Enhancement of Stability in Alkali Solution of Polyethylene Terephthalate Fibers using Low-Dose Gamma Irradiation for Fiber-Reinforced Neutron Shielding Concrete

Abstract

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.

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“…The preparation process of PETE fibers presented by Khemngern et al [1] is adopted in this study. The PETE fibers were gamma irradiated at 40 kGy using Gamma 220 Excel gamma cell with a cobalt-60 source at Thailand Institute of Nuclear Technology (public organization) with an absorbed dose rate of approximately 5 kGy/h and an irradiator temperature of approximately 40  C. The properties of fibers are shown in Tables 1 and 2.…”

“…Un-irradiated PETE fiber properties [1]. Property Value Density 1 1.37 g/cm 3 Glass transition temperature (Tg) 2 67  C Melting temperature 3 254.3  C Degree of crystallinity 3 39.68 Number average molecular weight (MW) 4 22455 ± 196 g/mol 1 Measurement operated at 25  C; 2 Operated using differential scanning calorimeter (DSC, Netzsch, DSC204F1) with temperature increasing rate of 10  C/min and temperature range of -100 to 300  C; 3 Operated using XRD (Bruker, D8 Advance); 4 Measured using membrane osmometry method. Table 3 summarized the mix proportion of concrete.…”

“…The testing method for thermal neutron attenuation in this study is referred from Khemngern et al [1]. Concrete specimens for the neutron attenuation test were in a cubical shape with the dimension on each side of 100 mm.…”

“…Polyethylene terephthalate (PETE) fibers were applied as a reinforcing agent to enrichment concrete strength as well as to shield against slow neutrons. Khemngern et al [1] intensified the indissolubility of PETE fibers in a concentrated basic solution characteristic of concrete (pH = 12) using lowdose gamma radiation to convince crosslinking of the polymeric chains. Results demonstrated that gamma ray dose of only 30 kGy responded in the excellent molecular weight, tensile strength and degree of crystallinity of PETE fibers.…”

Sustainable Potentials of Plastics Waste-cement Kiln Dust Blends on Strength Properties of Subbase Soil

“…Polyethylene terephthalate thromboplastic is among the utmost often employed polymers for food packing, subsequent in a variety of short-lifecycle objects that are discarded by consumers. Due to slow polymer breakdown, non-recycled plastic components of this sort wind up in landfills or are spread in the environment, generating a variety of environmental hazards [15,17,18]. Jaber et al [19] investigated the outcome of the addition of recycled waste plastic on subbase strength characteristics.…”