空间立体结构对芳香聚酰胺及其嵌段共聚物结晶行为的影响

采用高温溶液直接缩聚一步法和两步法分别合成了含全对位结构和含间位结构芳香聚酰胺预聚物及其脂肪聚酰胺-芳香聚酰胺-脂肪聚酰胺嵌段共聚物.采用差示扫描量热法(DSC)和广角X射线衍射法(WAXD)对所设计合成的不同空间立体结构的芳香聚酰胺及其与较低相对分子质量尼龙6的嵌段共聚物的结晶行为与结晶结构进行研究.结果表明,空间立体结构的变化显著影响预聚物和共聚物的结晶形态及结晶熔融行为,间位结构的引入使硬链段对软链段熔融结晶行为的影响更为深刻,结晶结构更为松散,晶粒尺寸增大,更有利于增强软硬分子间的相互作用从而抑制硬链段分子链本身的自聚集倾向.

The Stereoeffect on the Crystallization Behaviors of the Aromatic Polyamide Oligomers and Their Block Copolymers with Aliphatic Polyamide

Based on the relationship between polymer structures and properties, model tri-block copolymers with a chain sequence of aliphatic polyamide-aromatic polyamide-aliphatic polyamide were designed and synthesized by the so-called "one step" and "two step" high-temperature polycon-densation. DSC and WAXD were used to study the crystallization behaviors and crystal configuration of the designed aromatic polyamide with different stereo-sequence and their block copolymers with low molecular Nylon 6 oligomers. The results show that the crystalline structure and crystallization behaviors of the rigid oligomers and their copolymers are strongly affected by the introduction of the meta-position substituent in the molecular chains and the strong inter- and intra-molecular interactions between the two blocks, which would highly restrained the self-aggregation of the rigid segments and might be favourable to its dispersion in the matrix.