Properties of Biobased Epoxy Resins from Epoxidized Soybean Oil (ESBO) Cured with Maleic Anhydride (MA)

Abstract

Epoxidized soybean oil (ESBO), obtained from a renewable resource was used in the production of thermoset resins. Samples of the ESBO were initially treated with maleic anhydride, equal mixture of catalyst (1,3‐butanediol anhydrous and benzyldimethylamine) and the mixture was cured for 5 h at different temperatures. After the curing process, the ratio between the ESBO and the anhydride (ratio EEW:AEW) was evaluated in terms of the different mechanical properties produced using flexural, Shore D hardness and Charpy impact tests. The sample with the best mechanical properties was that with an EEW:AEW ratio of 1:1.0 which leads to best balanced behavior and this could be representative for the maximum crosslinking degree. Also, thermal characteristics were evaluated during the crosslinking process using differential scanning calorimetry, In addition, other thermal characteristics of the cured materials were obtained by determining the heat deflection temperature and the Vicat softening temperature. The coefficient of thermal expansion was determined using thermo‐mechanical analysis. In accordance with the mechanical behavior, the best thermal properties were obtained for samples with an EEW:AEW ratio of 1:1.0. As a result of this work, a biologically based epoxy resin with good mechanical properties and flexibility was obtained.

Synthesis and Properties of Polyesters from Waste Grapeseed Oil: Comparison with Soybean and Rapeseed Oils

“…Previous work with ESBO derived epoxy resins has shown that T g 's are lowered with decreasing levels of anhydride ([E:A ratio) [26,42] and this was observed for all six oil/anhydride combinations in this study. This is attributed to a lowering of crosslink density within each series as the anhydride levels are decreased, (due to unreacted epoxides), and provides the polymer with an increase in elasticity from the linear chains.…”

“…This correlates to the greater proportion of epoxidized linoleic chains and is in agreement with the trends found by Webster [37] for the polymerization of epoxy sucrose esters and cyclic anhydrides. The cure temperature range was similar to that observed for epoxy resins derived from ESBO and maleic anhydride (C T = 150°C) [26]. It was also possible to determine the enthalpy of polymerization from the area under the DSC curve.…”

“…The epoxidized oils and anhydrides were combined to give epoxide:anhydride functional group ratios (E:A) of 1:1 and 2:1 in line with previous reported work [26]. In addition an equimolar ratio of triglyceride to anhydride was used (*4:1 E:A ratio depending upon the oil) with the catalyst 4-MI (1 wt% relative to the total reaction mixture).…”

“…1) is one of the most common vegetable oil feedstocks used in industry, traditionally it has been used as a plasticizer for PVC [22,23], as well as for producing polyesters from anhydrides [24][25][26].…”

“…Unfortunately, replacing petrochemical epoxides (typically containing terminal epoxides) with less reactive plant oil derived internal epoxides leads to increases in cure temperatures by as much as 40°C [25]. Properties of the final plastic are affected by the stoichiometric ratio of epoxide to anhydride functional groups, with values greater or less than the optimum 1:1 ratio leading to a decrease in flexural modulus and hardness of materials due to incomplete curing of the epoxide [26].…”