Study On The Synthesis And Properties Of Biodegradable Polyester Based On 1,3-butanediol

Plastics are widely applied in people’s daily life,and traditional plastic products can′t be degraded,seriously polluting the environment.In view of the environmental problems caused by the plastics,people have studied and developed biodegradable plastics.Biodegradable plastics can be degraded into water,carbon dioxide（or methane）and other biomass through the enzymatic action of microorganisms in the soil,effectively reducing the environmental pollution.At present,the common biodegradable plastics are mainly polyesters,such as poly（lactic acid）,poly（butylene succinate）,poly（hydroxyalkanoate）and poly（butyleneadipate-co-terephthalate）（PBAT）.Among them,PBAT is a kind of material of high concern,which is synthesized with 1,4-butanediol,terephthalic acid and adipic acid,and present excellent mechanical properties and biodegradability.In this study,in the view of the molecular structure of aliphatic aromatic copolymer PBAT,1,3-butanediol which can be derived from biomass was applied to replace or partially replace 1,4-butanediol to synthesize the aliphatic aromatic copolymer.A series of biodegradable polyesters based on 1,3-butanediol were synthesized by direct esterification and melt polycondensation,and the effect of structure on their properties was studied.This paper mainly studies from the following three aspects:（1）A series of degradable poly（1,3-butyl adipate-co-1,3-butyl terephthalate）copolyesters（PB′AT）were synthesized by direct esterification and melt polycondensation using terephthalic acid,adipic acid and 1,3-butanediol as reactive monomers,and hexamethylene diisocyanate（HDI）was added for chain extension.The results showed that high molecular weight degradable PB′AT polyesters were successfully synthesized,with the M_n of over 50000.PB′AT was shown to be an amorphous polymer with good thermal stability,adhesiveness and biodegradability,and its peel strength can reach 3.9 KN/m.The adhsion property of PB′AT was derived from the formation of hydrogen bonds between abundant polar groups of PB′AT and the polyimide substrate.Moreover,the molecular chain movement of PB′AT and polyimide led to mutual diffusion,and thus the excellent adhesion ability.The results showed that PB′AT polyester can be used as biodegradable polyester hot melt adhesive,and have a good application prospect.（2）A series of degradable poly（1,3-butylene adipate-co-1,4-butylene terephthalate）copolyesters（PB′ABT）were synthesized by direct esterification and melt polycondensation using terephthalic acid,adipic acid,1,3-butanediol and1,4-butanediol as reactive monomers.The results showed that a series of degradable PB′ABT polyesters were successfully synthesized,with the M_n of 51500-61700 g/mol,PDI of 1.9,intrinsic viscosity of 0.91-1.01 d L/g and crystallinity of 20-33%.PB′ABT presented good thermal stability,and the T_d,5%can be up to 367°C.Furthermore,PB′ABT had excellent tensile properties.The tensile strength was above 20 MPa,and can be up to 45.2 MPa.The elongation at break was more than 700%,and can be up to 1457.9%.Moreover,the tensile property of PB′ABT-55（The molar content of BT is 55%）was better than that of commercial PBAT when the content of 1,4-butadiene terephthalate（BT）was same,which was due to the stronger rigidity of the 1,3-butyl adipate（B′A）segment caused by 1,3-butanediol monomer in PB′ABT-55 compared with PBAT.Research has shown that PB′ABT polyester can be applied in the field of biodegradable packaging with good application prospects.（3）A series of degradable poly（1,3-butylene succinate-co-1,4-butylene terephthalate）copolyesters（PB′SBT）were synthesized by direct esterification and melt polycondensation using terephthalic acid,succinic acid,1,3-butanediol and1,4-butanediol as reactive monomers.The results showed that a series of degradable PB′SBT polyesters were successfully synthesized,with the M_n of 56900-63000 g/mol,PDI of 1.8-2.2,intrinsic viscosity of 0.98-1.02 d L/g and crystallinity of 21-34%.PB′SBT had good thermal stability with the T_d,5%up to 365°C.The PB′SBT had excellent tensile properties,with the tensile strength above 24 MPa,and can be up to48.5 MPa.The elongation at break was above 700%,and can be up to 1406.7%.When the content of BT was same,the tensile property of PB′SBT polyester was better than that of PB′ABT polyester,which was because the succinic acid had a shorter molecular chain than adipic acid,and the rigidity of polyester molecular chain was enhanced.Research has shown that PB’SBT polyester with excellent comprehensive properties can also be used in the field of biodegradable packaging.