Liquid ammonia treatment of (cationic) nanofibrillated cellulose/vermiculite composites

Abstract

AbstractLiquid ammonia was used to treat films of nanofibrillated cellulose (NFC), trimethylammonium‐modified NFC (TMA‐NFC), and their composites with vermiculite. Crystal structure, mechanical properties, water vapor permeation and water vapor adsorption of the resulting materials were investigated. Upon treatment, the crystal structure of (TMA‐)NFC both in presence and absence of vermiculite changed from cellulose I to III. With the exception of TMA‐NFC/vermiculite composites, pronounced effects on the addressed mechanical properties arose after exposure of the materials to ammonia. Furthermore, treatment of composite films with ammonia led to a distinct decrease in water vapor permeation. Remarkably, TMA‐NFC/vermiculite composites films show the best water vapor barrier properties, highest tensile strength and highest elastic modulus after treatment with liquid ammonia. This is regarded to be at least partially a consequence of electrostatic attraction between the positively charged ammonium groups in TMA‐NFC and the anionic silicate layers of vermiculite. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013