▎ 摘　　要

Polyamide 6 (PA6) is extensively used in many industrials due to its chemical and wear resistance, stiffness, excellent strength properties, low friction, and high melting points. In this study, PA6/nitrile butadiene rubber (NBR)/graphene nanocomposites were fabricated by twin-screw extruder (TSE) and friction stir process (FSP). The novelty of our present work is that the fracture mechanisms and failure analysis of PA6/NBR/graphene nanocomposites were studied by the essential work of fracture (EWF) methodology. The scanning electron microscopy and wide X-ray diffraction were used to study the morphology of TSE and FSP samples. The results illustrated that the higher shear stress in FSP compared to the TSE is the reason for better dispersion of the graphene in the PA6 matrix and smaller size of NBR particles. The smaller size of NBR particles and better distribution of graphene in PA6/NBR blend led to high total work of fracture (w(f)) in the FSP sample compared to the TSE sample. The results of the EWF test showed that the addition of 0.5% (wt) graphene nanoparticles into the PA6/ NBR blend in the TSE sample decreased the essential work of fracture (w(e)) from 105.6 N/mm to 87.8 N/mm and increased the non-essential work of fracture (beta W-p) from 2.76 N/mm(2) to 3.9 N/mm(2); whereas in FSP sample, w e and beta W-p increased to 115.58 N/mm and 4.66 N/mm(2), respectively.