Polypropylene Composite Material Properties And Fracture Behavior Of The Research

Polypropylene (PP) is one of the general plastic, which has the advantage of inexpensive, light quality, high used temperature, rigidity and high tensile strength, but there are also many shortcomings like low impact strength and brittle broken temperature, therefore, it was significant to modify polypropylene to improve its applied field. This paper focused on the polypropylene modification, through melting blending process and choosing rubber powder and calcium carbonate as the filling agent to get rubber powder/pp binary compound material and the powder rubber/calcium carbonate/pp binary compound material. And then discussing the filling agent reinforced mechanism which based on the detailed characterization about the microstructure characteristics of composite, mechanical properties, heat-resisting and rheology. Further on, this report has studied on polypropylene matrix composite fracture behavior and the influence of filling agent types and content to the fracture behavior that used basic fracture work method in order to provide theoretical basis for other modification of polymer materials.Main results as follows:(1) Through melting blending method to get rubber powder/pp composite material and meticulous research for the composite microscopic structure, crystallization behavior, heat resistance, mechanical strength and rheological properties. The results showed that using nanometer powder which got good dispersion as the filling agent could significantly improve the impact performance. When the addition amount up to12phr, impact strength increased to193.0%of the pure polypropylene but bending strength, tensile strength, depressed, reduction of9.4%and14.6%respectively, In contrast, micron grade powder increased its impact strength by33.0%, but bending strength and tensile strength fell27.0%and26.2%respectively. Nano powder played the role of heterogeneous nucleation and reduced the condenser depression of polypropylene, shorten the half crystallization time, common power for the crystallization and the melting behavior of polypropylene had no significant effect. Two kinds of powder could reduce their glass transition temperature and energy storage modulus, the loss factor also dropped and the polypropylene thermal degradation temperature increased and also reduce the polypropylene vicat softening temperature. All in all, the Vicat softening temperature of micron grade powder filling system was below of the nano system. With the increasing of nano powder filling quantity, the apparent viscosity of polypropylene was rising and in the low frequency, dynamic modulus gradually strengthened which showed a kind of solid response and the apparent viscosity shearing sensitivity of material enhanced.(2) Crumb rubber powder/calcium carbonate/polypropylene composites were prepared by melt blending and studied from the microstructure, crystallization behavior, heat resistance, mechanical strength and rheological properties of the composites. The results show that the filed of nano-crumb rubber and calcium carbonate can significantly increase the mechanical properties of polypropylene such as impact strength, flexural strength, while the filling ratio of nano-crumb rubber and calcium carbonate was8:4, the impact strength of polypropylene was increased by106%which was also the best impact strength we got. Two kinds of particles played the role of heterogeneous nucleation in polypropylene, reducing the undercooling of the system, shortening the half-time of crystallization and improving the crystalline properties. Heat decomposition performance of the material was improved as well as its thermal distortion performance. The glass transition temperature, storage modulus and loss factor of the material increased with increasing calcium carbonate filled. The apparent viscosity was very sensitive to shear rate, reducing with increasing calcium carbonate filled. Increased frequency was companied with increased viscous modulus of the system while similar solid viscoelastic response occurred in the low frequency region.(3) The fracture behavior of binary system of PP/nano powder and polypropylene/nano powder/calcium carbonate ternary system was investigated by essential work of fracture method with fracture process recorded by image collector and cross section morphology got through field emission scanning electron microscope. The results show that nano powder improved the essential rupture work of the polypropylene, when its filler content was8phr, the essential rupture work of the polypropylene was the biggest,2.17times than pure polypropylene. The essential rupture work changed not much before the material yielded while it increased significantly in neck-tear stage. The improved essential work of fracture of the materials indicated that the plastic deformation capability of polypropylene can be raised by nano-crumb rubber. The plasticity area of the material increased after rubber power was added through fracture images.Calcium carbonate particles and nano-crumb rubber can both improve polypropylene’s essential work of fracture and toughness in the PP/nano powder/calcium carbonate ternary blends. The we of the composite material reached the maximum when the filler content of carbonate particles and nano-crumb rubber both was6phr, which was2.4times of that of pure polypropylene. The essential rupture work changed not much before the material yielded while it increased significantly in neck-tear stage. With the increased filler content of calcium carbonate in the ternary composites, the essential rupture work was reduced, which indicated that nano-crumb rubber was superior to calcium carbonate in promoting the plastic deformation of polypropylene.