Single carbon fiber fracture embedded in an epoxy matrix modified by nanoparticles

Fiber–matrix interface is a key which influences the mechanical performance of fiber reinforced polymer composites. Herein, silica nanoparticles were added to epoxy matrix to enhance the interfacial adhesion between fiber and matrix. Both a single fiber fragment test and a micro-Raman spectroscopy were utilized to evaluate the stress transfer efficiency of a single fiber based model composites. Around 21–30% improvement on the interfacial shear strength was obtained after addition of 2 up to 14 vol.% silica nanoparticles inside matrices. The improved matrix shear yield stress and interfacial bonding were believed to be the driving force. Moreover, the stress transfer mechanisms of the composites exhibited a dependence on the applied strain level. At lower strain level, the systems filled with silica performed similar behavior to neat epoxy matrix, in which nearly no enhancement on the interfacial shear stress was observed due to the pre-existed thermal compressive stress acting on fibers. However, at larger strain level applied, the higher shear yield stress and better interfacial bonding due to the existence of rigid silica nanoparticles made the stress transferring more efficiently than neat matrix at the circumstance of partial- or total-debonded interface.