Role of Heating Condition in Polyethylene Behaviors under Nitrogen and Air Atmosphere

Recycle of plastic waste is an indisputable means to alleviate both environment and energy crisis.In this work,effects of heating condition on polyethylene behaviors in nitrogen and air were studied.It was observed that polyethylene behavior was a single step in nitrogen,while the multiple steps occurred in air.According to the weight loss and heat flow curves,polyethylene behaviors in air were divided into three regions:low-temperature(<340 ℃),middle-temperature(340 – 380 ℃) and high-temperature(> 380 ℃) regions.Kinetic analysis revealed that the partial oxidization took the dominance in the low-temperature region,which seldom formed CO and CO_(2);the combustion took the dominance in the middle-temperature region,which was positive to the formation of CO and CO_(2);the pyrolysis was initiated and enhanced in the high-temperature region,which inhibited the formation of CO and CO;.According to the kinetic simulation,a synergistic effect between the pyrolysis and combustion was proposed to account for the acceleration of polyethylene conversion.This work may provide useful information about polyethylene behaviors under heating condition,and help to design and optimize plastic waste incineration process.