Study On New Process Of Synthesis And Properties Of Biodegradable Aliphatic-Aromatic Copolyesters

At present, aromatic polyesters such as poly(ethylene terephthalate)(PET), poly(butylene terephthalate)(PBT), poly(propylene terephthalate)(PTT) have been produced and widely used for many daily applications. But these polymeric materials cannot naturally decompose and are considered to cause serious waste problems. Therefore, many scientists have made intensive efforts to develop new biodegradable polymers. Aliphatic-aromatic copolyesters with both better physical properties and biodegradability have become the focus of domestic and foreign academic research. In this work, biodegradable aliphatic-aromatic copolyester, poly(butylene adipate-co-butylene terephthalate) (PBAT) was first synthesized by using terephthalic acid (PTA), adipic acid (AA)、ethylene glycol (EG) and 1,4-butanediol (1,4-BD) through melt polycondensation method and the developed new catalysts. Then, on basis of synthesis process of PBAT copolyester, a new biodegradable aliphatic-aromatic copolyesters, poly(butylene adipate-co-butylene terephthalate-co-ethylene terephthalate-co-ethylene adipate) (PBATE), based on PTA, AA, BG and EG were synthesized. The physical properties, structure, biodegradation crystallization behavior, thermal properties, rhelological and mechanical properties of the above-mentioned material were studied. The thesis is divided into two parts:1. Synthesis and properties of PBAT copolyester2. Synthesis and properties of PBATE copolyesterThe innovation results of above research are listed in the following:1. Novel complex catalyst and synthesis techniques used in the synthesis of PBAT copolyester have not reported publicly. The new highly efficient complex catalytic system is suitable for the direct esterification process, making polyesters chips with good hue, high intrinsic viscosity, and excellent biodegradation. The product quality can have reached the level of foreign similar products. The advanced esterification technology at atmospheric pressure and low temperature is suitable for polyester industrial installation of PTA process. Based on the independent research and development of the PBAT copolyester material, the systematic evaluation of PBAT copolyester processing performance showed that the synthesis PBAT copolyester is suitable for application in the field of injection molding. 2. Based on the PBAT synthesis process, the design idea, which the synthesis of new biodegradable aliphatic-aromatic copolyester PBATE using PTA, AA, BG and EG as basic raw material was proposed, and the purpose was obtained by systematicly research. The density of prepared PBATE copolyester chip was slightly lower than that of PBAT. Compared with PBAT, the crystallintiy of PBATE copolyester decreased, but thermal properties were improved and the biodegradable property was good. The systematic evaluation of PBATE copolyester processing performance showed that the synthesis PBATE copolyester is suitable for application in the field of blow molding.