Current environmental issues reduce the use of materials obtained from fossil resources. The usual plastics therefore tend to be replaced by more green polymers such as polylactic acid (PLA), a bio-based and biodegradable polymer. Knowledge on the properties of this material is essential, especially in terms of fatigue strength and influence of temperature on tensile stiffness and strenght. In this study, the PLA samples are submitted to monotonic tensile tests, according to ASTM D638-10, at various temperatures between room temperature (23°C) and the glass transition temperature of the material (55-60°C). The results show a decrease of 30% of the modulus of elasticity and 60% of the tensile strength between these two temperatures. This decrease is mainly due to a significant drop in the mechanicalproperties beyond 50°C. In addition, tensile fatigue tests were conducted at loads rate between 40 and 80% of tensile strength, at room temperature in order to plot the Wöhler curve of PLA. The ruptured specimens were finally observed with a scanning electron microscope (SEM) to analyze the failure mechanisms in fatigue of PLA.
Ménard, C. (Author),
Ngô (Supervisor) &
Demarquette (Co-supervisor),
23 Jun 2015Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering