Sugiarto, S., Wu, T., Sathasivam, T., Pong, R. R., Jia, L., Chidambaram, A. S. O., Zhu, Q., Fei, X., Hashimoto, M., & Kai, D. (2025). Biodegradable lignin-based polyurethane thermoplastics: Synthesis, characterization, and 3D printing. Industrial Crops and Products, 236, 122069. https://doi.org/10.1016/j.indcrop.2025.122069
Abstract:
Lignocellulosic materials offer a sustainable alternative to fossil-based plastics, but challenges such as inferior mechanical properties and unclear biodegradability hinder their broader application. In this work, we developed biodegradable lignin-based polyurethane (LPU) thermoplastics using kraft lignin and polycaprolactone (PCL) diols with molecular weights of 530 and 2000 g mol⁻¹ (PCL530 and PCL2k, respectively). The LPUs were synthesized via step-growth polymerization and characterized to evaluate its chemical, thermal and mechanical properties. The developed LPU films incorporating PCL2k exhibited superior mechanical properties, with a tensile strength of up to 13.7 MPa and an elongation exceeding 884%. The LPU inks were formulated at 60 wt% and demonstrated excellent rheological properties for 3D printing via direct ink writing (DIW). Structures were successfully printed both in air and within an ethanol gel-based support medium, achieving a resolution of 410 µm and enabling the fabrication of complex and overhanging geometries. Moreover, Ultraviolet (UV) degradation studies revealed that LPUs prepared with PCL2k (L-PCL2k) demonstrated enhanced UV stability, with only a 4% reduction in molecular weight, compared to a 15% loss for LPUs prepared with PCL530 (L-PCL530). The aerobic biodegradation performance of the LPUs in the presence of seawater and sewage sludge demonstrated a 17.4% biodegradation degree over 90 days. This work demonstrates the potential of lignin-based LPU thermoplastics as biodegradable, mechanically robust, and processable materials for sustainable additive manufacturing.
License type:
Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Funding Info:
This research / project is supported by the Agency of Science, Technology and Research - Manufacturing, Trade, and Connectivity Individual Research Grants
Grant Reference no. : M22K2c0085
This research / project is supported by the Agency of Science, Technology and Research - Manufacturing, Trade, and Connectivity Programmatic Fund
Grant Reference no. : M25O2b0016