CYCLIC POLYESTERS .7. PREPARATION AND CHARACTERIZATION OF CYCLIC OLIGOMERS FROM SOLUTION RING-CHAIN REACTIONS OF POLY(BUTYLENE TEREPHTHALATE)

Solution ring-chain reactions of poly(butylene terephthalate) (PBT) we re carried out using 1,2-dichlorobenzene (b.p. 180 degrees C) with a c atalyst. By increasing the dilution to 1:70 (polymer/solvent ratio w/v ), cyclic PBT oligomers were obtained in a yield of 70 wt%. This compa res to cyclic oligomers of PBT extracted from commercial PBT chip usin g mixed xylene isomers, in a yield of 1 wt%. The cyclic oligomers prod uced in the solution ring-chain reaction and obtained from the extract were found to contain oligomers (CO.C6H4CO.O.(CH2)(4)O)(x), where x = 2-9. The cyclic oligomers of PBT were analysed using PL-gel mixed E g el permeation chromatographic columns, fast atom bombardment mass spec trometry and liquid chromatography tandem mass spectrometry. The cycli c dimer of PBT, (CO.C6H4CO.O.(CH2)(4)O)(2), was separated, purified an d crystallized and its X-ray crystal structure determined. (C) 1997 El sevier Science Ltd.