Study On Preparation And Properties Of Controllable Biodegradable Polyester

PET/PLA blends and poly(ethylene terephthalate/ethylene adipate)(PETA)copolyester were prepared by physical and chemical methods, in order to study ontheir properties, for the exploration and development of new biodegradable polyesterproducts providing a theoretical basis.Polyethylene terephthalate (PET) and polylactic acid (PLA) as raw materials,Ti(OBu)4as a compatibilizing agent, PET/PLA blends with different mass ratioswere prepared by melt blending. Controllable biodegradability, the relationshipbetween mechanical properties, morphology, thermal stability, thermal properties andmass ratio, respectively, before biodegradation were studied. The biodegradationresults showed that biodegradability of PET/PLA blends depends on different massratio. When the content of PET or PLA is20%, the biodegradable weight loss rate ofthe blends reaches at14.86%and15.31%after28days biodegradation. Theproperties of hardness, impact strength and biodegradable performance of thePET/PLA blends are reduced with biodegradation time prolonged. The morphology,thermal stability and thermal properties analysis demonstrated that PET/PLA blendsexhibit good compatibility and the thermal stability is improved. The mechanicalproperties Analysis indicated that the tensile strength of PET/PLA blends is up to2.53times compared with pure PLA at maximum, notches impact strength up to2.12times compared with pure PET at maximum.Dimethyl terephthalate, ethylene glycol and adipic acid as raw materials,poly(ethylene terephthalate/ethylene adipate)(PETA) copolyester was prepared byTransesterification-esterification-polycondensation three steps method. The density, viscosity and other basic physical properties, and the relationship between thermalstability, biodegradability and copolymerization ratio, respectively, were discussed.The results indicated that Sb2O3/Ti(OBu)4composite is selected as synthesis catalyst.The optimum conditions for the synthesis of polyester PETA are determined: molarratio (EG/(DMT+AA)1.5:1, transesterification reaction temperature180℃, theesterification reaction temperature190℃, polycondensation reaction temperature260℃, vacuum polycondensation time0.5h. The1HNMR spectral analysisdemonstrated that the copolymerization ratio and the copolymerization compositionratio of PETA are basically the same, and the polyester composition in the actualproduction could be controlled by regulating the copolymerization ratio of PETA.The density test results showed that copolyesters obtained by synthesis are randomcopolyesters. The biodegradation results indicated that the weight loss rate ofcopolyester PETA increases gradually after14days biodegradation. Thebiodegradation weight loss of PETA20reaches at11.26%after28days degradation.The controllable biodegradability of PETA is controlled by regulating thecopolymerization ratio.