bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separation of stat‐copoly(styrene/2‐methoxyethyl methacrylate) samples according to composition by gradient high‐performance liquid chromatography
Authors: Glöckner Gottfried , Stickler Manfred , Wunderlich Winfried 
Published: April 2003

AbstractStatistical copolymers of styrene (S) and 2‐methoxyethyl methacrylate (MEMA) (13–87 mass % of the latter monomer) were investigated by gradient HPLC on columns with either silica or CN‐bonded phase packings. The samples were injected in THF solution. The starting eluent was in each case a nonsolvent (isooctane or mixtures of isooctane with THF and methanol). Separation was achieved by increasing the concentration of THF or methanol in the eluent. A calibration mixture of four copolymers (26, 49, 62, and 87% MEMA) was investigated according to the principles of chromatographic cross‐fractionation (CCF) by size exclusion chromatography and subsequent gradient HPLC. The influence of molar mass on HPLC retention was small and, for the samples investigated by CCF, independent of copolymer composition. The composition effect on detector signal was also studied. At 230 nm wavelength and with MEMA content in the range between 20 and 40%, the effect was small and caused the average composition calculated from CCF results to deviate from the directly measured value by not more than 0.2 or 0.8% for the two copolymers investigated.
Effect of tetrabromobisphenol A diallyl ether on the flame retardancy of high impact‐strength polystyrene
Authors: Yang Chin‐Ping , Sheen Biing‐Shiow 
Published: April 2003

AbstractThe effect of tetrabromobisphenol A diallyl ether (TBBA–DAE) on the flame retardancy of high impact‐strength polystyrene (HIPS) was studied and compared with that of tetrabromobisphenol A (TBBA). Experimental results showed that the flame retardancy of TBBA–DAE was superior to that of TBA by thermomixing in the solid state. However, this phenomenon was not obvious by mixing in solution. This effect might result from the bromination of HIPS by the modified Claisen rearrangement of TBBA–DAE during thermomixing in the solid state. Simultaneous addition of the mixture of TBBA–DAE or TBBA with diphenyl isooctylphosphite (DPIOP) into HIPS caused a synergistic effect of flame retardancy and the effect of TBBA‐DAE was better than that of TBBA.
Differential scanning calorimetry study on intermolecular interactions in polymer–diluent blends involving polyisoprenes and dimethyl terephthalate
Authors: Ng S. C. , Chee K. K. 
Published: April 2003

AbstractThe classical expression for estimating the polymer‐solvent interaction parameter χ from melting point data of the solvent is refined by considering χ to be concentration‐dependent. Differential scanning calorimetry (DSC) measurements are performed on blends of cis‐polyiso‐prene‐dimethyl terephthalate (DMT) and trans‐polyisoprene–DMT. It is found that the presence of DMT would not affect the DSC events of the polyisoprenes appreciably. However, in both cases, the melting point of DMT decreases, and the rate of depression increases with increasing proportions of polymer. These DSC data are analyzed by the proposed procedure. The results on the interaction energy density parameter are presented as a function of the blend concentration, and rationalized by the specific interactions between different moieties on the component molecules. The limitations of the present technique are discussed.
Methylcentralite concentration profiles in monoperforated extruded nitrocellulose and nitrocellulose/nitroglycerine propellant grains by Raman microspectroscopy
Authors: Louden J. D. , Kelly J. , Phillipson J. 
Published: April 2003

AbstractRaman microscopy was used to determine the methylcentralite (MC) concentration profiles diffused into single‐base (nitrocellulose) (NC) and double‐based (nitrocellulose/nitroglycerine) (NC/NG) small‐arms propellant grains. External and internal concentration profiles were determined by measuring the concentration of MC relative to the NC and NC/NG at 5‐μm intervals into the grain from the edge inward and the perforation edge outward. The external profile was constant with a diffusion and interaction mechanism, i.e., a level concentration of deterrent through the outer region of the grain followed by a gradual dropoff in concentration with distance into the grains, whereas the internal profile was found to be dependent on perforation size with either a diffusion and interaction mechanism profile or a gradual decrease in concentration profile.
Ionomers: The sodium salt of poly(ethylene‐co‐methacrylic acid)
Authors: Han Keling , Williams H. Leverne 
Published: April 2003

