bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nylon 6,6 copolyamides of bis(2‐carboxyethyl) methylphosphine oxide
Authors: Ridgway James S. 
Published: April 2003

AbstractCopolyamides of nylon 6,6 with bis(2‐carboxyethyl)methylphosphine oxide (CEMPO) were prepared by melt polycondensation of nylon 6,6 salt with CEMPO and hexamethylene diamine. The effect of CEMPO upon melting point, moisture regain, boiling water shrinkage, water wicking, tensile properties, thermal stability, static dissipation, and flammability of nylon 6,6 fibers and fabrics was determined. The fiber properties were greatly affected by the high water absorption and solubility characteristics of the phosphine oxide linkage. However, crystallinity and orientation were not greatly disturbed by up to 30–40M% CEMPO substitution in nylon 6,6. The copolyamides were of improved flame resistance compared to nylon 6,6 and were also found to give improved flame resistance in blends of the copolymer with various commercial plastics. In addition, CEMPO and the corresponding diamine, bis(3‐aminopropyl)methylphosphine oxide were used to prepare a series of cycloaliphatic and aromatic ring‐containing polyamides, but problems were encountered with moisture sensitivity and low melting points with some of these polymers.
Structures, properties, and alkali metal ion transport membrane of polyelectrolyte complexes consisting of methyl glycol chitosan, glycol chitosan, and poly(vinyl sulfate)
Authors: Kikuchi Yasuo , Kubota Naoji , Mitsuishi Hiroshi 
Published: April 2003

AbstractMixtures of methyl glycol chitosan and glycol chitosan were reacted with poly(vinyl sulfate) to form many different water‐insoluble polyelectrolyte complexes (PEC) in aqueous solution at various hydrogen ion concentrations. It was revealed from elemental analyses, infrared (IR) spectroscopy, and solubilities of PEC that molecular structures of each PEC are dependent on [H+]. PEC membranes were made from casting solutions of all kinds of PEC, and transport phenomena through the membrane of PEC prepared in a pH 13.0 solution were investigated under various conditions. The transport ratio of Na+ and the electric potential difference between the left‐ and right‐hand sides of the membrane were measured, and it is suggested that the driving force for active transport depends on the membrane potential, Donnan potential and diffusion potential. Moreover, permeability of K+ was higher than that of Na+ in selective transport.
Characterization of styrene–methyl methacrylate–n‐butyl acrylate terpolymers. II. Effects of sequence distribution on glass transition temperature
Authors: Kobayashi Minoru 
Published: April 2003

AbstractThe effects of sequence distribution on the glass transition temperature (Tg) of the title terpolymers prepared by radical polymerization were studied. Tg was examined by thermomechanical analysis. The average diad concentrations, as estimation of sequence distributions were calculated from monomer reactivity ratios. A modified Gibbs–Dimarzio equation for binary copolymers was extended to terpolymers to explain the relation between observed Tg and average diad concentrations. The observed Tg showed good agreement with the calculated values determined by the extended equation.
High activity mixed metal alkyl cocatalysts for α‐olefin polymerization
Authors: Bacskai R. 
Published: April 2003

AbstractHigh activity α‐olefin polymerization catalysts are generally obtained by mixing MgCl2‐supported TiCl4 (MgCl2/TiCl4) with an aluminum trialkyl cocatalyst. Surprisingly, AlEt2Cl, which is the preferred cocatalyst in polymerizations employing nonsupported Ti compounds, is a poor cocatalyst when used with MgCl2/TiCl4. It was found that in propylene and 1‐butene polymerizations, using different MgCl2/TiCl4 catalysts, the cocatalyst activity of AlEt2Cl can be greatly improved by the addition of a magnesium or lithium alkyl. The mixed metal alkyl obtained from AlEt2Cl and MgBu2 is a particularly effective cocatalyst always yielding more polymer, of about the same stereospecificity, than the conventional aluminum trialkyls. The exact nature of the mixed metal alkyl cocatalysts is not known, but the available evidence argues against in situ aluminum trialkyl formation resulting from the alkylation of AlEt2Cl by the second metal alkyl.
Development of crystalline structure during tubular film blowing of low‐density polyethylene
Authors: Kwack Tae Hoon , Han Chang Dae , Vickers M. E. 
Published: April 2003

