Wide angle X‐ray diffraction and Fourier transform infrared dichroism studies of stretched‐recovery‐restretched process of polyurethane/clay nanocomposite

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     

Organocatalytic enantioselective conjugate addition of ketones to isatylidine malononitriles

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.     

一种全方位激光束检测仪

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。     

光学轮廓仪对光学元件表面空间波长回应的研究

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。     

同步辐射在高分子研究中的应用

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。     

THE FTIR STUDIES OF PHOTO-OXIDATIVE DEGRADATION OF POLYPROPYLENE

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.     

超临界CO2中苯甲酸与乙醇和二甲基亚砜的相互作用

在３５．０℃、１２．ＭＰａ条件下，用红外光谱法研究了超临ＣＯ２中苯甲苯与乙醇和二甲亚砜的相互作用。结果表明，在纯超临界ＣＯ２中，苯甲酸以单体和二了本的形式存在。     

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

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．     

Significant suppression of leakage current in (Ba x ,Sr1-x )TiO3/MgO heterostructured thin films by thin MgO layers insertion

The leakage behavior and dielectric property of BST80/MgO heterostructured thin films deposited on LaNiO₃ (LNO)/Si substrates by sol-gel were investigated. The dielectric constant and the leakage current are modified by MgO insertion. The dramatic reduction in the leakage current effectively increased the charge retention of the capacitors consisted of heterostructured thin films as compared to the pure BST films. The significant reduction in the leakage current can be attributed to the minute solid solubility of MgO in the BST lattice and the potential barrier built in the interface between BST and MgO layers in the heterostructured thin films.     

升温在位红外研究物理老化对间规聚苯乙烯结晶行为的影响

通过在位红外光谱测量研究了物理老化对非晶和δ晶型的间规聚苯乙烯（ＳＰＳ）升温结晶过程的影响。发现对于晶样品来说,在物理老化前后,其结晶（即非晶→α晶型）的温度区间变化不大;但对于δ晶型的样品而言其物理老化后的晶型转变（即δ晶型→γ晶型）温度区间是１０４～１２７℃,与未物理老化的晶型转变温度区间９０～１１２℃相比,转变温度升高了约１４℃,这充分说明了物理老化使溶致型的δ晶型更加稳定,其溶剂与晶体的结