Multiscale Reinforcement of Polymers Combining Cellulosic Wood Pulp with Layered Silicate Nanoplatelets

Synergies resulting from the combination of discontinuous reinforcing elements at two different size scales are examined in two polymer types — rubbery matrices comprising acrylonitrile-co-butadiene (NBR) elastomer and a high density polyethylene plastic. The latter is derived from a recycled post-consumer waste stream that is upgraded by the reinforcement to compensate for any degradation experienced during prior use or impurities introduced during recycling. The two reinforcements are wood pulp at the microscale and exfoliating layered silicate clays at the nanoscale. Appropriate compatibilizing agents are employed to allow wetting of the reinforcement with the polymer matrix, promote dispersion and provide a strong interface. In general, the microscale elements provide mechanical strengthening in tension, while the nanoscale reinforcements enhance stiffening and reduce failure propagation by tearing. The use of natural reinforcements and recycled feedstocks imparts environmental acceptability to such formulations.