Study on the synthesis and thermal properties improvement of transparent biodegradable polyesters

Abstract

In this dissertation, various types of polyesters were synthesized and characterized to make transparent biodegradable polyester. In chapter 2, the effect of various monomers on thermal properties and crystallization of co-polyesters was investigated. CHDM showed large effect on Tg enhancement. As a result, by incorporating CHDM into PEST, we synthesized amorphous co-polyesters with high Tg. In chapter 3, We studied properties of PECST. It was characterized mainly in terms of thermal properties. As CHDM content was increased in PECST, Tg was also gradually increased. So, Tg of PEC30ST70 was $47.3 ^\circ C$ . A thin film made of PEC30ST70 was highly transparent. And tensile modulus and flexural modulus of PEC30ST70 were much lower than that of PLA, which means it is more flexible than PLA. Finally, PEC30ST70 showed about 49% biodegradability after 50 days in biodegradability test under compost condition. In chapter 4, the effect of Isosorbide (IS) was investigated. It showed extraordinary effect on thermal properties enhancement. So, as a result, PEI30ST70 showed very high Tg of $74.2 ^\circ C . PEI30ST70 was also proved biodegradable by showing 38% biodegradability after 50 days. It was also shown that this co-polyester had more flexible property than PLA. Thus, in conclusion, two types of novel biodegradable polyesters, PEC30ST70 and PE30IST70, were synthesized and characterized in this study. And in the light of this study, PEC30ST70 and PE30IST70, owing to their transparency, biodegradability, thermal stability and flexibility, could be attractive materials for packaging applications.