Creep behaviour of polylactic acid reinforced by woven hemp fabric

Woven hemp fabric reinforced polylactic acid composites with different fibre volume fraction (20, 30 and 40%) were manufactured by compression moulding process. To better understand the industrial application limits of the investigated bio-composite, flexural and impact properties were determined and compared to those of the unreinforced bio-polymer and the creep behaviour at different values of temperature was widely investigated adopting the Arrhenius theory. In addition, to predict the long-term mechanical performance of the investigated bio-composite, the possibility to use the Time-Temperature Superposition model was investigated. For this purpose, Dynamic-Mechanical tests were conducted to evaluate the activation energy and then to apply the Time-Temperature Superposition model to the compliance curves, obtained by short-time creep tests under different load conditions. Therefore, to examine the validity of the theoretical model, experimental long-time tests were also carried out. The results show interesting mechanical properties and a good fit between the theoretical and the experimental creep curves, particularly when the fibre volume fraction was equal to 20 and 30%.