Investigation Of Radiation Resistant Materials Including Thermal Platstic Elastomer SEBS

Much attention has been paid to the styrene-ethylene-butadiene-styrene copolymer (SEBS), which is an emergent-solving problem for radiation resistance to satisfy special environment with high safe, such as wire and cable in nuclear industry, cable and protective jacket in space technology, and so on. SEBS, as a novel thermal plastic elastomer, enjoys a wide usage in many fields. However, there are few research works in radiation stability of SEBS or its blends.In this thesis, the influence of polystyrene and a variety of aromatic compounds on the radiation stability of SEBS and its blend were firstly studied. Firstly, the effect of high doses (0-2.0 MGy) of gamma irradiation on the mechanical, electrical and thermal behavior, at room temperature and in the presence of air, of SEBS/PS blends (100/0-50/50) has been studied. From the obtained results, it was indicated that the gamma irradiation stability of SEBS was enhanced by blending with PS. After the irradiation treatment, the tensile strength, volume resistivity of blends decreased and the dielectric dissipation factor of blends increased as the absorbed dose increased. Thermal analysis data showed that the introduction of PS improved the thermal property of the blends. But the addition of PS made the elongation at break of blends decreased intensively with the increasing of absorbed dose, especially at high dose.Then, to further enhance the radiation stability of SEBS/PS (60/40), aromatic compounds were added. The aromatic additives used involved various kinds such as diphenylacetylene (DPA), biphenyl (BP), anthracene (An), pyrene (Py). It was found that a serious deterioration of mechanical properties of all samples due to gamma radiation dose; however, the deterioration was less pronounced for the aromatic additives stabilized samples. Dielectric properties measurements showed that during irradiation the stabilized samples exhibited a better radiation resistance because of aromatic additives'protection, and Py had the best performance. Melt flow rate (MFR) measurements and thermogravimetric analysis (TGA) got the similar results. Finally, aromatic compounds'protection to polymers from a worsening in degradation should be attributed to the reactivity with the transient intermediates, which brought the excess energy release from molecules, was an important factor of radiation protection. In addition, the higher efficiency of Py to irradiation protection was assigned to its higher degree of aromaticity giving higher reactivity.Finally, a polymeric material with excellent radiation resistance obtained in this study, is SEBS/PS/Py (60/40/4) composite with elongation at break of 198%, 56.6% retention of tensile strength, DC volume resistivity of 5.35×1016 ?*cm, dielectric dissipation factor of 1×10-3 and good thermal stability after 2.0 MGy dose irradiation.