Mechanical characteristics of tire/clay modified epoxy used in fabrication of medical prostheses and artificial human parts
Epoxy is used in many dental and medical applications such as manufacturing prostheses. This polymer is not toxic and is a good candidate for easily forming of artificial hand, leg, etc. In recent years, the recycled waste tire has been concerned as inexpensive modifier for improving the toughness characteristics of many thermoset resins such as epoxy. Herein, the influence of addition of nanoclay on mechanical characteristics of waste tire-modified epoxy was investigated. Mechanical properties i.e. compressive and flexural characteristics, fracture toughness and impact strength of the samples were investigated. The fracture surfaces of the specimens were examined using scanning electron microscope (SEM). Moreover the glass transition temperature (T ) of the samples were measured. Results reveal that nanoclay can improve the g mechanical characteristics of waste tire-modified epoxies.
Fracture of an epoxy polymer containing recycled elastomeric particles
The fracture behavior of elastomer-modified epoxy was investigated using compact-tension geometry. The elastomeric modifiers included a liquid carboxyl-terminated butadiene acrylonitrile and solid rubber particles of different sizes which were obtained from recycled automobile tires. When used with solid rubber alone, no significant improvement in the fracture toughness was observed. However, when used in combination with the liquid rubber modifier, it was observed that the fracture toughness of these hybrid epoxies was higher than that of those toughened with liquid rubber alone. This synergistic effect is explained in terms of crack deflection and localized shear yielding. Furthermore, we observed a slight improvement in the fracture toughness as the size of the solid rubber particles increased. Although using a combination of both reactive rubber liquids and solid rubber particles as toughening agents had been investigated previously, in this study, the solid rubber particles used were from recycled rubber tires. Therefore, we have clearly demonstrated an application of producing high-quality engineering epoxy systems using toughening modifiers that are relatively low in cost and created higher-value products for recycled solid rubber.
Effects of residual stresses on the failure micromechanisms in toughened epoxy systems
The residual stress-strain distributions in various toughened epoxy systems have been analysed and related to their failure micromechanisms. The thermal expansion mismatch between epoxy and dispersed fillers gives rise to either compressive or tensile radial stresses at the interface. The interplay of these and the crack-tip stresses can profoundly govern the nature of crack tip-filler interactions which in turn dictate the micromechanisms of failure. Control of these stresses may be tailored to improve the fracture resistance and crack growth stability of toughened epoxies.