Effect of laccol‐modified epoxy on fracture toughness of carbon fabric reinforced biobased epoxy composite

Abstract

AbstractLaccol is a main component of Vietnamese lacquer sap (Rhus succedanea), it is a natural phenol with two hydroxyl groups in octo‐position and unsaturated side chains. The laccol‐modified epoxy was directly dispersed in the epoxy resin and then the modified matrices were cured with cyanethyl‐diethylenetriamine (CEDETA) as a curing agent. The reaction of the epoxy epikote 828 with the laccol was studied using mid FT‐IR spectroscopic techniques. Effects of laccol contents in the epoxy matrix and carbon fabric/epoxy (CF/EP) composites on the izod impact strength and mode‐I interlaminar fracture toughness were investigated. The obtained testing results showed that the izod impact strength of epoxy matrix significantly increased by 35 % when 20 wt.% laccol was dispersed in the epoxy matrix. In addition, the mode‐I interlaminar fracture toughness of CF/EP composites at crack initiation (GIC) and propagation (GIP) were also improved by 59 % and 43 %, respectively, by using 20 wt.% laccol. Damaged surfaces of fractured samples were investigated using scanning electron microscopy (SEM) techniques. The overall results have shown that it is possible to obtain excellent impact strength and mode I interlaminar fracture toughness with the use of laccol as a toughness agent for the epoxy resins.