Characteristics of cellulose nanofibril films prepared by liquid- and gas-phase esterification processes

• Published in: e-Polymers Vol. 24; no. 1; pp. 5479 - 14
• Main Authors: Kim, Jeong-Ki, Bandi, Rajkumar, Dadigala, Ramakrishna, Han, Song-Yi, Van Hai, Le, Cho, Seung-Woo, Ma, Seo-Young, Lee, Da-Young, Kwon, Gu-Joong, Lee, Seung-Hwan
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 21-09-2024; Walter de Gruyter GmbH
• Subjects: Biomedical materials; Cellulose; Cellulose esters; Chloride; Chlorides; Contact angle; Crystallinity; Environmental science; Esterification; fatty acid chlorides; Fatty acids; Hot pressing; Humidity; Hydrophobicity; Liquid phases; Modulus of elasticity; nanocellulose; Nitrogen; Solvents; Spectrum analysis; tensile properties; Tensile strength; Thermogravimetric analysis
• ISSN: 1618-7229; 2197-4586; 1618-7229
• DOI: 10.1515/epoly-2023-0093

Cellulose nanofibrils (CNFs) are versatile materials, but their sensitivity to humidity affects performance. Esterification with fatty acids enhances the hydrophobicity of CNF films. This study compared gas- and liquid-phase esterification using three fatty acid chlorides at different dosages. Gas-phase esterification minimally affected cellulose crystallinity, maintaining a crystallinity index exceeding 55.8%, whereas liquid-phase esterification significantly reduced crystallinity. Gas-phase esterification achieved hydrophobicity (water contact angle >100°) with less fatty acid chlorides (0.50 eq/OH) compared to liquid-phase esterification (1.00 eq/OH). Tensile strength significantly dropped in the liquid phase (68.4–6 MPa) and up to an 8-fold decrease in the elastic modulus. Conversely, gas-phase esterification maintained tensile strength over 40 MPa, and elastic modulus increased by a minimum of 2.5 times. However, gas-phase esterification resulted in a 5-fold reduction in elongation at break (%). Thermogravimetric analysis indicated a high
of 362°C for liquid-phase esterified samples and a substantial 24.9% residual weight for gas-phase esterified samples.