bluuebunny/crossref_metadata_2025 huggingface dataset:
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

The 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

A 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

Interpenetrating 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

The 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

Photoacoustic 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

Homogeneous 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

The 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

A 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

Plasticizer 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

Attempts 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

A 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

Previously 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

Plasma 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.
Effect of gamma‐radiation on a water‐insoluble arabinoxylan
Authors: Ebringerová Anna , Pružinec Jozef , Kačuráková Marta , Hromádková Zdenka
Published: April 2003

The effect of gamma radiation on a water‐insoluble L‐arabino‐D‐xylan has been studied by functional group and structural analysis using chemical methods and IR spectroscopy, by sugar composition analysis, and by viscosity measurements. The gamma irradiation has been shown to modify both sugar components of the arabinoxylan, accompanied by cleavage of the glycosidic linkages, depolymerization, and sugar decomposition, depending on the applied radiation dose, thus increasing the molecular and chemical heterogeneity of the polysaccharide.
Preparation and properties of graft copolymers of vinyl chloride on atactic polypropylene
Authors: Schellenberg J. , Hamann B.
Published: April 2003

The possible uses of atactic polypropylene as the basis of grafting for the preparation of graft polymers of vinyl chloride are studied. Graft parameters and glass transition temperatures of the graft products obtained are specified at different compositions of the graft products. After blending the graft products with pure poly(vinyl chloride) or ABS/poly(vinyl chloride) blends, some application‐related properties are discussed with respect to the grafting degree and the amount of graft product contained.
Solution processing of composite fibers containing rodlike and thermoplastic polymers
Authors: Gabriel Carmen A. , Farris J. , Malone Michael F.
Published: April 2003

The solution processing and mechanical properties made from blends of the rodlike polymer poly(p‐phenylene benzobisthiazole) with either poly(ether ether ketone) or nylon 6,6 is described. The concentration dependence of the isotropic‐nematic phase transition for solutions of these polymers in methane sulfonic acid is in qualitative agreement with a theory of Flory. The mechanical properties of fibers that were wet spun from isotropic solutions of poly(ether ether ketone) and poly(p‐phenylene benzobisthiazole) are very sensitive to the concentration of the spinning solution. Fibers spun at concentrations near the isotropic‐nematic phase boundary have poor mechanical properties, resulting from phase separation during coagulation. However, when the solution concentration is significantly below the critical value, stiff and strong fibers are produced. In contrast, when nylon 6,6 is used as the thermoplastic component, the mechanical properties are good and are insensitive to the solution concentration. We attribute the solution concentration effects to two factors. The first is the difference in the solubility of poly(ether ether ketone) and nylon 6,6 in methane sulfonic acid‐water mixtures. The second is the connectivity of the nematic phase, which also depends on concentration and has a major impact on the mechanical properties of the resulting fiber.
Loop polymerization of vinyl acetate
Authors: Bataille P. , Dalpé J. F.
Published: April 2003

The emulsion polymerization of vinyl acetate was studied using a loop reactor. The results were compared with some earlier work done in a batch reactor. A parallel was drawn with the results obtained with a tubular loop reactor and with a continuous reactor using styrene as monomer. The same phenomena of the optimum conversion peak with styrene at the laminar turbulent flow transition zone also occurred for the vinyl acetate. The peak obtained in this case was, however, broader and in the lower turbulent zone. The effect of the surfactant concentration on the broadness of the peak is discussed.
Effect of γ‐irradiation and temperature on the structure of metal chloride‐treated poly(vinyl alcohol)
Authors: Rabie S. M. , Abdel‐Hakeem Nagwa , Moharram M. A.
Published: April 2003

The infrared and ultraviolet spectra of poly(vinyl alcohol) (PVA) treated with ferric chloride and zinc chloride were recorded. Careful examination of the infrared spectra revealed that these treatments cause significant changes in the crystallinity of PVA, particularly in the case of the treatment with ZnCl2. The results showed that exposure of untreated and FeCl3‐treated PVA to 12 or 28 Mrads results in no observable changes in their ultraviolet and infrared spectral features, whereas exposure of ZnCl2‐treated PVA at the same dosages, results in the appearance of an absorption band at 1595 cm−1 corresponding to β‐diketone groups. It was also found that γ‐irradiation of ZnCl2‐treated PVA produces a remarkable change in its crystallinity. Moreover, the effect of heat on the spectral features of the ZnCl2‐treated PVA was discussed. It was found that the treatment of PVA with ZnCl2 helps in oxidative degradation of PVA.
Surface analysis by ESCA of sulfite post‐treated CTMP
Authors: Barry A. O. , Koran Z. , Kaliaguine S.
Published: April 2003

