Preparation And Properties Of Epoxy Resin Composites Modified By Nano Alumina/phenolic Resin

This article is based on the broad application prospects of polymer based nanocomposites in fields such as marine equipment and marine engineering.Nano alumina（Al₂O₃）doped PF/EP polymer matrix composites were prepared by synergistic modification of epoxy resin with phenolic resin（PF）and nano alumina（Al₂O₃）in a step curing manner.The composites were characterized by means of FTIR,SEM,Taber wear test,hardness test,water absorption test,contact angle test,electrochemical impedance spectroscopy（EIS）test and differential scanning calorimetry（DSC）.The effects of changes in PF and nano Al₂O₃ content on the friction,wear,and corrosion resistance of composite materials were studied,and the wear and corrosion resistance mechanisms and mechanisms of composite materials were explored at the micro level;Explored the curing mechanism of PF/EP system and formulated the curing process flow,and established its related reaction kinetics mechanism model.The main content and conclusions of this article are as follows:In terms of wear resistance,the results showed that the FTIR measurements confirmed the involvement of silane-modified nano-Al₂O₃ in the curing reaction between PF and EP;the addition of both nano-Al₂O₃ and PF improved the hardness and wear resistance of EP,and the composite with PF content of 30%（mass fraction）and3%（mass fraction）nano-Al₂O₃ doping had the lowest wear weight loss（784 mg）compared to EP,and its hardness The SEM results showed that the silane-modified nano-Al₂O₃ bonded well with the PF/EP polymer matrix,and the silver streaks on the fracture surface and the uniformly dispersed nano-Al₂O₃ improved the toughness and denseness of the composite,and the wear surface became flatter and denser,and the wear mechanism was mainly adhesive wear.During the friction process of the composite,the lubricating film formed by the exfoliated nano-Al₂O₃ slows down the wear of the composite and the counterpart surface.Meanwhile,nano-Al₂O₃ and PF improve the wear resistance of the composites by increasing the stiffness and load-bearing capacity of the composites,which in turn improves the wear resistance of the composites.In terms of corrosion resistance,the results showed that the composite coating doped with 3%nano-Al₂O₃ had the smallest water absorption（0.65%）and the largest contact angle（80.7°）,which was 17.6°higher than that of the EP coating;the composite coating had the largest low-frequency impedance modulus value（1.46×10⁷Ω·cm²）after immersion in 3.5%（mass fraction）Na Cl solution for 576 h,which was one order of magnitude higher than that of the EP coating by one order of magnitude.The hydroxyl groups on the modified nano-Al₂O₃ surface were replaced and the hydrophilic groups were reduced,which improved the hydrophobicity of the coating surface.Meanwhile,the amino group on the surface of nano-Al₂O₃ is covalently bonded with EP,which improves the compatibility of nanoparticles in the composite coating and the denseness of the coating.In addition,These nanoparticles hinder the diffusion of corrosive media and reduce the diffusion rate of corrosive media,thus improving the corrosion resistance of the composite coating.In terms of curing kinetics,it was found that the curing reaction of the PF/EP system can be divided into two stages:the first stage is the etherification reaction between the epoxy group in EP and the phenolic hydroxyl group in PF,and the reaction between the hydroxyl group in EP and the hydroxymethyl group in PF.The second stage is the side reaction generated by the condensation of PF itself at high temperature;The PF/EP system curing process flow has been developed as 90℃/1h+100℃/2h+110℃/2h,providing guidance for later experiments and curing processes;The reaction kinetics mechanism model equation was established and verified.The autocatalysis model can accurately describe and predict the curing reaction process of PF/EP system.