Preparation and Properties of Bio-based PBS Multiblock Copolyesters Containing Isosorbide Units

In order to obtain copolyesters containing sugar-units with high meling point and crystallization ability, poly(butylene succinate-isosorbide succinate) multiblock copolyesters (PBIS) were successfully synthesized by chain-extension of the dihydroxyl terminated prepolymers. GPC results showed that high molecular weight PBS-based copolyesters with high content of isosorbide were easily obtained through chain extension. Their M-n values were in the range of 35000 - 70000. TGA and DSC results indicated that the PBISx multiblock copolyesters still maintained the good thermal stability and crystallization ability. When the content of isosorbide was up to 60 mol%, the T-m of copolyesters only declined 2 K compared with that of PBS. The effect of composition on the miscibility of PBS and PIS segments in PBISx multiblock copolyesters was studied by DMA. The results indicated that the miscibility of PBS and PIS segments in PBISx multiblock copolyesters changed from miscible to partially miscible, and finally changed to miscible with increasing isosorbide content. And the T-g values of copolyester increased with the increase of Is content, in which the T-g of PB(45)I(34)S60 was as high as 68 degrees C. The mechanical properties of PBS were improved and controlled by adjusting the content of isosorbide. The tensile strength of PBISx firstly increased and then decreased, and their elongation at break was double that of pure PBS. When the content of isosorbide was 60 mol%, its tensile yield increased from 35. 0 MPa of PB45S to 43. 0 MPa.