Handsheets of post‐treated chemithermomechanical pulps (CTMP) and a sample of Whatman paper no. 1 were analyzed using an ESCA spectrometer. All of these samples revealed the presence of the C1, C2, and C3 components in the carbon (1s) peak and the O2 component in the oxygen (1s) peak; the O1 peak component which was present in the other samples was missing from the Whatman paper. Pulp sulfonation produced a reduction in C1 representing the group of carbon not bonded to oxygen, and an increase in C2 with C3 remaining relatively constant. These changes imply reductions in lignin and extractives and a corresponding increase in cellulose content on the fiber surface. Extrapolation of the C1, C2, C1/C2, and O/C curves of CTMP to zero percent sulfonation yielded the same values as those obtained for pure TMP. ESCA analysis allows us to monitor the increase of sulfur content as a function of sulfonation in accordance with results obtained from bulk pulp sulfonate content titration.
Interaction of some solutes with certain cationic polymers and its effect on film permeability
Authors: Okor R. S.
Published: April 2003

Permeabilities of cast films of certain cationic acrylate methacrylate copolymers have been determined using a double (donor and acceptor) compartment cell. Permeation rates of urea (nonionic permeant) and sodium chloride (ionic permeant) were determined as functions of the polymer cation content. A decrease in film permeability accompanied the decrease in polymer cation content generally; the change was more marked with sodium chloride compared with urea. The films were also generally more permeable to urea; the difference increased at lower polymer cation content to about 400‐fold. While urea promoted film swelling, sodium chloride decreased it. Electron micrographs of the film section displayed compact skin zones which must be swelled to allow solute permeation. Asymmetry characterized the flux, the film lower surface (in contact with the mold during casting) being more permeable than its upper surface. This effect was more pronounced when sodium chloride was used as permeant.
Studies on adhesive monomers for teeth. V. Influence of substituents in methacrylamide derivatives
Authors: Kitoh Shinya , Miyake Mikio , Hayashi Satoshi , Kurita Keisuke
Published: April 2003

In order to shed light on the relationship of monomer structure and adhesiveness to tooth enamel, methacrylamides having various substituents were synthesized and evaluated as dental adhesives. Among 17 methacrylamides synthesized here, those having N‐m‐ and N‐p‐carbethoxyphenyl, N‐p‐fluorophenyl, and N‐3‐carboxycyclohexyl groups showed adhesive tensile strength of more than 100 kg/cm2 with minimal drops in strength on standing, indicating high potentials as novel adhesives. It was also confirmed that a carboxyl group enhances adhesive tensile strength peculiarly regardless of skeletal structures.
Effects of resole phenol adhesives on the crystallinity of cellulose
Authors: So Solomon , Teh J. W. , Rudin Alfred , Tchir William J. , Fyfe Colin A.
Published: April 2003

Resole phenolic resins are widely used for gluing wood structures. Solid state 13C‐NMR and wide angle X‐ray scattering experiments show that a typical resole adhesive disrupts some of the crystallinity of the cellulose. Several explanations are offered for this observation. It is possible that this effect is connected with the adhesive action of the phenolic polymer. If this is so, then measurements of the type described here could be used to understand the adhesion better and to develop better wood glues.
Hydrolytic degradation of melt‐extruded fibers from poly(β‐propiolactone)
Authors: Mathisen Torbjörn , Albertsson Ann‐Christine
Published: April 2003

β‐Propiolactone was polymerized in bulk at 5°C using pyridine as initiator. The melt spun fibers were drawn at 50°C and subjected to degradation, which was monitored by mechanical, thermal, and molecular weight measurements. The hydrolytic degradation of poly(β‐propiolactone) fibers has been investigated in a buffered salt solution (pH 7.2) maintained at 37°C. The degradation was found to be very rapid during the first 90 days of immersion, with respect to mechanical properties and the weight average molecular weight. Between 90 and 180 days there were no significant changes in the mechanical properties which, however, rapidly decreased thereafter and finally reached zero at 240 days. The crystallinity seemed to increase in a linear fashion, during the same period, from about 55 to 70%.
Synthesis of bioactive 2,2‐dichloropropionic acid esters of carboxymethyl cellulose and investigations on their release behavior
Authors: Schnabelrauch Matthias , Geschwend Günter , Klemm Dieter
Published: April 2003

