Abstract
The purpose of this study was to examine the dehydrochlorination of a flexible polyvinyl chloride (PVC), which was comprised of 59.2% PVC, 29.7% dioctyl phthalate (DOP) and approximately 12% stabilizers, and a rigid PVC that were treated with a 2-16mol/L NaOH concentration, and then microwave-heated at a temperature between 100-200°C for 0-60 minutes. At this time, 0-0.2g of polyurethane cushioning materials used in packaging were added to each sample. 98% of all chlorides were removed in 30 minutes by heating at 190°C, in a 2-mol/L NaOH solution with 0.02-g of polyurethane additives, and the residue was converted into carbon and hydrogen compounds. We presumed this to be the result of the organic amines detected in the NaOH solution and the hydrolysis of polyurethane. Since we presumed that the amine promoted dehydrochlorination, we further investigated dehydrochlorination results by using hydrazine hydrate, aqueous ammonia, trimethyl amine, and 2-amino ethanol additives that were heated at 190°C in a 2-mol/L NaOH solution for 30 minutes under the same conditions. As a result, we found that chlorides were removed at maximum rates of 99.6%, 94.6%, 96.3% and 92.9%, respectively. This study discovered that amine additives are effective dehydrochlorination additives since they allowed for similar results using a 2-mol/L NaOH solution that was only 1/8 the NaOH concentration of known methods, and it was possible to lower the heating temperature compared to conventional methods as well.
