摘要
利用转矩流变仪、DSC、SEM及WAXD等表征手段研究了PET/PC共混体系的酯交换反应对其高压结晶行为的影响.SEM观察表明,PET和PC熔混时的酯交换反应有利于PET/PC体系在高压结晶时生成厚度较大的伸直链晶体,且可以促进其高压下酯交换反应的发生.楔形伸直链晶体和弯曲伸直链晶体的存在证明链滑移扩散和酯交换反应两种机制对体系中聚酯伸直链晶体的增厚有贡献.拟合分峰法和War-ren-Averbach傅里叶分析法的计算结果表明,随PET/PC体系熔混时酯交换反应程度的增加,高压结晶共混物的结晶度降低,PET的平均微晶尺寸增大,点阵畸变平均值则减小,而微晶尺寸分布变宽.提出了在共聚物组分都具备结晶能力时,结晶诱导化学反应和化学反应诱导结晶两种过程在一定条件下可同时发生的观点.
Effect of transesterification on high-pressure crystallization behaviour of PET/PC blend system was investigated by torque rheometer, DSC, SEM and WAXD measurements. The crystallized samples of 20%PC in PET/PC blends mixed at 30 r/min and 523, 533 and 553 K for 15 min were obtained at 300 MPa and 613 K for 6 h with a self-made piston-cylinder high-pressure apparatus. SEM observation revealed that transesterification during mixing profited a quick thickening of extended-chain crystals and enhanced ester interchange at a high pressure. Wedge-shaped and bending extended-chain crystals found in these samples indicated that chain-sliding diffusion and transesterification contributed to the growth of such polyester crystal. With transesterification extent rising, the result of WAXD profile deconvolution and WA/FT showed that the total crystallinity letted up, the mean crystallite size and micro-strain of PET increased and decreased respectively and crystallite distribution for PET widened correspondingly. The result obtained suggests that under certain conditions two procedures, i.e. crystallization-induced reaction and reaction-induced crystallization can concur for such copolymer wholly composed of crystallizable units.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第8期1556-1560,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:29434010
59473002)资助.
