Use of cyclohexane as solvent in thermal degradation of low density polyethylene wastes

Thermal degradation of low density polyethylene (LDPE) wastes was investigated in this study as a step in chemical recycling. The effects of the degradation temperature, the solvent-LDPE ratio, and the reaction time were researched in the respective ranges 375-450degreesC, 0:1-6:1, and 30-120 min. Experiments at a cyclohexane:LDPE ratio of 6:1 showed that up to 425degreesC the solid residue decreased whereas the liquid yield and the total conversion increased. There were no significant changes thereafter. Solventless degradation at 425degreesC gave the weight percentages of 4.7, 75.6, and 19.7 for solid, liquid, and gaseous products, respectively. The use of cyclohexane as a solvent brought about approximately 20% gain in liquid yield and diminished the solid residue to negligible levels. Alkanes, alkenes, and cycloalkanes were the identified compounds in the light liquid products of degradation. The solvent reacted with the products. Reactions between alkanes and alkenes also contributed to cyclization that increased with temperature. The gas chromatography analyses identified methane and C2-C4 in the gaseous products. Reaction time tests showed unimportant changes in yield figures.