AbstractDevelopment of crystalline structure during the tubular film blowing of low‐density polyethylene was investigated, using wide‐angle X‐ray diffraction technique, low‐angle light scattering, and scanning electron microscopy. In the study, commercial grades of both high‐pressure low‐density polyethylene (HP‐LDPE) and low‐pressure low‐density polyethylene (LP‐LDPE) (also, commonly referred to as linear low‐density polyethylene, LLDPE) were used. The applied stresses at the freeze line were determined using theoretical expressions derived in an earlier publication [C. D. Han and T. H. Kwack, J. Appl. Polym. Sci., 28, 3399 (1983)]. The applied stresses, S11F and S33F, at and above the freeze line in the machine and transverse directions were expressed in terms of the tension at the take‐up device, take‐up ratio, blow‐up ratio, and the pressure difference across the film of the bubble. These applied stresses were used to interpret the crystalline axes' orientation in the tubular blown films. It was found that the magnitude of S11F is an important process parameter for the crystalline axes' orientation and that the biaxial stress ratio (S11F/S33F) appears to be a determining factor in the distribution of fibrillous nuclei and crystalline texture, as well as film anisotropy.
Photopolymerization of vinyl monomers using benzophenone‐tetrahydrofuran initiation system and aldehydes at low temperatures
Authors: Matsuzawa Shuji , Yamaura Kazuo , Yamada Sinichiroh , Shinke Yosihide , Nakano Yasumasa , Koike Yohtaroh 
Published: April 2003

AbstractThe photopolymerizations of vinyl trifluoroacetate (VTFAc), vinyl acetate (VAc), and methyl methacrylate (MMA) using the initiation system benzophenone–tetrahydrofuran were studied at low temperatures. At −78°C the rate of polymerization of VTFAc was higher than that of VAc, while MMA, which was solidified, did not polymerize. After melting the irradiated solid mixture the polymerization occurred at 4°C. The photoinduced polymerization of VTFAc occurred in the presence of butylaldehyde or isobutylaldehyde at −70°C. The degrees of polymerization and syndiotacticities of the polymers prepared were investigated.
On the structure of glassy polymers. VIII. Use of Z contrast to elucidate the microstructure of epoxy and polyimid resins
Authors: Di Filippo G. V. , Sande J. B. Vander , Uhlmann D. R. 
Published: April 2003

AbstractThe technique of ultramicrotomy of polymers, followed by staining of the resulting thin sections with heavy metal ions and viewing with Z enhancement in the scanning transmission electron microscope is described. When applied to anhydride‐cured epoxy resins, the structure is found to be heterogeneously crosslinked on a scale of a few hundred angströms. When the technique is applied to amine‐cured epoxy resins, the microstructure is found to change from homogeneous to inhomogeneously crosslinked, depending on stoichiometries and cure cycles. For amine‐cured resins whose cure conditions are within the range of microstructural change, the bright field of the stained specimens alone does not detect heterogeneities, and the Z contrast becomes crucial to discern the kind of microstructure. A commercial polyimide film examined in the same way is found to exhibit systematic variations in structure through the thickness of the film.
Thermovulcanization of polychloroprene rubber and its blends with poly(vinyl chloride)
Authors: Běhal Miroslav , Ducháček Vratislav 
Published: April 2003

AbstractHeat and mechanical stressing at higher temperatures effect changes in polychloroprene rubber leading to network formation. During thermovulcanization of polychloroprene rubber in the temperature range of 150–200°C, two reactions have been observed and their kinetic parameters determined. When the rubber is stressed by shearing forces, the rate of degradation crosslinking is fairly high even at relatively low temperatures (90–150°C). Thermovulcanization of polychloroprene rubber/poly(vinyl chloride) blends has been investigated in the entire concentration range at 180°C. Maxima have been observed on the dependences of some kinetic parameters of the thermovulcanization reaction on polymer blend composition.
Influence of agitation on the creation of coagulum during the emulsion polymerization of the system styrene–butylacrylate–acrylic acid
Authors: Matějíček Alois , Pivoňková Alena , Kaška Jiří , Ditl Pavel , Formánek Leopold 
Published: April 2003

