| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 89 === Abstract
A method of recycling polystyrene(PS) waste by dissolution and evaporation or precipitation has been studied. The PS material was dissolved in a plant-derived oil, and then the solution was subjected to evaporation or precipitation to recover the PS. Both general PS(GPS) and expanded PS(EPS) were studied. The plant-derived oils used were camphor white oil, citrus peel oil, and turpentine oil.
The solubilities of GPS and EPS were the highest in citrus peel oil and the lowest in turpentine oil. The solubility of EPS was higher than that of GPS. The solubility increased with increasing temperature of oil .
The ranking of the measured dissolution rates of GPS and EPS in plant derived oils was : citrus peel oil >camphor white oil>turpentine oil. Increasing temperature and stirring speed increased the dissolution rate. EPS dissolved faster than GPS. EPS dissolution was controlled by mass transfer and the dissolution rate varied with the orientation of the surface due to the effect caused by the bubbles generated. GPS dissolution was mass transfer controlled ,and the mass transfer coefficient was the highest in citrus peel oil and the lowest in turpentine oil.
The molecular weight and glass transition temperature of the PS regenerated by evaporation method were lower than those of the original PS, probably due to the damage of molecular structure by high evaporation temperature. Recovery of PS by the evaporation method was about 85%. The PS regenerated by precipitation in ethanol or acetone had molecular weight and glass transition temperature similar to those of the original PS. Increasing the quantity of ethanol or acetone increased the recovery of PS, which was about 95% when the volume of ethanol or acetone was fifty times that of the PS solution. PS precipitates in ethanol were in the form of solid particles, which were easier to be filtrated than the gel particles formed in acetone.
Key Words: Polystyrene, Plant-derived oil, Camphor White Oil, Citrus Peel Oil, Turpentine Oil, Dissolution, Recycle.
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