Assessment of selective flame-retardant transport to household dust from polymeric matrices

Abstract

In this study, the migration behavior of three commercially relevant flame retardants—decabromodiphenyl ethane, tetrabromobisphenol A, and resorcinol bis(diphenyl phosphate)—was investigated in acrylonitrile–butadiene–styrene, polypropylene, and polycarbonate/acrylonitrile–butadiene–styrene matrices. Thermal stability, fire performance, blooming behavior, and dust transfer were evaluated using thermogravimetric analysis, Underwriters Laboratory (UL-94) vertical flame testing, ion chromatography, inductively coupled plasma optical emission spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and diffusion modeling. All flame-retardant formulations achieved UL-94 V-0 classification, demonstrating effective fire performance relative to untreated controls. Reliable quantification by ion chromatography and inductively coupled plasma optical emission spectroscopy was achieved using compound-specific extraction and digestion procedures that demonstrated quantitative recovery of the target analytes. No measurable blooming was observed for acrylonitrile–butadiene–styrene + decabromodiphenyl ethane, acrylonitrile–butadiene–styrene + tetrabromobisphenol A, or polycarbonate/acrylonitrile–butadiene–styrene + resorcinol bis(diphenyl phosphate) during 30 days of accelerated aging at 70°C. In contrast, polypropylene + decabromodiphenyl ethane exhibited measurable surface migration, with bromine recoveries of 2.33 ± 0.01, 2.77 ± 0.33, and 0.72 ± 0.08 mg/cm 2 at days 1, 14, and 30, respectively. No measurable blooming was detected for any formulation during ambient aging at 25°C. The initial polypropylene + decabromodiphenyl ethane blooming regime was adequately described by Fick’s diffusion model, yielding an effective diffusion coefficient of 1.2 × 10 −13 m 2 /s. Measurable bromine transfer to settled dust was observed only for polypropylene + decabromodiphenyl ethane under accelerated aging (70°C), and reducing the dust loading from 60 to 30 g/m 2 resulted in an approximately 50-fold decrease in bromine concentration. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy confirmed the presence and spatial distribution of bromine within the collected dust but did not resolve the underlying transfer mechanism. Collectively, the results demonstrate formulation- and temperature-dependent differences in flame-retardant blooming and dust transfer and establish an association between measurable surface blooming and subsequent dust transfer under the conditions investigated.