AbstractThis paper gives the results of the estimated coagulum content in the final sample of a dispersion based on styrene–butylacrylate–acrylic acid, prepared by semicontinuous emulsion polymerization. The results were gained from experiments on 25 L and 5 m3 reactors. The dependence of the amount of coagulum on the agitation intensity was studied. It was found that it is necessary to divide the results into two regions: (a) for specific power input smaller than 80 W/m3; (b) for specific power input greater than 80 W/m3. It was found that polymerization scaling up from the point of constant coagulum content in the system studied is possible under the conditions of constant specific power input. The specific power input varied in the range from 5 to 3000 W/m2. For the first region was gained the empiric correlation Y = 2.16(ℰV)−1 and for the second region the equation Y = 3.5 × 10−5(ℰV)1.5, where Y is the amount of coagulum (wt %). For the existence of two regions we propose the following hypothesis according to which increasing mixing intensity improves the temperature and concentration nonuniformity which results in the decrease of coagulum content. From the certain value of specific power input, which is specific for each system, the amount of coagulum starts to increase due to increasing shear stress.
Properties of syndiotactic‐rich poly(vinyl alcohol) thin film in water. V. Effect of initial temperature of heating on elongation
Authors: Yamaura Kazuo , Masuzawa Tatsuaki , Tanigami Tetsuya , Matsuzawa Shuji 
Published: April 2003

AbstractThe effect of the initial temperature of heating on the elongation of syndiotactic‐rich poly(vinyl alcohol) thin films was investigated in water under a load. The elongation ratios Ei after 4 h at fixed temperatures increased roughly with an increase in the initial temperature Ti and a decrease in the annealing temperature. Ei after 4 h was the smallest at Ti = 45°C for the films annealed at temperatures below 100°C. Ei was 6.8 at Ti = 60°C for the unannealed film and 1.12 at Ti = 70°C for the film annealed at 200°C. The elongation at break decreased and the temperature at break increased with an increase in annealing temperature, but those at the annealing temperature of 100°C were the smallest. The films annealed at 200°C did not break even at 98°C (boiling temperature) in water and the elongation ratio was 1.42–1.97 in the initial temperature range of 10–70°C. From these results, the relation between the elongation in water and the state of polymer chains in film was discussed.
Copolymerization of N‐vinyl‐2‐pyrrolidone and 2‐phenyl‐1,1‐dicyanoethene
Authors: Kharas Gregory B. 
Published: April 2003

AbstractRadical copolymerization of N‐vinyl‐2‐pyrrolidone (NVP) with 2‐phenyl‐1,1‐dicyanoethene (PDE) was studied in benzene at 70°C. Terminal, penultimate, and monomer complex participation kinetic models were applied to compositional data for best prediction of the copolymer composition. Both penultimate and complex models described satisfactorily the deviation from the terminal copolymerization model, although the complex model did not predict as well as the penultimate model at high NVP/PDE monomer feed ratios. Copolymerization reactivity ratios rNVP = 0.08 and r′NVP = 1.8 indicated substantial effect of the penultimate PDE monomer unit associated with polar repulsion of cyano groups. Equilibrium constant of NVP‐PDE comonomer complex formation was found to be 0.08 L/mol as estimated by proton nuclear magnetic resonance (NMR) analysis of PDE's vinylic proton chemical shift upon complexation. Rate constants of propagation reactions were estimated by applying terminal complex copolymerization model.
Molecular orientation and young's modulus of plasticized and nonplasticized poly(vinyl chloride)
Authors: King J. , Bower D. I. , Maddams W. F. 
Published: April 2003

AbstractThe Young's moduli of samples of poly(vinyl chloride) containing either no plasticizer or 5 pph of dioctyl sebacate were drawn uniaxially at 80°C to draw ratios, λ, in the range 1–3.3. The moduli, determined by a three‐point bending method were found to increase monotonically with λ to a value of 6.3 GPa for the nonplasticized samples and to reach a maximum value of about 4.5 GPa for the plasticized samples above λ = 2.3, which showed voiding. The lower moduli of the plasticized samples for a given degree of orientation, as assessed from birefringence measurements, can be attributed to the diluent effect of the plasticizer on the load‐bearing chains. The Raman measurements suggest that the crystallites probably orient rather like rigid rods in an affinely deforming matrix, with some relaxation.
Effects of thermodynamic models on the predictions of free volume diffusion theory for concentrated polymer solutions
Authors: Mossner Linda S. , Grulke Eric A. 
Published: April 2003

