Lightweight rigid foams from highly reactive epoxy resins derived from vegetable oil for automotive applications

For the two last decades, the reduction of fuel consumption and CO2 emissions is a topic of first importance in automotive industry. Among the possible technical approaches, the reduction of the vehicles weight seems to be a promising solution. This option can be achieved by the growing use of lightweight structures based on rigid foams. However, most of the commercial materials are oil-based and sometimes involve harmful chemical compounds. Moreover, some products that require long time processes are inadequate for fulfilling automotive cadence. In this paper, we investigated the development of new generation of highly reactive epoxy foams. These materials were obtained by mixing epoxidized plant oil-derivates with a cycloaliphatic amine hardener (isophorone diamine IPDA) and a harmless foaming agent (sodium bicarbonate NaHCO3 named SB). The chemical composition of the reactive mixture was optimized by adding several chemical additives acting as exothermicity regulators (ER) in order to control more particularly the exothermicity of the curing reaction. Their efficiency in the consumption of the heat excess released during cross-linking was explored. Kinetic rheological analyses, DSC and TGA experiments were used to tune the dosing of each chemical component in the reactive formulation. They made it possible the production of foams in a few minutes (<3 min) with an ultimate glass transition temperature close to 48 degrees C and apparent density of about 0.17 g cm(-3). (C) 2015 Elsevier Ltd. All rights reserved.