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201.
Blends of ABS (acrylonitrile–butadiene–styrene) with phenoxy(poly(hydroxyether bisphenol A)) were prepared using a Branender single screw extruder. Scanning and transmission electron micrographs (SEM, TEM) showed a typical two-phase morphology; particle-in-matrix (90/10) (ABS/phenoxy by weight), 70/30, 10/90), island/sea (30/70) and co-continuous (50/50) morphologies. The glass transition temperature (Tg) of SAN was almost unchanged in the blends, while the Tg of phenoxy increased by about 5 °C in the blends. The synergistic effect of tensile modulus and strength was noted in ABS-rich blends, where a drastic drop of ductility was seen, and the results were interpreted in terms of rubber particle migration form SAN to phenoxy phase, which was visualized by TEM. Melt viscosity showed yield in ABS-rich blends, and generally followed the log additivity. 相似文献
202.
Heung-Jin Choi Dong-Hee Lee Yeon Sil Park In-Kyu Lee Young-Chul Kim 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):15-18
Octahedrally converging hexadentate macrocyclic receptors 1 and 2, based on L-tartaric acid and furanmoieties, were synthesized andtheir complexation properties studied. In this paper,magnesium ion selectivitiesdetermined by ISE experiments, chiroptical changes observedby circular dichroism(CD) on complexation, and association constants measuredby NMR titration arediscussed. 相似文献
203.
Transmission gratings of holographic polymer-dispersed liquid crystals (HPDLC) are prepared under controlled reaction conditions by adding various amounts of chain-transfer agent (CTA). The resulting films have a higher gel content with lower cross-link density, less dark reaction, less grating shrinkage with much smoother LC/polymer interfaces, smaller induction period, and fast saturation of diffraction efficiency, which shows a maximum of 95 % with 1 % CTA. An optimum LC content of 35 % is verified on the basis of morphology and reaction kinetics. 相似文献
204.
Riehn C Matylitsky VV Jarzeba W Brutschy B Tarakeshwar P Kim KS 《Journal of the American Chemical Society》2003,125(52):16455-16462
In this paper, we report the use of femtosecond time-resolved degenerate four-wave mixing rotationally resolved spectroscopy to obtain very accurate structural information on the symmetric top cyclohexane. Apart from highlighting the versatility of this method in determining accurate structures of large and complex molecules without dipole moment, the present study also details the comparison of the experimentally determined rotational constant B(0) with that obtained from high-level ab initio calculations. The theoretical calculations, which were carried out at both the second-order M?ller-Plesset (MP2) and coupled-cluster with single, double, and perturbative triple substitutions [CCSD(T)] levels of theory, also take into account vibrational averaging effects. A detailed investigation of the vibrational averaging effects reveals that the corrections emerge from only the six highly symmetric A(1g) modes, a justification of which is provided by an analysis of these modes. 相似文献
205.
Jeong Gwi-Taek Park Don-Hee Hwang Baik Park Kyungmoon Kim Si-Wouk Woo Je-Chang 《Applied biochemistry and biotechnology》2002,98(1-9):1115-1127
The growth properties of Panax ginseng hairy roots transformed by Agrobacterium rhizogenes were compared between flask and aerated column or stirred bioreactor. In flask cultures, sucrose, initially 30 g/L, was nearly
exhausted after 45 d of culture. The pH of the medium dropped from 5.5 to 4.96 after 10 d, but afterward it gradually increased
to 6.4. After 45 d, hairy roots grew about 16-folds. The growth rate of hairy roots in air-bubble column or stirred bioreactor
cultures was 1.13 (1.11) to 1.23 (1.20) g fresh wt (dry wt)/(g of cells·d), respectively. For both bioreactors, growth was
about three times as high as in the flask cultivation. 相似文献
206.
The surface-enhanced Raman scatterings of dimethyl sulfide, diethyl sulfide and dimethyl disulfide have been investigated in silver sol. The dimethyl disulfide molecule decomposes on silver to the corresponding mercaptide implying facile cleavage of its S---S bond. The C---S bond in dialkyl monosulfide appears not to cleave on silver. For diethyl sulfide, the C2 conformation seems to be favorable on silver than other conformations. 相似文献
207.
208.
Tae Oan Ahn Jung Ho Kim Jong Chan Lee Han Mo Jeong Jong-Yoon Park 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):435-441
A macro-azoinitiator containing polyarylate segment and azo group was prepared by the solution polycondensation of azobiscyanopentanoyl chloride and hydroxy-terminated polyarylates having viscosity-average molecular weights of 6200, 8100, and 12 400. These macro-azoinitiators were used in the radical polymerization of styrene to synthesize polyarylate-polystyrene block copolymers. Thermal properties measured by the differential scanning calorimetry indicated the phase separated morphology of the block copolymers except at low molecular weight of the block constituents. © 1993 John Wiley & Sons, Inc. 相似文献
209.
Headspace gas chromatography-mass spectrometry (GC-MS) has been successfully applied to the analysis of the highly volatile species trimethyl amine (TMA). TMA quantitation in fiberglass insulation resins (ultimately used by the automotive and building products industries) is of interest because of its highly odoriferous nature. The release of TMA from fiberglass insulation products is the principal component responsible for the "fishy" odor encountered in automobiles. Currently, the industry standard for the analysis of TMA involves injecting an aqueous insulation extract into the GC-MS equipped with a polyethylene glycol column. Several problems inherent in this analysis prohibit consistent performance and enhance the possibility for wide variations in the quantitative results. This article reports the development of a new approach to the quantitation of TMA from fiberglass insulation between the levels of 1 and 150 ppm. 相似文献
210.