Mixed-mode I/III fracture toughness of polymer matrix composites toughened with waste particles

Fracture toughness of particle-filled polymer composite beams with different particle content for varying of crack inclination angles was investigated in mode I and mode III loading conditions. The beams were tested using three-point bending test with crack inclination angles of 30 degrees, 45 degrees, 75 degrees, and 90 degrees. Sewage sludge ash (SSA), fly ash (FA), and silicon carbide (SiC) microparticles were used as toughening fillers with 5,10,15, and 20 wt% contents of the total weight of the polymer composites. The scanning electron microscope (SEM) micrographs showed that a good indication was observed for dispersion of FA, SSA, and SiC particles within the polymer matrix. The critical crack tip stress intensity factors K-Ic (crack angle 90 degrees) and K-IIIc, and the critical strain energy release rates G(Ic) and G(IIIc) were calculated and their results were compared. The mode I and mode III fracture toughness of the particulate polyester composite were improved by addition of particulate fillers. The maximum values of fracture toughness mode I (K-Ic, and G(Ic)) and mode III (K-IIIc and G(IIIc)) were recorded at particle content of 5 wt% polymer composites.