AbstractA chemical method and an improved absorbance ratio method are presented to determine the degree of neutralization of poly(ethylene‐co‐methacrylic acid). Compared to the chemical method, the absorbance ratio method is simple and fast. It can be used also to determine the degree of neutralization when the chemical method is not suited to the system. By means of this absorbance ratio method, the influences of various reaction conditions on the rates of neutralization were observed. In the neutral system at the optimal water content a maximal rate of neutralization is obtained. The rate of neutralization is increased by increasing the temperature or the concentration of metal hydroxide or by decreasing the concentration of the copolymer.
Proton‐NMR studies of polyacetal copolymers
Authors: Ogawa Toshio , Ishitobi Wataru , Jinta Kazuya 
Published: April 2003

AbstractSequence length of ethylene oxide and the amount of end groups in polyacetal copolymers were determined using proton NMR. Peaks from ethylene oxide usually appear in the region from 3.5 to 3.8 ppm, when tetramethylsilane was used as the internal standard. These peaks were divided into three triad sequences, i.e., MEM, MEE, EEE (E = ethylene oxide, M = methylene oxide) by referring to several polymers of similar structure. The sequence length in a copolymer prepared from ethylene oxide was 1.37 and that from trioxocan was 2.00. Small peaks from end groups usually appear in the region higher than 3.5 ppm. The peaks from methoxy and ethoxy groups were easily detected and determined quantitatively. The peak from hydroxy groups was detected after acetylation of a copolymer, because the original sample did not give a distinct peak corresponding to that group. The number‐average molecular weight of the copolymer prepared from trioxocane was estimated from the content of methoxy, ethoxy, and hydroxy groups. The value thus obtained was consistent with that obtained by gel permeation chromatography.
Free‐radical transport from latex particles
Authors: Mead R. N. , Poehlein G. W. 
Published: April 2003

AbstractA rate constant for the diffusion of monomer radicals from latex particles is derived using the transport equations describing the generation, diffusion, and reaction of monomer radicals within the particles. Calculations for styrene emulsion polymerization show that this “desorption constant” accounts for nonuniform distribution of monomer radicals within the particle while some previously published theories do not. The difference in the desorption constant calculated with the model derived in this work and the “uniform concentration” models could be an order of magnitude when diffusivity of monomer radicals in the particles is small. The monomer radical transport theory is extended to emulsion copolymerization. Desorption rate constants accounting for nonuniform distribution of monomer radicals are derived for emulsion copolymerization.
Infrared attenuated total reflectance study of latex paint films exposed to aqueous sulfur dioxide
Authors: Xu J. R. , Balik C. M. 
Published: April 2003

AbstractFourier‐transform infrared/attenuated total reflectance (FTIR–ATR) has been used to investigate the effects of acidic deposition on latex paint films with and without a calcium carbonate extender additive. Paint films approximately 5 mils thick were exposed to aqueous SO2(pH 2.0) for various times by simple immersion. Rapid and complete removal of CaCO3 from the paint film was found to occur, and the kinetics of the removal process were monitored using both weight loss and FTIR–ATR measurements. Both methods revealed Fickian diffusion, with an apparent diffusion coefficient D = 1.84 × 10−9 cm2/s. Good agreement was obtained between D measured via FTIR–ATR and from the weight lost data. The mechanism of removal of CaCO3 from the latex paint films appears to be controlled by the rate at which water and other components of the aqueous SO2 solution can diffuse into the film.
Preparation of latex carriers for controlled release by concentrated emulsion polymerization
Authors: Kim Kyu‐Jun , Ruckenstein Eli 
Published: April 2003

AbstractSpherical latexes of submicron diameter containing a model hydrophobic herbicide, namely, 2‐(2,4‐dichlorophenoxy)‐propionic acid, were prepared by the concentrated emulsion polymerization method. A mixture of styrene, herbicide, and initiator was dispersed into a small amount of water (6% by volume based on the entire emulsion) containing surfactant, at room temperature. The heating at 40°C of the foam like gel thus obtained led to the formation of latexes containing the herbicide. It was found that the model herbicide dispersed in the polymer latex was released to water over a period of serveral weeks and that the amount released was strongly dependent upon temperature and latex concentration in water.
Studies on elastic hydrogel membrane. I. Effect of preparation conditions on the membrane performance
Authors: Hirai Toshihiro , Asada Yukio , Suzuki Takashi , Hayashi Sadao , Nambu Masao 
Published: April 2003

