Studies on Thermal Degradation of Synthetic Polymers (Part 10)

Thermal Gasification of Polyolefins

Abstract

Thermal gasification of polyethylene (PE), polypropylene (PP), and polyisobutylene (PIB) was carried out under atmospheric pressure using the flow system of a fixed bed reactor. From an experimental equation, I_F=Tθ^a, product yields were estimated, where I_F is the intensity function (°C•sec^a), T is the reaction temperature (°C), θ is the residence time (sec), and a is a constant (-). The effect of the structure of polyolefin on the value of "a" was also discussed.
The pyrolysts conditions used in this study were as follows: temperature, 500∼800°C; the residence time, 0.6∼7.1sec; and the dilution ratio of steam to polymer by weight, 0.6∼7.5.
The operating factors were inferred to be reaction temperature and residence time. For a given product yield, these two factors were interchangeable. Equations for yielding methane were expressed as_follows: (PE): I_F=Tθ^0.04, (PP); I_F=Tθ^0.05, (PIB); I_F=Tθ^0.07.
As I_F was correlated to the product yield, the product yield could be predicted by some appropriate choice of pyrolysis conditions. The value of "a" of a polyolefin was correlated to the activation energy (ΔE) for thermal degradation and to temperature (T_1/2) corresponding to 50% weight loss. These two parameters were determined from the TG curve.