In this research, the synergistic effect of fiber and matrix modification on the mechanical properties and interfacial shear strength of UHMWPE/epoxy nanocomposite were investigated. Fibers have been modified by 5 wt.% Glycidyl methacrylate (GMA). In the mean time epoxy resin has been modified by differenet concentration (1,3,5% by weight of epoxy resin) of nanoclay cloisite 30B (C30B). Then success of the GMA grafting and C30B dispersing were proved with scanning electron microscopy (SEM), attenuated total reflectance infra-red (ATR-IR) and X-ray diffraction (XRD), transmission electron microscopy (TEM) respectively. Afterward, in order to investigate changes in the adhesion between the fiber and matrix, micro bond (Pull-out) test of the different samples were accomplished. Tensile and Flexural test on manufactured two-phase epoxy/C30B nanocomposites and three-phase UHMWPE fiber/epoxy/C30B nanocomposites were also carried out in order to investigate the effect of fiber and matrix modification on their mechanical properties. In the first step, the micro bond pullout-test results showed that the addition of 3 wt.% C30B in the epoxy resin, besides chemical grafting of the UHMWPE fiber, resulting an increment of IFSS as high as 228.8 % compared with the as-received fiber reinforced resin. Afterward, the macro step results showed that the maximum improvement of mechanical properties was detected for the samples in which the fiber and matrix were modified concurrently with 1 wt.% of C30B. Enhancement in the tensile modulus, flexural modulus, tensile strength and flexural strength were gained by 26.76 , 35.17 , 48.32 and 38.02 % respectively for 3phase nanocomposites. So the highest micro and macro properties were observed as the fiber and matrix were treated at the same time. In addition 2phase epoxy-C30B nanocomposites results showed that the failure strain decreased by more than 70% in, and SEM examination of tensile fracture surfaces revealed that fractures toughness were enhanced by adding nanoclay platelets. Furthermore microscopic results showed that the intercalated structure of epoxy/nanoclay composites, aggregates and trapped bubble or anyway incomplete degassing gave detrimental effect on the large number of nanocomposites properties
