Paul D. Bloom

Al-Cu-Fe quasicrystal/ultra-high molecular weight polyethylene composites as biomaterials for acetabular cup prosthetics

Polymer composites of Al-Cu-Fe quasicrystals and ultra-high molecular weight polyethylene (UHMWPE) were investigated for use in acetabular cup prosthetics. The wear properties of the Al-Cu-Fe/UHMWPE samples and a 440 steel ball counterface were measured. The mechanical strength of the Al-Cu-Fe/UHMWPE composites was compared to UHMWPE and alumina/UHMWPE. The biocompatibility of the composite material was tested using a direct contact cytotoxicity assay. Al-Cu-Fe/UHMWPE demonstrated lower volume loss after wear and higher mechanical strength than UHMWPE. This composite material also showed no increase in counterface wear or cytotoxicity relative to UHMWPE. These combined results demonstrate that Al-Cu-Fe/UHMWPE composites are promising candidate materials for acetabular cup prosthetics.

Development of novel polymer/quasicrystal composite materials

Abstract We report on a new class of materials, polymer/quasicrystal composites with useful properties for beneficial exploitation in applications, such as dry bearings and composite gears. Our preliminary results indicate that our new composites are a means of enhancing the properties of certain organic polymers while providing a new means of processing quasicrystals. Al–Cu–Fe quasicrystalline materials significantly improved wear resistance to volume loss in polymer-based composites. Furthermore, mechanical testing results showed a two-fold increase in the storage modulus of the reinforced composites compared with the polymer samples. The fabrication in addition to the thermal, mechanical, and wear properties of these unique materials will be described.

Fabrication and wear resistance of Al–Cu–Fe quasicrystal-epoxy composite materials

Abstract Wear resistant polymer composites are prepared using a novel filler material, Al–Cu–Fe quasicrystals (QC). Novolac epoxy filled with Al–Cu–Fe quasicrystalline powder are evaluated by pin-on-disk testing using a 52100 steel counterface. Epoxy samples filled with aluminum, copper, iron, aluminum oxide, and silicon carbide are tested for comparison. The use of Al–Cu–Fe QC powder, as a filler in epoxy, maximizes the composite wear resistance while minimizing abrasion of the 52100 steel counterface. Wear mechanisms of the Al–Cu–Fe composites were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The fabrication and wear properties of these unique materials will be described.

Bilayer nanocomposite molecular coatings from elastomeric/rigid polymers: fabrication, morphology, and micromechanical properties

We fabricated bilayered nanocomposite coatings composed of a hard polymer layer placed on top of an elastomeric layer. The primary layer of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) was attached to the surface by grafting to a chemically reactive silicon surface functionalized with epoxy-terminated SAM. The SEBS layer served as the compliant interlayer in the bilayered polymer coating. The topmost hard layer was a high performance polymer made of epoxy resin (EP) and an amino functionalized poly(paraphenylene) (PPP). We built the bilayered structure by spincoating the EP/PPP mixture on top of the grafted SEBS layer. The solidification of the topmost layer was initiated at low temperatures (40 - 50 °C) to avoid dewetting. The curing of the film was finished at 110 °C (15 hours) and the EP/PPP layer was strongly attached to the SEBS layer. It was found that the EP/PPP layer did not penetrate inside the elastic primary layer during the solidification. The elastic response of the hard polymer layer was affected significantly by the underlying elastomeric layer. The SEBS layer served as a compliant interlayer capable of dissipating the interfacial stresses originating from dissimilarities in the physical properties between the polymer coating and the inorganic substrate.