端羟丁腈聚氨酯/聚甲基丙烯酸甲酯互穿网络高聚物的T_g和形态研究——Ⅰ.组分比和交联程度的影响

用同步法合成了端羟丁腈聚氨酯/聚甲基丙烯酸甲酯互穿网络高聚物[PU(HTBN)/PMMA-IPN]。用动态力学方法和透射电镜研究了它们的T_(?)转变行为和形态。理论计算和实验结果表明,样品具有两个明显相互分离但又各自连续的相结构,呈现出分属于组分聚合物的两个Tg转变(Tg_1,Tg_2)。在全IPN中,PMMA相区的尺寸(1000—2000?),比在接枝共聚物(3000—6000?)和半IPN(—3000?)中的明显变小。适当的交联程度可使相区进一步变小,变均匀,相连续性增加。这是网络互穿造成的“强迫互容”所致。部分丁腈羟(HTBN)分子同PMMA的反应,使一些样品出现了Tg_2升高的现象。

TRANSITION BEHAVIOR AND MORPHOLOGY OF PU(HTBN)/PMMA IPN's: Ⅰ. EFFECTS OF COMPOSITION AND DEGREE OF CROSSLINKAGE

PU(HTBN)/PMMA interpenetrating polymer networks (IPN'S) were synthesized by simultaneous polymerization, and were investigated by dynamic mechanical spectros-copy and transmission electron microscopy. Theoretical calculation by Davie 's equation and experimental results showed that there are two continuous phases which separate from each other, and two glass transition temperatures (Tg1, Tg2) corresponding to the components in the polymer networks. Owing to the "forced compatibility" produced by interpenetration, the phase domains are much finer in full-IPN's (1000-2000A) than in grafts (3000-6000 A) and semi-IPN's (about 3000 A), and become more smaller and uniform with the increase of phase continuity by appropriate crosslinkage. The reaction between some HTBN molecules and MMA bring about the increase of T01.