聚丙烯对聚丁烯-1晶型Ⅱ-Ⅰ转变的影响

Influences of Polypropylene on Phase Ⅱ-Ⅰ Transformation of Polybutene-1

等规聚丁烯-1 (PB)晶型Ⅱ-Ⅰ转变与晶型调控影响着其加工成型周期及性能,因此PB晶型Ⅱ-Ⅰ转变一直是研究的热点。PB/等规聚丙烯(PP)共混物作为典型的结晶/结晶聚合物共混体系,其组分含量、结晶温度对其聚集态结构产生重要影响,进而影响PB的晶型转变。本文研究了PB/PP共混体系中PP组分含量对PB晶型Ⅰ成核及晶型Ⅱ-Ⅰ转变的影响。采用广角X射线衍射仪(WAXD)、差示扫描量热仪(DSC)、小角X射线散射仪(SAXS)和偏光显微镜(POM)观察PB/PP共混物的结晶形貌及晶型Ⅱ的晶体结构,原位观察不同含量的PP对PB晶型Ⅱ-Ⅰ转变过程的影响。研究发现,低含量PP(≤20wt%)的加入,共混物中PB晶型Ⅰ成核及晶型Ⅱ-Ⅰ转变速率随PP含量增加而增加;而当PP含量≥25wt%,共混物中PB晶型Ⅰ成核及晶型Ⅱ-Ⅰ转变速率随PP含量增加而逐渐降低。当PP含量为20wt%时,PB/PP共混物中PB晶型Ⅰ成核最多,晶型Ⅱ-Ⅰ转变最快,晶型Ⅰ结晶度最高。进一步探讨了PB/PP共混物中PP的含量对PB晶型Ⅱ-Ⅰ转变影响的内在机制。

Crystal-crystal Ⅱ-Ⅰ transformation and crystal form regulation of isotactic polybutene-1(PB)determined its molding period and properties.Study on crystal-crystal Ⅱ-Ⅰ transformation of PB has always been the research hot issue.As the typical crystalline/crystalline polymer blends,the aggregation structures and thus the crystal-crystal transformation of PB in the PB/polypropylene(PP)blends are influenced greatly by PP content and crystallization temperature.In this work,the effects of PP content on the nucleation and transformation rate of PB form Ⅰ were studied.The crystallization morphology of PB/PP blends and crystal structure of PB form Ⅱ were studied by wide-angle X-ray diffraction(WAXD),differential scanning calorimetry(DSC),small-angle X-ray scattering(SAXS)and polarizing microscopy(POM).The influence of PP content on the PB form Ⅱ-Ⅰ transition was in situ observed.It was found that the nucleation of PB form Ⅰ and form Ⅱ-Ⅰ transition rate increased with the increase in PP content when≤20 wt%PP was blended.While the nucleation of PB form Ⅰ and form Ⅱ-Ⅰ transition rate decreased gradually with the increase in PP content when more than 25 wt%PP was blended.The nucleation of PB form Ⅰ,PB form Ⅱ-Ⅰ transition rate and transition degree in PB/PP(80/20)blend reached the highest.The influencing mechanism of PP component on PB form Ⅱ-Ⅰ transition was discussed.