Polymer bound bioactive agents are prepared by linking 2,2‐dichloropropionic acid to the hydroxyl groups of carboxymethyl cellulose (CMC) and enzymatically cleavable CMC networks, and to the carboxyl groups of CMC via enzymatically cleavable spacer units using a simple as well as effective CMC activation procedure. The hydrolytic release of the bioactive agent is mainly dependent on the hydrophilicity of the CMC esters. In the case of polymers containing enzymatically cleavable structural units the release can be accelerated by addition of esterases.
Polyesters containing sulfur. I. Products of melt polycondensation of diphenylmethane‐4,4′‐di(methylthioacetic acid) with some diols
Authors: Kultys Anna , Podkoscielny Wawrzyniec
Published: April 2003

Several new polyesters containing sulfur in the main chain were obtained by melt polycondensation of diphenylmethane‐4,4′‐di(methylthioacetic acid) with ethanediol, 1,3‐propane diol, 1,4‐butanediol, 1,5‐pentenediol, 1,6‐hexanediol, 1,2‐propanediol, and 2,2′‐oxydiethanol. The structure of all polyesters was determined from elemental analysis and infrared (IR) spectra. Yield, reduced viscosity, molecular weight, and softening temperature for reaction products have been found. Initial decomposition and initial intensive decomposition temperature were defined from the curves of thermogravimetric analysis.
Grafting of the acrylic acid on poly(ethylene terephthalate)
Authors: Osipenko I. F. , Martinovicz V. I.
Published: April 2003

A study has been made of the effect of solvent nature, concentrations of monomer, initiator and homopolymerization inhibitors, and initial polymer structure on the modification of poly(ethylene terephthalate) (PET) films and fibers by grafting the acrylic acid (AA). AA grafting initiated by radicals formed from thermal decomposition of benzoyl peroxide. It has been established that preswelling of PET in dichloroethane leads to changes in its sorption–diffusion properties and favors an increase in the degree of grafting. Addition of the Fe(II), Ni(II), and Cu(II) salts to AA solution decreased homopolymer yield. The studied process of grafting can be described by equations of diffusion kinetics. Distribution of the poly(acrylic acid) (PAA) over the cross section of samples and a number of physical and chemical properties depend also on conditions of performing the graft polymerization.
Crosslinking studies of polyether–ester‐based polyurethane systems
Authors: Kothandaraman H. , Venkatarao K. , Thanoo B. Chithambara
Published: April 2003

Ether‐ and ester‐based prepolymeric diols suitable for polyurethane elastomer formation were prepared from polyoxytetramethyleneglycol and polyoxytetramethylene–oxypropyleneglycol with dicarboxylic acids like adipic acid, maleicacid, and phthalic acid. Crosslinked polyurethane elastomers were prepared from these prepolymers using various concentrations of trimethylolpropane as a crosslinker and toluenediisocyanate as the curing agent. Crosslinked polyurethanes were also prepared by a method taking excess toluenedisocyanate other than that of the stochiometric requirement and curing it at a comparatively higher temperature. The data on mechanical properties of these elastomers show that both methods of crosslinking in polyurethane imparts a similar effect on mechanical properties.
Preparation of hydrogel beads from crosslinked poly(methyl methacrylate) microspheres by alkaline hydrolysis
Authors: Thanoo B. Chithambara , Jayakrishnan A.
Published: April 2003

Poly(methyl methacrylate)/(PMMA) microspheres crosslinked with various concentrations of ethylene glycol dimethacrylate (EGDM) were prepared by a suspension polymerization procedure. They were subjected to alkaline hydrolysis in ethylene glycol at high temperature (> 175°C), resulting in the rapid conversion of methacrylate ester functions to methacrylic acid, while retaining the spherical shape of the microspheres intact. The method provides a novel approach to obtain smooth, nearly perfect spherical, mechanically strong, high water‐absorbing hydrogel beads from crosslinked PMMA. The reaction has been found to be considerably faster than many of the hydrolysis procedures reported previously. The effect of concentration of alkali, particle size, crosslinking density, and reaction time on the extent of hydrolysis has been investigated to a limited extent.
Evaluation of some side effects from the use of formaldehyde scavengers
Authors: Vail Sidney L. , Beck Keith R.
Published: April 2003

