A review on nanocellulose as a lightweight filler of polyolefin composites

•Surface modifications of nanocellulose and polyolefin are summarized.•Three common preparations of nanocellulose/polyolefin composites are discussed.•The lightweight application of nanocellulose/polyolefin composites is discussed.•Challenges in the development of nanocellulose/polyolefin nanocomposites are outlined. Nanocellulose (NC) possesses low density, high aspect ratio, impressive mechanical properties, nanoscale dimensions, which shows huge potential applications as a reinforced filler. Polyolefin (PO), represented by polyethylene (PE) and polypropylene (PP), has been widely used in industries. Recently nanocellulose/polyolefin nanocomposites (NC/PO nanocomposites) have caught more attention from the application of automotive components, aerospace, furniture, building, home appliances, and sport. In this review, the surface modifications of nanocellulose and polyolefin are summarized respectively, such as surface adsorption modification, small molecule modification, and graft copolymerization modification. The common preparations of NC/PO nanocomposites are discussed, including the melting compounding, the solvent casting, and the in-situ polymerization. The lightweight, mechanical properties, and aging-resistant properties of NC/PO nanocomposites are highlighted. Finally, the potentials and challenges for industrial production development of NC/PO nanocomposites are discussed.