~(13)C-NMR研究聚丁二烯的序列结构

本文采用~13C-NMR方法研究了不同催化体系制备的聚丁二烯。经分析指出,聚丁二烯分子链的三种序列(顺-1,4-序列、反-1,4-序列和1,2-序列)和十七类脂碳碳核为~13C-NNR谱贡献了十六个谱峰。经数据的解析,得到一组计算聚丁二烯脂碳部分各谱峰化学位移的经验参数。在本文条件下,应用该组参数得到的计算值与实验值符合较好。本文确认了聚丁二烯反-1,4-序列第四峰(T_4)的存在。初步研究了聚丁二烯~13℃-NMR谱图的定量处理问题。     

SEQUENCE STRUCTURE OF ETHYLENE-VINYL SUBSTITUTED COPOLYMER WITH ~(13)C NMR IV——CHLORINATED POLYETHYLENE

The substituent chemical shift (SCS) has been applied to the assignment of the ~(13)C NMRspectrum of chlorinated polyethylene (CPE). CPE of different chlorine contents has been em-ployed and their sequence structure discussed. The results show that characteristic of CPEwith medium chlorine content is the dichloroethane structure in molecular chain. SCS param-etets have been obtained from the ~(13)C NMR spectra. It was found that the effects of chlorinecontent and temperature on SCS are negligible, but the substituent parameter S_1 reduced by0.39 ppm when C_2Cl_4 was added to solvent ODCB.     

SYNTHESIS AND CHARACTERIZATION OF THERMOTROPIC COPOLYESTERS AND COPOLY (ESTER-AMIDE)S CONTAINING OXYETHYLENE-ETHER AS THE SPACER

Flexible oxyethylene-ether was introduced into the aromatic copolyesters and copoly(es-ter-amide)s to reduce the melting point of resulting polymers. The melting point was greatlyreduced to 200℃ or even lower in some cases, and the molecular weight was satisfactorilyhigh as reflected by inherent viscosity. The polymers exhibited high thermal stability and goodmechanical properties as determined by TGA and mechanical tests. The copolyester showedbetter crystallinity and liquid crystallinity than corresponding copoly(ester-amide)s with simi-lar monomer composition as reflected by POM observation and WAXD study. The meltingpoints for both copolyesters and copoly (ester-amide)s showed great dependence on the p-acetoxybenzoic acid (PAB) content in monomer composition and reached the lowest valuewhen PAB was 29 mol%.     

有机/无机纳米杂化材料负载钛催化剂及聚合研究 Ⅰ.乙烯聚合

有机/无机纳米杂化材料负载钛催化剂及聚合研究 Ⅰ.乙烯聚合     

聚β-羟基丁酸酯/聚氧化乙烯共混体系力学性能研究

本文详细研究了可完全生物降解的聚 β 羟基丁酸酯 (PHB)与水溶性聚氧化乙烯 (PEO)两元共混体系的拉伸力学性能 .讨论了PEO分子量、共混组成及热处理条件对共混体系力学性能的影响 .其中 ,PHB与超高分子量PEO(重均分子量 5× 10 6)共混 ,两组分力学上具有相容性 ,共混物的拉伸强度、断裂伸长率及模量都有明显的正的协同效应 .共混改性效果显著PHB的力学性能得到很大改善 ,尤其PHB的脆性缺陷 .并且 ,共混物在经过适当温度退火处理之后 ,共混物性能还可进一步改善     

~(13)C-NMR化学位移与聚合物的构象——Ⅰ.1,2-聚丁二烯乙烯基叔碳(-CH=)的~(13)C-NMR谱研究

本文应用半经验方法来解析无规1,2-聚丁二烯乙烯基叔碳(—CH=)的~(13)C-NMR谱图。研究指出只有主链CH与乙烯基叔碳之间的gauche排列和由此产生的屏蔽效应对后者的化学位移的改变作出了贡献。因此,可以直接利用键概率来归属十个五元组立构异构体的排列顺序。由于上述原因,得到了对于无规1,2-聚丁二烯乙烯基叔碳的~(13)C-NMR谱的一种新的归属,并且通过研究全同和间同1,2-聚丁二烯的~(13)C-NMR谱图予以证明。     

聚合物链构象的研究 Ⅰ.1,2-聚丁二烯的构象分析

本文应用Flory的链分子统计理论研究1,2-聚丁二烯的链构象,选择固定键长和键角的分子模型,计算构象能,构成势能面图,并由势能面的构型积分,得到了表征1,2-聚丁二烯链构象特征的统计权重矩阵.     

反,反-和顺,反-2,4-己二烯的简正振动分析

为研究聚乙炔(PA)的分子结构及振动光谱,对反,反-2,4-己二烯(TTHF)和顺,反-2,4-己二烯(CTHE)进行了红外(IR)和拉曼(Raman)光谱的检测和简正振动分析。主要结果如下: (1) TTHE的C_2h分子对称性,导致真观测谱带严格遵守IR-Raman相互排斥规则。而CTHE的分子不对称性,使其并无此现象发生。(2) TTHE和CTHE的简正振动分析都得到了42个非零的计算频率,这是符合3N-6规则的。(3) 计算所得TTHE和CTHE的位能分布值,与我们听做的经验指认吻合得较好。伹TTHE和CTHE的大部分骨架的简正振动模式都是由多个经验模式的贡献,这表明了平面和共轭结构所造成的骨架振动的复杂性。(4) 对TTHE和CTHE进行力场精化,所得计算频率与观测值的平均绝对偏差为14cm~(-1),平均相对偏差为1.8%。     

MORPHOLOGY OF BISPHENOL A POLYSULFONE-POLYOXYPROPYLENE SEGMENTED COPOLYMERS

Morphology of bisphenol A polysulfone-polyoxypropylene segmented copolymers was inves-tigated by means of differential scanning calorimetry and transmission electron microscopy. Theresults show that the molecular weights of the hard and soft segments have a pronounced effect onthe morphology of these segmented copolymers, which may changr from three-phase to single-phasestructure depending on the size and the relahve size of the segments. Heat treatment will enhancethe process of phase separation, increasing the domain size of the dispersed phase, Results obtainedby study on the dynamic mechanical properties of these copolymers well support the existence ofthree-phase morphological structure.     

EVAc共聚物的序列结构和它的~(13)C NMR谱的关系

本文以EVAc共聚物为例,阐述了EV共聚物序列结构的符号表示与Bovey关系(Ⅰ)的一致性。在此基础上,选择了EV共聚物序列结构的Sung表示并赋予它以化学位移的意义,在二元组和三元组序列水平上分析了EV共聚物的13种序列结构与Sung表示,与取代基参数,与其~(13)C NMR谱13个谱峰之间的一一对应关系。其主要内容由Sung表示与取代基参数之间的α～S_1,β～S_2,γ～S_3,δ～S_4,δ~+～0ppm对应关系表征,从而构架了由EV共聚物的~(13)C NMR谱通向其序列结构的桥梁,建立起研究EV共聚物序列结构的普适方法。