Paper Number
SF11 

Session
Surfactants, Foams, and Emulsions

Title
Bubble-size predictions for polyurethane foam using a population balance equation

Presentation Date and Time
October 21, 2019 (Monday) 4:10

Track / Room
Track 5 / Room 306A

Authors (Click on name to view author profile)

  1. Rao, Rekha R. (Sandia National Laboratories, Fluid and Reactive Processes)
  2. Ortiz, Weston (University of New Mexico, Chemical and Biological Engineering)
  3. Roberts, Christine (Sandia National Laboratories, Diagnostic Science & Engineering)

Author and Affiliation Lines (in printed abstract book)
Rekha R. Rao1, Weston Ortiz2, and Christine Roberts3
1Fluid and Reactive Processes, Sandia National Laboratories, Albuquerque, NM 87185-0836; 2Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM 87131-0001; 3Diagnostic Science & Engineering, Sandia National Laboratories, Albuquerque, NM 87185-0346

Speaker / Presenter 
Rao, Rekha R.

Text of Abstract
Polyurethane foams are widely used in manufacturing in part due to their ease of use and beneficial material properties, such as low thermal conductivity, stress and shock cushioning, and tunable density. Our goal is to develop computational models to predict these foam properties as a function of precursor formulations and processing conditions to aid in the manufacturing of polyurethane products. In this presentation, we focus on PMDI polyurethane foams, which are chemically blown foams used for electronic encapsulation and lightweight structural parts. A recently published kinetic model [1] is extended with a population balance equation using the Quadrature Method of Moments (QMOM) [2] in order to predict bubble size evolution as well as density variations during mold filling. We use a stabilized finite element method to solve the conservation equations; equations of motion, energy balance equation, species conservation with reaction, and transport of moments for QMOM. We combine these equations with the level set method in order to track the free surface between the foam and the surrounding gas. This model is used to predict final foam properties including density, thermal conductivity, and bubble size evolution in a three-dimensional foam bar geometry. Results for final densities are compared to experimental X-ray CT data. Bubble size evolution and final distributions are compared to experimental optical and SEM data. [1] Rao, Rekha, et al., Computers & Fluids 175 (2018): 20-35. [2] Karimi, Mohsen, et al., Macromolecular Symposia. Vol. 360. No. 1. 2016. *Sandia National Laboratories is a multi mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.