排序方式: 共有109条查询结果,搜索用时 15 毫秒
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计算烷烃沸点的新方法-基团键贡献法 总被引:2,自引:0,他引:2
根据分子中基团的特性和连接性,将基团贡献法和化学键贡献法结合在一起,发展了一种直接根据分子结构信息计算烷烃沸点的新方法-基团键贡献法,此方法同时具有基团贡献法和化学键贡献法的特点。对753种烷烃(C2~C100)的计算结果表明,沸点计算值与实验值的一致性令人满意,平均误差0.46%。 相似文献
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《Composite Interfaces》2013,20(6):589-609
The transverse properties of unidirectional metal matrix composites (MMCs) are dominated by the fiber/matrix interfacial properties, residual stresses and matrix mechanical response. In order to monitor and study, in situ, the failure of interfaces in titanium-based composites subjected to transverse loading conditions, an ultrasonic imaging technique has been developed. The interface was imaged ultrasonically and the change in ultrasonic amplitude with the transverse loading was monitored, indicating the sensitivity of the technique to fracture and deformation of interfaces. This change in amplitude has been explained in terms of the multiple reflection theory of ultrasonic waves. The multiple reflection theory enabled estimation of the interfacial deformation and debonding as a function of loading. The ultrasonic technique was also used in conjunction with finite element modeling in order to quantify the fiber/matrix interfacial transverse strength in situ in MMCs. 相似文献
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《Composite Interfaces》2013,20(7-9):829-839
Composites were fabricated with alkali (10%, 15% and 20%) treated bamboo fibers incorporated to the extent of 50% (by volume) and polyester resin. Impact test was made on bamboo strips and composites samples. It was observed that the fracture energy undergoes an increase from untreated to alkali treated bamboo strips. Alkali treated bamboo fiber composites show higher fracture energy value than the untreated bamboo fiber composites. The phenomenal change was quite evident from scanning electron micrographs of the fractured surface. Considering the effects of all factors, the work of fracture shows maximum value in the case of 20% alkali treated bamboo strip composites. It was also observed that the rate of increase of work of fracture value is much higher in the case of composite samples than the bamboo sample. It was explained on the basis of synergism obtained by improved interfacial adhesion between fiber and matrix, and removal of hemicellulose from the bamboo itself, which was evident from the intermolecular H-bonding formation studied by FT-IR. 相似文献
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Improvement of resin impregnation into glass cloth by silane treatment in resin transfer molding 总被引:1,自引:0,他引:1
《Composite Interfaces》2013,20(7):683-689
An evaluation method was proposed for resin impregnation using resin transfer molding of unsaturated polyester matrix composites with silane-treated glass cloth. The determination of whitening of the composite was carried out as a parameter of incompleteness of resin impregnation. The change of whitening with silane concentration was compared with the bending modulus as a parameter of chemical reinforcement. The materials used were unsaturated polyester resin as a matrix and methacryloxypropyltrimethoxysilane as a silane coupling agent for glass cloth. Resin transfer molding was used to produce four plies of glass cloth laminates by impregnating the resin. The silane-treated glass cloth repressed whitening above 0.026 w/w% of silane in aqueous solution, while the chemical reinforcement due to silane gave no appearance below 0.2 w/w% based on the bending test of the laminates. The large difference between the concentrations suggested that silane has a couple of functions, that is, chemical reinforcement and physico-chemical resin wettability. 相似文献
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应用AM1方法全优化了11种电荷传输材料的稳定构型。根据Law提出空穴注入轨道模型,研究了光敏性E~5~0与电荷传输材料和电荷传输材料的HOMO能级差ΔE~T~-~G的关系。计算结果表明,lgE~5~0与ΔE~T~-~G存在线性关系。采用成键能较低构型的HOMO能级得到的相关性(r=0.837)优于成键能较高构型的HOMO能级得到的相关性(r=0.728)。增加空穴传输活性氮原子的净电荷后,相关性被进一步提高(r=0.911)。这表明分层光感受器的光敏性与光电转换的后两个过程都相关,其中从电荷产生层(CGL)到(CTL)电荷传输层的空穴注入效率占主导作用,空穴在CTL中的迁移率也至关重要。 相似文献
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探讨了一类具有高位阻特征的烃基膦酸单十六烷基酯萃取剂R^1(R^2O)P(O)OH从氯化物介质中萃取Yb(III)和Lu(III)的结构与性能关系。其中,R^1分别为CH~3,C~2H~5,i-C~3H~7,cyclo-C~6H~1~1和C~6H~5,R^2为C~4H~9CH(C~2H~5)C~2H~4CH(C~6H~1~3)或C~6H~1~3CH(CH~3)CH~2CH(C~6H~1~3)。结果表明,这类萃取剂对于Yb,Lu的萃取和分离能力随着其分子中取代基空间位阻的增大而降低。 相似文献