This article mainly explores the mechanism and deformation of polypropylene random copolymer at different temperatures and the role of microstructure in the toughening process. Firstly, the conventional differential scanning calorimetry, wide-angle X-ray diffraction, and scanning electron microscopy were employed to study different structures of crystalline and amorphous regions. Furthermore, the dynamic thermomechanical analysis was used to study the changes in the molecular mobility in samples. Secondly, the toughness and fracture morphology of the material was analyzed by notched Izod impact test and scanning electron microscopy. Thirdly, samples were stretched and combined 2D-WAXD to analyses the changes in its crystal regions. The thickness and distribution of the lamellae, as well as stress transmitters, work synergistically during polypropylene random copolymer deformation. The yield is due to the spherulite deformation and a small part of lamellae rotation and reorientation when the temperature is 25 C. When near the glass transition temperature, a large number of lamellae are crushed and oriented to form a large number of microfibers at the yield point. The in-situ formed rubber phase in polypropylene random copolymer plays a significant role in the toughening process. When the temperature is 25 C the yield is due to the spherulite deformation and a small part of lamellae rotation and reorientation. While a large number of lamellae are crushed and oriented to form a large number of microfibers at the yield point when the temperature is 0 C.
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