Ethylene glycol was used for degradation of poly-ethylene 2 , 6-naphthalate dicarboxylate ( PEN ). The alcoholysis products were characterized and the alcoholysis mechanism was discussed. The results showed that : The ester bond in PEN was broken after alcoholysis , caused the stellate hydroxyl groups in PEN modules converting to the intermolecular associative hydroxyl groups and the free hydroxyl groups on the monomer bis ( hydroxyethyl ) naphthalate ( BHEN );After alcoholysis , the ratio of O and C atoms in the alcoholysis product increased from 0.28 to 0.38 , the mass ratio of two O atom content ( C = O and CO ) was 1 ∶ 2.18 , the mass ratio of three C atom content ( CC , CO and O-C = O ) was 5.38 ∶ 2.22 ∶ 1 , and the average molecular weight of the products was about 200;The main alcoholysis products were BHEN and oligomers , and the purity of the monomer BHEN was above 90 % with 25.95 % of yield. The essence of the alcoholysis reaction was a continuous fracture and polymerization process of ester groups , with the shortening of PEN chain.
Environmental Protection of Chemical Industry
poly -ethylene 2 , 6 -naphthalene dicarboxylate ( PEN )
bis ( hydroxyethyl ) naphthalate ( BHEN )