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101.
Guangming Chen Yongmei Ma Xianjun Zheng Guangyang Xu Jun Liu Jiaqi Fan Deyan Shen Zongneng Qi 《Journal of Polymer Science.Polymer Physics》2007,45(6):654-660
An intercalated polyurethane (PU) /clay nanocomposite was prepared by in situ intercalative polymerization. The PU/clay nanocomposite pellet or film samples were stretched‐recovery‐restretched, using selfmade microstretching tools. The changes of the basal spacings of clay and the orientation of polymer chain segments during the stretched‐recovery‐restretched process were studied by wide angle X‐ray diffraction (WAXD) and Fourier transform infrared (FTIR) dichoism techniques. The WAXD results show that the basal spacing of clay did not change obviously, indicating that no macromolecular chains entered or moved out of the interlayer space, and the orientations of both hard and soft segments inside the interlayer space did not change obviously, either. The FTIR dichroism tests suggest that outside the interlayer space, the orientation of the hard chain segment increased, decreased, and then increased again during the stretched‐recovery‐restretched process. However, no obvious changes of the degree of orientation of the soft segment were observed during the processes, the slightly orientation might be released during the relaxation process before the measurements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 654–660, 2007 相似文献
102.
Liu L Wu D Li X Wang S Li H Li J Wang W 《Chemical communications (Cambridge, England)》2012,48(11):1692-1694
An enantioselective Michael addition of ketones to alkylidenemalononitriles catalyzed by chiral primary amine I with (R)-5c as a co-catalyst in good yields (>90%) and with good enantioselectivities (85-96% ee) has been developed. The strategy has also been extended to a three-component version through a domino Knoevenagel/Michael sequence with similar or better outcomes. 相似文献
103.
It is important to develop methods to sensitively and selectively determine chromium(VI) because chromium(VI) plays crucial roles in pathological and physiological processes. We developed an easy-to-perform, low-cost, and efficient method for synthesizing carbon dots from shrimp shells by calcining the shells without using any chemical reagents. The as-prepared carbon dots exhibited excitation-dependent fluorescence, with excitation and emission maxima at 350 and 400?nm, respectively. The Carbon dots were found to be excellent fluorescent probes for detecting chromium(VI) using the fluorescence quenching effect. The Carbon dots allowed chromium(VI) to be determined with a high degree of sensitivity. The chromium(VI) detection limit was 0.1?µM, and the relationship between the chromium(VI) concentration and the response was linear up to a chromium(VI) concentration of 70?µM. The method for synthesizing carbon dots is novel and the carbon dots produced offer promise for monitoring chromium(VI) in environmental matrices. 相似文献
104.
105.
基于单平板的两种旋转特性(绕表面中心法及绕入射光束光轴旋转)作者提出了一种任意剪切方向的全方位剪切干涉仪,这不仅对于旋转对称发光,尤其对于非旋转对称激光束的定量检测具有十分重要的应用价值,文中描述了该仪器原理,参数及应用实例。 相似文献
106.
光学轮廓仪对光学元件表面空间波长回应的研究 总被引:2,自引:0,他引:2
在分析光学轮廓仪的空间分辨率和带限功率谱密度函数的基础上,用新测不同要品的大量数据研究了光学元件表面粗糙度测量与光学轮廓仪对表面空间波长的带限顺应关系,对由光学轮廓仪不同带宽限制内测量元件表面粗糙度不同回应所引起的不同偏差的解决办法提出了几点建议。 相似文献
107.
简要介绍了同步辐射的原理、装置和特点,综述了它在高分子取向态结晶、熔化、相分离、相转变和银纹产生等高分子研究方面的应用。 相似文献
108.
The photo-oxidative degradation process of polypropylene film containing iron ions was investigated via FTIR and absorbance substraction technique. It is shown that the iron ions play an important role in the decomposition of hydroperoxide and the increase of the degradation rate of polypropylene film. The amorphous region of PP film undergoes degradation prior to the crystalline one. 相似文献
109.
110.
非晶态聚对苯二甲酸乙二酯膜应力屈服机制的示差扫描量热研究 总被引:1,自引:2,他引:1
采用示差扫描量热法、应力应变测量研究了物理老化对非晶态聚对苯二甲酸乙二酯(PET)膜单轴拉伸过程中应力屈服行为的影响.结果表明,非晶高聚物经物理老化后屈服应力,应力屈服峰及热焓吸热峰均增大;屈服前后的DSC结果表明,经过屈服点后试样热焓吸热峰消失,屈服后的试样经物理老化后,应力屈服峰又再现.从凝聚缠结的观点解释了非晶高聚物物理老化和应力屈服的本质. 相似文献