聚丙烯酸酯型高分子侧链液晶的合成及其对聚乙烯成核结晶行为的影响

基于聚烯烃用成核剂的结构特征设计合成了两种极性基团和非极性基团交替排列的乙烯基单体,并利用自由基引发聚合,制备出相应的侧链型液晶聚合物.采用元素分析、红外光谱和核磁共振氢谱对所合成单体和聚合物的结构进行了确认.并采用热失重(TGA)和差示扫描量热仪(DSC)研究了聚合物的热稳定性和相转变温度.结果表明,所合成聚合物的起始热分解温度均在337℃以上,具有优异的热稳定性;液晶相变温度区间可达186 K,具有较宽的液晶态温度范围.热台偏光显微镜(HS-POM)研究结果表明,聚合物均呈现出纹影织构,证明所合成的聚合物均为热致向列型侧链液晶高分子.采用DSC和HS-POM研究了所合成的侧链液晶聚合物对高密度聚乙烯(HDPE)异相成核结晶行为的影响.结果表明,侧链型液晶聚合物在提高HDPE结晶温度、结晶度以及降低HDPE晶粒的尺寸及分布方面均有优异的效果,是一类HDPE有效的成核剂.

SYNTHESIS AND CHARACTERIZATION OF SIDE CHAIN LIQUID CRYSTALLINE POLYACRYLATES AND THEIR EFFECT ON THE CRYSTALLIZATION OF POLYETHYLENE USING AS A NUCLEATING AGENT

The present work was focused on investigating the potential of using side chain liquid crystalline polymers(SCLCP) as nucleating agents for semicrystalline polymers.For this purpose,two vinyl monomers with liquid crystalline properties were designed and prepared.By means of homopolymerization two side chain liquid crystalline polymers having different architectures were synthesized.The monomers and the polymers obtained were characterized by elemental analysis,FTIR and()~1H-NMR measurements.DSC and HS-POM were employed to study the phase-transition temperatures and mesophase textures for the polymers.The thermal stability of the polymers was measured by TGA.The results showed that the polymers were all thermotropic side chain liquid crystalline polymers with wide liquid crystalline phase temperature range and excellent thermal stability.The effect of one of the SCLCPs used as a nucleating agent in the crystallization of high density polyethylene(HDPE) was investigated by DSC and HS-POM.The results indicated that SCLCP could effectively increase the crystallization temperature,crystallization speed and the crystallinity for HDPE.It was found that the synthesized SCLCP could be an effective nucleating agent for HDPE.