AbstractThe properties and the permeation characteristics of poly(vinyl alcohol) hydrogel membranes were investigated. The membranes have excellent elasticity and showed reversible compaction by operating pressure. The membrane performance was also changed reversibly by pressure, and was held stable at ambient temperature for more than 12 months. The hydrogel membrane was stable against temperature up to 40°C, and was melted down at 70°C. Rejection increased with operating pressure. In the case of 1% (w/w) aqueous solution of poly(ethylene glycol) whose degree of polymerization is 400, the rejection increased from 30 to 85% by changing operating pressure from 5 kg/cm2 to 60 kg/cm2. These results suggested the possibility for the pressure controlled fractionation of molecular weight.
Mechanical properties of UV‐cured urethane films
Authors: Nakazato S. , Amari T. , Yamaoka T. 
Published: April 2003

AbstractA series of novel photosensitive urethane oligomers was synthesized in which methacryloyl group was contained in the hard segment. The hard segment was prepared by reacting 4,4′‐diphenylmethane diisocyanate with glycerine mono methacrylate, which was successively reacted with three kinds of glycols involving 1,4‐poly(butadiene glycol), poly(propylene glycol), and poly(caprolactone diol). The mechanical properties of synthesized urethane oligomers after irradiating with ultraviolet light were evaluated to elucidate the effect of the molecular structure and the content of the hard segment on the mechanical property.
Interpenetrating polymer networks of polyurethane and polystyrene ionomers
Authors: Hsieh K. H. , Chou L. M. 
Published: April 2003

AbstractInterpenetrating polymer networks (IPNs) and linear blends of polyurethane (PUN) and poly(styrene–acrylic acid) (PSAA), which contain mutually opposite charge groups, i.e., tertiary amine and carboxyl groups, respectively, were synthesized through simultaneous bulk polymerization. Physical and mechanical properties of these IPNs and linear blends are discussed in the present paper. The tensile strength of both PUN/PSAA IPNs and linear blends has shown to increase with an increase of acrylic acid (AA) content in PSAA in any PUN/PSAA composition. A maximum value emerged in both polymer systems with 30 mol % AA in PSAA and the PUN/PSAA ratio of 25/75. A minimum swelling ratio as well as a maximum density was also observed in the IPNs and linear blends, respectively, related to this PUN/PSAA ratio. From dynamic mechanical analysis, two distinct relaxation transitions for the IPN or linear blend without AA in the system have merged into a single broad transition as the AA was introduced into PSAA. Two‐Phase morphology was observed from scanning electron microscopy studies for the polymer systems in the absence of charge groups; however, one‐phase morphology was observed when the charge groups were introduced.
Vapor phase photografting of methyl methacrylate on polymer films: Accelerating effects of solvent mixed with monomer
Authors: Kubota Hitoshi , Ogiwara Yoshitaka 
Published: April 2003

AbstractThe effects of solvent mixed with monomer on benzopheneone‐sensitized photografting of methyl methacrylate on polymer films were investigated in vapor phase at 60°C. The grafting on nylon 6 film was promoted by adding a pertinent quantity of solvent, such as phenol, m‐cresol, benzyl alcohol, and formic acid, to the monomer. The similar effects accelerating the grafting on polyester film were observed for solvent, such as m‐cresol, phenol, o‐chlorophenol, and nitrobenzene. Such an accelerating function of the solvents is supposed to originate in the swelling of the film substrates due to solvents. On the other hand, solvents such as n‐decane, decalin, and p‐xylene retarded the grafting on low density polyethylene and polypropylene films. The differences in the solvent effects by the types of film substrates are discussed in terms of photoinduced radicals on the substrates containing solvents.
Thermal degradation of a poly(vinyl formal)‐containing adhesive film on a polyethylene rubber surface. A photoacoustic fourier transform infrared spectroscopic investigation
Authors: Nguyen T. T. 
Published: April 2003