Concentrations of methylol carbamates in several crosslinking formulations prepared from methyl carbamate and formaldehyde and with and without urea or ethyleneurea as scavengers were determined by nuclear magnetic resonance spectroscopy. The scavengers were effective in reducing the free formaldehyde in the solution, but the dimethylol methyl carbamate concentration was reduced by about 25%. Selected chemical and physical properties were obtained from cotton fabrics finished with five different formulations of known composition. Fabric strengths were improved by use of a scavenger, but some undesirable side effects were observed.
Dielectric constant, optical transmission, and thermal diffusivity monitoring of iodine‐impregnated polystyrene films
Authors: Leite N. F. , Franzan A. H. , Torres‐Filho A. , Miranda L. C. M.
Published: April 2003

A simple method for the iodine doping of atactic polystyrene films is described. The marked changes in the physical properties of the polystyrene films, such as dielectric constant, optical absorption coefficient, and thermal diffusivity, are presented as a function of the doping time. The results show strong evidences of the onset of an order–disorder transition as a function of the doping time.
Structure investigations on drawn high‐density blown PE films
Authors: Hofmann D. , Geiss D. , Janke A. , Michler G. H. , Fiedler P.
Published: April 2003

The supermolecular structure of blown HDPE films, which were obtained by a combination of film blowing under a very low blowup ratio and slow takeoff velocity with subsequent uniaxial drawing, is characterized using WAXS texture and profile analysis, EM and mechanical investigations. Samples with low uniaxial drawing ratios (λ ≲ 1.5) contain low stress crystalline and transcrystalline material and show an a‐texture, while samples with higher uniaxial drawing ratios only consist of high stress crystalline material and show a c‐texture. With one exception the results of texture investigations can be related to the results of the mechanical investigations.
Studies of latex paint films exposed to aqueous SO2: pH effects
Authors: Xu J. R. , Balik C. M.
Published: April 2003

Latex paint films containing the acid‐soluble extender calcium carbonate have been exposed to aqueous SO2 and other acidic solutions to evaluate the effects of acidic deposition at different pH values on the coatings. CaCO3 is completely removed from these films upon immersion in acidic solutions. The leaching process was monitored with weight loss and infrared measurements. The removal rate was found to be strongly dependent on pH, decreasing with increasing pH. Removal of CaCO3 occurs even for distilled water which has been allowed to equilibrate with atmospheric CO2 (pH 5.6). The removal rate seems to depend only on [H+]; the identity of the acidic anion is apparently insignificant. An empirical relation between the rate of removal and pH was formulated from the weight loss data. The analyses of the results from both weight loss and infrared methods suggested that the mechanism of removal at pH 2.0 is diffusion controlled, whereas a chemical reaction involving H+ becomes more important at higher pH values.
A consideration of secondary electron emission from organic solids
Authors: Kishimoto Yoshio , Ohshima Tsutomu , Hashimoto Masashi , Hayashi Tomonao
Published: April 2003

The behavior of the secondary electron emission (SEE) from organic solids has been considered. It has been shown that the maximum SEE yields of many hydrocarbon compounds exponentially depend on the extinction coefficient of secondary electron defined by the π‐electron fraction in molecule, which is correlated to Dionne's theoretical equation. The concept that the extinction coefficient of secondary electron is represented in terms of the fraction of the delocalized and low energy‐gap electron‐like π‐electron will be convenient for a rough estimation of the SEE yield of other various materials. On the other hand, a novel universal equation representing the normalized SEE yield curve has also been proposed in this paper, by which an analysis of the normalized SEE yield curves of many organic solids have been tried.
The effect of bisphenol monomer structure on the gas permeability of aromatic polycarbonates
Authors: Schmidhauser John C. , Longley Kathyrn L.
Published: April 2003

