Lifetime prediction for polymers via the temperature of initial decomposition

The temperature of initial decompositionT _id was determined from TG and DTG curves of mass loss during thermooxidative polymer decomposition in an environmental air atmosphere. The values ofT _id were applied for comparison of the thermal stabilities of several polymers, e.g. PC-A, PBT, PET, PPO and PVC. Both the activation energies of initial decompositionE _id and the preexponential termsA _id of the Arrhenius equation were calculated by using the Kissinger approach. The initial mass loss is proposed as a criterion for calculation of the time to failuret _f from the known values ofE _id andA _id, and hence for a prediction of the lifetime of polymer materials.The following thermal stability sequence was found for the investigated polymer materials: PC-A (st)>PC-A (nst)>PBT>PET>PPO>PVC (e)>PVC (c). The activation energy of initial decomposition had a mean value ofE _id=83 kJ mol^–1 for PC-A, PBT, PET and PPO, andE _id=73 kJ mol^–1 for the PVC samples.The calculated time to failure,t _f, for PC-A, PET and PVC under specified conditions was in reasonable agreement with published experimental data.The proposed parameters of thermal decompositionT _id,E _id andt _f, can be applied for the characterization and comparison of various polymer materials, and for a prediction of their lifetime.Financial support from the Polish Scientific Research Committee, the grant No. 7 761791 02, is gratefully acknowledged.