ORGS5-0997
Elucidating the Role of Lignin Structure in Thermoplastic Polyurethane Composites: Effects of Source and Extraction Method on Interfacial Interactions and Mechanical Performance
Topic
GS5. Graduate Student Oral Session V: Sustainable Polymers and Circular Materials
When and Where
Sep 28, 2026
16:00 - 16:12
Room 105
Session Chairs
Taehoo CHANG
Taejun EOM
Chae Bin KIM
Presenter(s)
Seoku Lee (Hanyang University)
Co-Author(s)
Abstract
Lignin has attracted significant attention as a sustainable bio-based filler for polymer composites; however, the influence of lignin structural characteristics on polymer compatibility and composite performance remains insufficiently understood. In this study, three lignin samples derived from different biomass sources (softwood and hardwood) and extraction processes (kraft and hydrothermal) were incorporated into thermoplastic polyurethane (TPU) through melt blending to investigate structure–property relationships.
Comprehensive structural analyses revealed substantial differences in hydroxyl group distribution and condensation degree depending on lignin origin and recovery method. Quantitative NMR characterization demonstrated that hydrothermally extracted hardwood lignin (HW-HT) possessed the highest content of aliphatic hydroxyl groups and the lowest degree of condensation among the lignins examined. These structural features promoted stronger intermolecular hydrogen bonding with the urethane groups of TPU, resulting in enhanced interfacial compatibility.
The improved molecular interactions were reflected in the composite properties. TPU composites containing HW-HT exhibited superior thermal stability and mechanical performance compared with those containing other lignin types. Notably, the incorporation of only 0.5 vol% HW-HT increased toughness by 58% relative to neat TPU while maintaining favorable thermal characteristics.
These findings demonstrate that lignin source and extraction method critically influence lignin chemistry and subsequent polymer interactions. In particular, aliphatic hydroxyl content was identified as a key parameter governing interfacial bonding and composite performance. This work provides molecular-level insights for the rational selection and design of lignin feedstocks for high-performance, sustainable polyurethane-based composites.
Comprehensive structural analyses revealed substantial differences in hydroxyl group distribution and condensation degree depending on lignin origin and recovery method. Quantitative NMR characterization demonstrated that hydrothermally extracted hardwood lignin (HW-HT) possessed the highest content of aliphatic hydroxyl groups and the lowest degree of condensation among the lignins examined. These structural features promoted stronger intermolecular hydrogen bonding with the urethane groups of TPU, resulting in enhanced interfacial compatibility.
The improved molecular interactions were reflected in the composite properties. TPU composites containing HW-HT exhibited superior thermal stability and mechanical performance compared with those containing other lignin types. Notably, the incorporation of only 0.5 vol% HW-HT increased toughness by 58% relative to neat TPU while maintaining favorable thermal characteristics.
These findings demonstrate that lignin source and extraction method critically influence lignin chemistry and subsequent polymer interactions. In particular, aliphatic hydroxyl content was identified as a key parameter governing interfacial bonding and composite performance. This work provides molecular-level insights for the rational selection and design of lignin feedstocks for high-performance, sustainable polyurethane-based composites.
