On the development of a green composites based on poly (lactic acid)/poly (butylene succinate) blend matrix reinforced by long flax fibers

Abstract Because of their mechanical properties and low density, flax fibers seem to be competitive with glass fibers. However, these fibers present a non-uniformity in many of their characteristics (non-constant diameter along the fiber, variable length, presence of defects…). This leads to a dispersion of their mechanical properties. This study focuses on the development of fully biodegradable green composites based on poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) matrix reinforced by flax fibers to determine their elastic characteristics and to analyze their tensile and flexural failure in order to evaluate the influence of the processes on the mechanical properties. The main task is to incorporate flax fibers of several millimeters into the polymer matrix and study of the influence of the twin-screw extrusion and single-screw extrusion which are used for the elaboration of the compound and after the injection of the materials. The first objective is to identify the optimal parameters of the manufacturing processes which permit to elaborate satisfactory products presenting acceptable mechanical properties. The study aims to understand the effect of the introduction of flax reinforcements from a thermal and mechanical point of view. From the main results, the thermal analyses show that the introduction of 20% PBS into the PLA matrix improves the thermal stability of PLA and increases the onset temperature of decomposition. The mechanical characterizations have shown that the stiffness of the resulted composites has been improved after the incorporation of the flax fibers from 1457 MPa to 4353 MPa compared to the matrix. On the contrary, a decrease in deformation rate was observed owing the addition of flax fibers from 4.4% to 1.9%. These preliminary results show the possibility to develop new bio-composites which are thermoplastic, recyclable, with configurable mechanical properties depending on the selected matrix.