The use of nature’s own chemistry to produce hydrophobic binders for nonwovens, combining a polyelectrolyte complex and pea protein

Abstract

Chemically bonded nonwovens are strong, paper-like materials that traditionally contains a latex binder comprising a plastic polymer and (often) cellulosic fibers. With this composition, these materials are only partly biobased, having a low biodegradability and cannot be recycled in traditional waste streams. In the strive for a fully biobased nonwoven system with a hydrophobic character, a biobased binder (polyelectrolyte complex, PEC) out of carboxymethyl cellulose and chitosan dissolved in citric acid) was here combined with pea protein (PP). By varying the fat content in the pea protein, as well as the content of the protein in the binder, it was possible to obtain different degrees of cellulosic nonwoven hydrophobicity and mechanical properties. At equal amounts of PEC and PP, the cured system showed a contact angle of ≈ 120°, which was stable in time. As compared to the binder-free nonwoven, the dry strength was doubled in the presence of defatted PP, and the stiffness and strength in the wet state was significantly higher for all combinations between PEC and PP.