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Keywords:

  • adsorption;
  • barrier;
  • biomaterials;
  • cellulose I;
  • cellulose III;
  • clay;
  • diffusion;
  • fibers;
  • films;
  • layered silicate;
  • liquid ammonia;
  • mechanical properties;
  • morphology;
  • trimethylammonium-modified nanofibrillated cellulose;
  • vermiculite;
  • water vapor adsorption;
  • water vapor permeability;
  • water vapor transmission rate

Abstract

Liquid 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