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双酚A型聚碳酸酯(BAPC)因重复结构单元中含有两个苯撑而使分子链过于刚硬,导致其结晶极其缓慢。本文评述了BAPC的三类结晶增速改性剂,即成核剂(NAs)、晶体生长促进剂(CGAs)及成核-晶体生长耦合改性剂(NA-CGAs);提出机理上不同于异相成核(HN)的“离子簇集诱导成核(IAIN)”的概念,即NA所含离子(对)经交换反应转移至BAPC链端,而后经(单)遥爪离子静电簇集引发与之共价相连的链段在离子簇近围紧密堆砌从而诱导结晶成核的过程。NAs包括无机填料、有机小分子及有机高分子等;前者属于HN,而后两者属于HN或IAIN,取决于其中是否含有可交换离子对。CGAs包括有机溶剂、超临界CO2、酯类增塑剂、液晶小分子及柔性聚合物等;其均通过降低BAPC链段间作用力而加速晶体生长。NA-CGAs为将NA与CGA配合使用、协同促进BAPC结晶的混合物。然而,在实际熔融加工时间尺度内BAPC的结晶增速仍显不足;HN-IAIN-CGAs三元耦合改性剂有望成为今后的重点发展方向。
Bisphenol A-type polycarbonate (BAPC) due to the repeating unit contains two benzene and the molecular chain is too rigid, resulting in extremely slow crystallization. This paper reviews three types of BAPC crystal growth modifiers: nucleating agents (NAs), crystal growth promoters (CGAs) and nucleation-crystal growth coupling modifiers (NA-CGAs) Heterogeneous nucleation (HN) “ion cluster induced nucleation (IAIN) ” concept, that NA contained ions (pairs) by the exchange reaction transferred to the BAPC chain end, and then by Clusters lead to the covalently linked segments tightly packed around the ion clusters to induce crystallization nucleation. NAs include inorganic fillers, organic small molecules and organic polymers; the former belongs to HN, and the latter two belong to HN or IAIN, depending on whether they contain exchangeable ion pairs. CGAs include organic solvents, supercritical CO2, ester plasticizers, liquid crystal small molecules and flexible polymers, all of which accelerate crystal growth by reducing the force between BAPC segments. NA-CGAs is a mixture of NA and CGA that synergistically promote the crystallization of BAPC. However, the crystallization rate of BAPC still lacks in the actual melt processing time scale. The HN-IAIN-CGAs ternary coupling modifier is expected to become the key development direction in the future.