ELASTOMERIC ELECTRON BEAM-CURED COATINGS - STRUCTURE-PROPERTY RELATIONSHIPS .2. CHAIN TRANSFER AGENTS

Properties of electron beam‐cured film from 100% reactive mixtures consisting of polyester diacrylourethane oligomer, copolymerizing monomer, and chain transfer agents were investigated. The inclusion of chain transfer agent in such polymerization reaction was aimed to reducing the degree of polymerization of the double at each end of the oligomer, which is believed to be responsible for the low extensibility of these films. In general, these agents were found to result in some retardation in the polymerization reaction, but none of them influenced the mechanical properties of the cured films except mercapto‐functional agents, which were found to drastically affect these properties. By the addition of a mere 2% to 3% of these agents it was possible to toughen the EB‐cured films by increasing both the extensibility and breaking strength. This confirms the above speculation and brings the properties of these films to a level almost comparable to those of linear polyurethanes. Copyright © 1979 John Wiley & Sons, Inc.