Mechanochemical activation of cellulose and its thermoplastic polyvinyl alcohol ecocomposites with enhanced physicochemical properties

The focus of this work is to study the influence of mechanochemical treatment of cellulose on the physicochemical properties of its polyvinyl alcohol (PVA) composites. Cellulose fibers subjected to pan-milling could be mechanochemically activated by breaking up the intra- and inter-molecular hydrogen bonds through shearing and compressing forces. Reactive hydroxyl groups were exposed on the cellulose surface, which could establish new hydrogen bonds with PVA. Moreover, the simultaneous reduction of particle size and large increment of specific surface area of pan-milled cellulose would benefit its dispersion as well as the interfacial adhesion with polymer matrix. PVA/cellulose composites were successfully processed by the melt in the presence of plasticizers containing formamide and water. Tensile tests demonstrated positive results from mechanochemical treatment. As pan-milling cycles of cellulose increased, the tensile strength of PVA/cellulose composites increased from 8.8 MPa to 16.4 MPa, while elongation at break increased from 76.8% to 374%. The composite materials also exhibited enhanced thermal stability and better biodegradability.