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Modification of Carbohydrate Polymers via Grafting in Air. 2. Ceric‐Initiated Graft Copolymerization of Acrylonitrile onto Natural and Modified Polysaccharides
Author(s) -
Pourjavadi Ali,
ZohuriaanMehr Mohammad J.
Publication year - 2002
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/1521-379x(200210)54:10<482::aid-star482>3.0.co;2-i
Subject(s) - grafting , acrylonitrile , comonomer , carboxymethyl cellulose , polymer chemistry , chemistry , cellulose , copolymer , tragacanth , intrinsic viscosity , xanthan gum , ceric ammonium nitrate , natural gum , polysaccharide , polymer , materials science , sodium , organic chemistry , food science , rheology , composite material
Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric‐carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N 2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi‐empirical expressions and time‐temperature profiles. An anomalous role of oxygen was observed, i.e., oxygen may act simultaneously as an inhibitor, comonomer and indirect initiator, depending on the type of polysaccharide. Measured grafting parameters, in most cases, showed a higher grafting yield and efficiency when the polymerization had been run under N 2 . However, medium to high grafting percentages were also achieved in air.