Linear segmented polyurethanes. III . Mathematical model for a two‐steps polymerization

POLO, MARA L.; SPONTÓN, MARISA E.; HUESPE, ALFREDO; ESTENOZ, DIANA A.; MEIRA, GREGORIO R.

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2020

0021-8995

In the first article of this sequel (J. Appl. Polym. Sci., 2018, 135, 45747), anexperimental and theoretical investigation was developed on the two-steps synthesisof linear segmented thermoplastic polyurethanes. The reactions werecarried out at 60C, with methylene diphenyl diisocyanate (MDI), twopoly(tetramethylene oxide) macrodiols, and 1,4-butanediol (BD) as chainextender. In our second article (J. Appl. Polym. Sci., 2019, 136, 46946), a mathematicalmodel for the prepolymerization was developed, that involved integratinga differential equation for each generated polymer species. The presentarticle extends such model, and predicts the molecular structure along thefinishing stage. In each stage, the new model first solves the molar balances atpolymer topologies level (i.e.,: Disregarding the molar mass distribution[MMD] of the reacted macrodiol chains), and then calculates the MMD of theevolving polymer and its main subsets through an algebraic convolution procedure.The model reproduces the prepolymerization predictions of our previousarticle, but is three orders of magnitude faster. In the finishing stage, up to156,000 polymer topologies and 4.53 × 108 polymer species were calculated;and the rate constant was readjusted to (k2 = 0.00129 L mol−1 s−1), in order tofit the measured MMDs.