Wear Models for Multiphase Materials and Synergistic Effects in Polymeric Hybrid Composites

Discontinuous Fiber-reinforced Composites above Critical Length

“…Surface roughness that encourages inactive micro-areas to support bacterial plaque (Friedrich, 1993;Quirynen and Bollen, 1995) develops in composites over time in the form of wear, marginal chipping, and interfacial porosity (Fukushima et al, 1988;Mazer et al, 1992;Friedrich, 1993). Subsequently, wear is associated with lower modulus, reduced interfacial shear bond strength, and low composite strength, in addition to fibers (with lengths less than the plowing groove) that are easily detached (Friedrich, 1993).…”

“…In addition, the ADA currently advocates smaller fillings, due to the adhesive bonding nature of composites that also requires less tooth undermining (ADA Council on Scientific Affairs, 1998). Thinner cavity widths in addition to longer fibers will thus promote the alignment of fiber planes (Petersen and Wenski, 2002) for higher strength and modulus (Bascom, 1987;Mallick, 1997;Chawla, 1998), which in turn will lead to improvements in other composite properties (Friedrich, 1993;Wypych, 1999).…”

“…Quartz is considered insoluble, but is extremely hard and difficult to grind, to such an extent that larger jagged particles have previously been identified with a higher rate of wear against enamel (Anusavice, 1996). By comparison, quartz fiber above critical length will align parallel to the occlusal table during compaction placement and should wear by thinning, to peel off as thin sheets through infrequent loss from the resin matrix (Friedrich, 1993); this must be tested for opposing enamel wear.…”

“…Reduced overall polymerization shrinkage occurs with increasing aspect ratio, particularly along the fiber axis (Cloud and Wolverton, 1978;Wypych, 1999), with less shrinkage stress and lower creep (Wypych, 1999). Wear improves in conjunction with underlying mechanical strength properties that support loading, particularly as the reinforcement length extends beyond the average plowing groove (Giltrow, 1973;Friedrich, 1993). Fibers can also be used as a carrier mechanism for structural adhesives to control bondline thickness/pressure and raise toughness (Bolger, 1983;Shetty and Spearing, 1997).…”

Composites 2000: An International Symposium on Composite Materials

“…The studies resulted in the recommendation of a hybrid composite, having both carbon fibers under parallel and aramid fibers under normal orientation, embedded in a high-temperature-resistant thermoplastic matrix. For further reduction of the coefficient of friction against the steel counterparts, additional PTFE fibers interwoven with the other two types of fibers were suggested [4].…”