Biodegradable Poly(butylene succinate) Copolyesters Modified by Rigid 2,2,4,4-Tetramethyl-1,3-Cyclobutanediol

Due to the shortage of fossil resource and pollution problems caused by traditional non-degradable polymers, biodegradable polyesters attract increasing interest. Poly(butylene succinate) (PBS) has good biodegradation characteristics, relatively high melt temperature, excellent thermal stability and processing properties. However, its unique chemical structure renders it possesses relatively lower glass transition temperature ( T g ), insufficient mechanical properties. In this work, novel aliphatic cyclic rigid monomer (2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) was introduced into the macromolecular chain of PBS to improve the mechanical properties of PBS. The resulting copolyesters (PBCBS) show T g ranging from −34.7 to −25.6 °C. Tensile tests showed that theses polymers possess high tensile strength (44-29 MPa) and elongation at break as high as 450 %, which is prominently higher than that of commercial PBS and most biodegradable packaging materials. The novel copolyesters were studied by wide-angle X-ray diffraction analysis. It has been found that the introduction of CBDO reduces the crystallization ability of PBCBS and the main reason for this phenomenon is that the aliphatic ring restricts the mobility of macromolecular chains and regular stacking. As crystallinity is reduced, more water molecules can enter into the amorphous region, contact with the ester group bonds, and accelerate the degradation. In addition, the transparency at 700 nm for PBCBS can reach 95 % and it showed better solvent resistance as compared to polycarbonate. The biodegradable polyesters with satisfied combined performance were reported in this work.