Aromatic-aliphatic copolyesters based on waste poly(ethylene terephthalate) and their biodegradability

Abstract

AbstractThe solvolysis of poly(ethylene terephthalate) from disposed beverage bottles by an aqueous solution of lactic acid, followed by the zinc acetate catalyzed polycondensation of the solvolytic product, yielded a series of aromatic-aliphatic copolyesters containing up to 55 mol.% of incorporated lactic acid structural units. Their molecular parameters were determined using SEC and viscometry. According to DSC, the copolyesters have amorphous structure. Selected copolyester samples were subjected to abiotic hydrolysis at pH 7 and 60 °C. After three days of hydrolysis, the mass of the samples decreased substantially and their molar mass was reduced. At 37 °C, strong degradation of copolyesters by action of the actinomycete Rhodococcuserythropolis was observed. Biodegradability of the copolyesters was confirmed by a composting test. In addition to the changes of the molecular structure of the composed samples, the physical degradation of the foils of the samples tested was also documented by SEM.