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81.
82.
To confirm the reliability of the theory of phase equibria of multicomponent polymer 1/multicomponent polymer 2 systems (i.e. quasi-binary systems) and the method of computer experiment based on this theory (Brit. Polym. J., 23 (1990)285; 23 (1990)299; Polym. Int., 29 (1992)219), could point curves (CPC), two-phase volume ratios ( R ) and critical solution points (CSP) have been determined experimentally for the quasi-binary mixtures of poly(ethylene oxide) (M¯w = 647, M¯w/M¯n = 1.15; M¯w and M¯n, the weight-average and numberaverage molecular weights, respectively) and poly(propylene oxide) (M¯w = 2028, M¯w/M¯n = 1.08; and Mw = 2987, Mw/Mn = 1.13). The hydroxyl end groups of both polymers were methoxylated in advance by the Cooper & Booth method (Polymer, 18 (1977)164). The thermodynamic interaction parameter between both polymers, χ12, and the concentration dependence parameters for the above quasi-binary systems were determined by the method proposed in a previous paper (Brit. Polym. J., 23 (1990)299). CPC, R and CSP values calculated on the basis of the theory are in good agreement with the values determined experimentally. 相似文献
83.
Shang-Ching Chou 《Journal of Automated Reasoning》1988,4(3):237-267
Wu's algebraic method for mechanically proving geometry theorems is presented at a level as elementary as possible with sufficient examples for further understanding the complete method.The work reported here was supported by NSF Grant DCR-8503498. 相似文献
84.
论校园文化和德育目标的一致性 总被引:3,自引:0,他引:3
冯峰 《河南机电高等专科学校学报》2002,10(1):13-14
中系统介绍了校园化和德育目标的关系,并找准两之间的结合点,通过分析两的一致性和辩证统一关系,达到育人目的。 相似文献
85.
86.
The main problems in estimating the uncertainty due to the presence of impurities in the material: the absence in the documents of a unique definition of the quantity being measured – the fixed point temperature, the lack of agreed methods of realizing the fixed points and the insufficient justification of the equations used for the estimate, are analyzed. The results of a measurement of the melting point of gallium are presented, which differ in the conditions in which they were realized – with one and two liquid-solid interfaces and different solidification conditions, are presented. The reasons for the considerable difference between the values of the temperatures obtained in these experiments are discussed. 相似文献
87.
88.
89.
Hamid Javaherian Naghash Ahmad Reza Momeni Hamid Alian Ahmad Reza Massah Shahla Ataie 《Polymer International》2005,54(11):1564-1571
Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L?1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier‐transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, Wg, and its equilibrium volume swelling ratio in benzene, qv, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry 相似文献
90.
卢金生 《理化检验(物理分册)》1995,31(6):27-30
通过对“软-软”、“中-软”、“中-中”、“中-硬”四组不同硬度匹配的滚子接触疲劳试验得出四条P-N曲线。并发现中硬度材料的接触疲劳寿命高于软材料,而当主试样为中硬时,与之相匹配的陪试件硬度越高,主试样的寿命越短,通过分析讨论解释了产生上述现象的原因及其失效机理。 相似文献