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