Composites Materials Reinforced by Flax FibresCorrelation between Adhesion of Fibre/Matrixand Mechanicals Properties of LaminatesAccording to Chemicals Treatments of Fibres

摘要

At this time, more and more importance is attached to use to natural fibre forrnthe reinforcement of composites materials. Previous works have shown that flaxrnfibers was one of more interesting solution for this goal.rnTo achieve optimal reinforcement in composites materials, it is necessary tornsubmit flax fibres to chemicals treatments. The aim of these treatments is tornseparate fibres because they are naturally in form of bundle, to clean theirrnsurface and to improve the compatibility (wetting and adhesion) with thernpolymer matrix. Chemicals treatments procedures must be established accordingrnto the nature of flax fibres. In our case, we use flax fibres dew retted.rnAt the microscopic scale, studies concern tensile test on monofibre of flax,rnsurface properties of fibres (surface tension) and fibre/matrix adhesionrn(microbond test).rnAt the macroscopic scale, tensile test was performed on laminates. Firstly, onrnlaminates reinforced by unidirectional fibres adjusted to an angle θ = 45° withrnrespect to the tensile test axis which allow to determine the shear strength in thernplane and also classical tensile test in transverse direction of fibres have beenrncarried out. Then, laminates made of layer of short fibres (10 mm length)rnpositioned in a randomize way (chopped strand mat) prepared by papermakingrntechnique were studied. For these three kinds of laminates, mechanicalsrnproperties are strongly dependent on the matrix and the fibre/matrix adhesion.rnAll these test have been done with an insaturated polyester matrix.rnResults show that chemicals treatments of flax fibres have a direct influencernon microscopic properties (strength, fibre/matrix adhesion). However, thisrninfluence of chemicals treatments is less significant at laminate's scale asrndetermined by tensile test which is mainly due to bundle of fibers present duringrnthe stratification.