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Increased thermal stability of nanocellulose composites by functionalization of the sulfate groups on cellulose nanocrystals with azetidinium ions
Author(s) -
Börjesson Mikaela,
Sahlin Karin,
Bernin Diana,
Westman Gunnar
Publication year - 2018
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.45963
Subject(s) - nanocellulose , thermal stability , nanocomposite , surface modification , sulfuric acid , materials science , cellulose , sulfate , chemical engineering , hydrolysis , reagent , nanocrystal , polymer chemistry , composite material , chemistry , organic chemistry , nanotechnology , engineering , metallurgy
ABSTRACT Cellulose nanocrystals (CNCs) prepared via sulfuric acid hydrolysis are decorated with sulfate groups that yield a stable water suspension. To make the CNCs adaptable for use in composites, the hydroxyl groups on the surface are usually hydrophobized. In this article, an alternative hydrophobization method is described in which the sulfate groups are conjugated with azetidinium salts. The results of this study show that the sulfate groups can be functionalized with azetidinium salts and from thermal studies, it was discovered that the functionalization led to a 100 °C increase in thermal stability, compared with unmodified CNCs. The nanocomposites prepared by extrusion of CNC‐coated low‐density polyethylene powder displayed similar mechanical properties as the CNC‐reference sample, but without the discoloration, due to the increased thermal stability. In conclusion, the azetidinium reagent reacts preferentially with sulfate groups, and this new type of chemical conversion of sulfate groups on polysaccharides will be beneficial in nanocomposite manufacturing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 45963.