AbstractThree thermodynamic models were used to demonstrate the effects of model choice on solvent–polymer binary diffusion coefficients predicted by free volume theory. Poly(vinyl acetate) and four solvents were used as typical solutions for these calculations. Thermodynamic models affect the predictions the most at high solvent weight fractions and for solutions which exhibit positive enthalpic interactions. For solutions dilute in solvent where Henry's law might describe phase equilibria, diffusion coefficients can be estimated without reference to thermodynamic data.
Quantitative branching of linear and branched polysaccharide mixtures by size exclusion chromatography and on‐line low‐angle laser light scattering detection
Authors: Yu Li‐Ping , Rollings J. E. 
Published: April 2003

AbstractThe quantitative branching characterization of polysaccharide via size exclusion chromatography (SEC) and on‐line low‐angle laser light scattering (LALLS) detection is presented from both theoretical arguments as well as direct experimental evidence. The two measurable branching parameters gv(m) [= (Ml/(Mn)m)v] and g′v(m) [ = (Ml/(Mw)m)v] of a sample mixture have been related theoretically to the mixture's composition. There exists linear relationships between gv(m) and Wb,v (the mass fraction of branched component in mixture) as well as between g′v(m)−1 and wb,v. The latter correlation has been demonstrated experimentally employing a combined SEC/LALLS technique, and displays excellent agreement with the theoretical predictions. Furthermore, this polymer branching characterization method has been applied to study enzymatic starch hydrolysates products. The molecular weight distribution and branching distribution have been obtained.
Structural determination of pyrolyzed PI‐2525 polyimide thin films
Authors: Hu C. Z. , Andrade J. D. , Dryden P. 
Published: April 2003

AbstractPolyimide was pyrolyzed in an argon atmosphere at various temperatures, and thermally converted to amorphous carbon films. The irreversible change of polyimide under progressive heat treatment is characterized by three successive structural changes: pyrolysis, carbonization, and graphitization. X‐ray photoelectron spectroscopy (XPS) studies show that the polyimide starts to dissociate at pyrolysis temperatures above 500°C. At temperatures higher than 650°C most functional groups of polyimide decompose to evolve gases from the sample. The polyimide then gradually becomes more carbon rich. It is believed that at pyrolysis temperature higher than 650°C the polyimide starts to form heterocyclic structures with residual oxygen and nitrogen incorporated into the heterocyclic carbon rings. X‐ray analyses indicate that the polyimide at pyrolysis temperatures less than 1000°C is amorphous carbon and no long‐term periodic structure can be detected. At pyrolysis temperatures higher than 2000°C, the polyimide is converted to microcrystalline graphite.
Pervaporation separation of acetic acid‐water mixtures using modified membranes. I. Blended polyacrylic acid (PAA)‐nylon 6 membranes
Authors: Huang R. Y. M. , Moreira A. , Notarfonzo R. , Xu Y. F. 
Published: April 2003

AbstractMembranes consisting of ionically crosslinked polyacrylic acid (PAA) and Nylon 6 were prepared and tested for the pervaporation separation of acetic acid‐water mixtures. The polyacrylic acid (PAA) membranes were crosslinked in aluminum nitrate aqueous solution while the polyacrylic acid (PAA)‐Nylon 6 blends were cast from homogeneous PAA‐Nylon 6 mixtures to appropriate thicknesses and then crosslinked in aqueous aluminum nitrate solutions. Optimum pervaporation results were obtained from blends of Nylon 6 and PAA in the weight ratio of 60–75 wt% Nylon 6 and 25–40 wt% PAA which have separation factors (water/acetic acid) of over 60 and flux rates higher than 100 g/m2 h at 15°C for the separation of acetic acid‐water mixtures. The flux rates and separation factors could be altered by changing the blend composition of the membrane. The effects of the feed composition on the separation factors were investigated.
Electrophoretic, dynamic, and static light scattering on charged polymer emulsions
Authors: Lin F.‐M. C. , Berry G. C. , Frye R. L. , Scala L. C. 
Published: April 2003

AbstractLight scattering studies on dispersions formed by phase separation of a polymer‐solvent‐non‐solvent mixture show that the dispersions comprise charged droplets of the polymer‐rich phase. The charge number is not large, and data on the electrophoretic‐scattering and the dynamic scattering in the absence of an external electric field are both consistent with distribution of charge among the droplets. Data on the dependence of the static scattering on concentration and scattering angle show that the droplets are also disperse in radius. The data are discussed in terms of an interaction potential among the charged droplets relating the electrostatic interactions to the charge number and radius of the droplets, and the ionic strength of the solvent.
Degradation of polyester waste by aliphatic and aromatic alcohols
Authors: Joshi K. A. , Naik G. A. , Nevrekar N. B. 
Published: April 2003

