Gamma-irradiated metallocenic polyethylene and ethylene-1-hexene copolymers

Authors

  • Angel José Satti,

    Corresponding author
    1. Laboratorio de Radioisótopos, Dpto. de Química, Universidad Nacional del Sur (UNS), 8000 Bahía Blanca, Argentina
    2. Planta Piloto de Ingeniería Química, PLAPIQUI, (UNS-CONICET) Camino “La Carrindanga”, Km 7 - CC 717- 8000 Bahía Blanca, Argentina
    • Laboratorio de Radioisótopos, Dpto. de Química, Universidad Nacional del Sur (UNS), 8000 Bahía Blanca, Argentina
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  • Noemí Amalia Andreucetti,

    1. Laboratorio de Radioisótopos, Dpto. de Química, Universidad Nacional del Sur (UNS), 8000 Bahía Blanca, Argentina
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  • Raúl Quijada,

    1. Departamento de Ingeniería Química, Fac. Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago 2777, Chile
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  • Claudia Sarmoria,

    1. Planta Piloto de Ingeniería Química, PLAPIQUI, (UNS-CONICET) Camino “La Carrindanga”, Km 7 - CC 717- 8000 Bahía Blanca, Argentina
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  • José María Pastor,

    1. Física de la Materia Condensada. E.T.S.I. Industriales, Facultad de Ciencias, Universidad de Valladolid, Paseo del Cauce s/n, Valladolid 47011, España
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  • Enrique Marcelo Vallés

    1. Planta Piloto de Ingeniería Química, PLAPIQUI, (UNS-CONICET) Camino “La Carrindanga”, Km 7 - CC 717- 8000 Bahía Blanca, Argentina
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Abstract

The aim of this work is to present a detailed study of the changes introduced by gamma radiation on several metallocenic polyethylene copolymers. Therefore, metallocenic polyethylene and copolymers with 3.3, 9.2, and 16.1 mol % of hexene comonomer content were synthesized and irradiated with 60Co gamma radiation under vacuum at room temperature with radiation doses ranging from 0 to 100 kGy. Size Exclusion Chromatography data show that crosslinking reactions predominate over scission, even for the copolymer with the highest tertiary carbon content. Over a certain critical dose, which depends on the molecular weight and molecular structure of the initial polymer, an insoluble gel forms. The irradiated polymers also exhibit complex rheological behavior with increasing melt viscosity and elasticity, consistent with long chain branching and/or crosslinking. FTIR confirms depletion of terminal vinyl groups and increase of trans unsaturations with dose. The rate at which these two reactions evolve seems to depend on the comonomer content of the irradiated copolymers. Differential scanning calorimetry and Raman spectroscopy analyzes indicate less crystallinity and thicker interphases in irradiated materials. A mathematical model, which accounts for scission and crosslinking reactions, fitted well the evolution with radiation dose of the measured molecular weight data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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