Cross-linking behavior of eutectic hardeners from natural acid mixtures

Abstract

Eutectic Hardeners (EH) are multi component mixtures that activate one or more of their constituents for curing at low temperatures and are characterized by a low melting point. In this paper, natural acids and their mixtures (Citric Acid (CA), Malic Acid (MA), and Tartaric Acid (TA)) are used in conjunction with the liquefactor Ethyl Lactate (EL) to cure epoxidized linseed oil (ELO). Their influence on curing speed and final material properties are investigated. Mixtures with MA proved to have a lower viscosity, which is beneficial for the preparation of homogenous samples, but showed slightly diminished tensile properties compared to materials cured with only CA. TA had an increased reaction speed thanks to a lower pK_a value and the final material properties of a CATA mixture with small amounts of TA were found to have improved toughness and tensile strength.