bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of water‐soluble polymers using hydrodynamic chromatography
Authors: Hoagland D. A. , Prud'Homme R. K. 
Published: April 2003

AbstractHydrodynamic chromatography (HDC) has been successfully applied to measurements of the molecular size and molecular size distribution of high molecular weight, water‐soluble polymers. The scope of the method has been probed by experiments with xanthan, a comparatively stiff polysaccharide, and hydrolyzed polyacrylamide, which possesses a more flexible backbone. Separation occurs during convection of dissolved polymer through the interstitial volume of a chromatography column packed with nonporous beads. Nonequilibrium polymer configurations are readily created by the complex flow between these beads. Such altered configurations strongly affect molecular size measurements. To maximize resolution, hydrodynamic stress must be reduced by employing extremely low flow rates. These low flow rates, particularly important for ultrahigh molecular weight samples, unavoidably lengthen analysis time. Conditions under which chromatograms reflect the size distribution of an injected sample are elucidated. A complete description includes selection of column packing, solvent composition, flow rate, column calibration, and sample detection.
Orientation of polymer chains in films of syndiotactic‐rich poly(vinyl alcohol)
Authors: Yamaura Kazuo , Takeyama Kuniko , Tanigami Tetsuya , Matsuzawa Shuji 
Published: April 2003

AbstractThe infrared spectra of the films of syndiotactic‐rich poly(vinyl alcohol) (s‐PVA) prepared by the casting, frame, and bubble methods were obtained. The band at 705 cm−1 decreased with the increased inclination of the film plane to the direction of the irradiation of infrared rays and was related to the orientation of the molecules in the adsorbed phases of both sides of film.
Study on rough‐surface biaxially oriented polypropylene film. III. Influence of MFI of base resin
Authors: Fujiyama Mitsuyoshi , Kawamura Yoshimasa , Wakino Tetsuo , Okamoto Tomomi 
Published: April 2003

AbstractIn Part II of this series we reported that by using a successively stretching tenter method, biaxially‐oriented polypropylene films (BOPs) with a crater‐like roughness have been obtained by selecting appropriate machine direction (MD) stretching conditions. In the present article, in order to select still better conditions, the influences of melt flow index (MFI) of base polypropylene (PP) and machine and transverse direction stretching conditions on the roughening of BOP have been studied. Rough‐surface BOPs were obtained by casting homoisotactic PPs, having MFIs of 1.3–9.8 dg/min and containing no β‐crystal nucleator, with a T‐die extruder into sheets which subsequently have been stretched successively in the machine direction (MD) and the transverse direction (TD) with a roll‐type stretching machine and a pantograph‐type stretching machine, respectively. The level of β‐crystal content in the cast sheet was maximum when a PP with MFI ≒ 8 dg/min was used as a raw material and the obtained roughness state of the BOP was the best. As for the MD‐stretching conditions, the roughness state of a BOP improved as the surface temperature of the heating roll was increased to a temperature range of 135–150°C, and there was the best roll rotation speed from the balance of the thermal conductivity of the sheet and the melt‐recrystallization rate of the β crystals. A temperature in a range of 150–155°C was best for the TD‐stretching.
Study on rough‐surface biaxially oriented polypropylene film. IV. Influence of addition of crystal nucleator
Authors: Fujiyama Mitsuyoshi , Kawamura Yoshimasa , Wakino Tetsuo , Okamoto Tomomi 
Published: April 2003

AbstractIn the roughening of biaxially oriented polypropylene film (BOP) by utilizing β‐form crystals in a successively stretching tenter method, the influence of an α‐crystal or β‐crystal nucleator added to base polypropylene (PP) during roughening of BOP has been studied. Rough‐surface BOPs were made from homoisotactic PPs which had a melt flow index (MFI) of 8.5 dg/min and contained the α or β nucleator at levels of 0‐10 ppm. The β crystals formed in cast sheets and the roughness of the BOPs was analyzed. Degree of roughness and the diameter of craters on BOP decreased with increasing α‐ or β‐nucleator content. This stems from the fact that the diameter of the β spherulites formed in the cast sheet decreases with increasing nucleator content. In the cases of nucleator content below 1 ppm, the diameter of the β spherulites in the cast sheet did not change significantly, and the decrease in diameter of the BOP craters was small. On the other hand, the degree of roughness of the BOP dropped significantly when nucleator content was above 10 ppm. Accordingly, a nucleator content of about 1 ppm is suitable for the roughening of BOP for both the α and β nucleators.
Dependence of viscoelastic properties on segregation degree of components in interpenetrating polymer networks
Authors: Lipatov Yu. S. , Rosovizky V. F. , Datsko P. V. , Maslak Yu. V. 
Published: April 2003

