Enhancement of Stability in Alkali Solution of Polyethylene Terephthalate Fibers using Low-Dose Gamma Irradiation for Fiber-Reinforced Neutron Shielding Concrete
Polyethylene terephthalate (PETE) fibers are used as a reinforcing agent to enhance concrete strength as well as to shield against thermal neutrons. This study increased the stability of PETE fibers in a strong alkali solution characteristic of concrete (pH = 12) using low-dose gamma radiation to induce crosslinking of the polymer chains. Results indicated that gamma ray dose of only 30 kGy resulted in the highest molecular weight, tensile strength and degree of crystallinity of PETE fibers with size 1.3 D. The surface topology using SEM micrography were also evaluated. An accelerated age testing revealed that these radiation-treated fibers will maintain their mechanical strength in concrete for up to at least 60 months. Thermal neutron attenuation test of fiber-reinforced concrete (FRC) indicated that the degree of thermal neutron shielding increased with increasing PETE fiber content, and that at 0.3% fiber content, FRC exhibited the highest thermal neutron attenuation of about 60% compared to unreinforced concrete. Therefore, these FRCs can readily be utilized as an effective neutron shielding material for nuclear and radiation applications to enhance radiation safety.