Aibn as initiator was found to have mnnbspaverage 1000 kg

Question

MSE 430 Fall 2015 Problem Set

Write down a reaction scheme for polymerization of styrene (CH₂=CHPh) initiated by thermolysis of azobisisobutyronitrile (AIBN), including both combination and disproportionation as possible modes of termination.

A sample of polystyrene prepared by bulk polymerization at 60°C using radioactive (¹⁴C) 

AIBN as initiator, was found to have M_n average = 1000 kg mol^-1 and a radioactivity of 6 x 10³counts s^-1 g^-1 (measured using a liquid- cintillation counter). Given that the AIBN has a radioactivity of 6 x 10⁹ counts s^-1 mol^-1, determine the mode of termination which operated in the preparation of the polystyrene sample