AbstractThe temperature dependences of elastic moduli, loss moduli, and mechanical loss angle tangent were investigated for the interpenetrating polymer networks: polyurethane–polyurethane acrylate by the method of dynamic mechanical spectroscopy (DMS). The segregation degree of components due to phase separation have been calculated from the parameters of relaxation maxima. An essential change was found in the segregation degree of components with the curing sequence of individual networks being changed. It was shown that, with the conditions and sequence of IPN formation changed, the phase separation degree can be fixed at a particular stage, i.e., the structures with a different segregation degree of components are obtainable. For the IPNs under investigation the variation of elastic moduli of the composites proved possible by fixing the separation degree of components.
Electrodeposition of polyimides from nonaqueous emulsions
Authors: Uebner Michael , Ng Ka M. 
Published: April 2003

AbstractA theoretical and experimental study was carried out to investigate the process of electrodepositing a polyamic acid film from a nonaqueous emulsion onto a metal surface (copper, aluminum) as well as the subsequent drying and imidization steps. The rate of film growth is controlled by the electrophoresis of the polymer emulsion particles to one of the electrodes and the concomitant film compaction due to the outflow of the solvent caused by electro‐osmosis. Parameters affecting the coating process such as particle size, charge, ζ potential, viscosity of the liquid medium, conductivity of the deposited film, etc. were considered.
Some physical properties of alkali‐treated bhindi fiber (Hibiscus esculentus linn.)
Authors: Sen K. K. , Saha S. C. , Mojumder P. , Ray P. K. 
Published: April 2003

AbstractStructural features of bhindi fiber have been studied by X‐ray diffractometry, scanning electron microscopy, and infrared spectroscopy. The fiber has multicellular structure and on alkali treatment, it behaves like other lignocellulosic fibers. Infrared spectra indicated that alkali degradation of cellulose and hemicellulose was quite significant in the fiber and that substantial portion of uronic acid was removed as a results of alkali treatment.
Conducting polypyrrole composite thin films chemically prepared by spreading on surface of aqueous solution containing oxidizing agent
Authors: Morita Mitsuyuki , Hashida Isao , Nishimura Masato 
Published: April 2003

AbstractPolypyrrole–PMMA composite films have been prepared with the chemical oxidative polymerization by spreading the water‐insoluble solvent solution of pyrrole and PMMA mixture on the surface of the aqueous solution containing K2S2O8, the oxidizing agent. The conductivity of the films increases rapidly, passes through a plateau, and then decreases gradually as the reaction time increases. The conductivity of the oxidized side of the film is higher by over 1 order of magnitude than that of the evaporated side. It is due to the fact that the former is rich in polypyrrole while the latter is rich in PMMA. The thickness of the films can be controlled by adjusting the PMMA concentration. However, the lower limit of the film thickness is practically in submicron order. The relationship between the transmittance and the logarithm of the conductivity of the films gives a straight line with a gradient, ca. −8. The conductivity of the films is stable on silicagels in a desiccator over 2000 h at 25°C. The conductivity of the film is, however, very sensitive to the moisture in atmosphere and gives rise to decrease with humidity.
Grafted chain as spacer for an insoluble polymer ligand. II. Two‐step polymerization using tetraethylthiuram disulfide as an initiator
Authors: Arai Kenichiro , Ogiwara Yoshitaka 
Published: April 2003

