Scalable manufacturing of cellulose nanofibrils assisted by organic stone waste to expand the melt-processing window of poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) is used in various fields as a degradable polymer with excellent physical properties. However, poor thermal processability impedes its development. Herein, cellulose nanofibers (CNFs) are added to the PVA matrix to form strong hydrogen bonding with molecular chains and achieve melt-processing of PVA under the synergy of plasticizers. Specifically, a facile but efficient mechanical exfoliation method with the aid of organic stone waste (OSW) is designed to realize scalable manufacturing of CNFs. As an industrial by-product, OSW has abundant oxygen-containing groups on the surface, which can interact with cellulose and enhance the shear and friction force of cellulose during the mechanical exfoliation process. The resulting CNFs with an average diameter of 33.85 nm can significantly expand the melt-processing window of PVA to 66.6 °C, and benefiting from the nucleation effect of CNFs, the grain size of the composite material is refined. The tensile strength of resulting composites is significantly improved by 72.5% with the incorporation of 10 wt% CNFs. This strategy not only opens up scalable manufacturing of CNFs but also provides a new path for PVA melt-processing.