Effect Of RE β-Nucleating Agent On The Crystallization Properties And Mechanical Properities Of PPH And PPR

PP possesses excellently comprehensive properties, it has a wide application in injection, molding, extrusion, blow molding etc. But its notch impact property is bad which limits its using range. Polypropylene is a polymorphic material with several crystal modifications including monoclinic(α),trigonal(β),and orthorhombic(γ) forms. Different crystal modifications, crystal structure and morphology have significant influences for the mechanical properties.In the study, using a new rare-earthβ-nucleating agent (WBGⅡ) to modify ethylene-propylene random copolymer(PPR) and homopolymerization polypropylene(PPH) and study on its nuclear effect in the process of the crystallization .Then study the crystallization behavior, crystal properties and the mechanical properties of polypropylene with the WBGⅡ.The conclusions are as follows:REβnucleating agent can induceβcrystal modification in polypropylene. WBGⅡcan accelerate the crystallization rate of PP and make the spherulite size smaller. The properties of polypropylene can be effectively improved by the REβnucleating agent.When the content of WBGⅡis about 0.2%, the impact toughness of PPR is improved by 60%, and the impact toughness of PPH is improved by 100~200%.When the addition was within the range of 0.1~0.5%, the impact toughness and elongation of PP decreased gradually after the first enhanced, and the tensile strength, flexural strength and bending modulus of PP enhanced gradually after first decreased as the concentration ofβ-nucleating agent increased.REβnucleating agent in polypropylene has the melt crystallization phenomenon.When the final temperature of heating is higher than 230℃, polypropylene crystal morphology changes.The nucleating agent gathered dendritic structures in polypropylene and then inducedβ-crystal formation. In this study we can observed a spectacular"flower"-like polypropylene crystal morphologyThe non-isothermal crystallization kinetics ofβ-PP was fit to use the method of Mozhishen's method.