AbstractIn order to increase the percent grafting in the graft polymerization of chloromethylstyrene onto a crosslinked polystyrene bead with UV light irradiation, a two‐step polymerization consisting of a suspension polymerization of styrene containing divinylbenzene using tetraethylthiuram disulfide as an initiator and then a subsequent graft polymerization of chloromethyl‐styrene onto the crosslinked polystyrene bead was carried out. The percent grafting of up to 180% was obtained, the value being about twofold larger than that for the usual method using benzoyl peroxide as an initiator. The higher percent grafting was found to result from the higher grafting efficiency due to the preferential decomposition of diethyldithiocarbamate group in the crosslinked polystyrene bead with UV light irradiation. The chloromethyl group in the grafted chain was converted to aminomethyl group, and then to the iminodiacetic acid group, which was a ligand group. The adsorption behavior of Cu(II) by the ligand polymer and the catalytic activity of the complex in the decomposition of hydrogen peroxide were examined, and both properties were found to be improved by introducing grafted chain as spacer, especially markedly at a higher percent grafting.
Postcrosslinking of linear polyesters. II. UV‐induced crosslinking agents having carboxyl reactive group
Authors: Inata Hiroo , Morinaga Tsutou , Matsumura Shunichi 
Published: April 2003

AbstractA previous article reported that polyallyl compounds such as triallyl cyanurate could be applied as an effective melt‐blend‐type ultraviolet (UV)‐induced crosslinking agent for linear polyesters to improve their thermal resistances without sacrificing their melt processabilities. The present article reports the results from further investigation to seek more effective crosslinking agents for the polyesters. Compounds having both allyl and carboxyl reactive groups, such as diallyl glycidyl isocyanurate and 2‐[β‐(3,5‐diallylisocyanuro)ethyl]carbamoyl‐2‐oxazoline have been proved to be more effective UV‐induced crosslinking agents than the simple polyallyl compounds reported previously. The former compounds were coupled with carboxyl terminal groups of the polyesters by reaction in the melt and act as an effective UV‐induced crosslinking agent, which was proved by the observation that the polyester having more carboxyl terminals resulted in higher UV crosslinkabilities. Addition of such compounds to the polyester did not seriously affect the melt stability of the mixtures.
Mechanical denaturation of high polymers in solutions. XXXIX. Flow‐induced crystallization of high molecular weight syndiotactic‐rich poly(vinyl alcohol)
Authors: Yamaura Kazuo , Daimoh Motokazu , Tanigami Tetsuya , Matsuzawa Shuji 
Published: April 2003

AbstractThe crystallization of syndiotactic‐rich poly(vinyl alcohol) (s‐PVA) with a molecular weight of 6.73 × 105 from aqueous solutions was carried out under Couette flow with or without seed crystals. The crystallization of s‐PVA from aqueous solutions occurred below the surface of the solutions even in the presence of seed placed in the solution; whereas, in the case of aqueous s‐PVA solutions containing 0.02% octyl alcohol (antifoaming reagent) only the longitudinal growth of seed occurred. The lengths of the fibers obtained were 2.5 to 3.0 cm.
Production of carbonaceous adsorbents by using novolac‐resin and cottonseed
Authors: Simitzis Johannis , Sfyrakis Johannis 
Published: April 2003

AbstractMixtures of novolac resin with pressed cottonseed in different proportions after their curing as small cylinders, and also pressed cottonseed as powder were pyrolyzed until 1000°C. Some samples follow, as well as an activation process by steam between 700 and 950°C. The weight losses of the samples are much higher, up to 500°C, while small weight losses are observed over 800°C. The weight losses for the 100% pressed cottonseed during the carbonization are essentially higher than those of the specimens also containing novolac; indeed, for the total weight losses up to 1000°C an increasing linear dependence was found with increasing proportion of the cottonseed in its mixture with novolac. The shrinkage of the specimens also containing novolac follows in general a curve similar to that of the weight losses for the corresponding case. The specific surface areas of the carbonaceous materials produced show higher values with measuring by CO2 than by N2 due to the larger dimensions of the N2 molecule as compared to the CO2 molecule, so that N2 areas are more sensitive to slight changes in aperture sizes of the porous materials produced. The specific surface areas of the materials that have also been activated indicate higher values in comparison with those without activation and also higher than activated carbon commercially available. The more increased and fine porous structure of the activated carbons as compared to those only pyrolyzed become also obvious from the corresponding photos obtained by the scanning electron microscope. These results are also in agreement with the discoloring ability of the produced adsorptive media for the methylene blue from aqueous solution, following the Freundlich equation for the adsorption.
Studies on the glass transition of blends of nylon‐6 and polyacrylic acid
Authors: Jin Y. , Huang R. Y. M. 
Published: April 2003

