Latex and two-roll mill processing of thermally-exfoliated graphite oxide/natural rubber nanocomposites

Thermally-exfoliated graphite oxide (TEGO) is a graphene-based material that has been previously shown to disperse effectively into thermoplastic polymers by melt processing. In this work, dispersion of TEGO into natural rubber (NR) directly on a two-roll mill did not result in substantial property enhancement. However, by pre-mixing the TEGO with NR latex by an ultrasonically-assisted latex co-coagulation procedure followed by two-roll milling, the properties were improved substantially over the TEGO/NR nanocomposites mixed only on the mill. Quantitative analysis of TEM micrographs suggested the difference in properties was primarily the result of improved dispersion, as fewer multi-layer tactoids and platelets of overall smaller dimensions were observed in the nanocomposites pre-mixed by latex co-coagulation. NR filled with carbon black showed comparable property enhancement to TEGO/NR mixed on the two-roll mill but much smaller property changes than the latex pre-mixed TEGO/NR nanocomposites.