▁and ▁ran ▁them ▁under ▁service ▁conditions ▁on ▁the ▁high ways . ▁The ▁test ▁results ▁showed ▁conclus ively ▁that ▁the ▁synth etic ▁c is - 1 , 4 - poly is op rene ▁was ▁essentially ▁equivalent ▁to ▁natural ▁rub ber . ▁During ▁the ▁factory ▁tri als , ▁the ▁research ▁team ▁was ▁delight ed ▁when ▁they ▁heard ▁the ▁factory ▁personnel ▁comment ▁during ▁the ▁rub ber ▁mixing ▁tri als ▁that ▁the ▁experimental ▁rub ber ▁was ▁nothing ▁new ▁– ▁it ▁mixed ▁just ▁like ▁natural ▁rub ber . ▁ ▁Poly but ad iene ▁After ▁he ▁discovered ▁the ▁s tere o ▁control ▁of ▁poly is op rene , ▁he ▁discovered ▁the ▁polym er ization ▁and ▁s tere o ▁control ▁of ▁but ad iene ▁as ▁well ▁as ▁many ▁other ▁alk yl but ad ien es . ▁The ▁polym er ization ▁of ▁but ad iene ▁can ▁lead ▁to ▁three ▁basic ▁structures : ▁the ▁c is - 1 , 4 - ▁and ▁the ▁trans - 1 , 4 - poly but ad ien es , ▁and ▁the ▁ 1 , 2 - poly but ad iene ▁with ▁a ▁vin yl ▁side ▁group . ▁From ▁these ▁three ▁basic ▁structures , ▁there ▁are ▁five ▁struct ur ally ▁different ▁polym ers : ▁the ▁c is ▁and ▁trans ▁ 1 , 4 - poly but ad ien es , ▁and ▁the ▁is ot actic , ▁synd iot actic , ▁and ▁at actic ▁ 1 , 2 - poly but ad ien es . ▁All ▁of ▁these ▁polym ers ▁have ▁been ▁isolated ▁in ▁pure ▁form . ▁