The effect of an impact polypropylene copolymer (IPC) having excellent stiffness–toughness balance on the microstructure and properties of a blend comprising 80 wt% recycled high density polyethylene (rHDPE) and 20 wt% recycled isotactic polypropylene (rPP) was studied. Morphological observations revealed improved interfacial interactions, a finer dispersion state and a more homogeneous phase morphology upon IPC incorporation into the blend up to 20 wt%. Flexural modulus, flexural strength, tensile strength and tensile ductility were steadily increased with IPC loading, and exhibited 13%, 14%, 35% and 520% improvement at 20 wt% IPC. A monotonic rise in Izod impact energy, accompanied by a transition from semi-brittle to fully ductile failure mode, was observed with IPC concentration, so that this parameter showed 110% increment at 20 wt% IPC. The change in properties was attributed to the compatibilization, toughening as well as reinforcing effects of the IPC phase in the modified blends. Melting and crystallization of the blends were studied by the DSC technique. Failure mechanisms and micro-deformations accompanying the impact fracture process of the blends were closely examined, and the role of IPC in improving the toughness and fracture resistance of the modified blends was clarified. The results were interpreted in terms of interfacial strength, efficiency of stress transfer across the phase boundaries, and stability of plastic micro-deformations during the fracture process. The results clearly demonstrate that simultaneous improvement in stiffness, strength and (impact) toughness of the incompatible rHDPE/rPP blend can be achieved by modification with a properly chosen IPC. The present work addresses some challenges, with respect to stiffness and strength, encountered with the use of conventional elastomeric and/or plastomeric olefin copolymers as common modifiers for polyolefin blends. © 2021 Society of Industrial Chemistry.

中文翻译：

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消费后回收的高密度聚乙烯/聚丙烯共混物，通过抗冲聚丙烯共聚物的改性提高了整体性能：形态、性能和抗断裂性

研究了具有优异刚度-韧性平衡的抗冲聚丙烯共聚物 (IPC) 对包含 80 wt% 回收高密度聚乙烯 (rHDPE) 和 20 wt% 回收全同立构聚丙烯 (rPP) 的共混物的微观结构和性能的影响。形态学观察表明，在将 IPC 掺入混合物中后，界面相互作用得到改善，分散状态更细，相形态更均匀，最高可达 20%。弯曲模量、弯曲强度、拉伸强度和拉伸延展性随着 IPC 加载而稳步增加，并在 20 wt% IPC 下表现出 13%、14%、35% 和 520% 的改进。在 IPC 浓度下观察到 Izod 冲击能单调上升，伴随着从半脆性破坏模式到完全延性破坏模式的转变，因此该参数在 IPC 浓度为 20 wt% 时增加了 110%。性能的变化归因于改性共混物中 IPC 相的增容、增韧和增强作用。通过DSC技术研究了共混物的熔融和结晶。仔细研究了伴随共混物冲击断裂过程的破坏机制和微变形，并阐明了 IPC 在提高改性共混物的韧性和抗断裂性方面的作用。结果被解释为界面强度、跨相边界的应力传递效率以及断裂过程中塑性微变形的稳定性。The results clearly demonstrate that simultaneous improvement in stiffness, strength and (impact) toughness of the incompatible rHDPE/rPP blend can be achieved by modification with a properly chosen IPC. 目前的工作解决了使用常规弹性和/或塑性烯烃共聚物作为聚烯烃共混物的常用改性剂时遇到的刚度和强度方面的一些挑战。© 2021 工业化学学会。