高于玻璃化温度T_g退火对无规聚甲基丙烯酸甲酯液-液转变的影响  

Effects of Annealing Above Glass Transition Temperature T_g on the Liquid-liquid Transition of Atactic Poly(methyl methacrylate)

作　　者：顾群[1] 沈德言[1] 

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实验室,北京100080

出　　处：《高等学校化学学报》2001年第3期508-510,共3页Chemical Journal of Chinese Universities

基　　金：科技部攀登计划! A"高分子凝聚态物理基本物理研究"(批准号 :95 -预 -12 )

摘　　要：Effects of annealing temperature( T a) and annealing time( t a) on the liquid liquid transition and transition intensity of atactic poly(methyl methacrylate) were studied by means of differential scanning calorimetry. With the increase of T a from 393 to 443 K, T ll shifted to higher temperature with the decrease in transition intensity, on the contrary, when T a was over 443 K, T ll declined and transition intensity increased. When T a kept constant with the increase of t a, T ll and transition intensity varied as the results described above. Moreover, the variation extent of T ll and transition intensity increased with the increase of T a, in other words, the time needed reaching the maximum extent of variation of the two parameters was decreased with the increase of T a. The dependence of T ll and transition intensity on annealing conditions may be explained by the formation of local ordered structure, i.e . stereocomplex, during the annealing process by means of Van der Waals forces between isotacitic and syndiotactic segments of the same or different chains of atactic poly(methyl methacrylate).Effects of annealing temperature( T a) and annealing time( t a) on the liquid liquid transition and transition intensity of atactic poly(methyl methacrylate) were studied by means of differential scanning calorimetry. With the increase of T a from 393 to 443 K, T ll shifted to higher temperature with the decrease in transition intensity, on the contrary, when T a was over 443 K, T ll declined and transition intensity increased. When T a kept constant with the increase of t a, T ll and transition intensity varied as the results described above. Moreover, the variation extent of T ll and transition intensity increased with the increase of T a, in other words, the time needed reaching the maximum extent of variation of the two parameters was decreased with the increase of T a. The dependence of T ll and transition intensity on annealing conditions may be explained by the formation of local ordered structure, i.e . stereocomplex, during the annealing process by means of Van der Waals forces between isotacitic and syndiotactic segments of the same or different chains of atactic poly(methyl methacrylate).

关 键 词：液-液转变 无规聚甲基丙烯酸甲酯 退火 热处理 结构 

分 类 号：O631.1[理学—高分子化学] O632.52[理学—化学]