AbstractThe glass transition temperatures (Tg) of blends of polyacrylic acid (PAA)–Nylon 6 in various proportions used as membrane material in pervaporation separation of acetic acid–water and ethanol–water mixtures were determined using differential scanning calorimetry (DSC). All the samples examined showed a single Tg which lay between the Tg of Nylon 6 and PAA, indicating that complete miscibility was achieved in these polymer blends. Further evidence of complete miscibility was obtained by scanning electron microscopy (SEM) of cross sections of the blended films which showed a uniform structure. An interesting phenomenon was observed during the DSC measurements which showed a shift in Tg of the blended samples with scanning time. Infrared and thermogravimetric measurements were conducted to further investigate this phenomenon and the results were explained as the change in Tg being caused by the elimination of water molecules and the formation of anhydrides in the polyacrylic acid portion of the polymer blends.
Study on ketalization reaction of polyvinylalcohol by ketones. III. Reaction between polyvinylalcohol and methyl ethyl ketone and behavior of polyvinylketal in water
Authors: Nakamura Naofumi , Aoshima Sadahito , Higashimura Toshinobu 
Published: April 2003

AbstractKetalization reaction of polyvinylalcohol (PVA) by methyl ethyl ketone (MEK), dimethyl‐sulfoxide (DMSO) as solvent, under the presence of acidic catalyst, in homogeneous system was carried out, and the synthesis of polyvinylketal with any ketalization degree was successfully performed. The reaction mechanism of PVA with MEK is identical with that with acetone: for both cases, the equilibrium constant is ca. 0.07 at 40°C and the heat of reaction is 7.5 kcal/mol. Films prepared from the polyvinylketal were soaked in water and degree of swell, solubility, and hydrolysis of films were measured. The reaction of film with water, in acidic side, easily proceeds, and at first the film swells; then, as deketalization reaction proceeds, the film dissolves in water. With polyvinylketal of the ketalization degree of above 15 mol %, dissolution time is controlled by both ketalization degree and pH of water, which reveals that deketalization reaction proceed proportionally to proton concentration at 37°C. On the other hand, in the neutral condition where hydrolysis does not proceed at all, polyvinylketal of ketalization degree of 10–40 mol % dissolves in water at 0°C. The polyvinylketal obtained by MEK is more stable in water than that from acetone since MEK has hydrophobicity.
Spectroscopic determination of copolymer composition in high isocyanate content polymers
Authors: Brown Richard G. , Glass J. Edward 
Published: April 2003

AbstractCopolymer compositions high in aliphatic isocyanate content cannot be determined by typical titration methods due to crosslinking during polymer workup. A quantitative method involving ultraviolet analysis of an isocyanate/absorbing amine adduct is presented. Agreement between the ultraviolet (UV) method and elemental analysis, in both composition data and reactivity ratios (r1r2, which are calculated from data obtained by the UV method) delineate a viable method of polymer analysis. Data from Fourier transform infrared (FTIR) analysis of the urea linkage is in good agreement with nitrogen analysis and the UV method, but is sufficiently biased to cause significant differences in r1r2 values. Bias in the infrared analysis may arise from the intra‐ or intermolecular interaction of CO and NH groups of the urea linkage. Hypochromic effects are observed in UV analysis in noncarbonylic solvents. Hypochromicity varied with copolymer composition and could be related to sequence distributions. The hypochromic effects observed were most pronounced in low amine adduct content polymers where the majority of phenyl chromophores are isolated between MMA units.
Graphitization studies of cured phenolic resins by high‐resolution 13C‐cross‐polarization magic angle spinning solid‐state NMR spectroscopy
Authors: Amram B. , Laval F. 
Published: April 2003

Abstract13C‐cross‐polarization/magic angle spinning solid‐state NMR spectroscopy is used to investigate the graphitization process of a pyrolyzed formophenolic resin. The formation of a 2‐dimensional graphitelike lattice, growing with the duration of the laser pyrolysis, is shown. A one‐parameter‐condensation model is used to estimate, from our dipolar‐dephasing NMR experimental data, the quaternary‐to‐tertiary aromatic fraction, the number of condensed aromatic rings (from 10 to 23 units), and the average cluster diameter (from 9 to 14 Å).
Synthesis, polymerization, and end‐use evaluation of 3‐pentadecylphenyl acrylate and methacrylate
Authors: Sitaramam B. S. , Chatterjee P. C. 
Published: April 2003

