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The conventional pyrolysis of waste plastics, carried out in a tank reactor or kiln, yields fuel oil with a wide boiling range. To improve the economic process of feedstock recycling of waste plastics, a new thermal process for fuel-gas production is proposed. Considering the role of sand as an effective heating medium and by using a reactor structure for suitably controlling the reaction temperature and reaction time, a new type of reactor equipped with a screw conveyor has been developed; this reactor is termed the moving-bed reactor. The formation of gaseous hydrocarbons was achieved at 82 wt % (pyrolysis) and 94 wt % (catalysis) in the operations research of the new process using polypropylene as feed.

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Thermal decomposition reactions of polystyrene using a new heating medium were carried out by a batch system at 190~280 o C to clarify the manner in which decomposition is initiated. Polystyrene obtained from a commercial source and low molecular weight compounds obtained from the thermal decomposition were analyzed by GC, GPC, IR, 13 C-NMR and GC-MS. The main chain underwent virtually no change by heat application. Polystyrene underwent decomposition below its molding temperature and the major decomposition products were 2,4,6-triphenyl-1-hexene (trimer), 2,4-diphenyl-1-butene (dimer) and styrene (monomer). Ethylbenzene, propylbenzene, naphthalene, benzaldehyde, biphenyl and 1,3-diphenylpropane were detected as minor products. This paper presents a new method for examining the decomposition of polystyrene at low temperature into volatile low molecular weight compounds.

The thermal decomposition of phthalate alone and with poly(vinyl chloride) (PVC) was carried out under a nitrogen atmosphere in a 4-necked separable flask. The thermal decomposition of phthalate in the presence of PVC began at 150°, about 100 o C lower than the decomposition of phthalate alone. The formation of octyl chloride indicated an interaction reaction between phthalate and PVC. From the analysis of the composition of commercially plasticized PVC sheet (film and board), the phthalates (dibutyl phthalate, dihexyl phthalate) and di(2-ethylhexyl) phthalate), 2-ethyl-1-hexanol, phthalic anhydride, and 2-ethylhexyl hydrogen phthalate were identified. The mutagenicities of these decomposition products were higher than those of phthalic diesters (phthalates).