The fractionation of trans-1

4-poly(butadiene-co-isoprene) copolymer rubbers (TBIR) was carried out by stepwise isothermal crystallization fractionation method

and the structure and composition of the TBIR fractions were studied.It was found that TBIR-20 was a semi-crystalline copolymer with long trans-1

4-polyisoprene (TPI) blocks and butadiene units randomly distributed in the molecular chain.While TBIR-40 was a copolymer containing TPI blocks and trans-1

4-polybutadiene (TPB) blocks.The application of TBIR as hump strip stocks in passenger car radical (PCR) tires was investigated.The NR/BR/TBIR compounds showed improved green strength

crystallinity and shore A hardness

as well as accelerated curing rate.For NR/BR/TBIR vulcanizates

physical and mechanical properties

such as tensile strength

tear strength

modulus and resilience stand in a high level

outstanding properties including decreased heat built- up

improved abrasion resistance and ageing- resistant performance

and excellent flexing fatigue properties were observed with the incorporation of TBIR.DMA tests showed that NR has a better compatibility with TBIR compared with BR.TEM results showed a good dispersion of carbon black in NR/BR/TBIR vulcanizates.So NR/BR/TBIR vulcanizates with about 20 phr TBIR showed satisfied mechanical properties

improved abrasion and ageing resistance

especially excellent dynamic properties like low heat built- up and very high flexing fatigue-resistance.