMLG in the membranes. It is suggested that the diffusion of gases in PMLG—DCE takes place in the side‐chain regions between helices, while in PMLG—FA the diffusion occurs across the polymer main chain whose mobility is depressed by the intermolecular hydrogen bonds. The effect of water on oxygen permeability of PMLG—DCE was small; on the contrary that of PMLG—FA was very large. Furthermore, it is assumed that the random‐coil conformation partly exists in PMLG—TFA.
Graft polymerization of acrylic acid onto polyethylene film by preirradiation method. II. Effects of oxygen at irradiation, storage time after irradiation, mohr's salt, and ethylene dichloride
Authors: Ishigaki Isao , Sugo Takanobu , Takayama Takashi , Okada Toshio , Okamoto Jiro , Machi Sueo 
Published: April 2003

AbstractIn the grafting of acrylic acid onto polyethylene by preirradiation method, the irradiation in air gave a higher rate of grafting than in N2, since the diffusion rate of monomer is larger for less crosslinked polyethylene. The rate of grafting decreased with increasing time of storaging polyethylene because of the decay of trapped radicals. The effects of storage conditions on the grafting activity was reasonably interpreted by assuming that grafting is predominantly controlled by both concentration of trapped radicals and monomer diffusibility in the polymer matrix. Mohr's salt was found to depress the homopolymerization of acrylic acid without marked change of grafting rate. The rate of grafting was increased by the addition of ethylene dichloride due to the increase in monomer diffusion.
New epoxy resins. I. The stability of epoxy–trialkoxyboroxines triaryloxyboroxine system
Authors: Chen C. S. , Bulkin B. J. , Pearce E. M. 
Published: April 2003

AbstractA polymer with high aromaticity and/or cyclic ring structures chain backbone usually has high heat, thermal, and flame resistance. Two diglycidyl ethers of bisphenols were prepared from 4,4′ isopropylidenediphenol (DGEBA) and 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) for evaluation. Four boroxines—trimethoxyboroxine (TMB), triethoxyboroxine (TEB), triisopropoxyboroxine (TIPB) and triphenoxyboroxine (TPB)—were used as the curing agents. DGEBA and DGEBF cured with various boroxines indicate that the trend for their respective glass transition temperature (Tg's), degradation temperatures (Td's), and gel fractions are TMB‐cured epoxy ≈ TEB‐cured epoxy < TIPB cured epoxy < TPB cured epoxy. The DGEBF system usually has a higherTg,Td, gel fraction, oxygen index (OI), and char yield than the related DGEBA system. DGEBF/DGEBA (80/20 mol ratio) shows a synergistic effect in regard to char formation. This effect exists not only in the copolymer system but also in blended homopolymers of the separately cured resins. A modified mechanism for the polymerization of phenyl glycidyl ether (PGE) with TMB has been proposed.
Mass transfer effects in polycondensation reactors wherein functional groups are not equally reactive
Authors: Gupta Santosh K. , Agarwalla N. L. , Kumar Anil 
Published: April 2003

AbstractThree simplified models of polycondensation reactors are considered in which the condensation product is continuously removed by application of vacuum. Reversible polycondensation reactions of monomers violating the equal reactivity hypothesis have been simulated in these reactors. The effect of various rate and reactor design variables on the molecular weight distribution (MWD) and its moments is studed. It is observed that when the reverse reactions are rapid, the results are fairly sensitive to the level of vacuum applied and to the mass transfer resistance; whereas when the forward reactions predominate, results lie very close to earlier plots for the corresponding irreversible polymerizations. These reactor variables then have relatively small influence on the MWD. Splitting of the MWD curves for odd and even values on n is observed under certain conditions, the effects being more pronounced in the presence of mass transfer than in its absence.
Drawing rate effects on morphological parameters in nylon‐6, PET, and PBT filaments
Authors: Song John W. , Abhiraman A. S. , Rickards Alan P. 
Published: April 2003

AbstractInfluence of drawing velocity on morphological parameters of nylon‐6, PET, and PBT filaments has been studied. The drawing was carried out at approximately 20°C above the effective glass transition temperature of these materials. The results are explained in terms of drawing‐induced changes in temperature and in rate of crystallization.
Effect of an additive on the radiation resistance of polyethylene and ethylene–propylene copolymer
Authors: Fujimura Takashi , Arakawa Kazuo , Hayakawa Naohiro , Kuriyama Isamu 
Published: April 2003

