Effects of the moisture and fiber content on the mechanical properties of biodegradable polymer-sisal fiber biocomposites

The matrix of the composites that were used in this work was a commercial blend based on starch and cellulose derivatives. The biodegradable polymer was reinforced by short-sisal fibers with a range in fiber content of 5-15 wt %. The effects of humidity on the diffusion coefficients, equilibrium moisture content, and mechanical properties were studied. Equations obtained from microscopic mass balances for diffusion in solids were used to predict the absorbed humidity in both components (the sisal fibers and biodegradable polymer) and in the composites as a function of time. Different model predictions of the composite diffusion coefficients as a function of the filler concentration were also examined, and they were found to be in agreement with the experimental results. (C) 2004 Wiley Periodicals, Inc.