Study On The Effect Of Mixing Equipment And Structure On The Properties Of Talc/PP Composites

In this thesis, the preparation of high performance Talc/PP composites as the research target, the effect of preparation technology and equipment structure on the microstructure and properties of the composites were studied, combined with the new continuous mixing equipment developed by our research team. The mixing characteristics of different mixing equipment were studied based on the analysis of flow field characteristics of new type continuous mixer with different rotor structures and twin screw extruder of kneading block element through POLYFLOW software; Talc/PP composite was prepared by means of twin-screw extruder, continuous mixing extruder; The mechanical and physical properties and microstructure characteristics of composite characterized with the aid of SEM, mechanical properties tester, cone plate rheometer and DSC. And the macro performance of the composites were studied. The effect of mixing flow field characteristics, the technological conditions and the equipment structure on the microstructure, rheological properties and the macro performance of the composites were studied. The main results are as follows:(1) When the rotor speed is higher, the RTD of polymer melt in the mixer is shorter, the maximum shear rate grows unceasingly, the Mmix and Lyapunov rises too, the effect of dispersion and distribution mixing in the mixing flow field gets better; When the rotor speed is lower, causes a reunion of the talcum powder in the PP matrix. However, when the rotor speed is too high, although talcum powder dispersed in PP matrix is better, but it will destroy the structure of Talc, making the talc powder particles shorter in PP matrix, which will affect the performance of the composite materials.(2) The influence of rotor structure of the mixing characteristics is relatively obvious. The Mmix of TSE is bigger than the rotors of mixer, however, the flow field of mixer rotors with strong tensile flow and chaotic flow, which influence on the microstructure of the preparation of composite materials, the length distribution of talcum powder in PP matrix is longer about 2-5?m and high shear flow field of TSE is mainly distributed in 1-3?m. In addition, the dispersion and distribution mixing of the mixer significantly better than that of the TSE.(3) For different rotor structures, the performance of the composite material prepared with chaotic type rotor is superior to those prepared with the classic rotor, their tensile strength, bending modulus and impact strength increase 4.8%,3.9% and 2.5% respectively. When talcum powder filler amount is 30 wt%, the tensile strength, bending modulus and impact strength of the composite material prepared with continuous mixer are higher than those of TSM 14.7%,26% and 60.5% respectively. In the condition of meeting the application requirements, the talcum powder can be increased by 5%-10% of the filling volume. In addition, the comprehensive performance of the composites prepared through masterbatch dilution method can meet the requirement of engineering application.