Thermal degradation of nitrogen-containing polymers, acrylonitrile-butadiene-styrene and styrene-acrylonitrile

Thermal degradation of nitrogen (N)-containing recycled plastics (styrene-acrylonitrile (SAN), acrylonitrilebutadiene-styrene (ABS)) was carried out in a stirred-batch reactor at 300–400 ‡C under nitrogen stream. The degradation oil began to be generated over 300 ‡C. Recycled SAN plastic was converted to oil with 91.3 wt% yield at 380 ‡C, while only 70.9 wt% of recycled ABS plastics was converted to oil at the same temperature and both oils contained about the same 3.7 wt% nitrogen as an elemental basis. Rate of oil formation from the thermal degradation of SAN was much higher than that of ABS, but showed a similar degradation pattern in terms of chemical composition. In oil products, aromatic contents obtained at 360 ‡C were 70 wt% for SAN and 79 wt% for ABS, respectively, and decreased to 59 wt% and 57 wt% at 380 ‡C with increasing degradation temperature. Dominant product of both degradation oils was styrene, and the following was ethylbenzene for ABS, but none in case of SAN. Both oils contained the N-containing plastic additives that give rise to a confusion for the identification of authentic N-containing degradation products.