Vegetal fibre composites for semi-structural applications in the medical environment

The mechanical behaviour of flax/polylactic acid (flax/PLA) and flax/polypropylene (flax/PP) bio-composites exposed to a medical environment (disinfectant and cleaning treatments) is studied for a use as a semi-structural part. Immersion tests in the different cleaning products were performed for both bio-composites in order to measure the absorption kinetic and monitor the evolution of the mechanical properties in the severe conditions. Pseudo-Fickian and Fickian behaviour were used to describe the absorption of the bio-composites. The absorption of the cleaning product results in a major loss of the mechanical properties. It was found that Terralin® is the most aggressive cleaning product followed by Surfanios® and water. However, coating the surfaces of these bio-composites could be a practical solution for increasing their durability in wet environments by reducing the sorption kinetics. The use of environmental friendly coatings such as layers of PLA should be favoured in an eco-design approach. In order to quantify in terms of absorption, the cleaning operation used in the medical environment and cleaning cycles were reproduced during a week. It was shown that the weight gained by the bio-composite during one cleaning cycle is very low, 1.98% of the initial mass in the worst case. Moreover, it was also shown that the initial weight is recovered before each cleaning cycle. Therefore, the saturated state is never reached in service condition, and only a low reduction of the mechanical properties (−5.3% and −7.6% of the tensile strength and modulus, respectively) has been observed. This shows that the flax/PLA and flax/PP bio-composites submitted to disinfectant and cleaning cycles can be used in a medical environment. Based on these conditions, a dimensioning strategy has been proposed for the parts submitted to the periodic cleaning treatments.