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.