Cellulose fibers have come under increasing focus as reinforcing materials for plastics of late and R&D activity in the field is not only limited to North America. A joint effort between industry, academia and the public sector has realized plant-derived cellulose nanofibers exhibiting a high degree of compatibility towards polypropylene (PP) and other resins, opening up opportunities for lightweighting in vehicles.
Cellulose nanofiber (CNF) obtained from the pulp use in manufacturing paper have been surface-modified to enable uniform dispersion in a PP matrix, thereby boosting strength by a factor of up to four and reducing the coefficient of thermal expansion by 80%. The developers, headed by the New Energy and Industrial Technology Development Organization (NEDO) and including include DIC, Mitsubishi Chemical, Oji Paper, and Kyoto University, estimate that if employed as a reinforcing material in the approximately 110 kg of plastic parts used in a typical motor vehicle, an approximately 20-kg weight reduction would be possible.
CNF obtained via pulp nano-defibrating is surface-modified to render the surface hydrophobic and thereby compatible with PP, polyethylene (PE) and polyamide (PA) resins. Adding a 10-15% loading of CNF boosts the elastic modulus of a plastic by a factor of three to four according to the developers. In the case of a 10% loading in a PE resin, elastic modulus was boosted from 0.8 MPa to 3.5 MPa. Moreover, coefficient of thermal expansion was reduced from 248 ppm/K to 47 ppm/K.
Besides automotive, the developers also see opportunities for use in appliances, building materials, and packaging. Moving forward though, the initial aim is to work with injection molding machine builders and automakers to develop commercial-scale production technologies.