AbstractIn low‐density polyethylene containing the additive propylfluorancene, radiation energy received by polyethylene is transferred to propylfluorancence, and the production of radicals at 77 K in polyethylene is suppressed. Propylfluoranncene also increases the rate of the decay of radicals of polyethylene at room temperature. The depression of radical production and accelaration of radical decay at room temperature results in the depression of gas production and crosslinks at room temperature in low‐density polyethylene containing propylfluorancene. Similar results were obtained in ethylen–propylene copolymer containing the same additive.
Structurally bound stabilizers: Melt grafting of UV stabilizers onto polypropylene, polyethylene, and polystyrene
Authors: Sharma Y. N. , Naqvi M. K. , Gawande P. S. , Bhardwaj I. S. 
Published: April 2003

AbstractMonomeric ultraviolet stabilizers, 2‐hydroxy‐4‐methacryloyloxy benzophenone and 2‐hydroxy‐4‐acryloyloxy benzophenone were synthesized by a modified process. These reactive UV stabilizers were grafted onto the backbone of polypropylene (PP), low‐density polyethylene (LDPE), and polystyrene (PS) by melt processing in the mixer of Brabender Plasticorder. An infrared spectroscopic method was standardized for the quantitative determination of the extent grafting of these additives on the polymer backbone. Grafting of both the additives occurred in the order PS > LDPE > PP. Methacryloxy derivative of benzophenone was found to be more reactive towards the polymers studied than the acryloxy derivative.
An interpolymer anionic composite reverse osmosis membrane derived from poly(vinyl alcohol) and poly(styrene sulfonic acid)
Authors: Koyama Kiyoshi , Okada Minoru , Nishimura Masato 
Published: April 2003

AbstractAn interpolymer anionic composite membrane for reverse osmosis was prepared from poly(vinyl alcohol) and poly(styrene sulfonic acid). The effects of composition of a casting solution, heat‐curing periods, and casting thickness on the reverse osmosis performance of resulted membranes have been examined. A mixture of water and ethyl alcohol (12/7, wt %) was found to be a proper solvent for casting an interpolymer membrane on the supporter. The composite membrane was formed by casting the polymer solution in ultrathin film on a microporous polypropylene supporter, evaporating the solvent, and heat‐curing at 120°C for a proper period. the optimum composition of a casting solution was as follows: wt % of poly(vinyl alcohol)/poly(styrene sulfonic acid)/solvent was 3/2/95. The membrane heat‐cured at 120°C for 2 h has a good performance for reverse osmosis, viz., water flux of 9.1–28.4 L/m2.h at salt rejection level of 88.1–93.4% under applied pressure of 80 kg/cm2 with 0.5% NaCl aqueous solution. The formation mechanism of a water‐insoluble membrane was discussed.
New epoxy resins. II. The preparation, characterization, and curing of epoxy resins and their copolymers
Authors: Chen C. S. , Bulkin B. J. , Pearce E. M. 
Published: April 2003

AbstractA polymer having high aromaticity and/or cyclic ring structures in the chain backbone usually gives high heat resistance and flame resistance. Five glycidyl ether‐type epoxy resins are prepared from bisphenol A (DGEBA), 9,9‐bis(4‐hydroxyphenyl)fluorene (DGEBF), 3,6‐dihydroxyspiro‐[fluorene‐9,9′‐xanthane] (DGEFX), 10,10‐bis(4‐hydroxyphenyl) anthrone (DGEA), and 9,9,10,10‐tetrakis(4‐hydroxyphenyl)anthracene (TGETA) in order to study structure–thermal stability–flame resistance property relationships. In this study, trimethoxyboroxine (TMB) and diaminodiphenylsulfone (DDS) are employed as the curing agents. The char yield at 700°C under a nitrogen atmosphere and the glass transition temperature (Tg) for the uncured resins decrease according to the sequence TGETA > DGEFX > DGEA > DGEBF > DGEBA. The Tg values for these cured epoxy resins are DGEBA < DGEBF < DGEFX < DGEA. A Tg for the TGETA is not obtainable but would be expected to be the highest. The char yields at 700°C of these cured epoxy resins have the same trend as the uncured resins. DGEBF, DGEFX, DGEA, and TGETA added to the DGEBA system show increases in the char yield, Tg, and oxygen index with increasing concentration of these novel epoxy resins.