Study On The Synthesis And Properties Of Biodegradable PBS Modified By PEG

At present,the traditional plastic is faced with the problem of oil raw material drying up and waste plastic pollution of the environment.Development of biodegradable plastic has become one of the best way to solve this problem,poly(butylene succinate)(PBS)with its excellent comprehensive performance has attracted great interest of researchers in the study of biodegradable materials and has potential to be widely used.However,PBS has some shortcomings,such as high price and low degradation rate,which affect its application.Therefore,we used copolymerization and chain extension methods with the aim to improve mechanical properties and biodegradable performance,and to fulfill the requirements of the current society further.In this paper,we introduced Poly(ethylene glycol)(PEG)into PBS chain using three different synthesis methods,and a series of biodegradable PBSEG copolymers,poly(ester ether urethane)(PBS-b-PEG)block copolymers,PEG-PBS-PEG three amphiphilic block copolymer were synthesized.The structure,non-isothermal crystallization behavior,crystalline morphology and crystal structure of copolyesters were characterized by 1H NMR,differential scanning calorimetry(DSC),polarized optical microscope(POM)and wide angle X-ray diffraction(WAXD),respectively.The main contents of the thesis are as follows:Biodegradable PBSEG copolymers with various PEG content were synthesized through polycondensation.PBSEG crystal morphology was studied by POM,with the increase of the content of PEG,PBSEG crystal morphology with band spherulite turn into mixed crystal morphology with band spherulite and typical cross extinction spherulite.The crystals of the PBS chains corresponded to monoclinic unit cell,which is as same as that of PBS homopolymer.The crystal melting behavior of PBSEG was measured by DSC,along with the increase of the PEG content,melting point of PBS chain became lower,however,the melting point of PEG segment increased,which indicated that the integrity of crystallization of the PBS get lower.The experiment results also showed that the addition of PEG could increase the mechanical properties,degradation of performance.A series of biodegradable poly(ester ether urethane)block copolymers(PEEUs)was synthesized using IPDI as chain extender,POM results showed that the crystallization morphology of copolymers was obvious band spherulite.DSC test showed that when the PEG content reached 60%,copolymer appeared two peaks.The addition of PEG to PEEU improved the mechanics performance,degradation performance.With the increase of PEG content,the elongation at break and degradation rate of copolymers increased.Amphiphilic three block copolymer(PEG-PBS-PEG)was synthesized by the chloride base PEG(MePEG-COCl)and hydroxyl-terminated poly(butylene succinate)(HO-PBS-OH)reaction.The Avrami equation revised by the Jeziorny and Mo method was employed to describe the nonisothermal crystallization kinetics of the copolyesters,it was found that Jeziorny equation and Mo method is suitable to describe nonisothermal crystallization process.At the same time,Enzyme degradation test showed that the degradation rate of the copolymer improved significantly.