Kinetic analysis of VOC emissions thermally generated from polymers at processing temperatures

The kinetics of VOC emissions were studied under dynamic conditions, where the polymer samples were heated at different temperature ramp rates (5°, 10°, 15°, and 20°C/min). According to the integrated area under the VOC evolution profile, fewer VOC were emitted at higher heating rate, as the time required to reach the given temperature was shorter. With the increase of heating rate, the VOC evolution profile shifted to a higher temperature range. At 250°-350°C, the results were in very close agreement with literature data. Lower activation energy (Ea) values were observed at even lower temperature range (< 250°C), which resulted from the presence of weaker links throughout the polymers. For the recycled polymers, significant amount of small molecules could be present due to the contaminants, aging, degradation, etc. Therefore, the Ea of VOC emissions was much lower, particularly from the first degradation stage (lower temperature range).