Influence of nanocellulose on mechanics and morphology of polyvinyl alcohol xerogels.

Xerogels are porous networks of crosslinked polymers that are useful for biomedical applications such as drug delivery, scaffold engineering, tissue regeneration, cell culture and wound dressing. However, inferior mechanical properties curtail their applications to a considerable extent. Nanocellulose fibers and crystals are often added into the polymer matrix to improve their mechanical strength. Here, nanocellulose in the mass ratios of 7%, 13% and 18% are loaded into polyvinyl alcohol (PVA) matrix followed by thermo-morpho-mechanical characterization. With increase in nanocellulose content, thermal degradation occurs at a lower temperature. It is observed that addition of higher quantity of nanocellulose crystals leads to the formation of weak cellulose-rich regions causing xerogel rupture. This is predominantly observed for xerogel loaded with 18% nanocellulose crystals. Similarly, addition of higher quantity of nanocellulose fibers increase brittleness of the xerogels causing fracture. This is predominantly observed for xerogel loaded with 18% nanocellulose fibers. Creep strain and stress relaxation is observed to decrease with addition of nanocellulose loading owing to molecular chain restriction and polymer chain immobility.