Cold plasma treatment on starch foam reinforced with wood fiber for its surface hydrophobicity

Tray samples of starch foam reinforced with aspen wood fiber were produced using a lab model-baking machine. Surfaces of the trays were treated with CF4 and SF6 plasma to get hydrophobic properties on surfaces. Fluorine compounds were found in XPS analysis of plasma treated samples. Due to the hydrophobic fluorine-rich surface, the contact angle was increased up to 150° with distilled water. RF power and gas pressure were varied to evaluate the effects of each parameter on fluorination of surfaces. The fluorine concentrations of treated sample surfaces were ranged from 46.8% to 60.2%. CF4 treatment showed higher concentration of fluorine on surfaces than SF6 treatment did. Water liquid and vapor uptake tests showed that the fluorine-rich surfaces restricted the permeability of water into the inner-layer of the treated samples.