Influence of the fiber/matrix strength on the mechanical properties of a glass fiber/thermoplastic-matrix plain weave fabric composite

In this work, we analyze the influence of different fiber surface treatments on the mechanical properties of plain weave composites. The reinforcement is a glass fibers fabric and the matrix is an acrylic polymer. Until very recently, this thermoplastic polymer family was not used in composite industry. It is therefore necessary to study if the existing fiber surface treatments are suitable for acrylic resins or if new ones have to be found. At the macroscale, composite materials corresponding to different fiber surface treatments were characterized with: (i) monotonic in-plane shear tests and (ii) heat-build up fatigue measurements on specimens with ±45° fiber orientations with respect to the tensile force. At the mesoscale (fabric scale), the development of damage was experimentally analyzed from (i) 3-D DIC (Digital Image Correlation) full-field strain measurements with spatial resolution smaller than the textile repeating unit and (ii) X-ray microtomography. We show that the analyzed composite materials exhibit linear viscoelastic behavior until a given stress threshold above which damage develops in the material. It was also found that the application on the fibers of a coupling agent specifically developed for promoting the bond between glass fibers and acrylic resins improves the composite mechanical properties, in particular the fatigue properties.