AbstractPhotoacoustic Fourier transform infrared (PAS/FT‐IR) spectra of an adhesive film containing poly(vinyl formal) (PVF) coated on a modified polyethylene (PE) rubber surface are reported, and their vibrational assignments proposed. The spectrum of PVF/PE/rubber closely resembled that of the adhesive itself, which was mainly dominated by intense and characteristic bands due to PVF. As found for the PVF compound, the formal group in the PVF polymer of the adhesive was deduced to exist mainly in the form of a six‐membered intrachain cyclic structure analogous to the m‐dioxane ring. The PVF/PE/rubber system was found to be thermally stable after storage at 20°C for more than 10 months and also unaffected by repeated temperature cycligs (−50 to 60°C). Thermal treatment in air at 60°C for 5 months, however, led to an almost complete loss of the adhesive film on the substrate, as evidenced by the disappearance of bands due to PVF. First‐order kinetic parameters were experimentally obtained for the loss of PVF on the rubber surface. The final thermal degradation products were identified as structures containing both carbonyl and olefinic groups. The degradation reactions were primarily a process of oxidation and crosslinking, which led to formation of an embrittled material as evidenced from visual inspection of the degraded film. The behavior of PVF in the adhesive/substrate system was very similar to the thermal degradation behavior of the compound PVF itself.
Periodate oxidation of cellulose by homogeneous reaction
Authors: Morooka Toshiro , Norimoto Misato , Yamada Tadashi 
Published: April 2003

AbstractHomogeneous periodate oxidation of cellulose was achieved through methylol cellulose. The dissolution of methylol cellulose into aqueous periodate solution was followed by the gradual decomposition of methylol groups at random sites along the methylol cellulose chain. The recovery of glycol hydroxyl groups at the C2 and C3 positions on the glucopyranose ring during the above decomposition process caused uniform cleavage of C2C3 bonds by the periodate ion. The oxidation level reached nearly 100% in 10 h. The reduced product of the resulting dialdehyde cellulose, i.e., dialcohol cellulose, resulted in mechanical properties quite different from those of conventional dialcohol cellulose. Examination of the thermal deformation and tensile properties revealed that no notable cellulose degradation occurred during the reaction. Our dialcohol cellulose gave a clear and transparent film with a flexible nature.
Rheological behavior of ultrahigh molecular weight polyethylene semidilute solutions. I. Solvent effect
Authors: Zhang Anqiu , Chen Kequan , Zhao Hentai , Wu Zongquan 
Published: April 2003

AbstractThe rheological behavior of ultrahigh molecular weight polyethylene (UHMWPE) semidilute solutions with different solvents has been studied. In a temperature range of 150–185°C, the viscosity of a UHMWPE semidilute solution with paraffin oil as solvent (soln 1) is more temperature‐independent and viscosity‐stable than that with decalin as solvent (soln 2). Usually the reduction of the molecular entanglement density in solution causes a rapid reduction in viscosity. Apparently soln 1 has a different entanglement density compared with soln 2. The activation energy of UHMWPE semidilute solutions changes with both shear stress and shear rate. The regressive equations for both solutions in between Eσ and σ or Eṙ and \documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma } $\end{document} have been obtained from a least‐squares method. Finally, there is a discontinuity in the non‐Newtonian flow region of η vs. \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} curve, no matter which temperature or solvent was used. The discontinuity occurs at a shear rate of about 70 s−1, where a transformation from a qualitative change in entanglement in the solution takes place.
Effect of branching of polyolefin backbone chain on catalytic gasification reaction
Authors: Ishihara Yumiko , Nambu Hidesaburo , Ikemura Tadashi , Takesue Tomoyuki 
Published: April 2003

AbstractA basic study on the catalytic gasification of polyolefins such as PE and PP, which account for a major part of general waste plastics, was conducted in order to develop a technique for effective recycling of these wastes. In the case of PE, the gasification of PE is considered to consist of the following scheme: polymer → catalytically degraded polymer → catalytically degraded oligomer → liquid component → gas component. The gasification of PE does not occur directly from the polymer chains, but gaseous C4 substances are selectively found from the liquid components with the highest branching frequency. The overall yield of C4 components including isobutane was 74.5 and 60.5% molar for PE and PP. These liquid components (gasification precursors) have the branching frequencies. For example, a molecule with M̄w of 400 contains about eight branches for every 30 methylenes. From the catalytic gasification of PE, PP, and PIB, the gas conversion rate is also found to increase with increasing frequency of the backbone branching. It is concluded that the branching frequency is the key factor governing the gas conversion rate of polyolefins.
Plasticizer transfer from plasticized poly(vinyl chloride) sheets to petroleum oils
Authors: Papaspyrides C. D. , Duvis T. 
Published: April 2003

