Described herein is a mixture comprising: a non-self-crosslinking polymer; and a modifying compound comprising at least two different functional groups. The first functional group of the modifying compound is capable of reacting with the non-self-crosslinking polymer and the second functional group is capable of crosslinking with a curing agent. Also, described are compositions, curable polymeric compositions, articles using such curable polymeric compositions, and methods of making cured polymeric compositions.