Permeability measurements for oxygen and, to a lesser extent, carbon dioxide were carried out on a series of 24 structurally different aromatic polycarbonates. Polymers were prepared from bisphenols bearing substituents on the aromatic rings and/or the central aliphatic carbon atom. A strong correlation between monomer structure and polymer permeability was found, with gas transport rates varying by over two orders of magnitude between the most and the least permeable materials. In addition, a semilogarithmic relationship was found between oxygen transmission rates and monomer composition for two series of copolycarbonates. Of several methods explored, an excess free volume model was found best able to relate the experimental permeability values to the polymer molecular structure.
Analysis of branched poly(ethylene terephthalate)
Authors: Weisskopf Klaus
Published: April 2003

Poly(ethylene terephthalate) modified with 1,1,1‐trishydroxymethyl propane (THP) and pentaerythritol was analyzed with respect to branching by combined GPC/viscometry measurements. The average effective functionality of the branching molecules was calculated and compared with the theoretically attainable functionality, thus permitting one to distinguish between different branching theories. Maximum effectiveness was achieved only at low concentrations of the modifiers added. Pentaerythritol and THP were found equivalent in the ratio 1 : 3, estimated from their influence on the polydispersities of the branched polyester. It was shown that apparent molecular weights obtained from GPC calibration with linear standards can be converted by correction factors. The resulting molecular weight averages of the branched PET samples were in a good agreement with those from the GPC/viscometry iteration procedure.
Effect of temperature on gas permeation of polymer blends. I. Poly(ethylene oxide)/copolyester–polyurethane
Authors: Qipeng Guo , Hechang Xu , Dezhu Ma
Published: April 2003

The transport behavior of H2, N2, and CO2, was studied for blends of poly(ethylene oxide) (PEO) with a copolyester–polyurethane (PU) at various temperatures from 20 to 80°C. It was found that there was an abrupt change in slope or discontinuity around the melting point of PEO in Arrhenius plot of the permeability vs. temperature. The relationships between the logarithms of gas permeability and blend composition were strongly dependent on the temperature and showed very different shapes at temperature below and above the melting point of PEO. The activation energy of gas permeation for the blends had different values below and above the melting temperature of PEO.
Determination of additives in biomer and lycra spandex by pyrolysis tandem mass spectrometry and time temperature resolved pyrolysis mass spectrometry
Authors: Richards Joseph M. , McClennen William H. , Meuzelaar Henk L. C.
Published: April 2003

Pyrolysis mass spectrometry (Py‐MS), time/temperature resolved Py‐MS (TTR‐Py‐MS), and pyrolysis tandem mass spectrometry (Py‐MS/MS) were used to determine the structure of an additive present in Biomer and Lycra Spandex. The additive was found to form a second phase in the polymer matrix which was insoulble in N,N′‐dimethylacetamide. This insoluble portion (7% by weight) was separated by centrifugation. The structure of this additive is proposed to be poly(2‐diisopropyl amino ethyl methacrylate)(DPA‐EMA). The additive is present as a stabilizer for UV radiation and chloride and hypochlorite ion attack. A chloride containing compound of similar structure (2‐diisopropyl amino ethyl chloride) (CAS No. 96‐79‐7) is also detected. This chloride‐containing compound may be formed by reaction of the polymeric additive with chloride ions during storage or pyrolysis.
Capillary flow properties of thermotropic hydroxypropylcelluloses
Authors: Fujiyama Mitsuyoshi
Published: April 2003

The influences of molecular weight, temperature, and shear rate on the capillary flow properties of thermotropic hydroxypropycelluloses have been studied. The crystalline/liquid crystalline transition temperature and the temperatures at which the liquid crystalline/isotropic transition begins and ends are higher as the molecular weight is higher. The flow curves show yield stresses and, contrary to general thermoplastic resins, the slope of log(viscosity)–log(shear rate) curve decreases as the shear rate increases. This tendency is more notable as the molecular weight is higher. The temperature change of the viscosity shows a minimum and the minimum moves to a higher temperature with increasing shear rate. The moving rate is higher as the molecular weight is higher. This is because the molecular orientation of the isotropic phase increases with increasing shear rate. Contrary to general thermoplastic resins, the molecular weight dependence of the viscosity increases with increasing shear rate. The yield stress is higher as the molecular weight is higher and shows a minimum at 200–210°C. The molecular weight dependence of the entrance pressure loss is higher than that of the viscosity. The end correction coefficients of the hydroxypropylcelluloses are very much higher than those of general thermoplastic resins: They exceed 50 in some cases. The temperature change of the end correction coefficient shows a maximum and the temperature at the maximum is higher as the molecular weight is higher. The die swell ratio shows a minimum at 180–220°C at low shear rates and the minimum swell ratio is lower than unity in some cases. The die swell ratio is higher as the molecular weight is increased.
The effect of carbon surface functionality on tetrafunctional epoxy resin–diaminodiphenylsulfone cure reactions
Authors: Wang Shiping , Garton Andrew , Stevenson William T. K.
Published: April 2003

