Structure–property relationship of cellulose nanofibril-reinforced polyvinylpyrrolidone nanocomposites

Abstract Cellulose nanofibrils (CNFs) have been shown significant promises as reinforcement for polymers, but their properties can be greatly influenced by factors such as CNF source, pretreatment methods, and morphology. The present study aims at determining the effects of three different CNF treatment methods, which include highly oxidized CNFs (HCNFs), low oxidation CNFs (LCNFs), and mechanically disintegrated CNFs (MCNFs), on the tensile behavior of polyvinylpyrrolidone (PVP)/CNF nanocomposites. The results indicate that CNF dispersion, CNF-matrix interaction, and formation of CNF network in PVP determine the effectiveness of CNFs in enhancing the tensile properties of PVP/CNF nanocomposites. It is found that HCNFs exhibit the best dispersion in PVP, leading to the best improvement in Young’s modulus before a connected CNF network is formed. LCNFs and MCNFs possess longer fiber length and can achieve mechanically interlocked network in PVP more readily after a connected CNF network is formed (i.e., 20 wt.% CNF loading), which helps enhance tensile strength and modulus. The implication of the work for the preparation of CNF-reinforced polymer nanocomposites is discussed.