Reactivity Ratios and Copolymer Composition Evolution During Styrene(St)/Bis Phenol-A Dimethacrylate(BDMA) Free-Radical Crosslinking Copolymerization

W. F. SCHROEDER; M. I. ARANGUREN; J. BORRAJO

JOURNAL OF APPLIED POLYMER SCIENCE

Wiley

Lugar: NY; Año: 2010 vol. 115 p. 3081 - 3091

0021-8995

ABSTRACT: In this article, experimental and simulated results are presented for the evolution of the copolymer composition as unsaturations are consumed in the freeradical cross-linking copolymerization of Styrene(St) and BisphenolA glycerolate dimethacrylate (BDMA). Real time FTIR measurements were performed to monitor the depletion of each comonomer double bond during the isothermal curing reaction at 80 C. From the experimental data corresponding to different feed compositions, the initial reactivity ratios and their evolution with conversion were determined via a nonlinear least squares optimization of the integrated form of the copolymerization equation. The reactivity ratio of St increases continuously and exponentially with the overall reaction conversion, while that of BDMA decreases linearly. A modified terminal copolymerization model including the dependence of the ratios with the overall conversion was proposed. application of this model provides a consistent the conversion of each comonomer during all stages, even at high conversion values where large diffusion and topological restrictions for chain movements present. Simulations show that the concentration styrene units added to the copolymer increases with overall reaction conversion, while that for the BDMA bonds diminishes. Structures rich in homopolymerized styrene are predicted at later stages of the reaction. Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2009 Key words: dimethacrylate; copolymerization; ratios; radical polymerization; crosslinking