Acidic functionality on the surface of oxidized carbon blacks modifies the cure processes of the tetrafunctional epoxy resin MY720 (largely tetraglycidyldiaminodiphenylmethane, TGDDM) crosslinked with diaminodiphenylsulfone (DDS). In the early stages of the cure (up to 60 min at 140°C), the rate of consumption of TGDDM and DDS and the rate of production of the 1 : 1 adduct are increased, together with an increase in the production of ether functionality. These chemical changes are associated with an increase in exotherm. an increase in gel fraction, and preferential adsorption of the amine curing agent on the carbon surface. During the middle stages of the cure (after 180 min at 140°C), the acidic carbon black has a slight retarding effect on the cure; but, on completion of the later stages of the cure, the effect of the carbon surface functionality diminishes, and, in contrast to earlier studies with difunctional epoxy resins, neither the total cure exotherm nor the final glass transition temperature is affected greatly. We attribute this difference to the greater ease of etherification reactions for the tetrafunctional resin compared to the difunctional case. Basic functionality on the surface of carbon black (induced by carbon dioxide treatment) has a slight retarding effect on TGDDM consumption in early stages of the cure. Less adsorption occurs on the basic carbon than on the acidic carbon, and the adsorbed material appears to be rich in resin. These results imply that treated carbon surfaces may advance or retard the local cure state of an MY720–DDS matrix, but will not affect markedly the final cure state.
Toughening of SMA copolymers with an SAN‐grafted rubber
Authors: Kim J. H. , Keskkula H. , Paul D. R.
Published: April 2003

Styrene/maleic anhydride (SMA) copolymers were toughened by blending with a styrene/acrylonitrile (SAN) grafted rubber. The AN content of the SAN graft was fixed at 22.5% and the MA content of the SMA matrix was varied from 8 to 25%. The maximum impact strength was observed for blends based on SMA copolymers containing 14–17% MA (depending on the rubber content). These compositions are near the boundary of miscibility between the SMA matrix and SAN graft since miscibility of SMA and SAN occurs when the MA and AN contents are about the same in each Dilatational processes were shown to be the major mechanism of defor‐mation for these blends. Scanning electron microscopy was used to observe fracture surfaces as the miscibility between SMA and SAN or as the rubber content was changed. Toughening of miscible SMA/SAN matrices by this impact modifier was also examined. The results are discussed in terms of a variety of possible contributing factors including the coupling of the rubber to the matrix via miscibility of the latter with the SAN graft.
A study of some linear aliphatic nylons by thermally stimulated creep
Authors: Tang Henry H. Y. , Williams H. Leverne
Published: April 2003

The mechanical behavior of nylons 6,66,666,610,612,11 and 12 was studied using the method of thermally stimulated creep at 96°C. The resultant creep moduli were calculated. The strain recovery and strain recovery rates were measured and the retardation time spectra calculated as a function of temperature. The effects of humidity on the creep and subsequent recovery behavior were compared using samples conditioned to 0, 33, and 97% relative humidity at room temperature.
Two‐stage drawing of acetone treated poly(ethylene terephthalate) fibers
Authors: Ito Masayoshi , Miya Hisakazu , Watanabe Miho , Kanamoto Tetsuo
Published: April 2003

Acetone‐treated fibers of poly(ethylene terephthalate) were drawn by a two‐stage drawing technique: cold‐drawing at 25°C followed by hot‐drawing at 230°C by tensile force. The maximum achievable draw ratios (TDRs) for the treated and the untreated original fibers were 11.5 and 9.5, respectively. The highest modulus and strength of 28 and 1.2 GPa, respectively, were obtained by drawing the treated fibers with the highest TDR. These values were about 20% higher than those for the untreated drawn fibers with the highest TDR. Although annealing of the untreated drawn fibers under tensions singificantly improved the tensile modulus up to the maximum modulus for the treated drawn fibers, the tensile strength of such annealed fibers decreased remarkably due to the degradation occurring during annealing. The crystallinity of the drawn sample from the treated fiber was higher than that from the untreated fiber, leading the former to a higher structural stability against heat than the latter. These results were explained by the existence of small and/or less perfect crystals in the treated fibers induced by acetone.
Polyamic acid interactions with aminopropylsilane surface conditioners on metal
Authors: Linde H. G.
Published: April 2003

