等规度和热处理对聚丙烯硬弹性膜力学性能的影响

Effects of Isotacticity and Annealing on Deformation Mechanism of Hard Elastic Polypropylene Film

选取聚丙烯硬弹性膜专用料树脂S801和F401,引入二甲苯可溶物含量、差示扫描量热法和连续自成核退火(SSA)热分级联用的方法,研究了两者等规度的差异;对在不同温度下热处理(105℃、130℃、140℃和150℃下退火)的硬弹性膜,通过二向红外、回弹率和单轴拉伸测试所获得的结果,从取向和结晶的角度进行分析。发现退火过后,取向度和结晶度都有了显著的提升。同时,随着退火温度升高,一次屈服强度下降,二次屈服强度上升,这与材料内部的取向和结晶有关;具有更高等规度的S801比F401具有更高的模量。在结晶度相同时,高等规度的样品具备更高的回弹率,说明取向度对于聚丙烯硬弹性膜的回弹率的贡献比结晶度更大。

Isotacticity difference of a series of elastic film resins （S801 and F401） was studied via xylene soluble content （XS）, differential scanning calorimetry （DSC） and successive self-nucleation and annealing （SSA） thermal fractionation. FT-IR, elastic recovery （ER） and uniaxial tensile test were applied to analysis the deformation mechanism of hard elastic films which were annealed at different temperature （105 ℃,130 ℃,140 ℃and 150 ℃）. The results were discussed from isotactcity and crystallization. It is found that as the annealing temperature increases, the orientation functions obtained from FT-IR and crystallization increases. Furthermore, the primary yield strength decreases while the second yield strength increases, it may be affected by isotactcity and crystallization. The S801 which has higher isotactcity will have higher elasticity modulus. Meanwhile, S801 also has higher elastic recovery than F401 at the same crystallization. It means that isotactcity plays a more important role than crystallization in affecting elastic recovery.