The curing process or hardening of epoxy resins requires the addition of crosslinking agents that transform the polymer into an insoluble crosslinked polymer, a three-dimensional network of covalent bonds, chemically very stable, with excellent mechanical properties. Although there are several types of hardeners, amines and polyamides are the most commonly used for epoxy resins. However, they present low equivalent weight compared to epoxy resins, which complicates the mixing process, and low molecular weight, leading to odor and toxicity problems due to their high volatility. Moreover, in the industry, the curing agents used are based on petroleum derivatives amines.
In this study, curing agents based on poly(amidoamines) have been obtained from residual vegetable oils as raw materials, due to their low cost, biodegradability and availability. They are composed of mixtures of fatty acids and glycerol esters, which, together with the unsaturation of double bonds, have allowed obtaining poly(amidoamines) capable of forming crosslinked polymers.
Experimental variables during synthesis have been evaluated. The samples properties have been characterized, obtaining that the reaction yield and the %conversion to poly(amidoamine) mainly depend on the stoichiometric ratio and the reaction temperature, as well as the glass transition temperature of the epoxy resin cured with the different poly(amidoamines) prepared.
Co-authors: Francisca Aran Ais, Daniel Sepulcre