In this study, the thermo-mechanical performance of flax fibre reinforced poly lactic acid (PLA) biocomposites
was investigated for the potential use in load bearing application such as body-in-white and body
structures in the automotive sector. Focus was given into the relationships between the thermal and
mechanical properties, and the material response under different loading and environmental conditions.
The strength (72 MPa) and stiffness (13 GPa) of flax/PLA composites investigated indicate a very
promising material to replace traditional choices in load bearing application. The PLA’s crystallinity
was measured to approximately 27%. Annealing above 100 C for an hour decreased that value to 30%,
but analysis of tensile results of annealed specimens reveals a significant reduction of both the tensile
strength and modulus. This reduction is associated with micro-cracking that occurred on the surface of
PLA during the heating as well as deterioration of the flax properties due to drying. The study results
show that strength and modulus increased with increasing strain rates, while elongation at break reduces
respectively. A modulus of 22 GPa was recorded in 4.2 m/s crosshead velocity. Further, flax/PLA showed
significantly higher modulus than flax/epoxy for the composites studied. Improvement of the interfacial
bonding and the temperature characteristics, combined the thermoplastic nature of PLA, demonstrates
that flax/PLA composites is ideal for use in structural automotive applications.
2014 Elsevier Ltd. All rights reserved.
Thermo-mechanical performance of poly(lactic acid)/flax
fibre-reinforced biocomposites