Structural laminated hybrid composites based on raffia and glass fibers: Effect of alkali treatment, mechanical and thermal properties

This work deals with the effect of the alkaline treatment of laminated hybrid composite materials based on Rafia fibers and glass fibers in sandwich structure. Structural analysis (Fourier Transform Infrared Spectroscopy) has shown that most of the changes caused by the alkaline treatment of Rafia fibers involve the removal of fiber surface from a certain amount of wax, hemicellulose, pectin and lignin. These changes are at the origin of the improvement of the mechanical properties of the composites. Flexural modulus results show an increase of 3.4 GPa-3.6 GPa for the untreated and treated Rafia fiber sandwich composites, respectively. The degree of interfacial adhesion quantified by a droplet test, shows that the alkaline modification reveals a sharp increase in shear stress for processed Rafia fibers with a 38% gain compared to untreated fibers. In addition, the measurement of the thermal conductivity has proved that the alkaline treatment decreases the thermal conductivity of the fibers. Finally, the mixing rule technique was used to predict the flexural modulus of the laminates using the mechanical parameters of each layer and the result was compared to the experimental data. It is assumed that Rafia fiber treatments will support the development of synthetic fiber reinforced sandwich polymer composites for industrial applications.