Average comonomer composition parameters

Use of Average Comonomer Composition Parameters Benoit provided a useful alteruative representation of in terms of mass weighted moments of the copolymer composition distribution. Generalizing his method to N comonomers, F. is expressed as ... 

Brar and Sunita [58] described a method for the analysis of acrylonitrile-butyl acrylate (A/B) copolymers of different monomer compositions. Copolymer compositions were determined by elemental analyses and comonomers reactivity ratios were determined using a non-linear least squares errors-in-variables model. Terminal and penultimate reactivity ratios were calculated using the observed distribution determined from C( H)-NMR spectra. The triad sequence distribution was used to calculate diad concentrations, conditional probability parameters, number-average sequence lengths and block character of the copolymers. The observed triad sequence concentrations determined from C( H)-NMR spectra agreed well with those calculated from reactivity ratios. 

Kapur and Brar [179] prepared acrylonitrile-ethyl methacrylate (A/E) copolymers of different monomer concentrations in bulk by free radical initiation. Copolymer composition was determined by nitrogen analysis and the comonomer reactivity ratios were determined by the method of Kelen-Tiidos. C-NMR spectra of several A/E copolymers are discussed in terms of their triad monomer sequence and cotacticity. Terminal and penultimate reactivity ratios were calculated using the observed monomer triad sequence distribution determined from C-NMR spectroscopy for individual samples. Triad sequence distribution was used to calculate dyad concentrations, probability parameters, number average sequence lengths, and the comonomer mole fractions in the copolymers. The configurational sequence distributions in terms of all the 10 A-centred and 10 E-centred triad cotactic sequences have been determined and found to be in excellent agreement with those obtained using various cotactic probability parameters. 

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