Present research work deals with synthesis of phenalkamines and their use as curing agents for blocked polyisocyanates to yield high performance polyurea coatings. In this work, several phenalkamines were synthesized by conventional Mannich reaction; selecting various structural amines such as hexamethylene diamine (HMDA), isophorone diamine (IPDA), diaminodiphenyl methane (DDM), Jeffamine D-400 and Jeffamine T-403. Structures of these phenalkamines were confirmed by FTIR, 1H NMR spectroscopy and evaluation of amine value. These curing agents were mixed with HDI and IPDI based blocked polyisocyanates to obtain polyurea coatings which were subsequently characterized for mechanical, chemical, optical, thermal and anticorrosive properties. In addition, structure property relationship of all the systems was studied and compared with commercial phenalkamine (AG-141). Anticorrosive properties evaluated by salt spray test and electrochemical impedance spectroscopy (EIS) revealed significant improvement in anticorrosive performance when compared with commercial phenalkamine. All polyurea coatings exhibited excellent performance properties irrespective of the isocyanates used.
Volume 106, May 2017, Pages 96–110