Study On Preparation Technology Of Long Glass Fiber Reinforced Polypropylene Composite For Improving Antistatic Performance

Long glass fiber reinforced polypropylene composites are widely used in automobile instrument panels,battery packs,and other components because of their excellent specific strength,recyclability,and lightweight.In the preparation process,an antistatic agent or conductive filler is usually added to make it have a certain antistatic performance,to avoid electrostatic interference to automotive electronic devices.In this paper,the preparation method of long glass fiber reinforced polypropylene composite containing antistatic agent bistrifluoromethanesulfonimidate(Li-TFSI)was studied,and the effect of Li-TFSI on the antistatic and mechanical properties of the composite was studied.The research contents and conclusions of this paper are as follows:(1)Polypropylene composite with 50wt% long glass fiber content was prepared by injection molding,and the effects of injection temperature and screw speed on mechanical properties of the composite were studied.The results show that the tensile strength increases with the increase of injection temperature in the range of 190°C to220°C,but the overall increase of tensile strength is small.When the injection temperature was 190°C and the screw speed was in the range of 15rpm～45rpm,the tensile strength of the material increased firstly and then decreased with the increase of the screw speed,when the screw rotation speed is 35 rpm,the tensile strength of the composite reaches the maximum value.(2)The effect of different Li-TFSI content on the surface resistivity and mechanical properties of the composites was analyzed,and the strengthening mechanism of the fiber-matrix interface was studied.The results show that the polarity between Li-TFSI and LGF makes Li-TFSI adsorbed on the LGF surface and forms a conductive path.The length and space-occupying effect of LGF was beneficial to reduce the surface resistivity of the composites.The addition of0.15wt/wt% Li-TFSI reached the seepage threshold of the composites,and the tensile strength increased by 6.8%.Through comprehensive analysis of crystallization behavior,mechanical properties,and fiber fracture failure forms of composites,Li-TFSI has excellent heterogeneous nucleation ability.The coating effect of spherulite on Li-TFSI enhances the anchoring effect of fiber on the matrix,and the anchoring effect of fiber on the matrix is closely related to the compact degree of arrangement between Li-TFSI.(3)Maleic anhydride grafted polypropylene was used as a compatibilizer to analyze the effect of Li-TFSI content on the surface resistivity and mechanical properties of the composites,and the relationship between the synergistic effect of crystal structure and failure strain was established.The results showed that adding0.35wt/wt% Li-TFSI reached the percolation threshold of the material.Although the addition of Li-TFSI reduces the tensile strength of the composite,the tensile strength of the composite with the Li-TFSI content still increases by 13.6% compared with the composite with the percolation threshold of 0.15wt/w t%.In addition,Li-TFSI has a coating effect on maleic anhydride,and Li-TFSI butt graft can clean the silane on the long glass fiber,resulting in the reduction of residual matrix on the fiber surface and the gap between the fiber and the matrix interface after elongation fracture.