AbstractTwo new polymerizable monomers, namely, 3‐pentadecylphenyl acrylate and methacrylate, were synthesized starting from Cashew Nut Shell Liquid. The synthetic method used is simple, and is of general utility. These monomers were homopolymerized by bulk, solution, and emulsion polymerization techniques which yielded moderately high molecular weight polymers that showed promise as pressure‐sensitive adhesive.
Synthesis of nylon 4 through the use of the carbon dioxide/potassium pyrrolydonate catalyst system with and without added 18‐Crown‐6 ether activator
Authors: Huang Robert Y. M. , Rhim Ji‐Won 
Published: April 2003

AbstractThe anionic polymerization of 2‐pyrrolidone at 40°C via CO2/KOH and CO2/KOH/18‐Crown ether catalyst for membrane separation purposes was investigated in detail. The effects of reaction time, CO2 quantity, and potassium hydroxide concentration including crown ether on yield and intrinsic viscosity were also studied. Under the reaction conditions of reaction temperature 40°C, reaction time 24 h, CO2 quantity of 60 s at a constant flow rate of 3.5 L/min and 1.98 mol % Crown ether a maximum yield of 95.36% of nylon 4 polymer with intrinsic viscosity of 3.28 was obtained.
Bonding a HTPB liner to modern rocket case materials
Authors: Sandén Roland , Wingborg Niklas 
Published: April 2003

AbstractMethods for bonding propellants based on HTPB (hydroxyl‐terminated polybutadiene) to modern rocket motor case materials have been studied. Thus a typical rocket propellant liner, based on HTPB, was adhesion tested to various polymer materials and to an aluminum alloy. The polymer materials are an epoxy resin and composite materials, based on epoxy‐poly(ether sulfone), poly(ether ether ketone), poly(amide imide), and poly(phenylene sulfide). With proper surface treatment, excellent results were obtained at separation tests for all materials with cohesive failure in the liner.
Influence of emulsifiers on film formation from cellulose acetate latexes. Modeling approach to the fate of emulsifiers in highly plasticized films. II
Authors: Bindschaedler C. , Gurny R. , Doelker E. 
Published: April 2003

AbstractExperimental results on the redistribution of sodium dodecyl sulfate in cellulose acetate membranes produced from latexes (Part I) are interpreted in terms of a framework involving both thermodynamic (affinity of the components, composition) and kinetic (plasticizer evaporation rate) parameters. Two situations were examined, corresponding to liquid–liquid and liquid–solid phase separation. The proposed model better accounts for the observed phenomena than more classical views about the fate of emulsifiers.
Correlated color temperature detection of radiation damage in thermoplastic polyurethane
Authors: Lawandy S. N. , Amera A. M. 
Published: April 2003

AbstractThe correlated color temperature change in a polymer was used as a technique to determine the degree of damage sustained due to radiation exposure. This technique shows fair agreement with the swelling technique. These two methods were used to detect radiation damage in four thermoplastic polyurethane grades of different hardness. Polymers that possess higher amounts of isocyanate groups give better resistance to radiation than to lower isocyanate‐content polymers.
Scratch resistant low friction/low surface energy coating for silicon substrate
Authors: Chen H. H. 
Published: April 2003

AbstractA smooth, ultrathin film of a polydimethylsiloxane (PDMS) on a silicon substrate has been prepared by spin‐coating. This film gives a 0.06 dynamic coefficient of friction against paper, the lowest value ever reported for polymer–paper sliding pairs. The value is only about one‐third of the coefficient of friction (0.21) between polytetrafluoroethylene and paper. The coating is not scratchable by sliding a stainless steel stylus over the surface with a pressure greater than 3.6 × 1010 dyn/cm2. The film displays a surface tension of 20.5 dyn/cm. It is stable in water and propylene glycol. The film is an effective and durable solid lubricant. The surface characteristics of a spray‐coated PDMS and a plasma‐copolymerized thin film of perfluoropropane and 3,3,3‐trifluoropropylmethyldimethoxysilane have also been investigated. Both films show much lower scratch resistance, weaker adhesion to the silicon substrate, and higher friction. The plasma film yields the same surface tension as the spin‐coated PDMS. Its surface energy, however, increases after soaking in water or propylene glycol. The exceptionally low friction and the unusually high scratch resistance of the ultrathin film of PDMS are attributed to the absence of deformation and tearing components and a low adhesion components in the sliding friction mechanism.