Synthesis And Properties Of Phenolic Resin Nanocomposites Modifiedwith Epoxy Resin

Phenolic resin with available raw materials,simple synthesis procedure,high mechanical strength,good ablation resistance and heat resistance also broad room for modification,is widely used for adhesive,coating,carbon,fiber reinforced composite materials in civilian and military industry.Modification of phenolic resin for better comprehensive performance has became the focus of the present study.In order to improve the heat resistance and toughness and broaden its application range,phenolic resin was modified with epoxy resin and nano silicaOn the basis of the existing technology,nano silica was modified with KH560 on the surface,influence of surface modification on nano silica dispersion properties was systematically studied.Phenolic resin and its composite materials modified with epoxy and nano silica were prepared,and the influence of epoxy and nano silica modification on its performance was studied.Modified SiO₂ nanoparticles were synthesized successfully in toluene solvent by using silane coupling agent KH560 as surface modification agent.The FTIR spectrum analysis showed that KH560 reacted with nano silica to generate new chemical bond.KH560 surface modification improved the dispersion of nano SiO₂ in organic solvent.With the increase of dosage of silane coupling agent,the average particle size of nano SiO₂ decreased and then increased,the dispersion of nano SiO₂ increased and then decreased.Furthermore,when the dosage of silane coupling agent was 20%,the dispersion of modified nano SiO₂ in ethanol was the best.Phenolic resinmodified withEpoxy and nano SiO₂ was prepared by situ polymerization method.The FTIR spectrum analysis showed that epoxy resin reacted with phenolic resin chemically.With the increase of dosage of epoxy,the average molecular weight and softening point of modified phenolic resin decreased gradually,polymerization time first increased and then decreased,epoxy value increased gradually,and free phenol content was less than 5%.With the increase of dosage of nano SiO₂,the average molecular weight and softening point of modified phenolic resin first increased and then decreased,polymerization time first decreased and then increased,and free phenol content was less than 5%.Under the comprehensive consideration,the best dosage of epoxy resin was 10%while nano SiO₂ was 1%.Phenolic resin based composite materials modified with epoxy resin and nano SiO₂were prepared by compression molding technology.The TG analysis showed that the addition of epoxy resin and nano SiO₂ improved the heat resistance of modified phenolic resin.Meanwhile,the addition of epoxy resin and nano SiO₂ improved the toughness of modified phenolic resin.