AbstractPolyester waste was degraded with ethanol, n‐propanol, and benzyl alcohol in an autoclave at 280°C under pressure to give seven unknown compounds. The products of each reaction were isolated by using column chromatography and were identified on the basis of elemental analysis and spectral data.
The kinetics of polyarylate hydrolytic embrittlement
Authors: Golovoy A. , Cheung M. F. , Zinbo M. 
Published: April 2003

AbstractThe hydrolysis of polyarylate in water between 55 and 98°C was found to be a zero‐order process with an activation energy of 19.2 kcal/mol, determined by changes in molecular weight. The equation for the effect of temperature on the rate of hydrolysis is ln k = 34.1 − 104/T, where k is in day−1. The decrease in molecular weight is accompanied by a loss in ductility. The transition from a ductile to brittle failure in tension occurs at M̄w of about 35,000 and M̄n of 12,700. At 27°C (80°F) and high humidity environment this would occur after 21 years. But during injection molding, the material, if not properly dried, would embrittle in a matter of seconds.
Solid state C‐13 NMR characterization of textiles: Qualitative and quantitative analysis
Authors: Colletti Ronald F. , Mathias Lon J. 
Published: April 2003

AbstractCross‐polarization magic angle spinning (CP/MAS) carbon 13 NMR was used to qualitatively and quantitatively characterize textiles of various compositions. Rapid and accurate determination of cotton/polyester blends was accomplished with minimal sample preparation using an empirical peak height relationship. Qualitative identification was demonstrated for various fiber blends.
Surface composition of polystyrene
Authors: Goldblatt Ronald D. , Scilla Gerald J. , Park Jae M. , Johnson Julian F. , Huang Samuel J. 
Published: April 2003

AbstractThe physical and chemical properties of bulk polymers are well understood and have been measured exhaustively for numerous systems, but the properties of polymer surfaces are quite often different from those observed in the bulk and are usually not as easily measurable. Since many polymer properties vary with molecular weight, it is of interest to determine whether or not there is any segregation in a homopolymer system based on molecular weight. In particular, does the surface of a polymer sample have the same molecular weight composition as the bulk? The current work answers this question for a polystyrene system. Through the use of secondary ion mass spectrometry and tagged polystyrene, it has been shown that surface and bulk molecular weight composition are indistinguishable within the limits of the experimental method's sensitivity. The sensitivity of the technique is documented using samples artificially created with different surface and bulk molecular weight compositions.
Dyeing of silk cloth with colloidal gold
Authors: Nakao Yukimichi , Kaeriyama Kyoji 
Published: April 2003

AbstractSilk cloth was dyed successfully by dipping it in a gold hydrosol which was prepared in the presence of a cationic surfactant, stearyltrimethylammonium chloride (SC). The color of thus dyed silk cloths is due to colloidal gold particles adsorbed on silk fibers and varies from reddish purple to dark purple according to the periods of dipping time and the amounts of SC in the gold hydrosol used. The mechanism for the adsorption of colloidal gold on the silk fibers is proposed.
Radiation‐induced polymerization of methyl methacrylate and alkyl acrylates at high dose rate
Authors: Hayashi Kanae , Takezaki Jun'ichi , Okada Toshio , Sakurada Ichiro 
Published: April 2003

AbstractPolymerization of methyl methacrylate and methyl, ethyl, and n‐butyl acrylates was carried out in a wide range of dose rate, 10–106 rad/s by γ‐ray and electron beam irradiation. With methyl methacrylate and n‐butyl acrylate, and steady‐state kinetics in radical polymerization was maintained in an entire dose rate range at about the initial stage of the polymerization. With methyl and ethyl acrylates, the rate of polymerization increased much less markedly than expected from the square root law and the molecular weight decreased much less gradually with dose rate. In all these monomers it was found that autoacceleration of the rate of polymerization due to gel effect becomes vague at high dose rate. Two‐peaked molecular weight distribution was observed for the polymers obtained at high dose rate.