The effect of primary, secondary, and hindered‐secondary hydroxyl groups on reactions and temperature profiles of polyurethane gels was investigated and modeled using a computer simulation that simultaneously solves over a dozen differential equations. Using urethane gel reaction temperature profiles of the reference compounds 1‐pentanol, 2‐pentanol, and Voranol 360 reactivity parameters were determined for reference primary, secondary, and hindered‐secondary hydroxyl moieties. The reaction parameters, including Arrhenius constants and heats of reaction, were consistent with previous values reported in literature. The approach of using fractions primary, secondary, and hindered‐secondary hydroxyl content to characterize reactivity sets the basis for a powerful approach to simulating/predicting urethane reaction performance with limited data on new polyols and catalysts. This code can be used for all polyols, as the kinetic parameters are based on the fraction primary, secondary, and hindered‐secondary alcohol moieties, not the type of the polyol. Kinetic parameters are also specific to catalysts where at least one parameter specific to each catalyst is necessary to simulate the impact of that catalyst. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40388.

One of the obstacles to displacing petroleum-based polyols with soy-based polyols in rigid urethane foam formulations is foam shrinkage, especially at displacements greater than 50%.

A series of over 30 differential equations were solved to model experimental data on urethane foam formation. Methyl formate and C5−C6 hydrocarbons were used as physical blowing agents, and water was used as a chemical blowing agent. The rate of evaporation of the physical blowing agents was estimated using an overall mass-transfer coefficient times the difference in activity in the gas phase inside the bubbles and in the resin walls of the bubbles. The rate of CO 2 diffusion was expressed as the overall mass-transfer coefficient times the rate of CO 2 generation. The overall mass-transfer coefficient was found to decrease to near zero as the gel point of the resin was approached. Only one fitted parameter was used for the overall mass-transfer calculation for all blowing agents. The simulation results for foam height agree with the experimental data. Bubble growth and bubble pressure were simulated for the first time as compared to the available literature.

A computer-based simulation for rigid polyurethane foam-forming reactions was compared with experimental data for six blowing agents including methyl formate and C5-C6 hydrocarbons. Evaporation of blowing agent was modeled as an overall mass transfer coefficient times the difference in activity of the blowing agent in the gas foam cells versus the resin walls of the cells. Successful modeling hinged upon use of a mass transfer coefficient that decreased to near zero as the foam resin approached its gel point. Modeling on density agreed with experimental measurements. The fitted parameters allowed for interpretations of the final disposition of the blowing agent, especially, if the blowing agent successfully led to larger foam cells versus being entrapped in the resin. The only component-specific fitted parameters used in the modeling was the activity coefficient that was lower for methyl formate than the value used for hydrocarbons.