Design,Preparation And Perfomances Of Bio-Based Polyesters As 3D-printing Materials

Biomass resources are renewable,low-pollution and rich in reserves.Biomass conversion technology can be used to convert biomass resources into bio-based chemicals,and further to make bio-based materials to achieve sustainable development of materials.As the core technology of the third industrial revolution,3D-printing technology has achieved remarkable research results in its processes and materials,among which the fused deposition modeling(FDM)3D-printing technology is the most widely studied process forming method,its raw materials are mostly thermoplastics.In this dissertation,we chose 2,5-furandicarboxylic acid,which is one of the bio-based monomers,has been studied in recent years.Its rigid ring structure can provide certain mechanical properties,and we used it to react with other bio-based diols to prepare novel amorphous bio-based copolyesters which can be used in FDM 3D-printing application,and expand the types of 3D-printing materials.(1)2,3-Butanediol has two pendant groups,which can destroy crystallization.We conducted melt polycondensation of 2,5-furandicarboxylic acid,1,6-hexanediol and 2,3-butanediol.The influence of the synthesis conditions(acid-to-alcohol ratio,catalyst amount and esterification temperature)on the reaction was investigated.It was found that regardless of the synthesis conditions,2,3-butanediol still cannot be copolymerized and only PHF binary polyester can be obtained.(2)We used 1,2-propanediol with only one pendant group to replace 2,3-butanediol,which reduced steric hindrance.By adjusting the content of 1,2-propanediol,a series of novel amorphous poly(2,5-furandicarboxylic acid/1,6-hexanediol/1,2-propanediol)ester(PHPF)were successfully obtained.The number-average molecular weights of the PHPF bio-based copolyesters were 1.27×104 to 3.17×104 g/mol,the temperature at the maximum rate of their degradation(Td,max)were higher than 380℃.PHPF copolyesters were confirmed to have excellent toughness,especially for PHPF-10 copolyester,its elongation at break and impact strength were 515%and 35.62 KJ/m2,respectively,and it can be printed at 220℃.3D-printing samples had the layer structures which were firmly connected to each other,and had excellent mechanical properties.The renewable origins,excellent thermal stability and toughness and superior 3D-printing performances allow the PHPF bio-based copolyesters to be successfully applied for 3D-printing applications.(3)If the printing temperature is too high,it will accelerate the damage of the nozzle and cause a certain safety hazard.The temperature is directly related to the material viscosity,and the viscosity of the material is inextricably linked with the molecular weight.Therefore,we synthesized a series of low-molecular-weight poly(2,5-furandicarboxylic acid/1,6-hexanediol/1,2-propanediol)ester having 10%contents of 1,2-propanediol(PHPF-10)by reducing the melt polycondensation time.The number-average molecular weights of the PHPF-10 copolyesters were 0.60×104～2.14×104 g/mol,They had excellent flowability and their melting index was much higher than that of commercial 3D-printing materials.PHPF-10 copolyesters with polycondensation time of 2h,1h and 0.5h could be printed at 180℃,150℃ and 130℃,respectively.Compared with the polycondensation time of 3h,which printed at the temperature of 220℃,the reduction of printing temperature was obvious,which meaned that the goal of 3D-printing at a low temperature was achieved.