opening additive per 100 parts of polyol (pphb), wherein the cell opening additive com-prises an active methylene or methine compound containing at least one tertiary amine represented by one of the formulae: wherein in formulae (I)-(IV) Y and Y' are, independently substituted C6-C10 aryl or CXX'X" wherein X, X', and X" are, independently hydrogen, halogen, C1-C20 alkyl, C1-C20 alkylether, C1 ...