An ecofriendly approach for hydrophobization of cellulosic nonwovens: A comparative study of different biobased agents

The purpose of this research was to render hydrophobicity on three different cellulosic nonwovens (NW) using green biobased materials including betulin (Bt), stearic acid (SA), ethyl cellulose (EC), and beeswax (BW). A commercially available Alkyl ketene dimer-based hydrophobizing agent (AKD) was also used for benchmarking. A comparative analysis and comprehensive characterization of the coated samples was conducted using various analytical techniques, including scanning electron microscope (SEM), Fourier transform infrared (FTIR), capillary flow porometry, optical tensiometry, and tensile testing. The treatment of NW materials with selected biobased agents significantly enhanced their hydrophobicity. A water-absorbing air-laid NW1 became hydrophobic after functionalization with Bt achieving the highest water contact angle (WCA) of 134° compared with other biobased agents. To achieve complete hydrophobization of NW2 and NW3, which have larger pore sizes, mixtures of EC with SA and EC with Bt were applied, resulting in WCAs greater than 109°. The SEM micrographs of the coated NW2 and NW3 samples revealed that Bt and SA induced microroughness on the coating surface, with specific portions protruding outward over EC. The treatments did not significantly affect the porosity and tensile strength of the nonwovens, except for AKD and SA treated samples.