Synthesis and characterization of biodegradable and weather-durable PET/PEG/NDC copolymers.

Polyethylene terephthalate/poly(ethylene glycol)/2, 6-naphthalene dicarboxylate (PET/PEG/NDC) copolymers were synthesized and characterized. The results demonstrated that T dramatically decreased-by approximately 20 °C-when 8 wt.% PEG was added to neat PET. However, T slightly increased-by around 6 °C-from the reduced value, when a third ingredient, NDC, was incorporated. The melting temperature T and fusion enthalpy △ H decreased when the 8 wt.% PEG was copolymerized. Further incorporation of NDC into the PET/8 % PEG copolymer, after a small initial increase in T and △ H for PET/8 % PEG/2.3 % NDC, caused substantially reduce in both properties for PET/8 % PEG/9.2 % NDC. A mechanical test revealed that PET/8 % PEG/NDC copolymers maintained high mechanical integrity until degradation, verifying that the inclusion of NDC enhances the weatherability of PET/PEG copolymer. The rheological Cole-Cole plots indicated the occurrence of phase separation in PET/PEG melt, but the incorporation of NDC suppressed this incompatibility. The biodegradation results indicated that the degradation comprised two stages-a period of rapid degradation, which was associated with the hydrolysis of PEG segments, and a period of slow degradation, which was caused by erosion of the short aliphatic segments by the microbes. [ABSTRACT FROM AUTHOR]