β成核剂对PPH拉伸双屈服行为的影响  

Effect ofβNucleating Agent on Tensile Double Yielding Behavior of PPH

作　　者：樊泽鹏 王克俭[1] 陈雅波 王志伟 李思涵 FAN Zepeng;WANG Kejian;CHEN Yabo;WANG Zhiwei;LI Sihan(College of Mechanical and Electrical Engineering,Beijing University of Chemical Technology,Beijing 100029,China)

机构地区：[1]北京化工大学,机电工程学院,北京100029

出　　处：《塑料》2024年第4期22-25,共4页Plastics

摘　　要：均聚聚丙烯(PPH)广泛应用于制备餐盒和编织袋,加入β成核剂后,改善了PPH的韧性,但是,关于β成核剂对其拉伸双屈服行为影响的研究仍较少。因此,将β成核剂加入PPH熔体中,制备β⁃PPH粒料,再进行注射成型,得到样条测试其性能。将β成核剂加入PPH后,熔融曲线中出现了明显的β晶型熔融峰,随着其结晶峰值温度的升高,PPH的结晶能力得到提高,当β成核剂的含量为0.2%时,PPH中β晶型的相对含量达到最大值,其值为49.8%,断裂伸长率达到最佳;当β成核剂的添加量大于0.2%时,PPH中β晶型的相对含量逐渐降低,断裂伸长率下降。采用50 mm/min的速率进行拉伸,PPH发生高应力的双屈服行为,其第二次屈服应力值为35.53 MPa。而β⁃PPH的2次屈服应力值均较低,与β⁃PPH的第一次屈服应力值相比,其第二次屈服应力值更低,第一个屈服阶段,β⁃PPH产生应力发白现象且温度无明显变化;第二个屈服阶段,β⁃PPH产生局部颈缩且有明显温升现象。随着β成核剂含量的增大,β⁃PPH的第一次屈服应变值、第一次屈服应力值及第二次屈服应力值均减小,第二次屈服应变值增大。Polypropylene homopolymer(PPH)was widely used in food containers and woven bags.The addition ofβnucleating agent improved the toughness of PPH.For the first time,the influence on its tensile double yielding behavior had been reported.Theβnucleating agent was mixed into PPH melt to prepareβPPH pellets,after which specimens were injection molded and tested of their performance.Whenβnucleating agent was added into PPH(Shortened asβ⁃PPH),a distinctβcrystalline melt peak appeared in DSC curves,the crystallization peak temperature increased,and the crystallization degree was enhanced.Theβcrystalline phase content in 0.2%β⁃PPH was the highest,reaching 49.8%and the elongation at rupture was the best.As the content ofβnucleating agent increased,the relative content ofβcrystalline phase decreased and the toughness deteriorated.When stretched at a rate of 50 mm/min,PPH exhibited a high⁃stress double yielding behavior,and its second yield stress value was 35.53 MPa.In contrast,β⁃PPH showed a lower first yield stress value and a further lower second yield stress value.At the first yielding,stress whitening occurred where there was no significant change in temperature.At the second yielding,localized necking occurred with a noticeable temperature rise.With the increase of the content ofβnucleating agent,the first yielding strain,the first yielding stress and the second yielding stress decreased forβ⁃PPH while the second yielding strain increased.

关 键 词：聚丙烯 Β成核剂 应力-应变曲线 拉伸双屈服 红外热成像 

分 类 号：TQ325.14[化学工程—合成树脂塑料工业]