The graft copolymerization of styrene and lignin. I. Hydrochloric acid lignin

Authors

  • R. B. Phillips,

    1. Departments of Chemical Engineering and Wood and Paper Science, North Carolina State University, Raleigh, North Carolina 27607
    Current affiliation:
    1. Centre Technique du Papier, University of Grenoble, France
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  • W. Brown,

    1. Departments of Chemical Engineering and Wood and Paper Science, North Carolina State University, Raleigh, North Carolina 27607
    Current affiliation:
    1. Department of Physical Chemistry, University of Uppsala, Sweden
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  • V. T. Stannett

    1. Departments of Chemical Engineering and Wood and Paper Science, North Carolina State University, Raleigh, North Carolina 27607
    Current affiliation:
    1. Camille Dreyfus Professor of Chemical Engineering, North Carolina State University, Raleigh, North Carolina
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Abstract

The effects of methylation of phenolic hydroxyl groups and addition of solvent on the radiation and chemically initiated graft copolymerization of styrene and hydrochloric acid softwood lignin were studied. In the radiation-induced experiments, methylation is found to increase the maximum per cent graft obtainable two or threefold, while methanol addition may increase the value tenfold. Chemically initiated experiments indicate that the main effect of methanol addition is to increase the accessibility of the lignin particles. A mechanism of graft copolymerization of polystyrene and lignin is proposed which requires the reaction to proceed primarily by chain transfer of a polystyrene chain radical to lignin and the subsequent reinitiation of polymerization (i.e., initiation of graft copolymerization) by the lignin radical. The grafting of lignin modifications is then dependent on the type of radical formation (i.e., phenoxy or benzylic) most favored, as well as the usual accessibility considerations.

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