Synthesis And Properties Of PBAT And Related Non-Isocyanate Thermoplastic Polyurethanes

Poly(butylene adipate-co-terephthalate)(PBAT)is a biodegradable aliphatic-aromatic copolyester.It has combined characteristics of polybutylene adipate(PBA)and polybutylene terephthalate(PBT),and can be used as a biodegradable substitute of popular polyethylene and polypropylene.In this paper,PBAT was synthesized by melt polycondensation and a chain extension.Through a non-isocyanate method,a series of PBAT related thermoplastic polyurethanes(NI-TPUs)based on the structure of PBAT were prepared.The NI-TPUs had different soft segments(SSs)and content of different SS or hard segments(HSs).The main work is described as follows:1.Bis(4-hydroxybutyl)terephthalate(BHBT)was synthesized from the esterification of terephthalic acid with excessive 1,4-butanediol.Several PBAT prepolymers(PrePBATs)were synthesized through melt polycondensation from BHBT,adipic acid and the excessive 1,4-butanediol.Chain extension was conducted using o-Phthalic anhydride and mbox as combined chain extenders,and chain extented PBATs(ExtPBATs)were obtained.Results showed that chain extension method was effective,and the molecular weight of polymers was greatly improved after chain extension.IR and NMR spectra confirmed the synthesis of target products.All obtained ExtPBATs were crystallizable.The crystallinity and melting point of ExtPBATs were affected by the molar ratio of terephthalic acid to adipic acid.The maximum tensile strength of them reached 22 MPa,and the maximum elongation at break reached 1775.83%with tensile strength of 13.66 MPa.2.Bis(hydroxyethyl)hexanediurethane(BHHDU)was synthesized from the ring-opening reaction of ethylene carbonate and 1,6-hexanediamine.Melt transurethane polycondensation of BHHDU with BHBT and PBA was conducted,and a series of crystalline non-isocyanate thermoplastic polyurethane elastomers(NI-TPUs)with polyester SSs were prepared.IR and NMR spectra confirmed the successful synthesis of the target products.The crystallinity of the NI-TPUs was characterized by XRD.NI-TPUs exhibited Mn close to 20000 g·mol-1,Tg between-38.39? and-3.33?,and initial decomposition temperature of over 245?.This series of NI-TPUs had a maximum tensile strength of 24.92MPa and a maximum elongation at break of 1937.63%.The resilience at 200%fixed-length was between 80%and 92%.All NI-TPUs all showed good resilience.3.Melt transurethane polycondensation of BHHDU,BHBT,PBA,and PEG was conducted,and a series of NI-TPUs containing polyether/polyester combined SSs were prepared.XRD and DSC characterization showed that the series of polymers were all crystalline,and Tg varies from-8.65? to 2.50?.These NI-TPUs exhibited good micro-phase separation between SSs and HSs.Their tensile strength reached 45 MPa with the elongation at break between 652.61%and 790.12%.The resilience at 200%fixed-length was between 77%and 92%.NI-TPUs with good crystallization,relatively high Tm,and excellent mechanical properties were successfully synthesized.