Preparation And Properties Of PET Fiber/Polypropylene Composites

Fiber reinforced thermoplastic matrix composites possesses enhanced toughness and strength,corrosion resistant,and have been rapidly developed recently,in which glass fiber reinforced thermoplastic composites are most widely used.However,the glass fiber composites have some disadvantages such as high density,serious processing equipment wear,difficult recycling application,and environmental pollution and so on.These disadvantages have limited the application of these glass fiber composites.The organic fiber reinforced thermoplastic composites has attracted great interesting because of their low production cost and density,enhanced performance,and possible recycling application.Therefore,the research on organic fiber composites possesses important theory and application significance,is also important direction to improve the application of the fiber reinforcement composites.PET fiber/PP composites are prepared by melt blending and mechanical properties are investigated in this thesis.The results show that the mechanical properties of the composites are related with the condition of fiber modification,fiber content,fiber length,and the PP melt index. The interfacial action and compatibility between PET fiber and PP are obviously enhanced by modified PET fiber,which was treated with 10%NaOH,at 70℃for 60min.During the mixing and twin-screw extrusion processing,high screw speed and large pitch could effectively avoid serious shrinkage and strength decrease of PET fiber,which is caused by the local superheat.The modified PET fiber with 3-5mm length in 10wt.%content shows the best enhanced effect on PP with a meld index of 10g/10min,and the tensile strength of the composite reach 38.78MPa,and the impact strength is 2.20KJ/m².The Nano-CaCO₃/PP,PET fibers/PP and nano-CaCO₃/PET fibers/PP composites are prepared by melt blending method,and their structure and mechanical properties are investigated.The results show that the nano-CaCO₃/PET fibers/PP three-phase composites displays significantly better mechanical properties than PET fibers/PP and nano-CaCO₃/PP composites.The XRD,DMA and SEM were used to investigate the reinforcement mechanism of composites.The results indicate that the interfacial action and compatibility between PET fiber and PP are obviously enhanced by the addition of nano-CaCO₃ particles in the three-phase composites and the mechanical property enhancement may be mainly originated from the formation ofβ-form crystallites of PP,which is induced by the synergistic effect between PET fibers and nano-CaCO₃.Finally,the crystallization behavior of composites was investigated by non-isothermal crystallization kinetics.The results show that the non-isothermal crystallization process of PP,PET fiber/PP, nano-CaCO₃/PET fiber/PP composites can be well described by the Avrami equation and the Mo Zhisheng equation and nucleation models of all three composites are three-dimensional mode.Simultaneously,it is found that the rate of crystallization of PP can be effectively raised by addition of nano-CaCO₃ particles.