Study On The Preparation And Properties Of High Strength And High Modulus Epoxy Molding Compound

Epoxy molding plastics are widely used in aerospace,military,deep-sea and other fields of packaging circuit,mainly composed of epoxy resin and inorganic filler,the interface between epoxy resin and inorganic filler as a stress transfer "bridge" to limit the strength and modulus improvement,high strength and high modulus has become the urgent pursuit of performance,so the molding plastics of Interfacial modification of molding plastics has become a hot topic of research.In this paper,a high strength and high modulus epoxy molding compound with excellent interfacial properties was developed by using hyperbranched polymer modified fillers and designing and preparing epoxy molding compound reinforced by wollastonite powder and glass fiber.(1)Polyamino hyperbranched silane-modified wollastonite powder was prepared for reinforcing epoxy composites.The grafting of hyperbranched polymers,the changes of surface morphology of wollastonite powder,and resin wettability were characterized,and the corresponding epoxy composites were tested for mechanical and thermomechanical properties,and the mechanism of interfacial interaction was proposed.It was found that the surface of wollastonite powder passivated,the weight loss rate increased,and the contact angle and oil absorption value decreased significantly.When the mass fraction ratio of wollastonite powder to silane monomer was 1:0.75,the modified wollastonite powder was carried out,and the mechanical properties of the composite were best at this time;SEM of tensile section observed that the modified wollastonite powder was uniformly dispersed in the resin and a large amount of resin adhered to the surface,and the cross section appeared uneven and the interfacial effect was enhanced;DMTA further verified the improvement of the interfacial properties.(2)Polyhydroxy hyperbranched polyester modified glass fibers were prepared for reinforcing epoxy composites.The grafting of hyperbranched polymers,the changes of glass fiber surface morphology,and resin wettability were characterized,and the corresponding epoxy composites were tested for mechanical and thermomechanical properties,and the mechanism of interfacial interaction was proposed.It was found that a film structure appeared on the glass fiber surface,the weight loss rate increased,and the contact angle and oil absorption value decreased significantly.When the glass fibers were graft-modified with H204(hydroxyl amount 40-45/mol),the mechanical properties of the composites were best at this time;SEM of tensile sections revealed resin adhesion on the modified glass fiber surface and enhanced interfacial action;DMTA further verified the improvement of interfacial properties;the epoxy resin and hyperbranched polymer interpenetrated to form a physical cross-linked structure,resulting in physical crosslinking between molecules.(3)Multi-scale high-strength and high-modulus epoxy molding compounds were prepared using wollastonite powder glass fibers as fillers,and the fillers were modified by hyperbranched grafting to prepare high-strength and high-modulus epoxy molding compounds.The curing exotherm,mechanical properties and cross-sectional morphology of the multi-scale epoxy molding plastic were tested,and the mechanical properties,cross-sectional morphology,electrical insulation properties and thermal conductivity of the modified molding plastic were tested.The results showed that the best mechanical properties of the prepared multiscale epoxy molding compounds were obtained at the mass fraction ratio of wollastonite powder to glass fiber of 3:4,and the filler was observed to be pulled out in SEM sections.The bending,tensile,compressive,and impact strengths of the epoxy molding compounds prepared after the filler was modified with hyperbranched polymer were improved to 176.29 MPa,81.33 MPa,306.19 MPa,and16.80 KJ/m2,respectively,compared with the unmodified ones,which were nearly24.04%,15.29%,10.04%,and 13.89%,and the bending and tensile moduli improved to21.93 GPa and 19.43 GPa,respectively,compared with the unmodified ones,which increased by 5.28% and 4.91%,respectively;SEM in the fracture surface found that the modified fibers and fillers were evenly dispersed,a large amount of resin residue existed on the surface,a large number of grooves appeared,and the fibers and fillers played an efficient synergistic role to achieve the enhancement of the molded plastic interface,and the epoxy molded plastic was found to have excellent electrical insulation and thermal conductivity.