Thermal stability of PVC formulations gamma irradiated at different dose rates

• PVC formulations were crosslinked with gamma radiation.
• Two different thermal stabilizing systems were used to Project PVC.
• Two gamma dose rates were used to crosslink PVC formulations.
• Non-toxic Ca/Zn stabilizing system has a lower activation energy (Ea).

Polyvinyl chloride (PVC) formulated with two different stabilizer systems (Ca/Zn stearates and dibasic lead phthalate) irradiated at 75 kGy at two different dose rates were studied in order to evaluate their effect in thermal stability. Samples were degraded in a TGA instrument at different heating rates and the activation energy (Ea) to dehydrochlorination was calculated using the Arrhenius method in accordance with ASTM E 1641-07. TGA evaluations show that temperature for HCl evolution is higher when increasing heating rate, as well as higher resistance to degradation, for irradiated lead formulations; however, after activation energies calculation the irradiated Ca/Zn formulations are more stable. The controversial results are due to the low initial stability of lead additives in PVC.