Application of the Sanchez-Lacombe lattice fluid theory to the system pvme/ps and model calculations

Cloud point curves reported in the literature for five representatives of the system poly(vinyl methyl ether)/polystyrene were evaluated theoretically by means of the Sanchez-Lacombe lattice fluid theory. The measured phase separation behavior can be described within experimental error using only one adjustable parameter (quantifying the interaction between the unlike mers). The Flory-Huggins interaction parameters calculated from this theoretical description depend in good approximation linearly on composition (volume fractions) and on the inverse temperature. An evaluation of these data yields a maximum heat effect which is almost one order of magnitude less (ca. -0.25 J/cm(3)) than obtained via Hess's cycle (dissolution of the components and of the blend) from calorimetric measurements. Model calculations on the basis of the present theory demonstrate that the critical points shift to a different extent upon a certain relative change in the molar mass of the blend components. The sensitivity of the calculated phase diagrams against changes in the scaling parameter decreases in the following order: interaction energies between unlike mers, differences in the scaling temperatures, pressures and densities.

稀土顺丁橡胶/SBR体系的力学性能

稀土顺丁橡胶与丁苯橡胶（ＳＢＲ）共混，可以改善ＳＢＲ的耐低温性能。当稀土顺丁橡胶／ＳＢＲ（质量比）为２０／８０时，－３０℃的ｔａｎδ仅小于ＳＢＲ，６０℃的ｔａｎδ最小。其共混胶的应力－应变性能、湿滑指数、磨耗及生热性能均优于镍系顺丁橡胶／ＳＢＲ共混体系。

Compatibilization effect of graft copolymer on immiscible polymer blends .2. LLDPE/PS/LLDPE-g-PS systems

The compatibilizing effect of graft copolymer, linear low density polyethylene-g-polystyrene (LLDPE-g-PS), on immiscible LLDPE/PS blends has been studied by means of C-13 CP-MAS NMR and DSC techniques. The results indicate that LLDPE-g-PS is an effective compatibilizer for LLDPE/PS blends, and the compatibilizing effect of LLDPE-g-PS on LLDPE/PS blends depends on the PS grafting yield and molecular structure of the compatibilizers and also on the composition of the blends. It was found that LLDPE-g-PS chains connect two immiscible components, LLDPE and PS, through solubilization of chemically identical segments of LLDPE-g-PS into the noncrystalline region of the LLDPE and PS domain, respectively. Meanwhile, LLDPE-g-PS chains connect the crystalline region of LLDPE by isomorphism, resulting in an obvious change in the crystallization behavior of LLDPE. (C) 1996 John Wiley & Sons, Inc.

稀土BR／SBR共混胶的性能

研究了４种共混比的ＬｎＢＲ／ＳＢＲ共混生胶、混炼胶及硫化胶的性能，并与ＮｉＢＲ／ＳＢＲ共混胶进行了对比。结果表明，共混生胶的ＭＬ均低于ＬｎＢＲ及ＳＢＲ；当ＬｎＢＲ／ＳＢＲ共混比大于２０／８０时，呈现２个Ｔｇ；而大于８０／２０则出现应变诱导结晶现象。ＬｎＢＲ／ＳＢＲ共混混炼胶的ＭＬ、剪切应力、出口膨胀及硫化速度均低于ＮｉＢＲ／ＳＢＲ共混胶，挤出物外观优于后者；共混硫化胶的拉伸强度、热空气老化、拉伸疲劳、湿滑、耐磨等性能均明显优于后者，生热和透气率高于后者。

用SBS或SBR或BR改进HIPS的冲击性能

采用机械共混法，在弹性体用量为５％～２５％时，研究了ＳＢＳ，ＳＢＲ，ＢＲ分别对ＨＩＰＳ的增韧效果。ＳＢＳ可使ＨＩＰＳ的冲击韧性大幅度提高，并随ＳＢＳ含量增加显著上升。ＳＢＲ也能提高ＨＩＰＳ的冲击韧性，但幅度不大。ＢＲ的加入使ＨＩＰＳ的冲击韧性下降。前两者的冲击试样断面平整而光洁，有明显的应力发白现象，属韧性断裂，后者的断面粗糙不平，无应力发白现象，属脆性断裂。改性ＨＰＳ的形态随着弹性体的不同以及含量的变化均有不同特点，与冲击韧性的变化相对应。

NMR研究LLDPE-g-PS对SBS/LLDPE的增容作用

最近,关于用接枝或嵌段共聚物作为增容剂来提高不相容聚合物共混体系相容性的研究越来越受到人们的重视因为这是开发新型高性能聚合物材料最简单最有效的方法之一.通常,适当选择接枝或嵌段共聚物,其链段可能同相应相区的链段相同,或者同某一相相容,因而可起到界面剂的作用:减小不相容组分的界

溶聚SBR和乳聚SBR的结构表征

用凝胶渗透色谱((GPC)和激光小角光散射(LALLS)联用法对不同牌号的溶聚SBR(S-SBR)和乳聚SBR(E-SBR)的分子量及其分布进行了测定。结果发现,E-SBR的(?)_w较大,分子量分布较宽,有些试样含有少量特大分子,还发现偶联的S-SBR图谱具有双峰。用氢质子核磁共振仪对两者的微观结构进行了表征,其中E-SBR不同试样的微观结构差别较小,而S-SBR不同试样的微观结构则存在明显差异,表明S-SBR链结构具有较大的可调节性。

微量PEO-PS-PEO/PEO共混体系结晶过程中共聚物胶束的成核作用

本工作将Leibler等近期关于含非晶两嵌段共聚物“稀固体溶液”的胶束理论推广并应用到含结晶三嵌段共聚物的“稀固体溶液”.对微量聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物/聚氧化乙烯均聚物共混体系的结晶行为进行了研究.结果表明,共聚物胶束在共混体系的结晶过程中可以起到成核剂的作用.这对改善结晶均聚物的性能具有一定的应用价值.

动、静态硫化(NR+SBR)/PE共混体系的结构与性能

用TEM研究了(NR+SBR)/PE共混体系经动、静态硫化后的形态结构及其与力学性能的关系。未硫化和静态硫化体系的形态结构与其组成有关,均以含量大的组份为连续相;对动态硫化体系,当(NR=SBR)/PE<70/30时,均以PE为连续相,其性能主要依赖于构成连续相组份的性质。 动态硫化体系的T_g值低于静态体系,随PE组份含量的增加变化不大,而静态硫化体系的T_g值则随PE含量增加向高温方向迁移。用DSC测得动态硫化体系的结晶度比静态体系的大。前者的应力-应变性能也低于后者。