Structure and properties of alkaline lignin-filled poly(butylene succinate) plastics

Poly(butylene succinate) (PBS), with similar physical properties to those of polyethylene, is degradable and can be used as a common material. However, it is not adopted widely in industry and domestic applications due to its high cost. In this work, to improve the performances and wide applicability of PBS, a new biodegradable blend has been prepared by incorporating alkaline lignin (AL) filler into PBS as a matrix. First, the AL and PBS, where the weight percentage of the former in the blends varied between 5 and 30%, were mixed at a rotating speed of 78 rpm for 10 min at 120°C; and then, the resultant mixture was compression-moulded into a sheet at 120°C under 20 MPa pressure for 5 min. Moreover, methylenediphenyl diisocyanate (MDI) was used as coupling agent to further modify new PBS/AL blends, and the weight percentage of MDI was regulated from 0.5 to 2%. The structure and properties of the resultant blends were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, swelling, tensile and water absorption tests. The results showed that the addition of AL inhibited the crystallization of PBS matrix, and enhanced the Young's modulus of the blends. In addition, it was found that the addition of MDI favoured further enhancements in tensile strength and Young's modulus, and reduced the water absorption of the blends.