Yarns and films from ligno-cellulosic fines

In this work the feasibility of the novel low-cost lignocellulosic fines (LCF) as a raw material of biodegradable all-cellulose applications, namely yarns and films, was investigated. LCF was prepared from softwood (spruce) using a traditional wood grinder equipped with a special patented V-surface stone. Produced LCF particles were in micrometer scale. The chemical and elemental composition analyses for LCF exhibited the chemical structure of native wood. The short length and rather low aspect ratio (when compared e.g. to cellulose nanofibrils) limited the bonding capacity of LCF particles, and a composite approach was chosen for the preparation of yarns and films. Carboxymethyl cellulose (CMC) was used in both cases as a binder polymer, and glycerol was used as a plasticizer. The yarns were made with dry-jet wet spinning with aluminium sulfate crosslinking. This method allowed fast manufacturing of the yarns with reasonable mechanical properties. The films were made with a simple solvent casting technique. The chemical composition, crosslinking mechanism, and mechanical properties of the composite yarns and films were investigated. The tensile strength of the LCF-CMC yarns was higher than whole hardwood fiber-thermoplastic starch composite yarns but below that of cellulose yarns made from pure viscose. Addition of plasticizer was found to give positive impacts on the flexibility and handling of the yarns. The tensile strength of LCF films was rather good being comparable e.g. with CMC-starch composite films and pure cellulose acetate films. The investigated low-cost fines are obviously an interesting novel option for all-lignocomposite applications with cellulose derivatives, where biodegradability and biobased characteristics are desired properties.