Nanocomposites of poly(methyl methacrylate) (PMMA) and montmorillonite (MMT) Brazilian clay: A tribological study

Nanocomposites of PMMA+MMT Brazilian clays were developed by mechanical mixing in co-rotational twin-screw extrusion and injection molding with varying weight fraction of MMT Brazilian clays. The clays were purchased in crude form and then washed and purified to extract the organic materials and contaminants. Dynamic friction and wear rate of these composites were studied as a function of concentration of the Brazilian clay. With an increase in the amount of MMT Brazilian clay, the dynamic friction of the nanocomposites increases, a clear but not large effect. It can be explained by sticky nature of clay; clay in the composite is also on the surface and sticks to the partner surface. The wear rate as a function of the clay concentration passes through a minimum at 1 wt% MMT; at this concentration the clay provides a reinforcement against abrasion. At higher clay concentrations we see a dramatic increase in wear - a consequence of clay agglomeration and increased brittleness. The conclusions are confirmed by microscopy results.