Effect of nano-OMMTs on mode I and mode II fracture toughness of continuous glass fibre reinforced polypropylene composites

The influence of nano-organic montmorillonites (nano-OMMTs) on mode I and mode II interlaminar fracture toughness of continuous glass fibre reinforced ammonium polyphosphate polypropylene (CGF/PP/APP) composites was experimentally studied in this paper. Nano-OMMTs modified CGF/PP/APP unidirectional prepreg composites were fabricated by hot-melt impregnation process. To investigate the effect of nano-OMMTs on the interlaminar fracture toughness of composites, double cantilever beam (DCB) test and end-notched flexure (ENF) test were conducted to obtain the mode I initiation interlaminar fracture toughness (G_{IC init.}), mode I propagation interlaminar fracture toughness (G_{IC prop.}), and mode II initiation interlaminar fracture toughness (G_{II C init.}) of samples, respectively. Through comparison against to the neat CGF/PP/APP composites, with the addition of 6.5 wt% nano-OMMTs into PP matrix, the G_{IC init.}, G_{IC prop.}, and G_{II C init.} of composites can be enhanced from 0.502 kJ/m², 0.746 kJ/m² and 0.623 kJ/m² to 0.712 kJ/m², 1.119 kJ/m², and 1.195 kJ/m², respectively. Finally, it was found that nano-OMMTs in matrix can act as “pins”, which could absorb energy in the forms of nano-particles pullout and enhance the interlaminar fracture toughness values in DCB and ENF tests.