Premium
Linear segmented polyurethanes. II. A mathematical model for the prepolymerization stage
Author(s) -
Polo M. L.,
Pesoa J. I.,
Nicolau V. V.,
Spontón M. E.,
Estenoz D. A.,
Meira G. R.
Publication year - 2019
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.46946
Subject(s) - molar mass , homogeneous , work (physics) , reaction rate constant , materials science , kinetics , constant (computer programming) , thermodynamics , polymer chemistry , kinetic energy , polymer science , composite material , physics , polymer , computer science , quantum mechanics , programming language
ABSTRACT In the first part of this sequel, an experimental investigation on the synthesis of linear segmented polyurethanes was presented, that included estimation of the kinetic constants at 60°C for the prepolymerization and finishing stages. This work presents two comprehensive mathematical models that simulate the mentioned prepolymerizations, in reactions between two poly(tetramethylene oxide) PTMO macrodiols and an excess of methylene diphenyl diisocyanate. The models require to input the molar mass distribution (MMD) of the initial macrodiol. The single‐phase (or homogeneous) model calculates a final MMD of approximately 40,000 different molecular species, and somewhat underestimates the observed molar mass dispersities. The double‐phases (or heterogeneous) model produces a better fit of the observed MMDs by simulating two independent polymerizations carried out in parallel. The double‐phases model contains three adjustable parameters: the reaction imbalances into both phases, and an “effective” rate constant. In part III of this sequel, the presented models will be extended to simulate the finishing stages. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 46946.