聚甲基丙烯酸甲酯(PMMA)/梯形聚苯基硅倍半氧烷(PPSQ)原位共混体系的正电子湮没行为  

Positron annihilation in poly-methyl methacrylate (PMMA)/ladderlike poly-phenyl silsesquioxane (PPSQ) in-situ blends

作　　者：李桂芝[1] 叶美玲[1] 施良和[1] 徐坚[1] 郁伟中[2] 

机构地区：[1]中国科学院化学研究所分子科学中心,高分子物理与化学国家重点实验室,北京100080 [2]清华大学物理系,北京100084

出　　处：《核技术》2002年第3期161-166,共6页Nuclear Techniques

基　　金：国家自然科学基金 (2 9374 184 )资助

摘　　要：聚甲基丙烯酸甲酯 (PMMA) /梯形聚苯基硅倍半氧烷 (PPSQ)原位共混物室温下的o -Ps寿命及强度随PPSQ含量变化的关系表明 ,该共混物中两种聚合物分子间存在一定程度的相互作用。通过研究具有 3种不同配比的PMMA/PPSQ(95 / 5 ,90 / 10 ,80 / 2 0 )原位共混物在 2 0— 15 0℃范围内的正电子湮没寿命温度谱 ,可观察到该共混试样的两种结构转变。在M 5 (PPSQ含量为5 % )中两聚合物间的相容性较好 ,相互作用较强 ,故其Tβ 较高 ;M 5及M 2 0的Tg 相近 ,这说明当PPSQ的含量较大 (>5 % )时 ,该共混物中出现分相。通过分析PMMA/PPSQ原位共混物的自由体积空穴尺寸及总自由体积分数随温度变化的规律可知 :在 3种共混试样中 ,M10的自由体积空穴尺寸及自由体积分数最大 ,故其Tgo-Ps lifetime and intensity of PMMA/ladderlike PPSQ in-situ blend sversus percentage of PPSQ showed that some interactions involved between PMMA and PPSQ. Positron annihilation lifetime spectra of PMMA/PPSQ blends at three different compositions (PMMA/PPSQ, 95/5, 90/10, 80/20) over 20—150℃ were studied. Two structural transitions were observable. β transition temperatue ( T β) of PMMA/PPSQ (95/5) was the highest among three blend samples due to good miscibility and strong interactions.The similarity of T g for samples M5 (PMMA/PPSQ 95/5) and M20 (PMMA/PPSQ 80/20) indicated that phase-separation occurred (PPSQ>5%). Characteristics of free-volume voids in the blends were also analyzed. Size and fraction of free-volume voids in PMMA/PPSQ (90/10) were the largest among three blend samples, so its T g was the lowest.

关 键 词：PMMA/PPSQ 原位共混物 正电子湮没 自由体积 结构转变 聚甲基丙烯酸甲酯 梯形聚苯基硅倍半氧烷 高聚物 

分 类 号：O631.1[理学—高分子化学] O572.322[理学—化学]