Natural rubber composites with high strength, modulus, water-resistance, and thermal stability, prepared with cellulose nanofibrils and sodium methacrylate

Natural rubber (NR) composite sheets consisting of TEMPO-oxidized cellulose nanofibrils (TEMPO-CNFs) and sodium methacrylate (mAANa) were prepared. An aqueous mixture of NR latex, TEMPO-CNFs, and mAANa was oven-dried; the dried material was kneaded to prepare cross-linked composite sheets. The NR/TEMPO-CNF/ mAANa (100/20/11.2 by mass) sheets exhibited high tensile strengths of - 23 MPa, whereas the tensile strengths of the neat NR sheets were - 5 MPa. Scanning electron microscopy observations indicate that the TEMPO-CNFs formed fewer aggregates in the composite sheet containing mAANa than in the mAANa-free sheets. Thermomechanical tests indicate that the NR/TEMPO-CNF/mAANa sheets had higher storage moduli over the entire range from - 100 degrees C to 200 degrees C than the neat NR sheet. The NR/TEMPO-CNF/mAANa composite sheets exhibited hysteresis loss and permanent deformation behaviors, similar to or better than those of NR/ carbon black composite sheets. Thus, the NR/TEMPO-CNF/mAANa composite sheets can be used in a similar manner as those consisting of all-carbon neutral components.