A Study of the Reaction Kinetics Involved in a Crosslinked LDPE Foam

The reaction kinetics of crosslinked low density polyethylene (LDPE) foam systems has been investigated. Dicumyl peroxide (DCP) was used as the crosslinker. The crosslinking reaction of LDPE/DCP system is controlled by a first order decomposition of DCP. The reaction kinetics of a chemical blowing agent, azodicarbon amide (ADCA), and its kicker, zinc oxide (ZnO), was also investigated. The rate of reaction of ADCA is very fast, and a general nth-order reaction kinetics fails to predict its conversion. A model combining a general nth-order reaction kinetics and autocatalytic reaction kinetics was adopted instead. The addition of ZnO into ADCA not only lowered the decomposition temperature, but also accelerated its decomposition. The reaction kinetics of the LDPE/ADCA/ZnO system was also studied, and was found to be similar to those of ADCA/ZnO system. The numerical results in this study serve as a framework for future prediction and simulation of molecular structure changes of a reactive polymeric foam system.