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891.
A systematic investigation is carried out on the gas phase of propylene during the initial instants of polymerization. The results confirm the positive impact of small amounts of mineral oil on the initial reaction rate and morphology. It is shown that polymerizing under conditions of mild temperature and pressure alone are not enough to achieve the same result. It is found that the presence of mineral oil, and low temperature of polymerization can be used to control the morphology of polymer particles and to obtain high activity in the main reaction. If enough oil is used, moderate to high temperatures of prepolymerization are acceptable in terms of controlling morphology but can compromise the activity of the main polymerization. It is also observed that the way in which the oil is introduced has an impact on the kinetics and particle morphology. Separate addition of oil from the precatalyst gives rise to relatively flat kinetics during prepolymerization and highest rate during main polymerization. To account for the activity enhancement, a selective quench‐labeling study employing methyl propargyl ether shows that the presence of mineral oil appears to increase the fraction of active titanium by a factor of almost 2. 相似文献
892.
Yuan Xue Jinbao Liu Maiying Xie Fengfei Chen Mingan Zhou Hualin Lin Fan Zhang Shizhou Liu Zhiqiao Wu Sheng Han 《中国化学快报》2020,31(2):345-348
In this study,various nonionic surfactants(NS) with different ethylene oxide(EO) numbers and tail lengths and its binary blends with anionic surfactants(AS) were used as emulsifiers for naphthenic oil to form the microemulsion metalworking fluids(MWFs),and the effects of them on the stability of the emulsion system were investigated by formulation triangle method.The results indicated that binary complex surfactants of NS and AS as emulsifiers exhibited better emulsifying effect than that of single NS.NS with different EO numbers and tail lengths presented various emulsifying effects.NS(EO=10)exhibited the greatest number of stable formulations,especially the TX-10,but no linear relationship existed between the number of stable formulations and the tail length of NS.In addition,aromatic primary alcohol ethoxy late(APAE) series surfactants containing benzene groups similar to the cycloalkanes in the naphthenic oil so that presented the best emulsifying affect and the greatest number of stable formulations.The co-surfactant of sodium dodecyl benzene sulfonate(SDBS) binary blends with NS exerted the best synergistic effect,and the stable formulations numbers were ranged from 5 to 7,next sodium stearate(SS) comes last followed by sodium dodecyl sulfate(SDS-1) and sodium dodecyl sulfonate(SDS-2). 相似文献
893.
Abdul Khaliq Syed Muhammad Ali Shah Muhammad Akram Naveed Munir Muhammad Daniyal Muhammad Irshad 《Natural product research》2020,34(13):1951-1955
AbstractThe olive (Olea europaea L.) is a worldwide famous tree crop having valuable commercial role due to nutritional as well as therapeutic benefits obtained from its edible oil. Eight varieties of Olea europaea L. fruits were obtained from three Agricultural research institutes located in different areas of Pakistan including Quetta, Lorallia and Zhob to extract and determine their oil contents by conventional method as solvent extraction (soxhlet apparatus). Statistical analysis showed significant (p?=?0.002) difference in oil composition of collected plants. Highest amount (percentage) of oil was obtained from Gemlik variety (65%) from Lorallia and lowest oil content from Dolece-agogia variety (17.5%) collected from Quetta. Further research is under consideration to rule out best suitable factors including some soil and environmental factors to obtained more potential cultivars of Olea europaea in Pakistan. 相似文献
894.
895.
W. G. Laidlaw G. R. Hamilton R. B. Flewwelling W. G. Wilson 《Journal of statistical physics》1988,53(3-4):713-731
Percolation invasion displacement of a compressible defender is examined for two cases: when only the smallest accessible site is entered at each step and when all accessible sites less than the size given by a reducing back pressure are entered at each time step. Although the fractions of invading fluid are different, their scaling properties are equivalent. The effect of limited control of a back pressure in a real displacement and the effect of viscosity in a real time displacement are examined. In these cases the scaling properties of a percolation process at breakthrough are removed. As a result, one should expect that realistic displacement models will not have the singular properties usually attributed to percolation processes. 相似文献
896.
897.
本文自留兰香油出发,合成了二氢香芹酮,经H^1NMR与C^13NMR研究,并没有发生二氢香芹酮的异构化。 相似文献
898.
季铵酚离子在水/硝基苯界面的转移 总被引:1,自引:0,他引:1
油/水界面上的电化学研究是近年来电化学研究中的一个新领域,对膜电化学的发展具有重要意义。目前研究油/水界面电化学中普遍使用循环伏安(CV)法和循环线扫电流计时电位(CLC)法。有关抗生素在油/水界面的转移已有报导,本文用CLC法和CV法对肌肉松弛剂季铵酚离子在水/硝基苯界面的转移行为进行了研究。 所用三碘季铵酚为中国科学院生物化学研究所生产的化学试剂,其他试剂及仪器均与前文相同 相似文献
899.
建立了管柱接触非线性问题的间隙元法。用此方法对试油测试射孔管柱的受力状态进行了分析,并通过现场应用实例证明了此方法的可靠性和准确性。根据此方法开发的应用软件可为井下管柱的结构设计提供理论依据。 相似文献
900.