Fracture toughness and ductile characteristics of diglycidyl ether of bisphenol-A resins modified with biodegradable epoxidized linseed oil

Epoxidized linseed oil (ELO) was synthesized to improve the biodegradability and fracture toughness of the diglycidyl ether of bisphenol-A (DGEBA). The ELO was characterized using Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), and epoxy equivalent weight (EEW) tests. DGEBA was blended with ELO contents from 10 to 40 wt% to obtain a modified network. DGEBA and the DGEBA/ELO blends were characterized by their biodegradability, thermal properties, and fracture toughness. The thermal properties of the DGEBA/ELO blends were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The fracture toughness of the DGEBA/ELO blends was studied by measuring the Izod impact strength and the critical stress intensity factor (KIC). The morphologies were observed by scanning electron microscopy (SEM). In the biodegradability results, the DGEBA/ELO blends degraded 5% of the initial weight. The thermal property results confirmed that the crosslinking density of the epoxy networks decreased. The impact strength of the DGEBA/ELO blends was significantly improved with the addition of ELO owing to the reduced cross-linking density of the epoxy network.