Physico-mechanical performances of flax fiber biobased composites: Retting and process effects

•Retting of flax fibers combined with processing parameters affect the organoleptic aspects of biobased composites.•Retting process affect the mechanical properties of technical flax fibers but allows the better ones for biobased composites.•Mechanical performances of flax biobased composites are very sensitive according to the processing parameters.•Optimized parameters (T = 160 °C, t = 130 min, P = 50 bars) allows highest fiber fraction for the lowest porosity fraction.•New method for determining the weight fiber content in biobased fibers composites using TGA has been proposed.