AbstractPlasticizer migration from poly(vinyl chloride) remains a critical problem due to the high consumption of this polymer in a flexible form. The systems poly(vinyl chloride) (PVC)/labeled dioctyl phthalate (DOP)/white spirit, kerosene, white oil, or lubricating oil have been considered in this article. Migration experiments were carried out at three different temperatures (30, 50, and 70°C) for extremely prolonged periods of time. At the initial stages the data collected fit well to short‐term Fickian behavior. The respective diffusion coefficients increase with temperature, conforming also to an Arrhenius form, but the eventually obtained migration values seem to pass through a minimum in the case of the lighter oils.
Mechanical behavior of polyblended polystyrene and ethylene–propylene–diene rubber by cationic reactions in the melt
Authors: Shaw S. , Singh R. P. 
Published: April 2003

AbstractAttempts have been made to obtain high impact polystyrene by Lewis‐acid‐initiated degradation process in the melt reactions of PS and EPDM. It is found that impact strength improves whereas tensile strength decreases. This can be interpreted by the increased solubility of the coupled rubber molecules in the continuous phase.
Synthesis and characterization of imide end‐capped oligomers of poly(diethyleneglycol terephthalate)
Authors: Acevedo M. , de la Campa J. G. , de Abajo J. 
Published: April 2003

AbstractA series of imide end‐capped oligoesters were prepared by reacting a number of hydroxylterminated poly(diethyleneglycol terephthalate) oligomers (X̄n ranging from 1 to 20) with N‐(4‐chlorocarbonylphenyl)maleimide and N‐(4‐chlorocarbonylphenyl)nadimide. All the oligomers were characterized by vapor pressure osmometry, 1H‐ and 13C‐NMR and GPC. The thermal properties were also investigated and a correlation of the thermal behavior with molecular weight and the type of reactive end groups was established. Molecular models were also synthesized and characterized to obtain reliable analytical data for the determination of the oligomers composition.
Plasticized poly(vinyl chloride)/dioctyl phathalate/petroleum oils: Plasticizer migration vs. liquid penetration
Authors: Papaspyrides C. D. 
Published: April 2003

AbstractPreviously presented migration data on the systems poly(vinyl chloride) (PVC)/labeled dioctyl phthalate (DOP)/white spirit, kerosene, white oil, or lubricating oil are now combined with liquid penetration results. Liquid penetration was found to be significant for the lighter oils while the white oil and the lubricating oil practically seem not to penetrate at all. In accordance with previous investigators this penetration phenomenon was proved to consist of a sorption step up to a point, followed by a desorption step. Both steps were considered separately but the desorption data failed to fit the short‐term Fickian approximation. On the other hand, in order to explain the minimum observed, as temperature increases, of the migration equilibrium values, it is proposed a polymer structure rearrangement to a more compact scheme at the later stages of the immersion experiments. For this rearrangement both temperature and liquid penetration seem to comprise contributing factors.
Plasma polymerization of perfluoro‐2‐butyltetrahydrofuran/methane and perfluorobezene/tetrafluoromethane mixtures and gas permeation properties of the plasma polymers
Authors: Inagaki N. , Tasaka S. , Murata T. 
Published: April 2003

AbstractPlasma polymer films prepared from perfluoro‐2‐butyltetrahydrofuran (PFBTHF) and perfluorobenzene (PFB) were investigated by elemental analysis, infrared spectroscopy, and ESCA. The gas separation properties were also investigated to seek plasma polymer films with good permselectivity. Plasma polymer films from PFBTHF and PFB were composed of polymer chains with fluorinated moieties such as C–CFn, CF, CF–CFn, CF2, and CF3 groups. Changes in the afcurrent as an operating condition for plasma polymerization showed less influence on the distribution of the fluorinated moieties but more influence on the permselectivity of the plasma polymer films formed. The permselectivity was improved by plasma polymerization in the PFBTHF/CH4 or PFB/CF4 mixture systems. The PO2/PN2 ratio for the plasma polymer films prepared from PFBTHF/CH4 and PFB/CF4 mixtures increased from 3.1 at 0 mol % CH4 to 4.0 at 50 mol % CH4 addition, and from 4.1 at 0 mol % CF4 to 5.0 at 25 mol % CF4 addition, respectively. The permselectivity of the plasma polymer films may be related to the crosslinkage and aggregation of polymer chains rather than the elemental composition.