Flame retardancy of photocured epoxy acrylate based coatings
The incorporation of allyl phosphinic amide (APA) into an epoxy acrylate decreased the gel contents and the double bond conversions. On the other hand the addition of octamercaptopropyl polyhedral oligomeric silsesquioxane (POSS-8SH) significantly increased the double bond conversions.
Addition of POSS-8SH decreases flame retardancy
Mechanical properties were significantly affected from the degree of cure. Tensile strength of the coatings decreased as the amount of the monofunctional APA was increased. Flammability of the photocured hybrid coatings was determined by the limiting oxygen index (LOI) and UL94 tests. Flame retardancy of the epoxy acrylate was increased with the addition of APA but decreased with the addition of POSS-8SH. 20 wt.% APA containing coatings showed a LOI value of 27 but they failed to pass the UL94 test.
The study is published in: Progress in Organic Coatings, Volume 105, April 2017, Pages 37–47