制备方法对iPP/EPR合金晶相结构的影响

用示差扫描量热仪(DSC)和广角X射线衍射仪(WAXD)研究了溶液共混法和熔融共混法制备的等规聚丙烯/二元乙丙橡胶(iPP/EPR)(85:15,W/W)合金的晶相结构.发现溶液共混法制得的iPP/EPR合金晶相中仅存在α-iPP,而熔融共混样品中则同时生成了α-iPP和β-iPP.这一结果表明,EPR并不是iPP/EPR合金中β-iPP生成的关键因素.考察了结晶温度和熔体热处理对iPP/EPR合金晶相结构的影响,发现通常的热处理并不能消除合金中β-iPP的生成.

EFFECT OF PREPARATION METHODS ON CRYSTALLINE STRUCTURE OF iPP/EPR BLENDS

The crystalline structure of isotactic polypropylene/ethylene-propylene rubber(iPP/EPR,85:15,W/W) blends prepared by melt-blending and solution-blending methods,respectively was studied by using modulated differential scanning calorimetry(MDSC) and wide angle X-ray diffraction(WAXD).The experimental results reveal that α-iPP and β-iPP coexist in the PP85m sample prepared by melt-blending method,but only α-iPP appeared in the PP85s sample prepared by solution-blending method,and its crystalline structure is independent on isothermal crystallization temperature.The β-iPP content in PP85m is dependent on the crystallization temperature and approaches to a maximum at about 125℃.In addition,it is found that the iPP/EPR samples experienced annealing at 200℃ for different times(5～30 min)demonstrate the same melting behavior,indicating that the annealing treatment for different times at 200℃ has little effect on the formation of β-iPP in PP85m samples.It is suggested that the formation of β-iPP in PP/EPR blends is dependent on its thermomechanical history.