Degradation of polycarbonates with fast neutrons and gamma rays and its application in radiation dosimetry

This work represents a development in the fast neutron and gamma ray dosimetry using polycarbonate in which radiation damage was registered. The average molecular weight of the irradiated polymer has been determined by measuring changes in intrinsic viscosity of polycarbonate solutions in chloroform or ethylene chloride at different concentrations. The results show that polycarbonate undergoes chain scission and that crosslinking apparently did not occur for all irradiated specimens with either gamma doses (10-2 to 10-4 rad) or fast neutron fluences (106 to 1012 n/cm2). Two empirical formulae for calculating the viscometric molecular weights of polycarbonates after fast neutron exposures to fluences over the range 106 to 1012 n/cm2 and to gamma doses over the range 10-2 to 104 rad have been achieved. The effect of neutron energies on the induced changes in the mean molecular weight of polycarbonate has been investigated. Moreover, the effect of storage at 500C for periods up to 48 h on these changes has been studied before and after irradiation. The solvent effect on the sensitivity of the viscometric molecular weight determination of the irradiated samples has been investigated. Moreover, a comparsion has been made between the induced gamma effects and the fast neutron effects on the mean molecular weight of polycarbonates. (orig.)