Polymer Thermally Conductive Composite Material Based On Sand Canal-stone Canal Conversion Mechanism Preparation Method Research

Polymer-based thermally conductive composite materials are currently widely used in many fields.Most of the thermally conductive composite materials are prepared by adding too many high thermal conductivity fillers to the matrix.As a result,the thermal conductivity is only slightly improved,and the mechanical properties of the composite material are caused.decline.During the research process,it was discovered that the same addition of fillers did not increase the thermal conductivity by orders of magnitude like the conductivity of conductive composites.In response to this phenomenon,Professor Wu Da ming’s team proposed a "sand canal-to-stone canal"conversion mechanism,the core of which is through compulsory The assembly method(SCFNA)to prepare a dense thermal network can significantly improve the thermal conductivity of composite materials.As one of the molding methods for preparing thermally conductive composite materials,injection molding has the characteristics of low cost,high efficiency,and precise processing.However,a self-assembled loose thermally conductive network is formed inside the injection molded composite material,the thermal conductivity is not improved much,and the mechanical properties are affected.In the early stage of the laboratory,hot embossing equipment was used to successfully prepare high thermal conductivity composite materials by the SCFNA method,but the hot embossing equipment has a single mold shape,which can only prepare single-layer thermally conductive composite materials of the same shape,and the processing efficiency is low.Therefore,it is difficult to achieve continuous production of thermally conductive materials.Based on the injection compression function of the injection molding machine,the SCFNA method is used to prepare high thermal conductivity composite materials.This paper proposes a new process for preparing multilayer thermally conductive composite materials—multilayer injection compression-space confinement forced assembly method(MLIC-SCFNA).The research content includes:(1)Based on the size of the stretched preform structure,design a set of injection molds.In the mold design process,based on the flow simulation plug-in,the fluid flow state in the mold core and punch channel is simulated,the flow rate and temperature distribution are analyzed,and the size and arrangement of the channel system are determined.Through the coordination of the electric heating device,the integrated cooling and heating mold temperature controller and the circulating heater,the rapid control of the mold temperature is realized.(2)Based on Moldflow mold flow analysis software,with warpage deformation,volume shrinkage,and residual stress as evaluation indicators of product performance,designL18(37)orthogonal test,single factor method focuses on analysis of compression speed,compression distance,compression time The effect of equal compression process parameters on product performance is compared,and the effects of different process parameters on injection compression and injection process product performance are compared,and the optimal injection compression process is finally obtained.At the same time,compared with traditional injection molding.Can reduce warpage deformation,volume shrinkage,and residual stress in the Z direction.(3)To study the relationship between carbon fiber orientation distribution and carbon fiber network construction,the MLIC-SCFNA process is more helpful to improve the degree of fiber orientation than conventional injection molding.And predict the thermal conductivity of the composite material in the horizontal plane through the flow behavior of the carbon fiber filling process.Fibers are unevenly distributed in various areas of the mold cavity,and it is difficult to build a heat-conducting network densely.In order to increase the thermal conductivity of the product along the flow direction(in the horizontal plane),it is necessary to ensure that the fiber orientation in the core layer and the surface layer is uniform.(4)Prepare single-layer,double-layer and multilayer injection compression-stretched preforms with ideal molding quality based on simulation data experiments.Under a certain experimental error range,combined with actual equipment and process conditions,multi-layer injection compression simulation has successfully guided the experiment and verified the feasibility of the new MLIC-SCFNA process to prepare multi-layer injection compression and tensile preforms.(5)The PP/CF multilayer injection compression thermally conductive composite material was prepared based on the MLIC-SCFNA process,which verified that the MLIC-SCFNA process can make a freely compressed self-assembled thermally conductive network,after forced compression,the arrangement is regular and dense,realizing sand canal change Stone canal,the thermal conductivity is significantly improved.