Controlling Water Permeability of Composite Films of Polylactide Acid, Cellulose, and Xyloglucan

To test the hypothesis that the introduction of a hydrophilic hemicellulose would affect viscoelastic properties and increase water permeability, xyloglucan (XG) was adsorbed onto the surface of microcrystalline cellulose (MCC) in water dispersion prior to the extrusion of 79-80 wt % polylactide acid (PLA), 20 wt % MCC, and 0-1 wt % XG. For comparison, composites of PLA, MCC, and non-absorbed XG were produced. Analysis of thermal properties showed no differences for glass-transition or melting temperatures, but the crystallinity of the films increased with the addition of MCC and XG. Storage modulus of the composite materials increased with XG content; however, at higher humidities storage modulus decreased, probably because of lower interfacial adhesion. Water permeability through the films increased more with the addition of XG adsorbed to the MCC than with the MCC and XG simply mixed in the same amounts. (C) 2014 The Authors. Journal of Applied Polymer Science Published by Wiley Periodicals, Inc.