The Development Of New Isoprene Polymer

The anionic polymerization of isoprene was studied with dilithium as initiator, TM~EDA as modifier and cyclohexane as solvent. The stereotriblock 3,4-1,4-3,4-polyisoprene was synthesized by two step feed with dilithium as. initiator, TMEDA as structure regulator and cyclohexane as solvent. The microphase of stereotriblock polyisoprene was investigated. The results showed that 1) With the increase of TMEDAI2Li and the decrease of temperature, the 3,4-content of pOlyisoprene increase. When 3,4-content increase to about 35%, 1,2-structure appeared and increase with the increase of TMEDAI2Li. 2) When TMEDAI2Li>0.2, with the increase of TMIEDAI2Li, the polymerization rate decreased. 3) Only when the molecular weight greater than 20 X 1 ~4, can the microphase separation of the stereo-block polyisoprene appear. 4) The hard block/soft block (Br) and 3,4-microstructure content influence the glass transition temperature of the stereo-block polyisoprene. The anionic copolymerization of styrene and isoprene was studied with dilithium as initiator and cyclohexane as solvent. A tapered SIS was synthesized by adding of isoprene and styrene simultaneously. The microphase and mechanical properties were investigated. The results showed that 1) With the increase of isoprene content and temperature, the polymerization rate increase. 2) With the decrease of temperature or with the increase of styrene content, the 3,4-structure of polyisoprene increased (without 1,2-structure). 3) Compared with pure block SIS, the tensile stress m / L of tapered SIS decreased. But the elongation at break increased. 4) The investigation of microphase shows that the tapered SIS is microphase separation. The degree of microphase separation decreased.