Non-isothermal decomposition kinetics of azodicarbonamide in high density polyethylene using a capillary rheometer

In this work, a capillary rheometer coupled with a closed die was used to study the non-isothermal decomposition kinetics of azodicarbonamide (ACA) in high density polyethylene (HDPE). Samples having 0.5% ACA were studied with or without the addition of 0.1% zinc oxide (ZnO) as an activator. Using different temperature settings, the pressure related to polymer swelling and blowing gas evolution was followed as a function of time until equilibrium was reached. Via some calibrations and corrections, an extent of reaction method was combined with general nth-order reaction kinetics and the autocatalytic theory to obtain some kinetic parameters. The results show that this simple method can give good representation of the decomposition process.