Hydrostability, mechanical resilience, and biodegradability of paper straws fabricated through lignin-based polyurethane and chitosan binary emulsion bonding

Zhenghong Wu; Shaomin Kang; Yena Liu; Peipei Wang; Tian Liu; Rani Bushra; Mohammad Rizwan Khan; Jiaqi Guo; Wenyuan Zhu; Huining Xiao; Junlong Song

doi:10.1016/j.ijbiomac.2024.132155

Hydrostability, mechanical resilience, and biodegradability of paper straws fabricated through lignin-based polyurethane and chitosan binary emulsion bonding

Int J Biol Macromol. 2024 May 9;270(Pt 1):132155. doi: 10.1016/j.ijbiomac.2024.132155. Online ahead of print.

Authors

Affiliations

¹ Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources and International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China; School of Automation and Electronic Information, Xiangtan University, Xiangtan 411105, China.
² Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources and International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China.
³ Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
⁴ Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3, Canada.
⁵ Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources and International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China. Electronic address: junlong.song@njfu.edu.cn.

PMID: 38729462
DOI: 10.1016/j.ijbiomac.2024.132155

Abstract

This study focuses on enhancing the strength and water stability of paper straws through a novel approach involving a binary emulsion of lignin-based polyurethane and chitosan. Kraft lignin serves as the raw material for synthesizing a blocked waterborne polyurethane, subsequently combined with carboxylated chitosan to form a stable binary emulsion. The resulting emulsion, exhibiting remarkable stability over at least 6 months, is applied to the base paper. Following emulsion application, the paper undergoes torrefaction at 155 °C. This process deblocks isocyanate groups, enabling their reaction with hydroxyl groups on chitosan and fibers, ultimately forming ester bonds. This reaction significantly improves the mechanical strength and hydrophobicity of paper straws. The composite paper straws demonstrate exceptional mechanical properties, including a tensile strength of 47.21 MPa, Young's modulus of 4.33 GPa, and flexural strength of 32.38 MPa. Notably, its water stability is greatly enhanced, with a wet tensile strength of 40.66 MPa, surpassing commercial paper straws by 8 folds. Furthermore, the composite straw achieves complete biodegradability within 120 days, outperforming conventional paper straws in terms of environmental impact. This innovative solution presents a promising and sustainable alternative to plastic straws, addressing the urgent need for eco-friendly products.

Keywords: Chitosan; Lignin; Paper straw; Polyurethane; Water stability.