A study of fire retardant blooming in HIPS by molecular modeling

The blooming process of two fire retardants: FR 1808 (by DSBG) and FR 8010 (by Albemarle) in high impact polystyrene (HIPS) was studied using experimental and computational methods. The degree of blooming was determined by accelerated aging followed by transmission electron microscopy (TEM) micrographs. Several levels of computational tools were used. On the molecular level, forced diffusion, calculations showed that the relative diffusion coefficient of FR 1808 in pure polystyrene (PS) is significantly higher than that of FR 8010. It was shown that this diffusion coefficient could be reduced by the addition of chloroprene and polychloroprene. Cohesive energy density (CED) solubility parameter and heat of mixing calculations showed that FR 1808 was compatible in PS, with an even higher compatibility in the interface of PS and butadiene in HIPS. TEM micrographs were in agreement with these findings. A three‐stage blooming mechanism was suggested: FR 1808 accumulates in the PS butadiene interface and diffuses to the surface, through the butadiene inclusions, due to FR 1808 concentration gradient. Copyright © 2010 John Wiley & Sons, Ltd.