High-performance composites from low-cost plant primary cell walls

Our aim was to develop means to produce purified cellulose cell wall fragments and cellulose microfibrils from primary cellular material at laboratory scale, to form novel composite materials with a range of matrix binders and to determine their tensile properties. Swede root was processed to produce cell wall fragments. Separation of microfibrils from the fragments of the cellulose wall 'skeleton' was achieved using a severe shear treatment provided by a high-pressure food homogeniser. Composites with four types of matrix material were formed from the wet state cellulose. For composites made with purified cell wall fragments (PCWF), an acrylic matrix gave the best strength (125 MPa) while the best stiffness was produced by PCWF and PVA (15.32 GPa). The best performance from the fibrilised cell wall material (FCWM) was obtained with PVA (tensile strength 145 MPa and tensile modulus 8.9 GPa). Cellulose composites made using a plant-derived hemicellulose matrix gave tensile strength 100 MPa and tensile modulus 6.0 GPa. These performances are within the range of chopped strand mat glass fibre and polyester composites. Feasibility of extraction and application in composite form has been demonstrated.