DNP NMR in biobased cellulose binder - A case study
The amount of disposable nonwovens used today for different purposes has an impact on the plastic waste streams which are built up from several single-use products. A particular problem comes from nonwoven products with “hidden” plastic (such as cellulose mixed with synthetic fibers or plastic binders) where the consumers cannot see or expect plastic.
The group of Hedenqvist et. al. at KTH has developed a sustainable binder based on natural components; wheat gluten and a polyelectrolyte complex made from chitosan, carboxymethyl cellulose and citric acid which can be used with cellulosic fibers, creating a fully biobased nonwoven product. The binder formed a stable dispersion that improved the mechanical properties of a model nonwoven. With wheat gluten added, both the dry and the wet strength of the impregnated nonwoven increased. The increased strength was explained as an enrichment of covalent bonds established during curing at 170 °C. The formation of the covalent bonds was confirmed by DNP NMR studies performed by Arthur Pinon at the Swedish NMR Centre at the University of Gothenburg.
