Synthesis And Characterization Of Multiblock Poly (ester-ether) Elastomers

Poly(ether-ester) elastomers is a kind of segmented copolymer, which contains the amorphous polyether soft segments of low glass transition temperature and polyester hard segments of easy crystallizability. These materials have outstanding integrated properties such as high strength, good elasticity, good heat resisitance and good chemistry resistance. Their properties could be adjusted by modification of chemical structre, the ratio of soft and hard segments and morphorlogy to meet different kinds of require. In this paper, a series of poly(ether-ester) elastomers was synthesized by a two-step method that melts transesterfication and subsequently polycondensation. The main experimental results are summarized as follows:Three kinds of poly(ether-ester) thermoplastic elastomer, poly(ester-ether-siloxane) PBT-co-PEG/PDMS, poly(ester-ether-siloxane) PBT-co-PTMG/PDMS and poly(ester-ether-butadiene) PBT-co-PTMG/ HTPB based on poly(butylene terephthalate) (PBT) as hard segment and poly(ethylene glycol) (PEG), poly(tetramethylene-oxide glycol) (PTMG), poly(dihydroxy methyl siloxane) (PDMS) and hydroxyl terminated polybutadiene (HTPB) as soft segment were prepared. The structures of polymerization products were ascertained by means of FTIR and 1H-NMR.The optimum condition of the synthesis of poly(ether-ester) was established by a series of experimems on the molecular weight of the products. It was revealed from the result of experimental that the best transesterification and polycondensation temperature was 160 oC and 270 oC, and the optimum reaction time was 90 minute and 150 minute.The physical and mechanical properties of polymerization products were investigated. The thermal performance is improved and the water absorption is deceased with the increasing loading of PDMS. The thermal behavior of PBT-co-PTMG/HTPB shows that the first melting endotherm (T_m1) is disappeared while the ratio of HTPB is more than 10%. The second melting endotherm (T_m2) is moved toward the higher temperature with HTPB units in the soft segments. The Mechanical properties of PBT-co-PEG/PDMS and PBT-co-PTMG/PDMS show that tensile strength increase with the increasing of PDMS but loss large elongation at break. Both the tensile strength and elongation at break increase with the content of HTPB when the HTPB concentration stays bellow 10%, but goes down while the HTPB concentration higher than 10% in PBT-co-PTMG/HTPB.