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951.
Poly(vinylidene fluoride) films were γ-irradiated in the dose range of 1–20 Mrad, resulting in up to 74% gel. The irradiated polymer undergoes both crosslinking and chain scission, about 5 : 3 events, respectively. Swelling measurements indicate an increasing crosslink density with the gel content, already at the lower doses. Thermal analysis of the gel fraction and the unextracted irradiated samples shows that although crosslinking affects the crystallization, degree of crystallinity, and the melting characteristics, the behavior of the crosslinked material is predominantly controlled by the extractable sol fraction which consists of the more mobile original chains, branched chains, and degraded ones. The crosslinks, already at low density, retard the development of ordinary crystalline polymer morphology. 相似文献
952.
The glassforming region in the system was roughly outlined and liquidus data were obtained for the three joins LiPO3 -BPO4 , Li4 P2 O7 -BPO4 , and Li3 PO4 -Li2 B4 O7 . Compatibility relations for the ternary subsystems Li4 P2 O7 -BPO4 -P2 O5 and Li2 O-Li3 PO4 -Li2 B8 O13 were established. Two ternary compounds with the probable compositions 22Li2 O - 11B2 O3 - 13P2 O5 and 2Li2 O 3B2 O3 P2 O5 were detected. 相似文献
953.
Plant fibers are rich in cellulose and they are a cheap, easily renewable source of fibers with the potential for polymer reinforcement. The presence of surface impurities and the large amount of hydroxyl groups make plant fibers less attractive for reinforcement of polymeric materials. Hemp, sisal, jute, and kapok fibers were subjected to alkalization by using sodium hydroxide. The thermal characteristics, crystallinity index, reactivity, and surface morphology of untreated and chemically modified fibers have been studied using differential scanning calorimetry (DSC), X‐ray diffraction (WAXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), respectively. Following alkalization the DSC showed a rapid degradation of the cellulose between 0.8 and 8% NaOH, beyond which degradation was found to be marginal. There was a marginal drop in the crystallinity index of hemp fiber while sisal, jute, and kapok fibers showed a slight increase in crystallinity at caustic soda concentration of 0.8–30%. FTIR showed that kapok fiber was found to be the most reactive followed by jute, sisal, and then hemp fiber. SEM showed a relatively smooth surface for all the untreated fibers; however, after alkalization, all the fibers showed uneven surfaces. These results show that alkalization modifies plant fibers promoting the development of fiber–resin adhesion, which then will result in increased interfacial energy and, hence, improvement in the mechanical and thermal stability of the composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2222–2234, 2002 相似文献
954.
Summary Inside a microporous polyethylene film, 2-acrylamido-2-methylpropane sulfonic acid was graft polymerized by ultraviolet irradiation. A humidity sensor was fabricated by depositing gold electrodes on both sides of the grafted film. The impedance was measured as a function of humidity for the acid and alkali salts of sulfonate. The sensor has long term stability and is resistant to water. 相似文献
955.
Y. M. CHIANG A. F. HENRIKSEN W. D. KINGERY D. FINELLO 《Journal of the American Ceramic Society》1981,64(7):385-389
Using Auger electron spectroscopy, segregation of Ca and Si corresponding to the adsorption of a partial monolayer adjacent the boundary in polycrystalline MgO was observed. Segregation of Sc is different in nature; the distribution consists of a 3.0-nm wide region corresponding to a positive space charge layer balancing a negative boundary charge. Various segregation models are applied to the observed behavior. 相似文献
956.
R. Usuki T. Suzuki Y. Endo T. Kaneda 《Journal of the American Oil Chemists' Society》1984,61(4):785-788
The quantities of chlorophyll (CHL) A and B, and pheophytin (PHY) A and B in 10 kinds of refined edible oils were estimated
by the fluorometric method. The results revealed that CHL and PHY were present in commercial edible oils. PHY A showed the
highest content at ca. 67% in total pigments. Compositional ratios of CHL and PHY were similar in different kinds of plant
oils. Through the analysis of rapessed oils at every refining step, we determined that PHY is not formed during oil refining.
In the autoxidation of soybean oils to which various amounts of CHL mixtures had been added, the peroxide value of tested
oils increased in proportion to the total chlorophyll content. In addition, the compositional changes of the 4 components
during autoxidation were investigated. 相似文献
957.
K. Sakata K. Kato Y. Iwase H. Okada K. Ina Y. Machiguchi 《Journal of chemical ecology》1991,17(1):185-193
Phagostimulant activity of glycerolipids such as digalactosyldiacylglycerol (DGDG), 6-sulfoquinovosyldiacylglycerol (SQDG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), etc., have been examined using the Avicel plate method for three kinds of marine herbivorous gastropods, the abaloneHaliotis discus, the turban shellTurbo cornutus, and the topshellOmphalius pfeifferi. DGDG showed strong activity for all the test animals. SQDG was much less active than the other glycerolipids for abalone. The turban shell and the top shell responded more or less sensitively to all tested glycerolipids at doses of 10–20g/sample zone.Chemical Studies on Phagostimulants for Marine Gastropods. Part VIII. For Part VII, see Sakata et al. (1988a). 相似文献
958.
The melting points (Tm) were measured for oligomers obtained by a direct continuous esterification process between terephthalic acid and ethylene glycol. Multiple regression analyses of data were carried out, and an equation was obtained for predicting melting points with correlation coefficient of ~0.99. 相似文献
959.
The crystallinity of rigid PVC specimens, stabilized by a tin mercaptide or a lead stabilizer, has been studied. It is found that the crystallinity of rigid PVC is greatly influenced by the type of stabilizer added, and that the response of the PVC toward subsequent UV exposure was also different. The effects of unstable structures and crystallinity, after UV irradiation, on the mechanical properties of rigid PVC have been investigated. 相似文献
960.
A technique for separating similar and diverse ionogenic mixtures into their individual homologs was studied by high performance
liquid chromatography on an octadecyl-silica (TSK Gel LS-410) column. Conditions used for the separation were: column size,
6 mm id×200 mm; mobile phase, water/methanol (15:85, v/v) containing (a) 1.0 M sodium perchlorate and adjsting to pH 2.5 with
phosphoric acid, (b) 0.1 M and pH 3.5; column temp., 50 C. By using 2 mobile phase conditions, various surfactant mixtures
were separated into their individual homologs and simultaneously distinguished from each other, regardless of their ionogenic
properties. 相似文献