Improving the thermal stability of wood-based cellulose by esterification

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials

Background:

• Wood-based cellulose, including needle-leaf bleached kraft pulp (NBKP) and wood cellulose nanofibers (WCNF), has limitations in thermal stability.
• Esterification is a potential method to improve the properties of cellulose materials.

Purpose of the Study:

• To investigate the effect of esterification on the thermal stability of NBKP and WCNF.
• To determine the optimal esterification conditions for enhancing thermal properties.
• To compare the efficacy of different ester groups (acetyl, myristoyl, benzoyl, pivaloyl) and their degree of substitution (DS).

Main Methods:

• Preparation of NBKP esters with varying DS using four different acyl groups.
• Evaluation of thermal stability using thermogravimetric analysis (TGA).
• Modification of WCNF via benzoylation and assessment of its thermal behavior.

Main Results:

• Optimum DS is crucial for significant thermal stability improvement, likely by esterifying hemicellulose and amorphous cellulose.
• Benzoyl (BNZ) and pivaloyl (PIV) esters showed higher thermal stability than acetyl (C2) and myristoyl (C14) esters.
• Benzoylation of WCNF increased its 1% weight loss temperature by 25°C and improved early-stage degradation resistance.
• DS variation (0.4-1.1) did not significantly alter WCNF ester thermal behavior, possibly due to fibrillation effects.

Conclusions:

• Esterification, especially benzoylation, effectively enhances the thermal stability of wood-based cellulose.
• Modified WCNF can achieve thermal stability comparable to bacterial cellulose.
• Understanding the role of DS and ester type is key to optimizing cellulose modification for high-performance applications.