Simulation of liquid physical blowing agents for forming rigid urethane foams

Abstract

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.

A comparison of a novel formulation of rigid polyurethane foams synthesis by hydrocarbon blowing agents

“…Blowing agents are chemical compounds used in the production of polyurethane, which was expanded by the introduction of gas bubbles form in a liquid [12,13], which has a low boiling point is higher than the room temperature (between 20 or 25°C) to avoid its evaporation during the foaming process [14]. There is also a variety of generations of physical blowing agents which are: chloro uorocarbons (CFCs), hydrochloro uorocarbons (HCFCs), hydro uorocarbons (HFCs), hydro uoroole ns (HFOs), liquid CO 2 , dimethoxymethane (methylal), hydrouoro-ole ns (HFO) and hydrocarbon blowing agents (HBAs) [11,[15][16][17][18][19].…”

First approach for modelling the physical foaming of tannin-based thermoset foams

“…Modelling the foaming of thermoset polymers might be done through a numerical approach. Several models have already been implemented, most of them in 0D geometry [2,3,[16][17][18][19][20], 2D [21,22] but also in 3D [23][24][25][26][27]. 0D simulations calculate one temperature and a total density for a macroscopic approach on the one hand, and cells dimensions for a microscopic approach on the other hand.…”

Viscosity-dependent frequency factor for modeling polymerization kinetics

“…9 In the current research, the impact of viscosity on the mass transfer limitation were studied for gel reactions. Previous studies 10,11 identify how to simulate the performance of blowing agents when provided parameters that characterize the gel reactions.…”