超声波降解对丙烯基塑性体性能的影响

利用自制的超声波辐照装置,对一种新型丙烯基塑性体(简称DP)熔体进行超声波降解,研究了超声波降解对DP结晶性能、力学性能和流变性能的影响。与等规聚丙烯相比,DP的结晶性能差,屈服拉伸强度低,但断裂伸长率明显提高。在超声波辐照下,DP熔体发生力化学降解,无规断链主要集中在高相对分子质量部分,相对分子质量分布变宽,大分子结构中出现羰基。超声波降解产生的低相对分子质量链段活动能力和极性增强,可在较高温度下结晶。另外,超声波降解也会导致DP的屈服拉伸强度下降,表观黏度降低。

Effects of ultrasonic degradation on properties of propylene based plastomer

The ultrasonic degradation experiment on a novel propylene based plastomer (DP) was conducted by means of a homemade ultrasonic wave irradiation facility. The effects of ultrasonic degradation on crystallization, mechanical properties and rheological behaviour of DP were studied. The results show that compared with isotactic polypropylene (iPP), DP has an inferior crystallinity and low tensile strength at yield, but a significantly higher elongation at break. Under the ultrasonic irradiation, mechanochemical degradation occurs in DP melt and random chain scissions concentrate mainly in portion of high molecular mass, along with the broadening of relative molecular mass distribution and formation of carbonyl in the macromolecular structure. The chain segments with low relative molecular mass induced by ultrasonic degradation can crystallize at higher temperature due to their enhanced mobility and polarity. In addition, ultrasonic degradation can lead to a reduction in tensile strength at yield and apparent viscosity of DP.