Variations of the glass-transition temperature in the imidization of poly(styrene-co-maleic anhydride)

The imidization of poly(styrene-co-maleic anhydride) (SMA) was conducted, and the glass-transition temperatures (T-g's) of the resulting products were measured with differential scanning calorimetry. The contributions from functional groups of maleic anhydride, N-phenylmaleamic acid, and N-phenylmaleimide to T-g were examined. T-g increased in the order of SMA < styrene-N-phenyl. maleimide. copolymer < styrene-N-phenyl maleamic acid copolymer and followed the Fox equation. T-g of the imidized products of SMA could be controlled by the conversions of both ring-opening and ring-closing reactions. (c) 2007 Wiley Periodicals, Inc.