Investigation of the reactor’s high neutron flux effects on the physical and chemical characteristics of polymeric material

Abstract

Changes in the physical and chemical characteristics of polymeric material in neutron field had been investigated. Neutron induced atomic displacement in poly allyl diglycol carbonate (PADC) was examined by X-ray diffraction (XRD), infrared absorption (FTIR), and ultraviolet absorption (UV) techniques. High neutron flux of 9×1013 n cm-2 s-1 in thermal energy range and 1.64×1011 n cm-2 s-1 lethargy−1 was used for sample irradiation using ET-RR-2 research reactor, Egypt. XRD measurements showed formation of molecular ordered structures with approximate separations of 2.1 and 4.2 Å. The 2.1 Åseparation was attributed to CCC, COC, OCO, and OCO ordered sequences with bonds angle between 90° and 101°. The 4.2 Åseparation was attributed to successive occurrence of conjugated three atoms ordered sequences. Results showed that free H2O is generated due to the high probability of hydrogen and oxygen displacements. The primary number displacement per atom was calculated using cumulative Gaussian cascade method. Calculations showed that 53.3% of displacements occur were for the H atoms compared to 16.1% for the O atoms and 25.6% for the C atoms. The survived displacements was confirmed to form free water within the polymer matrix, and increases the signature for carbonyl group and hydroxyl group whether do or do not attached to the original polymer. Generated water may be subject to dissociation in consequence to neutron irradiation forming active oxygen and OH group. Both radicals are active and react with the polymer which increase the signature for CO and the yield of ROH which was confirmed using the strong π→π∗ UV-absorption at λmax≈233 nm and the weak n →π∗ UV-absorption at λmax≈274 nm.