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. (C) 2008 Elsevier Ltd. All rights reserved.