Enhanced Hydrophobicity and Elasticity of Bacterial Cellulose Films by Addition of Beeswax

In this paper, bacterial cellulose (BC) based films incorporated with beeswax (BW) are investigated to study their potential application as packaging material. The films are prepared from 200 g BC suspension, which has a dry weight of about 1 g. Different concentrations (10-40 wt% based on dry weight of BC suspension) of BW are added to enhance hydrophobicity and elasticity of BC-based films. Carboxymethyl cellulose at 20 wt% and Tween 80 at 30 wt% based on dry weight of BC suspension are also added as the homogenizer and the surfactant, respectively. All components are mixed, degassed, casted, and dried in oven at 45 degrees C for 16-20 h. Contact angle measurements confirm significant enhancement of hydrophobicity of BC films from 53 degrees without BW to 124 degrees for addition of 40 wt% BW. Tensile testing reveals that elasticity of the films also increases according to percentage of elongation at break for about 38% by addition of 40 wt% BW, whereas tensile strength decreases for about a quarter. Scanning electron microscopy images show that BW covers the surface of BC network and penetrates the membrane pores. Moreover, addition of BW has no significant changes in total color difference and whiteness index of the films.