Preparation And Properties Of Continuous Carbon Fiber Reinforced Thermoplastic Composites

Recently,continuous fiber reinforced composites have become a research hotspot in resin matrix composites,because of their excellent properties such as light weight,high strength,corrosion resistance,impact resistance and thermal distortion resistance.Compared with injection molding of short/long fiber reinforced thermoplastic composites,continuous fiber reinforced thermoplastic composites have complicated process conditions,have difficulties in fiber impregnation,and lack effective theoretical model and mechanical properties research,which seriously affects their practical application.Combined with theoretical analysis and experimental research,continuous carbon fiber reinforced polycarbonate composites(CF/PC)was selected as the research object.The impregnation and compaction mechanism and mechanical properties of continuous fiber reinforced thermoplastic composites were systematically studied,laying a scientific foundation for process formulation.Based on the process mechanism of continuous fiber reinforced thermoplastic composite prepared by film stack and thermoforming method.The mathematic model for describing the fiber impregnation during the preparation of the composite prepreg and the mathematic model for describing the resin flow and fiber compaction during the thermoforming process of the laminate were established and the reliability of the models were verified.Processing temperature and holding pressure are key process parameters for the fabrication of continuous fiber reinforced thermoplastic composites.The effects of processing temperature and holding pressure on the mechanical properties of the CF/PC were studied.The microscopic morphology of the tensile fracture section of the composite was observed and analyzed.Finally,the optimum forming condition with a processing temperature of 255 ? and a holding pressure of 1.0 MPa were got.Void is one of the most common defects in continuous fiber reinforced composites,which can seriously affect the mechanical properties of composites.The effect of dwell time on the volume fraction,spatial distribution,geometry and three-dimensional size of the voids,and the effect of void content on the flexural property and interlaminar shear property in laminates were systematically studied.The results showed that with the dwell time increasing,the void content expressed an exponential decrease.The voids were elongated,flattened and roughly evenly distributed with short dwell time,while round and mainly concentrated in the center of the laminate with long dwell time.Also,the pore size gradually decreased.Meanwhile,the formation of voids severely reduced the flexural and interlaminar shear properties of the composites.The flexural strength and modulus decreased by about 23 MPa and 2.17 GPa for every 1% increase in void content,respectively.And the interlaminar shear strength also decreased parabolically with the increase of void content.