Thermal Degradation of High Density Polyethylene by Using a Continuous Flow Stirred Tank Reactor

Abstract

Experimental work on thermal degradation was done by using a continuous-flow stirred-tank reactor. Kinetic data of the carbon number distribution of volatile products, the molecular weight distribution of reactor contents and the rate of thermal degradation were obtained at a steady state, in the temperature range of 410-440°C under atmospheric pressure.
The observed gas chromatography results show that the volatile materials derived from polyethylene are produced exclusively by unzipping from the chain ends. However, the GPC results show that the reactor contents are the products of random scission. These evidences suggest that the thermal degradation of polyethylene is a simultaneous reaction of unzipping from the chain ends and random scission.
Assuming that the two kind of reaction are simultaneously taking place for thermal degradation of polyethylene, the molecular weight of the reactor contents should increase with the degradation temperature. The observed temperature dependency of average molecular weight of the reactor contents agree with that predicted.