Sequential photo-thermal curing of (meth)acrylate-epoxy thiol formulations

Identifier:  imarina:9228399

Handle: https://hdl.handle.net/20.500.11797/imarina9228399

Authors:  Roig, A; Ramis, X; De la Flor, S; Serra, A

Abstract:
In this work, a novel dual-curing procedure has been developed. It is a combination of a first radical UV-initiated thiol-(meth)acrylate reaction, followed by a second thermal thiol-epoxy step catalysed by a base. Since (meth) acrylates can lead to homopolymerization by radical mechanism, the amount of thiol has to be optimized to reach cross-linked materials with Tgs above room temperature and good mechanical performance. It should be considered, that if the amount of thiol in the intermediate materials is too low, epoxy homopolymerization can take place during the second step. The use of glycidyl methacrylate in combination with trifunctional meth (acrylates) allows this system to gel in the 1st stage and avoids possible dripping or exudation of free monomers during the storage of the intermediate materials. Moreover, this compound reacts in both stages acting as a covalent coupling between (meth)acrylates and epoxy networks. We selected trimethylolpropane tris(3mercaptopropionate) as the thiol, 2,2-dimethoxy-2-phenylacetophenone as UV initiator and 1-methylimidazole as the base catalyst. The curing evolution was studied by DSC and FTIR. All the materials obtained were characterized by thermogravimetry, thermomechanical analysis and tensile tests.