| In recent years,the increasingly environmental pollution caused by the blind production and abuse of the disposable petroleum-based plastics has aroused worldwild conceren.Developing and utilizing environmental-friendly biodegradable polymers to replace petroleum-based plastics is an effective way to solve this problem.Biodegradable polymers(such as poly(lactic acid)(PLA)and poly(butylene succinate)(PBS)and so on)have attracted great interest and attention.PLA has a hard texture and poor toughness and PBS has low impact resistance and melting point which limited their application areas.Poly(butyleneadipate-co-terephthalate)(PBAT)was developed to overcome the disadvantages of PBS.This copolymer greatly increased the mechanical and thermal properties.However,while the content of terephthalic acid is higher than 55%(TA/AA? 55/45),the polymer is difficult to degrade in the environment.To solve the problem,organic guanidine BGi catalyst for poly(Adipic acid-co-succinic acid-co-butylene terephthalate)(PBAST)synthesis was explored for the first time in this thesis.A biodegradable copolymer PLA-PBS was successfully synthesized with an organic guanidine catalyst for the first time.1.Different BA/BS/BT compositions of PBAST with high molecular weight(Mw 0.41 × 104Da)and narrow polydispersity(PDI 1.7?1.9)were successfully synthesized using biogenic guanidine catalyst BGi via MP-SSP.The thermomechanical properities,thermal stabilities of the product PBAST were characterized.1H-NMR characterization of the polymer structure indicated that the molar ratios of BA,BS to BT commer in PBAST copolyester were(50/5/45),(45/5/50),(40/5/55),(45/10/45),(40/10/50)or(35/10/55).The characteristic results of DSC showed that while the BS unit maintains a constant composition of 5 mol%,the melting pointing Tm improved from 162.45? to 179.77? with the increasing of aromatic composition;When the BS unit maintains a constant composition of 10 mol%,the Tm improved from 157.84? to177.41?.The analysis of TGA showed that when the BS unit maintains a constant composition of 5 mol%,with the increasing of the molar amount of BT units in the polymer(45 mol%-55 mol%),the initial thermal degradation temperature Td,i and the complete thermal degradation temperature Td,e of the polymer changed from 326? to 363 ? and 450?to 462?,respectively;while the BS unit maintains a constant composition of 10 mol%,with the increasing of the molar amount of BT units in the polymer(45 mol%?55 mol%),the Td,i and the Td,e of the polymer changed from 315? to 345?and 446? to 463?,respectively.The Tm value of the polymer is higher than 300?which proved the excellent thermal property of PBAST.Compared with the traditional synthesis by MP,MP-SSP method emplied in this thesis showed advantages of lower raction tenperature,short reaction time,snow white polymer and simple production technology,et al.2.Copolymer PLA-PBS was synthesized using biogenic guanidine BG2 as catalyst via MP:the molecular weight(Mw)of PBAST were 3.80 × 104 Da?8.55 × 104 Da and polydispersity were 1.6?1.8.1H-NMR characterization of the polemer structure indicated that the molar ratios of PLA and PBS in PLA-PBS copolymer was(10/90),(20/80),(30/70),(40/60),(50/50).Polymer tensile test showed that pure polylactic acid material has a tensile strength of 46.1 MPa and an elongation at break of 1.57%.The elongation at break of the polymer increased first and then decreased with the increasing of the molar content of PBS(10mol%?50mol%).When the molar content of PBS reached 30%,the elongation at break of the copolymer reached a maximum value of 106.61%.The results showed that with the increasing of PBS content,elongation at break of the copolymer increased significantly. |
PDF Full Text Request