Thermoplastic/thermoset multilayer composites: A way to improve the impact damage tolerance of thermosetting resin matrix composites

We present a method to improve the impact damage tolerance of thermoset resin matrix composites by exploiting thermoplastic material impact resistance properties. Two configurations of thermoplastic/thermoset multilayer composites are considered: (a) thermoplastic material is used on sample surface as shock absorber and (b) thermoplastic film is inserted in between thermoset layers to act as interlayer. We aim at increasing adhesion strength between thermoplastic and thermoset resin matrix. We show that mode I critical strain energy release rate, determined by the wedge double cantilever beam fracture test, increases significantly when a third amorphous polymer interlayer compatible with both thermoplastic and thermoset resin is inserted. The analysis of scanning electron microscope fracture surfaces helps us to clarify the adhesion mechanism involved. The high adhesion between thermoplastic and thermoset resins obtained with this method, together with the ability of thermoplastics to dissipate the impact damage in the first plies ensure the reliability of this stacked configuration. Finally, we show that these multilayer composite significantly increases the impact resistance of composite materials.