Synthesis and characterization of low relative molecular weight trans‐1,4‐poly(isoprene)

Low relative molecular weight trans‐1,4‐polyisoprene oligomers were synthesized successfully by bulk precipitation and solution polymerization with supported titanium catalyst using hydrogen as relative molecular weight modifier. The effects of polymerization conditions on intrinsic viscosity (η]), catalyst efficiency (CE) and structure of polymer were studied. Increasing the hydrogen pressure resulted in the decrease of η] of the polymer. With the increasing of hydrogen pressure and reaction temperature, CE decreased but still maintained above 2500 g polymer/g Ti. The percentage composition of (trans‐1, 4‐unit) in the polymer was over 90% in all results. The crystallinity of polymer was about 50–60% with T_m being about 60°C. The relative molecular weight distribution index (MWD) was quite difference according to the polymerization method. While number average molecular weight (M_n) exceeded 860, polymer turned from viscous materials to fragile wax materials, and then to toughness materials at 1800. Dynamic property testing showed that the additional of this oligomer could increase the wet‐skid resistance of the rubber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008