Bio-based thermoset composites from epoxidised linseed oil and expanded starch

Abstract

a Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid crosslinker (Pripol 1009) and starch are reported. High amylose corn starch in its native, gelatinised and retrograded forms were used in the formulation to yield water resistant films with good thermal stability. The textural properties of gelatinised and retrograded starches were characterised using scanning electron microscopy and porosimetry and their thermal stability was determined using thermogravimetric analysis. The inclusion of 20% gelatinised starch significantly improved the mechanical properties of the bio-based thermoset composite with tensile strength being enhanced by 227% and Young's modulus by 166% with respect to the starch-free counterparts. Unlike in formulations comprising native starch, no visible phase separation was noticed for gelatinised-or retrograded-starch thermosets. Thermal analysis and gel time study revealed retardation of the cure process in the presence of starch. However, the presence of hydroxyl groups within the starch was likely to promote a more extensive curing process, as indicated by the higher total enthalpy of reaction obtained. This was supported by thermal stability studies, which indicated a greater proportion of crosslinked material obtained in films with higher starch content.

New insights into the curing of epoxidized linseed oil with dicarboxylic acids

“…28 Based on previous studies, [29][30][31][32] the possible interactions between ELO, DCAs and DMAP are proposed as shown in Scheme 1. 28 Based on previous studies, [29][30][31][32] the possible interactions between ELO, DCAs and DMAP are proposed as shown in Scheme 1.…”

“…Vilela et al 44 studied the thermal stability of polyesters prepared from C 26 dicarboxylic acid with different chain length of diols (C 4 , C 12 , C 26 ) and their study confirmed that better thermal stability was obtained with higher chain length of polyesters. 29,46 While the second stage beyond 430 o C resulted from the ester groups formed by the ring-opening reactions between DCAs and epoxy groups. 7 (a) clearly shows that the resins experienced a twostage decomposition process in N 2 .…”

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

“…More recently, in 2014, Supanchaiyamat et al reported using epoxidised linseed oil and expanded starch (from the aforementioned Starbon ® process) to produce a fully bio-based composite with 227% improvement in tensile strength and 166% enhancement in Young’s modulus, compared to those with no added starch, suggesting it as a replacement for vinyl based films [249]. …”

Syringaresinol: A Renewable and Safer Alternative to Bisphenol A for Epoxy‐Amine Resins

“…Therefore, many works have been focused on the valorization of renewable resources towards epoxy resins to restrict the use of DGEBA . Numerous alternative precursors for DGEBA‐free resins have been described, such as terpenes, linseed oil derivatives, sucrose soyate, and rosin acid oligomers . Research on isosorbide‐based epoxy compounds also revealed good mechanical properties of the resulting cured materials and led to the commercialization of the diglycidyl ether of isosorbide .…”