Chain extension of biodegradable aliphatic/aromatic copolyester by reactive extrusion chain extension of poly(butylene terephthalate-co-butylene)

Chain extension of biodegradable aliphatic/aromatic copolyester-poly(butylene terephthalate-co-butylene) (PBTA) was carried out using different chain extenders in a twin-screw extruder. According to structural features of modified PBTA, peroxide is considered to be an appropriate chain extender for the copolyester system. Through analysis of structures, thermodynamic and rheology behaviors of PBTA copolyesters before and after chain extension, effect of chain extender dosage on their structures and properties were studied. Both melt viscosity and melt strength of the copolyester are improved. By adjusting the chain extender dosage, blow molding film can be processed from biodegradable copolyester in conventional way. Their biodegradabilities were also investigated through composting experiment. Besides the enhanced physical and processing properties, modified PBTA copolyesters still possess their original biodegradabilities.