RHEOLOGICAL CHARACTERIZATION OF PROCESSABILITY OF UNVULCANIZED POLYBUTADIENE

Rheological investigation on a series ot unvulcamzed polybutadiene elastomers of different processability has been carried out by means of a capillary extrusion rheometer. It is found that the processability of unvulcanized polybutadiene can be correlated with the occurrence of unsteady flow and the wall stress, dependence of the dimensionless number e characterizing the entrance elongational elasticity which has been found to be sensitive to the branching structure and the molecular weight distribution of the samples. Interpretations based on the structural data of unvulcanized polybutadiene were discussed.     

MORPHOLOGY OF POLYBUTADIENE “SHISH KEBABS”

Shish kebab structure of cis-1 , 4-polybutadiene has been obtained by quiescent solution crystallization at suitable temperature. The morphology and growth mechanism of formation of shish kebab structure have been studied in detail.The higher the molecular weight the faster the sample crystallizes.     

固定化酶不对称合成（S）＋—（＋）—布洛芬的研究

能够不对称水解布洛芬乙酯的酵母菌Ｔ１５８固定化在壳聚糖珠中，固定化酵母菌的活力回收达６０％，最适温度为４５℃，半衰期为７５ｄ以上。     

单边裂纹聚苯乙烯样品拉伸断裂过程的声发射

本文测定了单边裂纹聚苯乙烯(PS)样品在拉伸加载时的声发射以及声发射事件按幅度、脉宽、计数和位置的分布,实验证实,单边裂纹PS样品拉伸时的声发射来源于裂纹端部银纹区的变形、断裂和扩展,大部分总振铃计数由裂纹亚临界和失稳扩展引起,在重复加载时观察到PS声发射的Kaiser效应。     

TS和PTS单晶体的热刺激电流

测定了双(对甲基磺酸)2,4-己二炔-1,6-二醇酯(TS)及其不同聚合程度TS-PTS混合体和完全聚合的聚合物PTS在100-300K温度范围内的热刺激电流。在沿分子堆砌方向上(对PTS则是大分子链方向)上观察到了它们的热刺激电流,并在相应于它们相变152K和192K处呈现热刺激电流峰。研究了聚合程度对相变的影响,绘制了TS-PTS体系的相图。对另三个热刺激电流峰的归属作了定性解释。     

聚硅烷亚芳弹性体的凝胶渗透色谱测量

用简易GPC柱研究了在未知合适的Mark-Houwink 系数的情况下,通过GPC和特性粘度的数据,同时计算出宽分布硅烷亚芳弹性体聚合物的分子量和这种类型聚合物的 Mark-Houwink 系数的方法。装柱填料为多孔硅胶球,理论塔板数 4200—5500块/米以上,塔板高度 0.7—0.9毫米。其分子量分布宽度指数在2左右。素炼后,分子量分布变窄,分子量下降。     

绝热法研究己内酰胺阴离子聚合尼龙动力学

采用己内酰胺钠盐、N-75缩二脲作为反应催化体系, 确定反应温度在145-160 ℃之间, 通过计算得到动力学参数: 反应级数为准一级、活化能在73.2-77.1 kJ·mol-1之间、指前因子在2.9×1011-3.6×1011 mol1-n·s-1范围内. 本实验条件下测定并计算的反应热为134.5-137.3 J·g-1, 与文献值(138.6 J·g-1)吻合. 并在前人基础上修正并建构了己内酰胺阴离子绝热反应动力学模型, 对反应过程的模拟结果与实验数据基本吻合, 从而证明了本模型的正确合理.     

Two New Sesquiterpenes from Eupatorium lindleyanum

Various germacrane sesquiterpenes have been isolated from many species of the Eupatorium.In recent years these compounds have been increasing interest due to their insecticidal,cytotoxic,antitumor-promoting and insect-antifeedant activities1.In our present study,we have investigated the chemical constituents of Eupatorium lindleyanum DC.,which is a geo-authentic medicine of Jiangsu province.It is used as a antipyretic drug.Two novel germacrane sesquiterpenes(Figure1)were found by us from th…     

BANDED TEXTURE FORMATION IN NEMATIC SOLUTION OF POLY (1,4-BENZAMIDE) IN SULFURIC ACID

The banded texture in films prepared from nematic poly (1,4-benzamide) (PBA)/H_2SO_4 solution by shearing and without shearing has been studied by using microscopy techniques. The kinetic parameters of banded texture formation γ_c and τ_b were measured for nematic solution of PBA by using parallel-plate shearing apparatus. The banded texture was also observed in randomly packed domains for nematic solution of PBA on standing without shearing. The properties of banded texture show no difference between the two samples with or without shearing.     

CARBON-13 NMR STUDY OF MOLECULAR MOTION OF 1, 2-POLYBUTADIENES IN SOLUTION Ⅰ. STRUCTURE DEPENDENCE OF MOLECULAR MOTIOM

Proton decoupled, partially relaxed, Fourier-transform 50.3 MHz carbon-13 NMR in naturalabundance was used to determine spin-lattice times (T_1) and nuclear Overhauser enhancement fac-tors (NOE) of individual carbon of a serics of 1,2-polybutadienes with different structures in solutionin CDCl_2 The structure dependence of molecular metion and the internal motion of vinyl group in1,2-polybutadiene have been studied by nT_1 and NOE values. The nT_1 values of the carbons in cis-1,4-units are the highest and those of the carbons in 1.2-units are the lowest in three types of units in1,2-polybutadiene. The nT_1 values of carbons in the same unit become greater when the adjacent1,2-units are replaced by 1,4-units, and nT_1 values of the carbons in all units decrease sharply withthe increase of content of 1,2-units in the polymers. The fact that nT_1 values of --CH=are larger than those of=CH_2 in vinyl group impliesthat there are complex internal motions of vinyl group. It is shown by calculation that the dominantfactor causing the difference in nT_1 of--CH=and=CH_2 in vinyl group is a swing of vinyl group ina plane peopndicular to the chain backbone.