Synthesis Of Environment-friendly Materials PBST And PBPS With Organic Guanidine Catalysts

Recently,a wide variety of biodegradable polymers has attracted much attention owing to the increasing environmental concerns about white pollution by the abuse of the disposable petroleum-based plastics.Developing and utilizing environment-friendly biodegradable polymers to replace petroleum-based materials is an effective way to solve this problem at the source.Biomass material poly(butylene succinate)(PBS)has already been commercialized.However,the application field of PBS is limited by its low melt point and poor thermal properties.As the modified materials,poly(butylene succinate-co-butylene terephthalate)(PBST)and poly(butylene succinate-co-1,2-propylene succinate)(PBPS)have attracted great interest and attention recently.PBST can be made by introducing butylene terephthalate repeat units into PBS,its thermal properties are better than PBS;introducing 1,2-propylene succinate repeat units into PBS can synthesize PBPS,improving the tensile strength of PBS.Thus,the topic has great practical value.(1)In this thesis,PBST with high molecular weight(Mw=1.41×105 Da)and high thermal degradation temperature(Td=385℃,which was 15℃ above the literature)was synthesized via melt poly condensation(MP)catalyzed by organic guanidine catalyst for the first time.A series proportion of SA/TAranged from 90/10 to 30/70 was synthesized via melt polycondensation(MP),the structural performance was characterized by 1H-NMR.The molars ratio of BS to BT commoner in PBST copolyester were 89/11、69/31、48/52,corresponding to the feed ratio of TA to SA(10/90、30/70、50/50),the experimental value conformed well with the theoretical value.It proved the designed molar ratio of PBST was synthesized.The degree of randomness of PBST was close to 1,it signified the products were random copolymers.The characteristic results of DSC(Differential scanning calorimetry)and TGA(Thermo gravimetric analysis)on product PBST showed that the melting point(Tm)decreased firstly and then increased with the increasing of TA molar fraction.When the molar content of TA was 30%,the melting point achieved the lowest value(71℃).However,the thermal degradation temperature increased with the increasing of TA molar fraction.(2)In this thesis,PBPS with high molecular weight(Mw=1.32×105 Da)and high thermal degradation temperature(Td=341℃,which was 28℃ above the literature)was synthesized via melt polycondensation(MP)catalyzed by organic guanidine catalyts for the first time.The molar ratio of SA(succinic acid)to dihydric alcohol(BDO and 1,2-PDO)was 1.000 to 1.017,it was far below the lowest value reported in the literature(1.0:1.1),and the mass fraction of THF(tetrahydrofuran)was 1.0%,far below the lowest value reported in the literature(3.0%).A series proportion of BS/PS ranged from 95/5 to 60/40 was synthesized via melt polycondensation(MP),the structural performance was characterized by 1H-NMR.The molars ratio of BS to PS commoner in PBPS copolyester were about 89/11、69/31,corresponding to the feed ratio of BDO to 1,2-PDO(90/10、70/30),the experimental value conformed well with the theoretical value.It proved the designed molar ratio of PBPS was synthesized.The characteristic results of DSC on product PBPS showed that the melting point(Tm)decreased with the increasing of 1,2-PDO molar fraction from 116℃ to 76℃,enriching its application in the field of low melting point.