Study on Decrease of Molecular Weight of Low Cis-Polybutadiene Rubber

The molecular weight of Low cis-polybutadiene rubber(LCBR) has been decreased in this work by treating silicon coupling LCBR with the elemental iron and iodine. The carbon silicon bond of the LCBR can be selected breaked lead to the decreasing of coupling efficiency of the polymer, thereby decreasing the molecular weight of the polymer. The results show that the selectivity of the reaction is good, the method in decreasing the weight of the silicon coupling LCBR will not lead to other chemical bonds of the polymers break; moreover, through the regulation of the amount of catalyst, reaction time and reaction temperature can effectively control the reaction to obtain with the expected molecular weight of LCBR. The reaction condition of the method is mild, simple and easy to operate.