Study On The Preparation And Properties Of Graphene Modified Polyamide 66 Composites With Different Lateral Dimensions

Graphene has great research value in the field of improving the performance of composite materials.In recent years,great progress has been made in the research of graphene.However,the research on the properties of graphene-modified polymers with different lateral sizes is relatively lacking.This research studies the effect of the lateral size of graphene on the structure and mechanical properties of PA66.In the first step,four different lateral sizes of graphene were prepared by a high-speed shearing machine.In the second step,graphene/PA66 composites with different lateral sizes and different contents are prepared by twin-screw blending.The laser confocal scanning imaging Raman spectrometer,transmission electron microscope,scanning electron microscope,and Fourier transform infrared spectroscopy were used to observe the properties and sizes of graphene.The results show that high-speed shearing has little damage to graphene lateral size can be reduced to a certain extent.A differential scanning calorimeter,an X-ray diffractometer,and a universal testing machine were used to analyze the crystalline properties and mechanical properties of the graphene/PA66 composites to find the appropriate graphene content and size.The test results show that the mechanical properties of the composite are the best when the amount of graphene is 0.3%.The mechanical properties,crystallinity,and crystal size all increase first and then decrease as the graphene size decreases.At 2-3 ?m,the fracture strength of the composite material reaches 94.9 MPa,the crystallinity is 33.2%,the grain size of the D(101)(110)crystal plane reaches 3.83 nm,the graphene size decreases,the agglomeration effect increases,and the composite properties are improved.Therefore,the study of graphene size still has room for improvement in further improving the performance of PA66 composites.Molecular dynamics simulation was used to simulate the movement of PA66 molecular chains on the surface of graphene with different content sizes.Simulation results show that PA66 single molecular chains converge on the surface of graphene.When multiple molecular chains are distributed on the surface of graphene,the aggregation phenomenon is reduced compared to the aggregation of single molecular chains.In terms of adsorption on graphene surfaces,the molecular chains tend There is a boundary effect on the graphene surface.Small pieces will appear on both sides,showing a bridge on the graphene sheet.Graphene heterogeneous nucleation will increase,and it will also promote the crystallization of the polymer.However,due to the small size effect,the smaller the size,the higher the surface activation energy,the agglomeration phenomenon will increase and hinder crystallization.