{HEAD ~ iii) chain extending agents} and crosslinking agents having {TAIL ~ an average molecular weight} of 62 to 500 and having an average functionality of 2 to 4 and 
{ HEAD ~ iii ) chain extending agents } and crosslinking agents having { TAIL ~ an average molecular weight } of 62 to 500 and having an average functionality of 2 to 4 and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH