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991.
Nonlinear Dynamics - Vector similar structures for solutions with similar expressions of nonlinear models are paid attention in the previous literature. However, the demand of different localized... 相似文献
992.
Gang Wu Jiao-Dong Jiang Paul A. Tucker John A. Cuculo 《Journal of Polymer Science.Polymer Physics》1996,34(12):2035-2047
The development of an oriented noncrystalline phase in a semicrystalline polymer filament has been studied via X-ray scattering. These unique PET fibers contain a relatively high noncrystalline content and also have high tenacity, high modulus, and low breaking elongation. Fiber properties were found to be very responsive to the oriented amorphous phase content. This phase was utilized for interpreting noncrystalline orientation in PET fibers produced by a new extrusion technique. Here, the oriented noncrystalline regions in a series of PET fibers varies from 6% to 63%, depending strongly on the production conditions. In particular, samples produced with a newly developed threadline modification process possess a high content of oriented noncrystalline polymer. Measurements such as dynamic and static mechanical properties have been performed on various samples, and these properties are related to the oriented noncrystalline phase. The results provide direct evidence for the existence of highly oriented noncrystalline material in these unique PET fibers spun with a threadline modification process. © 1996 John Wiley & Sons, Inc. 相似文献
993.
Rui Xie Bingxing Yang Bingzheng Jiang 《Journal of Polymer Science.Polymer Physics》1996,34(8):1489-1499
Phase behavior of blends of poly(vinyl methyl ether) (PVME) with four styrene-butadiene-styrene (SBS) triblock copolymers, being of various molecular weights, architecture, and compositions, was investigated by small-angle light scattering. Small-angle X-ray scattering investigation was accomplished for one blend. Low critical solution temperature (LCST) and a unique phase behavior, resembling upper critical solution temperature (UCST), were observed. It was found that the architecture of the copolymer greatly influenced the phase behavior of the blends. Random phase approximation theory was used to calculate the spinodal phase transition curves of the ABA/C and BAB/C systems; LCST and resembling UCST phase behavior were observed as the parameters of the system changed. Qualitatively, the experimental and the theoretical results are consistent with each other. © 1996 John Wiley & Sons, Inc. 相似文献
994.
Silica-supported polystannazane–copper complex has been prepared and used as a catalyst for the oxidation of methanol. The results showed that the catalyst could catalyze the oxidation of methanol to formaldehyde at a high yield and selectivity at 30°C and under 1 atm mild conditions. The N/Cu mole ratio in the complex, temperature and the amount of NaOH additive had much influence on the catalytic activity. The complex was stable during the reaction and could be used repeatedly. 相似文献
995.
Chun-Wei Chen Long Zhang Shi-Jian Su Mei-Yu Huang Su-Fen Mao Ying-Yan Jiang 《先进技术聚合物》1996,7(8):711-714
Silica-supported polysilazane (SiO2-Si-N), and its platinum complex (SiO2-Si-N-Pt) were prepared. It was found that SiO2-Si-N–Pt can catalyze hydrogenation of o-xylene under mild conditions (40–50°C, 1 atm). The products of the reaction were cis-and trans-1,2-dimethylcyclohexane. The formation of trans-1,2-dimethylcyclohexane may be adequately explained according to the ‘roll-over’ model. The stereoselectivity was influenced by temperature and catalyst concentration, the proportion of the cis isomer decreasing with an increase in each of the two factors. The effects of other reaction parameters, such as the N/Pt mole ratio in the complex, solvents and reaction time, etc. on the hydrogenation of o-xylene were also studied. The SiO2-Si-N–Pt catalyst is very stable in reaction and turnover numbers amount to 200 in 80 hr. 相似文献
996.
Ying An Masahiro Suzuki Toshiki Koyama Kenji Hanabusa Hirofusa Shirai Mei-Yu Huang Ying-Jan Jiang 《先进技术聚合物》1996,7(8):652-656
The palladium cluster protected by silica-supported, crosslinking, partially phosphorylated poly(vinyl alcohol) (P-PVA) was prepared from a crosslinking P-PVA–Pd(II) complex by reduction in alcohol. The P-PVA–Pd complex and the palladium cluster protected by P-PVA were analyzed by electron spectroscopy, X-ray photoelectron spectrometry and transmission electron microscopy. The complex formation between the Pd(II) ion and phosphoric acid groups in P-PVA was important in the formation of a fine palladium cluster. Palladium clusters protected by silica-supported crosslinking P-PVA were used as catalysts for the hydrogenation of nitrobenzene or acrylic acid at 30°C under atmospheric pressure. The palladium cluster protected by crosslinking P-PVA supported on silica was the most active catalyst, was stable and had no by-products, compared with the palladium cluster protected by silica-supported noncrosslinking P-PVA or PVA. 相似文献
997.
Silica-supported mono-metal (such as Ni, Cu) complexes and mixed metal (such as Cu/Zn, Cu/Cr) complexes of chitosan have been prepared. It is found that these non-noble metal complexes could be used as efficient catalysts for the hydrogenation of aromatic nitro compounds. The effects of type of metal, reaction temperature and pressure, solvent, nitrogen/metal molar ratio in the complex catalysts on the yields from nitrobenzene to aniline have been examined. It was also found that catalysts are active for the catalytic hydrogenation of other aromatic nitro compounds such as 2-nitroanisole, 2-nitroaniline, 2-nitrotoluene and 1-chloro-4-nitrobenzene. 相似文献
998.
The epoxidation of styrene to styrene oxide at higher than 96% yield has been achieved by the catalysis by poly-(vinylbenzyl)acetylacetonate complexes of cobalt(II) or manganese(II) in the presence of isobutyraldehyde under an atmospheric pressure of molecular oxygen at room temperature. The kind of aldehyde and aldehyde/styrene molar ratio greatly influenced the reaction. The catalyst could be recycled, but after recycling for five times, the yield of styrene oxide decreased from 96.0% to 84.6%. 相似文献
999.
A new series of sulfur-containing side-chain liquid crystalline polymer is described. Mesomorphic side chains with methylene spacers of different lengths have been synthesized, and their structures were identified by nuclear magnetic resonance, infrared and mass spectrometry. The liquid crystalline nature of the polymers was characterized by microscopy and differential scanning calorimetry. 相似文献
1000.
We develop some recursive constructions for rotational Steiner triple systems with which the spectrum of a k-rotational Steiner triple system of order v is completely determined for each positive integer k. © 1996 John Wiley & Sons, Inc. 相似文献