复合成核剂对PET结晶性能的影响

设计了改性蒙脱土(MMT)/耐高温润滑剂和改性MMT/耐高温润滑剂/离子聚合物两个系列复合成核剂,利用熔融共混法制备聚对苯二甲酸乙二酯(PET)/复合成核剂复合体系。运用差示扫描量热分析仪、偏光显微镜、X射线衍射仪对复合体系的结晶性能进行表征。结果表明,耐高温润滑剂在一定程度上改善了改性MMT在PET中的分散性,使改性MMT的异相成核效果更为明显;当改性MMT、耐高温润滑剂的添加量均为1份时,使PET的结晶峰温度升至213.32℃,冷结晶峰温度降低了4.75℃,冷结晶峰明显减弱,结晶速率加快。另一方面,离子聚合物的引入,使PET的结晶峰温度进一步升高到216.75~219.25℃,冷结晶峰温度降低了5.71~11.85℃,冷结晶峰进一步减弱,半峰宽变得更窄,对PET结晶性能的改善更为显著,尤其是改性MMT/耐高温润滑剂/氧化聚乙烯蜡复合成核剂对PET结晶性能的改善最为全面。此外,两个系列复合成核剂都起到了细化晶粒的作用,形成微晶,并且对PET的晶型基本无影响。

Effects of Hybrid Nucleating Agent on Crystallization Behaviors of PET

Two series of hybrid nucleating agents,modified montmorillonite (MMT)/heat-resistant lubricant and modified MMT/heat-resistant lubricant/ionic polymer were designed,and then PET/hybrid nucleating agent composites systems were pre-pared by melt blending method. Crystallization behaviors of the composite system was characterized by differential scanning calo-rimetry,polarizing optical microscope and X-ray diffraction. The results indicate that heat-resistant lubricant can improve the disper-sion of modified MMT in PET to some extent and make modified MMT play a more obvious heterogeneous nucleation effect. When the addition of modified MMT,heat-resistant lubricant is 1 phrrespectively,the peak crystallization temperature of PET increases up to 213.32℃,the peak cold crystallization temperature of PET reduces by 4.75℃,the cold crystallization peak weakens,the crystal-lization rate becomes fast. After introducing theionic polymer into modified MMT/heat-resistant lubricant,the peak crystallization temperature of PET can further increase up to 216.75-219.25℃,the peak cold crystallization temperature of PET reduces by 5.71-11.85℃,the cold crystallization peak further weakens,the half peak width becomes narrower. The modified MMT/heat-resistant lubricant/ ionic polymer can markedly improve the crystallization properties of PET,especially modified MMT/heat-resistant lu-bricant/oxidized polyethylene wax. In addition,two series of hybrid nucleating agents both play an important role in refining grain, promoting the formation of microcrystalline,and they have little impact on the crystal type of PET.