Optimization of Tribological and Mechanical Properties of Nanocomposites of Polyurethane/Poly(vinyl acetate)/CaCO<SUB>3</SUB>

Abstract

Properties of samples containing polyurethane (PU), poly(vinyl acetate) (PVAc) and nanosize particles of calcium carbonate (CaCO3) are correlated with concentrations of these components. Interphase phenomena in PU/PVAc/CaCO3 nanohybrids have been studied before, we focus here on wear and scratch resistance. In addition to polymer blends containing CaCO3, the effects of adding CaCO3 with grafted PVAc, and CaCO3 with grafted silane and PVAc in varying ratios are also evaluated. For blends that do not contain the filler, a hypothesis explaining the concentration dependence of friction called the Bump Model is advanced and supported by the experimental results. In particular, we explain how creating a blend containing only 10% of a second polymer results in a dramatic drop of friction of the majority polymer. In single scratch testing, above 3% the filler displays 'its own' resistance to scratching. Chemical modification of the filler results in shallower residual depths--a consequence of improved interaction of the filler with the polymeric matrix. In sliding wear determination, strain hardening is seen for blends as well as for filler-containing composites. In tensile testing, addition of an unmodified filler increases the elongation at break and thus lowers the brittleness; the effect is even larger for chemically modified fillers.

Wear and friction of composites of an epoxy with boron containing wastes

“…The bumps model has been advanced before [23] and later confirmed in several cases [24,25] . Without the filler, the nominal contact area is equal to the real contact area.…”

Investigation of Wear Strength of Blast Furnace Slag Blended Polymer Materials

“…The wear border made the movement of the ball more difficult at high loading condition (see Fig. 6) and in this situation the indenter had moved across the entire surface of each region [19]. The indenter is not just jumping from bump to bump, as it was doing with little contact with the surface between the bumps.…”

Probing polymer chain constraint and synergistic effects in nylon 6-clay nanocomposites and nylon 6-silica flake sub-micro composites with nanomechanics

“…The change in H/E may have important implications for tribological applications where performance often is correlated with parameters such as H/E and H 3 /E 2 , with higher H 3 /E 2 commonly resulting in a higher load for non-elastic deformation, and higher wear resistance to wear as has been achieved by cross-linking ultra-high molecular weight polyethylene (UHMWPE) for replacement of hip prostheses. 37 The tribology and wear of polymers and polymer-based composites is complicated by viscoelastic recovery and brittleness, [38][39][40] with Brostow and co-workers reporting a direct correlation between a brittleness index and scratch recovery. 40 Although wear resistance may improve by adding silicate layers to nylon 6, this has been associated with an increase in brittle modes of deformation such as the formation of brittle cracks during scratching.…”

“…37 The tribology and wear of polymers and polymer-based composites is complicated by viscoelastic recovery and brittleness, [38][39][40] with Brostow and co-workers reporting a direct correlation between a brittleness index and scratch recovery. 40 Although wear resistance may improve by adding silicate layers to nylon 6, this has been associated with an increase in brittle modes of deformation such as the formation of brittle cracks during scratching. 41 A reduction in H/E when compared to matrix polymers has been reported previously for nylon 6 with 3-5% organoclay and for PEO with 7-15% and semi-crystalline polymers have shown that minimum values of the time constant 1/B are observed close to the glass transition region.…”