铸膜溶剂对CAB膜形态和性能的影响

以ＣＡＢ高分子为膜材料，研究了铸膜液的溶剂体生添加剂对膜形态及选择性渗透Ｎ２、Ｏ２、ＣＨ４、ＣＯ２等气体的影响。溶剂体系以丙酮为基本组分，混合甲酰胺或乙酸，可得到具有好的气体渗透性或气体选择性的非对称膜，通过溶剂的红外光谱羰基吸收峰的偏移，认为溶剂体系有可能存在Ｌｅｗｉｓ酸；碱络合物。     

用SN型催化剂合成苯乙烯一丙烯嵌段共聚物的研究──Ⅰ．聚合条件对共聚合反应的影响

用稀土化合物改性的钛系载体催化剂（ＳＮ催化剂）进行苯乙烯和丙烯顺序嵌段共聚合（Ｓｅｑｕｅｎｔｉａｌｂｌｏｃｋｃｏｐｏｌｙｍｅｒｉｚａｔｉｏｎ）的研究．考察了苯乙烯预聚时间、单体比、外加给电子体（ＥＢ）、烷基铝浓度、催化剂浓度和聚合温度等条件对共聚合的影响．发现外加酯（ＥＢ）降低了共聚合反应催化活性，在ＥＢ／Ｔｉ摩尔比为５范围内，外酯有助于提高嵌段共聚物（ｉＰＳ—ｂ—ｉＰＰ）中ＰＳ段和ＰＰ段的等规度及增加苯乙烯链节含量．ＳＮ型催化剂对苯乙烯一丙烯嵌段共聚合有较高的催化活性，催化效率在１００ｇ聚合物／ｇ－Ｔｉ以上．共聚物通过溶剂革取分级除去均聚物后，所得嵌段共聚物中苯乙烯链节含量可在１５～８５ｍｏｌ％之间调节．其结构表征续见第ＩＩ报．     

Morphology, crystallization behavior and properties of impact-modified polypropylene copolymer with or without sodium benzoate as a nucleating agent

 The morphology, crystallization behavior, and properties of an impact-modified polypropylene (PP) copolymer with or without sodium benzoate were investigated. The contents of ethylene–propylene rubber (EPR) in the reactor-made PP copolymer is about 15 wt%. For comparison, blends of PP and EPR containing the same EPR composition were prepared by melt-mixing. Morphological studies by scanning probe microscopy indicated that the impact-modified copolymer consists of three different phases, i.e., polyethylene, PP, and EPR phases, which is considerably different from the morphology of the conventional PP/EPR blend of the corresponding composition. The impact-modified PP copolymer exhibited a higher crystallization rate in terms of the lower crystallization half-time and thus higher thermal and mechanical properties, such as impact strength and hardness, than the PP/EPR blend did. The addition of sodium benzoate as a nucleating agent to the copolymer increased the crystallization rate and the mechanical properties. Received: 4 June 2001 Accepted: 31 October 2001     

醋酸乙烯酯在硅橡胶上的辐射接枝研究

研究了不同溶剂中的醋酸乙烯酯在硅橡胶上的辐射接技状况及接枝后硅橡胶表面结构情况．结果表明：（１）在硅橡胶－乙酸乙酯－醋酸乙烯酯体系中，接枝有自加速效应；（２）适量加入对苯二酚，接枝诱导期延长，接枝速率下降，凝胶效应消失，辐射接技经验关联式为ＲＰ＝０．２７×［Ｄ］（－０．５６０）×［Ｉ］（０．４９０）×［Ｃ］（０．９２０），接核反应为扩散控制反应；（３）不同的溶剂对硅橡胶接枝有不同的影响，如甲醇发生敏化作用，提高接枝速率，而苯发生惰化作用，降低接枝速率；（４）在合适的甲醇和苯配比时，接枝反应几乎恒速进行，用扫描电镜（ＳＥＭ）观察断面，接枝区比较均一，出现微相分离．     

Synthesis of poly[arylene ether sulfone-b-vinylidene fluoride] block copolymers

A series of α,ω-dihydroxy polyarylene sulfones (PAES) were synthesized comprising bisphenol A (PAES1, M_n=1800, 4900, and 9500 daltons), 4,4^′-biphenol (PAES2, M_n=4100 daltons), and hexafluorobisphenol A (PAES3, M_n=3300 daltons). These were reacted with α,ω-dibromo poly(vinylidene fluoride) (PVDF, M_n=1200 daltons) prepared by telomerization, to yield block copolymers possessing rigid and flexible segments. Block copolymers were characterized by FTIR, NMR, GPC, DSC, TGA and TEM. In several cases the block copolymers exhibited distinct thermal transitions, i.e. T_m and T_g for PVDF and PAES segments, respectively. Where observable, T_g of PAES domains in the block copolymers occurred at a temperature lower than the corresponding PAES homopolymer due to the flexible nature of the surrounding PVDF domains. Block copolymers exhibited a similar thermal stability to the corresponding PAES homopolymers but higher stability than the PVDF homopolymer, and much higher still than α,ω-dibromo PVDF. TEM analyses indicate that phase separation of PAES and PVDF domains occurs on the nanometer scale.     

Salt effects and the mechanism of electrophilic mercuration of unsaturated compounds

The reaction of Hg(OAc)₂ with bornylene in THF-H₂O and CH₃CN-H₂O mixed solvents (75 25, v/v) was studied. The effects of the addition of NaOAc on the reaction rate and the composition of products were investigated. In the CH₃CN-H₂O mixture, the addition of NaOAc decreases the amount of the rearranged product, fundamentally changes the ratio between the regioisomeric solvoadducts, and promotes the formation of products of Hg(OAc)₂ addition. The reaction proceedsvia an ion pair and free mercurinium ion; the cation of the ion pair and the free mercurinium ion have dissimilar structures.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 544–548, March, 1995.     

Catalysis of cationic surfactants in organic solvent: Hydrolysis of 2-nitro-4-carboxyphenyl acetate

The hydrolysis reaction of 2-nitro-4-carboxyphenyl acetate was studied in dichloromethane in the presence of an added electrolyte (NaOH) and cationic surfactants systems with varying quantities of added water at 25°C. The kinetic and conductivity data were correlated.     

Biological production of ethanol from coal synthesis gas

The anaerobic bacteriaClostridium ljungdahlii produces ethanol and acetate from CO, CO₂, and H₂ in synthesis gas. Early studies with the bacterium showed that relatively high concentrations of ethanol could be produced by lowering the fermentation pH and eliminating yeast extract from the medium in favor of a defined medium. This article presents the results from a medium development study based on the aerobic bacteriumEscherichia coli. The results of continuous-reactor studies in a continuously stirred tank reactor (CSTR) with and without cell recycle are shown to demonstrate the utility of this improved medium.     

CHARACTERIZATION OF RADIATION GRAFT COPOLYMER OF INORGANIC COMPOUND ONTO ALKENE

ＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＲＡＤＩＡＴＩＯＮＧＲＡＦＴＣＯＰＯＬＹＭＥＲＯＦＩＮＯＲＧＡＮＩＣＣＯＭＰＯＵＮＤＯＮＴＯＡＬＫＥＮＥＺｈａｎｇＷａｎｘｉ；ＣｈｅＪｉｔａｉ；ＹａｎＭｅｉｌａｎ（ＣｈａｎｇｃｈｕｎｉｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉ...