Wetting behavior of soy-based resin and unsaturated polyester on surface-modified sisal fiber mat

This paper presents the complex phenomena occurring during the wetting of natural fibers with epoxidized soybean oil/polyester in terms of contact angle and surface energy. The fibers are treated with various reagents to improve the wetting behavior. The observations demonstrate that NaOH treatment removes hemicelluloses and other impurities to a greater extent as observed through Fourier transform infrared spectroscopy and scanning electron microscopy. Besides, it is further noted that there is a considerable amount of increase in surface area of the exposed cellulose that aids in enhancement of wettability characteristics. Conversely, there is a formation of virtual layer on the fiber when treated with silane and isocyanate. An evaluation indicates coherence for silane and isocyanate-treated fiber when expressed in terms of contact angle and surface energy. Moreover, isocyanate-treated fiber exhibits good wetting in epoxidized soybean oil resin which may be attributed to change in polarity. Thermogravimetric analysis studies reveal that there is an appreciable enhancement in thermal stability for all the treatments.