Tensile behaviour and characterization of epoxy-clay-poly (ethylene terephthalate) nanocomposites

In the present research work, the effect of varying concentration of nanoclay and un-treated/treated polyethylene terephthalate fibers (PET fibers) on tensile strength of nanocomposites was investigated. Response surface methodology (RSM) using Minitab software was used in this investigation. A total 18 experiments with 2 replications each were designed using 'Extreme Vertices' design model. Maximum and minimum values for tensile strength were obtained as 43.3 MPa and 26.7 MPa respectively. X-ray diffraction (XRD) analysis revealed that an intercalated structure/morphology was achieved during processing of all nanocomposites. For improvement in interfacial adhesion of PET fibers with other constituents of composite system, alkaline treatment of PET fibers was performed. ∣For alkali treatment, different treatment times and temperatures were selected. This was followed by investigation of tensile behaviour of composites reinforced with surface-modified PET fibers treated under a given condition. SEM analysis of fractured tensile specimens was used to establish structure-property relationship. Fracture surface of tensile specimens of nanocomposites containing untreated PET fibers showed clean fiber surface and fiber pull-out locations; however, nanocomposites containing alkaline treated PET fibers exhibited fiber breakage and rough fiber surface indicating enhanced resistance to crack front growth. (paper)