Impregnation Simulation And Optimization Study Of Continuous Fiber Reinforced Thermoplastic Composite Materials

Melt impregnation process is one of the mainstream technology for manufacturing continuous fiber reinforced thermoplastic composites at home and abroad now, the main difficulty of this process is how to make the resin with high viscosity infiltrated into the fiber bundle well, and achieve a good combination between the fiber and resin. To solve this problem, a lot of researches about impregnating simulation and optimization of the process had been made at home and abroad, and the wedge areas between the pins and fiber, which have become major research focus, are recognized as the key areas to achieve driving force make melt impregnated into the fiber bundle. However, due to the feature of "black box" in the region, most of researches were combined with more empirical formula indirect modeling studies, which could’t accurately describe the relationship between the region and the impregnation degree of fiber bundle.This paper used the melt impregnation equipment developed independently, combined with experimental design methods to make preliminary experimental study of melt impregnation process of continuous glass fiber reinforced polypropylene composites, and established an empirical model of relationship between main process parameters (processing temperature, pulling speed, pin numbers) and impregnation degree of fiber bundle.Combined Reynolds equation with Darcy’s law to establish theoretical equations, which reflected the relationship between wedge areas’melt pressure and process parameters, used the theory of finite difference method to calculate the pressure distribution of the wedge area, and then established the efficiency evaluation system of melt impregnated fiber bundle in the wedge areas, analyzed the main process parameters’influence on the fiber bundle’s impregnation degree, experimental results verified the accuracy of the theoretical calculation model. Finally, further analyzed the influence of die’s structure parameters and the process parameters on the impregnation efficiency and impregnation degree of the fiber bundle in the wedge areas. The results show that increasing pulling speed and melt viscosity, decreasing pins’ radius, the efficiency for impregnating fiber bundle of the wedge area reduced. We had found that increasing pulling speed, reducing processing temperature and increasing the number of pins could increase the melt pressure of the wedge area effectively, but the fiber bundle’s impregnation degree is developed with decreasing pulling speed, increasing processing temperature and the number of pins. Meanwhile, increasing pins’radius or decreasing spacing between pins can increase wrap angle between fiber bundle and pins, which would scatter the broadening of fiber bundle, thus to improve the impregnation degree of fiber bundle.In order to enhance the wettability of fiber, improve the interface bonding strength between the fiber and resin, the paper used the Nano-SiO2 to modified the surface of fiber and combined with the compatibilizing effect of PP-g-MAH into PP, which effectively improve the interfacial bonding between the fibers and the resin. The porosity of composite modified decreased 59.88%, interlaminar shear strength increased by 116.06%, tensile strength improved by 109.14%, flexural strength increased by 99.85% and impact strength increased 116.70%.