Effects of simulated clinical fabrication heat treatment and artificial weathering on the hardness testing of prosthetics/orthotics polymers

Abstract

The tensile behavior was compared for five prosthetics/orthotics polymers : Durr-Plex (copolyester), Polypropylene (polypropylene), Subortholen (polyethylene), Surlyn (ionomer), and Uvex (and cellulose acetate butyrate). Tensile properties, yield strength, and modulus of elasticity are related to a number of factors including composition and condition of polymers. The polymers were examined in the as-received and simulated clinical fabrication heat-treated conditions. The simulated clinical fabrication heat-treated specimens were subsequently treated to 2 weeks, 4 weeks, and 8 weeks of artificial weathering conditions, consisting of exposure to cycles of ultraviolet light and heated condensation. Tensile testing was performed on an Instron mechanical testing system, until fracture occurred. The ranges and respective rankings of yield strength and modulus of elasticity in tension were determined. Analysis of Variance (ANOVA) and post hoc Scheffe statistical analyses were performed for different polymers of the same treatment condition, and different treatment conditions of the same polymer. The analysis of variance (ANOVA) showed significant yield strength and modulus differences for the five polymers. The choice of material significantly influences the tensile properties for prosthetics/orthotics polymers. The Uvex polymer had the highest yield strength and elastic modulus, and the Surlyn polymer had the lowest yield strength and elastic modulus. The ranking trend was Uvex > Durr-Plex > polypropylene > Subortholen > Surlyn.