Thediolefinic compound may be a diamide containing an rethylene double bond in tr-position to the carbonyls iof each of the amide linkages as, for example, diamides of the type H H O R RHC=( J( JI I(CHz)nl Tibi]=CHR where n is an integer of 1 or more and R may be hydrogen, alkyl, etc., examples of which are methylenebis(acrylamide), methylenebis(methacrylamide), methylenebis- (crotonamide), etc.