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Synthesis and distribution of structural units—Thermal property relationship of random and block butadiene-styrene copolymers with high trans 1,4 units content produced using an initiator composed of alkyl aluminum, n-butyl lithium, and barium alkoxide

Authors

  • Juan José Benvenuta-Tapia,

    Corresponding author
    1. Unidad de Desarrollo de Productos y Procesos, Resirene, S.A. de C.V. Km. 15.5 Carretera Federal Puebla-Tlaxcala, Tlaxcala, México
    • Unidad de Desarrollo de Productos y Procesos, Resirene, S.A. de C.V. Km. 15.5 Carretera Federal Puebla-Tlaxcala, Tlaxcala, México
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  • José Alfredo Tenorio-López,

    1. Facultad de Ciencias Químicas, Universidad Veracruzana, Coatzacoalcos, Veracruz, México
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  • Rafael Herrera-Nájera,

    1. Facultad de Química, Universidad Nacional Autónoma de México, Laboratorio de Polímeros, México L213, D.F.
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  • Leonardo Ríos-Guerrero

    1. Desarrollo Tecnológico y Negocios de Innovación, Consejo Nacional de Ciencias y Tecnología, México D.F.
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Abstract

Random, diblock, and triblock copolymers of butadiene and styrene, with a well-defined, high number of 1,4-trans units (c.a. 80%), were synthesized by anionic living polymerization using an initiator system composed of alkyl aluminum, n-butyl lithium, and barium alkoxide. The thermal properties of the block copolymers obtained by sequential addition of monomers were basically determined by the 1,4-trans units of the polybutadiene block. Kinetic data and 1H-nuclear magnetic resonance analyses showed that simultaneous polymerization of butadiene and styrene provided copolymers with a predominantly random distribution. By increasing the styrene content, the thermal properties of these copolymers were modified; polymers with 80% content of 1,4-trans units and 5% of styrene presented an endothermic transition at or slightly below room temperature (20°C), corresponding to the crystalline monoclinic form of high 1,4-trans polybutadiene, whereas copolymers with 25–50% styrene content were amorphous. The glass transition temperature of these copolymers increased significantly as the styrene content was increased. Both the block and random copolymers have a sufficient number of 1,4-trans units to display a regular distribution of structural units that makes them susceptible to strain-induced crystallization, which is important for the manufacture of products such as high-performance tires. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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