Synthesis of poly(butylene adipate) by condensation polymerization and a chain-extending reaction with adipoyl biscaprolactamate

HO-terminated poly butylene adipate (HO-PBA-OH) with molecular weight from 1044 to 3540 was synthesized through melt condensation Polymerization from adipic acid with excess of butanediol. A chain-extending reaction of HO-PBA-OH with adipoyl biscaprolactamate (ABC) was carried out at 200 similar to 240 degrees C under reduced pressure. At the optimal conditions, the chain-extended PBA with Mn up to 26589 and Mw upto 58236 was obtained. The chain-extended polyesters were characterized by gel permeation chromatography (GPC), IR spectrum, H-1 NMR spectrum, and differential scanning calorimetry (DSC). Based an the IR and H-1 NMR studies, the mechanism of the chain-extending reaction was proposed. The chain-extending reaction proceeds through the elimination of caprolactam ring in the chain-extender.