Mechanical response of PLA-based biocomposites under creep conditions

Abstract

Over the last decades, polymer composites containing natural fibers are receiving growing attention both from academia and the industry, as possible alternatives of composites containing synthetic fibers [1]. Moreover, in order to reduce the environmental impacts related to the use of oil-derived polymer matrices, biodegradable ones obtained from renewable sources such as poly(lactic acid) (PLA) have been considered [2]. Several papers are available regarding the mechanical behavior of natural fibers reinforced PLA composites, but only few deal with their creep behavior [3]. In the present work, the tensile creep behaviour of PLA based composites, containing flax and jute plain weave woven fabrics and produced by compression moulding technique, was investigated. Tensile creep tests were performed at different temperatures and applied stress. Fig. 1 shows the dimensionless (normalized) compliance as a function of creep time, for PLA and PLA/jute samples at both the test temperatures (40 and 60 °C). The results show that the creep behaviour of PLA is strongly influenced by the temperature. The presence of jute-based woven fabrics drastically modifies the creep response: at 40 °C, the compliance values are lower than those of the neat polymer; at 60 °C, the gap increases . In addition, the creep behaviour of the PLA/jute composite appears to not be influenced by the temperature increase. Regarding the PLA/flax composite (data not reported here), a significantly different behavior was found: flax woven fabric did not lead to a reduction of the creep compliance in comparison to PLA