Hunain Alkhateb

Experimental Evaluation and Numerical Simulations of Nanocoatings in Infrastructure Fire Applications

AbstractAlthough coating masonry walls with polymeric elastomers can mitigate the effects of a projectile strike in a blast or explosion, it may also increase the fire hazard to the structure and the occupants. Although a rigorous assessment of this problem would require full-scale fire tests, considerable insights can be gained by performing bench-scale tests in conjunction with computer simulations. A joint experimental/numerical methodology is presented in this paper to evaluate the extent to which blast-resistant coatings, applied on masonry walls, may contribute to the spread of existing fire. The experimental data are obtained by performing cone calorimeter heat release rate (HRR) measurements. Flammability characterization and the heat flux generated for structural systems and components that are coated with blast-resistant and fire-retardant polymeric coatings are performed using the NIST fire dynamic simulator (FDS). In these simulations, structural concrete columns and masonry walls are exposed ...

Molecular Dynamics Simulations and Hygrothermal Aging of Polyurea–POSS Nanocomposites

The long-term performance of any novel material in its working environment is an intriguing area of research. The combined effect of the moisture content (relative humidity) and temperature of the environment degrades the mechanical properties of polymer composites. In the first part of this manuscript, polyurea–polyhedral oligomeric silsesquioxane (POSS) nanocomposites are subjected to continuous hygrothermal cycling. The effects of prolonged hygrothermal aging on the mechanical performance of the composites are evaluated in terms of the change in tensile strength and elongation at failure. Aged composites are subjected to FTIR spectroscopy to study the chemical changes resulting from the hydrolysis of polyurea. In the second part, attempts are made to study the effect of the addition of POSS nanoreinforcement on the mechanical properties of the resulting composite materials using molecular dynamics (MD) simulations. Results obtained here show poor agreement between MD simulation results and results obtained using dynamic mechanical analysis studies. However, qualitatively, both simulation and experimental results exhibit similar effects due to addition of POSS nanoparticles on the mechanical properties of polyurea–POSS nanocomposites.