| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
The aim of the present study was the chemical recycling of conventional plastic wastes to the feedstock monomers in accordance to our basic concept "Complete Chemical Recycling of All Plastic Portions" (C_2RAP_2) without loosing any chemical component. The target plastic was poly(carbonate) (PC) which, by means of solvolytic depolymerization in carbohydrate polyols, was recycled to bisphenol A (BPA) and cyclic carbonates of carbohydrates. Both the products are the monomers of PC and, thus, the complete reclamation of PC to the virgin PC resin can be realized.
First, in advance to the use of PC, diphenyl carbonate (DPC) was used as the model of PC to optimize the conditions in the treatment with glycerol (GLY), i.e., the smallest carbohydrate polyol. Indeed, the base-catalyzed treatment of DPC with GLY produced hydroxymethyldioxorane (HMDO) and phenol almost quantitatively. The same conditions were adopted in the treatment of PC with GLY and, again, BPA and HMDO were quantitatively produced.
Second, glucose (GLU) was used instead of GLY. The treatment of DPC with GLU was carried out in aqueous solvent of DMF. Phenol and dicarbonate of GLU (GLU-DC) were the major products obtained in the yields of 40-55%. Then, PC was analogously treated with GLU to produce BPA and dicarbonate GLU-DC. The chemical structure of GLU-DC was elucidated spectroscopically to be 1,2;4,6-dicyclic carbonate of GLU leaving the OH group at 3-position intact.
To summarize, PC was depolymerized by the solvolytic action of both GLY and GLU to produce BPA and corresponding cyclic carbonate of carbohydrates. The cyclic carbonates are the reservoir of one carbon unit, i.e., CO, and they can be reused for the reproduction of virgin PC.
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