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ABA low molar mass triblock copolymers in reverse emulsions: A rheological study

Authors

  • Juan M. Gonzalez,

    1. Instituto de Química, Depto. Química Orgânica, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Cidade Universitária, CEP 21941-590, Rio de Janeiro, Brasil
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  • Jorge de A. Rodrigues Jr.,

    1. Instituto de Química, Depto. Química Orgânica, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Cidade Universitária, CEP 21941-590, Rio de Janeiro, Brasil
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  • Regina S. V. Nascimento

    Corresponding author
    1. Instituto de Química, Depto. Química Orgânica, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Cidade Universitária, CEP 21941-590, Rio de Janeiro, Brasil
    • Instituto de Química, Depto. Química Orgânica, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Cidade Universitária, CEP 21941-590, Rio de Janeiro, Brasil
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Abstract

The effect of blocks length and molar mass of ABA triblock copolymers on the rheological behavior of water in oil (w/o) emulsions was investigated. Emulsion parameters such as water droplet concentration (and droplet size) of a series of inverted emulsion systems were evaluated. All copolymer/emulsion systems studied showed a non-Newtonian behavior, and the presence of the copolymer in the emulsion system led to an increase of the low shear viscosity when the size of the midblock of the copolymer was in a specific size range. This suggests the formation of a transient network through the interconnection, by the copolymer, of the smaller water droplets present in the emulsion. Consequently, the systems behave as w/o emulsions containing reversibly crosslinked oil-soluble polymers in the continuous phase, resulting in a pronounced shear thinning behavior. For the different emulsions studied, the relative viscosity increased, with few exceptions, with increasing droplet concentration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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