Microwave heating and devolatilization characteristics of polyethylene particles in a fixed‐bed devolatilizer

Abstract

A new method of microwave‐enhanced devolatilization has been proposed to solve the problem that volatiles of polyethylene particles are difficult to remove. Using water as microwave susceptor in a fixed‐bed devolatilizer, microwave heating characteristics were studied by optical fiber thermometry and infrared thermal imaging, and particle devolatilization characteristics were investigated by headspace gas chromatography. The results showed that bed temperature rose and particle devolatilization efficiency increased with heating time, moisture content, and input microwave power. The non‐uniform devolatilization at different positions existed due to the non‐uniform distribution of bed temperature in both radial and axial directions. The effective diffusion coefficient of volatiles under microwave irradiation increased with moisture content and input microwave power, and the microwave‐enhanced coefficient of water also increased with input microwave power. Microwave heating and devolatilization mechanism of moist polyethylene particles were proposed, in which the modes of mass and energy transfer were clarified. In view of the above, the feasibility of microwave‐enhanced polyethylene devolatilization has been confirmed.