IMPROVED ELECTRICAL PROPERTIES, HYDROPHOBICITY, AND DEGRADABILITY OF ORTHO-VANILLIN-BASED EPOXY RESIN: ROLES OF SCHIFF BASE

Abstract

Conventional diglycidyl ether of bisphenol A epoxy resins (DGEBA) are made from non-renewable fossil re sources, which caused severe resource waste and environmental issues. It is of great importance to develop degradable epoxy resins with excellent physicochemical and electrical properties. In this work, a novel vanillin based epoxy resin (VEP) with Schiff base bond is synthesized from Ortho-vanillin (OVA) and L-phenylalanine (PHE) through a two-step procedure. After cured with 4, 4′-diaminodiphenylmethane (DDM), the vanillin-based epoxy resin (VEP/DDM) exhibits a high char yield of 31.15 %, and 110 % enhancement in storage modulus comparing to DGEBA/DDM. Meanwhile, VEP/DDM presents excellent electrical properties with breakdown strength of 33.16 kV/mm, dielectric constant of 4.00 and dielectric loss of 0.0059 at 50 Hz, respectively. Furthermore, the degradable Schiff base and hydrophobic groups on the side chain of PHE enable the VEP/DDM with good acid-catalytic degradation and hydrophobic properties. This work provides a new route for fabricating bio-based epoxy resins with promising physicochemical and electrical performance in practical engineering applications.