软硬链段含量及相对分子质量对PA 6基弹性体结构的影响

Effect of soft and hard segments contents and relative molecular mass on structure of PA 6-based elastomers

以己内酰胺(CPL)、己二酸(AA)、乙二醇(EG)和聚乙二醇(PEG)为原料,通过水解开环-预缩聚-酯化-酯交换,改变CPL与AA摩尔比、PEG相对分子质量和投料量,制备出具有不同软硬链段含量及相对分子质量的聚酰胺6(PA 6)基弹性体;采用核磁共振氢谱仪、凝胶渗透色谱仪和X射线衍射仪分析了PA 6基弹性体的化学结构和晶体结构,并给出了PA 6基弹性体的序列结构模型和计算式用以描述不同软硬链段含量及相对分子质量的PA 6基弹性体序列结构。结果表明:PA 6基弹性体的软硬链段含量和相对分子质量符合设计;当软硬链段含量一定时,软硬段的相对分子质量增加使PA 6基弹性体的总嵌段数下降,进而影响整体的序列结构;但软硬链段相对分子质量相同时,软硬链段含量对总嵌段数没有较大影响;PA 6基弹性体的晶体结构由PA 6链段主导,PEG链段大部分分布在无定形区。

Polyamide 6(PA 6)-based elastomers with different soft and hard segments contents and relative molecular mass were prepared from caprolactam(CPL),adipic acid(AA),ethylene glycol(EG)and polyethylene glycol(PEG)by changing the molar ratio of CPL to AA and relative molecular mass and feed weight of PEG via hydrolysis ring-opening-prepolycondensation-esterification-transesterification process.The chemical structure and crystal structure of PA 6-based elastomers were analyzed by nuclear magnetic resonance spectroscopy,gel permeation chromatography and X-ray diffraction.The sequence structure model and calculation formula were given to describe the sequence structure of PA 6-based elastomers with different soft and hard segments contents and relative molecular mass.The results showed that the PA 6-based elastomers met the design requirements in the contents and relative molecular mass of soft and hard segments;the increase of the relative molecular mass of soft and hard segments decreased the block number of PA 6-based elastomer and then impacted the overall sequence structure when the content of soft and hard segments was constant;however,the contents of soft and hard segments had no significant effect on the number of blocks when the soft and hard segments had the same relative molecular mass;and the crystal structure of PA 6-based elastomers was dominated by PA 6 segments when the most of PEG segments were distributed in the amorphous region.