New Flexible High Gamma Dose Dosimeter Based on Luminescent and Biodegradable Polymer Blend
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New Flexible High Gamma Dose Dosimeter Based on Luminescent and Biodegradable Polymer Blend T. Schimitberger1, M.R. Franco2, F.A. Lopes2, P.S. Curti2, R.F. Bianchi2 and L.O. Faria3 1 Departamento de Engenharia Nuclear, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-970 Belo Horizonte, MG, Brazil. 2 Laboratório de Polímeros e Propriedades Eletrônicas de Materiais, Universidade Federal de Ouro Preto, Campus Universitário Morro do Cruzeiro, 35400-000 Ouro Preto, MG, Brazil. 3 Centro de Desenvolvimento da Tecnologia Nuclear, Av. Antônio Carlos 6627, C.P. 941, 31270-901 Belo Horizonte, MG, Brazil. ABSTRACT In this work we investigate the radio-degradation of MEH-PPV polymer film as a tool for measuring high doses of gamma radiation. In order to produce film samples with thickness in the micron range, we have mixed the photoluminescent poly(2-methoxy-5(2'-ethylhexyloxy)-pphenylenevinylene) copolymer (MEH-PPV) with a biodegradable poly(butylene adipate-coterephthalate) copolymers (PBAT). The system was irradiated with a Co-60 source with doses ranging from 1 to 1,000 kGy. Ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy have been used to investigate the radiation induced changes in the absorption and photon-emission spectra of the irradiated samples. Results indicate that the PL emission intensity varies exponentially with the applied gamma radiation dose for doses ranging from 30 to 500 kGy. The unambiguous relationship between PL & Dose together with the good flexibility of the copolymer films indicate that MEH-PPV/PBAT blends have great potential for applications in high gamma dose dosimetry. INTRODUCTION The use of high doses of gamma and electron radiation in industrial processes has encountered several applications in different fields, as for example in the sterilization of medical products, to modify polymer properties and in food irradiation. Among the several polymeric materials investigated for dosimetric purposes, conjugated polymers have been studied as ionizing radiation detector since early 80s [1,2]. Therefore, it was only in 2005 and 2012 that the optical properties of poly(2-methoxy-5(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) films and solutions by Silva et al.,[3] and Schimitberger et al.,[4] respectively, were proposed to be used as a tool for evaluating radiation doses. Some authors have proposed that thin films of MEH-PPV to be used as radiation detectors [5]. However, for commercial applications, thicker films, with thickness ranging from 100 to 300 µm are best fitted for easily handling purposes. In this context, the blending of the photoluminescent MEH-PPV copolymer with another flexible polymer seems to be the better way to produce photoluminescent films in the required thickness. In this work we have explored the use of a copolyester poly(butylene adipate-coterephthalate) (PBAT) as a host matrix for MEH-PPV, in view of its good optical transparency and its known capacity of keeping good mechanical and thermal properties after exposed to high gamma d
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