Thermal, tensile and morphological properties of gamma-ray irradiated epoxy-clay nanocomposites toughened with a liquid rubber

This paper describes the process of mixing carboxyl-terminated butadiene-acrylonitrile (CTBN) with nano-clay to improve the toughness and mechanical strength of bisphenol A type epoxy, which tends to exhibit brittle fracture behavior. For evaluation of the degradation by radiation, gamma rays of 500 kGy, 1000 kGy, and 1500 kGy were used to irradiate the samples at a dose rate of 8 kGy/hr. The molecular structure changes, inter-layer distance of the clay, morphology, and radiation degradation behavior of epoxy and CTBN of the gamma-ray irradiated samples were measured using a Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), thermogravimetric analyzer (TGA), tensile machine and a field emission scanning electron microscope (FESEM). The FTIR results verified the band stretching of the -CN and the C=O bonding in CTBN from the spectra of CTBN-modified epoxies. The XRD results verified the easy intercalation of clay added to the epoxy and CTBN. In the TGA experiment, as the absorption dose increased and the heating rate decreased, the thermogravimetry-derivative thermogravimetry (TG-DTG) curves of the samples rapidly decreased. As the absorption dose increased, the tensile strengths of all the degraded samples sharply decreased, and morphologies, which were rubber particles fractured by gamma rays, were observed by FESEM. (C) 2009 Elsevier Ltd. All rights reserved.