(A) a polymer resin comprising at least one primary carbamate group, (B) a curing agent having groups that are reactive with polymer resin (A), and (C) a reactive additive comprising at least one compound having a molecular weight of from 233 to 2000 and leaving the formula: wherein X is a branched alkyl group of from 5 to 30 carbons, and one or both of (A) and (B) comprise groups that are reactiv