β成核剂和退火对rPP/rPE共混物性能的影响

Effects ofβnucleating agent and annealing on properties of recycled PP/PE blends

采用熔融共混法将β成核剂(β-NA)添加到废旧聚丙烯(PP)/废旧聚乙烯(PE)(rPP/rPE)共混物中,制备了rPP/rPE/β-NA共混物,并对共混物进行退火处理,研究了β-NA的含量以及退火对rPP/rPE/β-NA共混体系力学性能的影响,研究了含量为0.05%(rPP/rPE总质量的0.05%)的β-NA以及退火对共混物的热性能、结晶性能、动态力学性能、流变性能以及微观形貌的影响。力学性能测试表明,当β-NA含量为0.05%时,rPP/rPE/β-NA和退火后rPP/rPE/β-NA的缺口冲击强度、断裂伸长率最大,较rPP/rPE的4.42 kJ/m^(2)和295.10%分别增加了31.22%,115.21%和120.14%,12.75%;差示扫描量热测试和广角X射线衍射测试表明,β-NA诱导PP出现β晶,退火后共混物中PE和β晶PP(β-PP)结晶度增加,α晶PP(α-PP)结晶度基本不变;热重测试表明,r PP/rPE/β-NA热稳定性下降,退火后热稳定性增加,这是因为β-PP热稳定性比α-PP差,而退火后晶体结构完善热稳定性增加;流变性能测试表明,rPP/rPE/β-NA和退火后的共混物的复数黏度降低,β-NA起到润滑的作用,退火后共混物在熔融状态下流动性增强;动态力学性能测试表明,退火后的共混物玻璃化转变温度降低;扫描电子显微镜测试表明,退火后的共混物冲击断面比退火前粗糙,断裂形式为韧性断裂。

The recycled polypropylene(rPP)/recycled polyethylene(rPE)/βnucleating agent(β-NA)blends were prepared by addingβ-NA to the rPP/rPE blends using a melt blending method,and the effects ofβ-NA content and annealing on the mechanical properties of rPP/rPE/β-NA blends were studied.The effects of adding 0.05%(of the rPP/rPE total mass)β-NA and annealing on the thermal properties,crystallization properties,dynamic mechanical properties,rheological properties,and microstructure of the blends were studied.The mechanical properties test results show that whenβ-NA content is 0.05 wt%,the notched impact strength and elongation at break of rPP/rPE/β-NA and annealed rPP/rPE/β-NA are the highest,with an increase of 31.22%,115.21%and 120.14%,12.75%,respectively,compared to rPP/rPE's 4.42 kJ/m^(2)and 295.10%,respectively.Differential scanning calorimetry and wide-angle X-ray diffraction test results show thatβ-NA induces the formation ofβ-PP,and after annealing,the crystallinity of PE andβ-PP increases,while the crystallinity ofα-PP remains unchanged basically.Thermogravimetric test results show that the thermal stability of PP/rPE/β-NA decreases,but increases after annealing.This is because the thermal stability ofβ-PP is worse than that ofα-PP,the crystal structure becomes more perfect and the thermal stability increases.Rheological test results show that the complex viscosity of rPP/rPE/β-NA and the annealed blend decrease,andβ-NA plays a lubricating role.After annealing,the fluidity of the blend is enhanced in the molten state.Dynamic mechanical properties test results show that the glass transition temperature of the annealed blend decreases.Scanning electron microscopy test results show that the impact cross-section of the annealed blend is rougher than that before annealing,and the fracture form is ductile fracture.