A composite material comprising an elastomer and nanocellulose. The nanocellulose may comprise a nanocellulose material derived from plants having C4 leaf anatomy, or a nanocellulose material derived from a plant material having a lesser amount of lignin than hemi-cellulose, or a nanocellulose having a hemicellulose content of from 25% to 55% by weight of the nanocellulose material, or a nanocellulose comprising nanofibrils having a diameter of up to 5 nm, or a nanocellulose comprising nanocellulose material of plant origin comprising nanocellulose particles or fibres having an aspect ratio of at least 250, or the composite material having a stiffness of not greater than 2.5 times the stiffness of the elastomer without the nanocellulose material being present, or the nanocellulose particles or fibres being derived from a plant material having a hemicellulose content of 30% or higher (w/w). The nanocellulose may be derived from arid Spinifex.