Grazing incidence infrared analysis reveals that metal surfaces of Ag, Al, Cu, Cr, and Al/Cu or Al/Cu/Si alloys interact with APS solutions of natural pH (10.4) to produce passivating siloxane films. These films restrict polyamic acid interaction with metal and amine functionalities, so that covalent attachment of the amic acid to the surface, through the adhesion promoter, does not occur. Instead, imidization appears to proceed in a normal fashion above a siloxane interfacial region which is coordinated to the metal surface by amine‐metal interactions.
Pervaporation separation of water/ethanol mixtures through polysaccharide membranes. V. The relationships between the permselectivity of chitosan salt membrane and its solid state structure
Authors: Mochizuki Akira , Amiya Shigetoshi , Sato Yoshio , Ogawara Hisashi , Yamashita Shuzo
Published: April 2003

The separation of water/alcohol mixtures through chitosan salt membranes was investigated. When neutralized by sulfuric acid, the separation factor increased to over 1000, but neutralized by hydrochloric acid, it was at most 50. The difference was mainly explained not only by the contraction of the “hole” due to the conformation change of chitosan molecule but also by the mobility of chitosan molecule which would correspond to the fluctuation of the “hole” size. The conformation change and the mobility of chitosan molecule were meaśured using CP/MAS 13C‐NMR. The spin–lattice relaxation time reflects the mobility of chitosan molecule. The results of the spin–lattice relaxation time obtained from NMR indicated that the mobility of chitosan sulfate was not affected much by the neutralization degree, but the mobility of the hydrochloride was markedly affected. The difference of the selectivity in these membranes could be explained by these results.
Surface‐modified polysulfone hollow fibers. II. Fibers having CH2CH2CH2SO3− segments and immersed in HCI solution
Authors: Higuchi Akon , Iwata Noboru , Nakagawa Tsutomu
Published: April 2003

Polysulfone ultrafiltration hollow fibers were chemically modified on the surfaces with propane sultone and SnCI4, and immersed in HCI solution subsequently. The immersion of the fibers in HCI solution yielded lower molecular weight cutoff of the fibers than those without the immersion. The fiber, denoted as HP‐SB‐17H, rejected 5% of raffinose at feed concentration = 0.5 wt % and 14% of NaCI at the feed concentration = 0.0025 wt %. The rejection of NaCI for HP‐SB‐17H was found to increase with the decrease of the feed concentration, and showed the tendency of Donnan exclusion. The effective fixed charge density was estimated to be 7.74 × 10−4 eq/L for the fiber. Absorption of poly(ethylene glycol) and bovine serum albumin at pH 7.0 on nonmodified and modified fibers was estimated from the ratio of Jη/J0η0, where J is flux, η is viscosity, and the suffix zero shows the values of pure water. The modified fibers with the propane sultone showed better results of antiabsorption than the nonmodified and conventionally sulfonated fibers in this study. This was attributed to the high flexibility of a sulfonated group originating from the existence of a joint segment of (‐CH2‐)3 in the modified fibers.
Alumina fibers from poly[((3‐ethoxypropanoyl)oxy)aloxane]
Authors: Morita Hisao , Yamane Hideki , Kimura Yoshiharu , Kitao Toshio
Published: April 2003

Alumina fibers were obtained from the poly[((3‐ethoxypropanoyl)oxy)aloxane] (P‐3EPA) by using a polymeric precursor technology. The rheological properties of the concentrated solution of P‐3EPA related to the extrusion and spinning processes have been investigated to determine the processability into fine filaments. Thirty weight percent P‐3EPA dissolved into toluene showed an excellent spinnability and fine filaments of 20–30 μm in diameter were easily obtained. The phase changes during the sintering of the fiber were studied with wide‐angle X‐ray diffraction and were shown to be strongly related to the mechanical properties of the fiber. Further the addition of the ethyl silicate (ES) as a sintering agent which prevent the crystal growth of Al2O3 was found to be effective to improve the mechanical properties of the alumina fiber.