DETERMINATION OF MICROSTRUCTURE AND GLASS-TRANSITION TEMPERATURE OF ACRYLONITRILE METHYL ACRYLATE COPOLYMERS BY C-13-NMR SPECTROSCOPY

Acrylonitrile-methyl acrylate (A / M) copolymers of different monomer compositions were prepared by bulk polymerization using free radical initiator (benzoyl peroxide). Copolymer compositions were determined by elemental analyses and comonomer reactivity ratios were determined by the nonlinear least squares errors-in-variables methods (EVM). Terminal and penultimate reactivity ratios have been calculated using the observed monomer triad sequence distribution determined from C-13 {H-1} -NMR spectra. The triad sequence distribution was used to calculate diad concentrations, conditional probability parameters, number-average sequence lengths, and run number in the copolymers. The observed triad sequence concentrations determined from C-13{H-1} -NMR spectrum agreed well with those calculated from reactivity ratios. Glass transition temperatures (T(g)) of various copolymers determined from DSC gave good agreement with those obtained from NMR.