Identification of brominated flame retardants in polymers

Importance of the Topic

Identification of brominated flame retardants (BFRs) in polymers is critical for compliance with environmental regulations such as RoHS and WEEE. These regulations restrict the use of hazardous substances in electronic and electrical equipment to protect human health and reduce environmental contamination. Reliable detection and identification of BFRs in recycled and new polymer materials supports safe waste management, quality control and ensures regulatory adherence.

Objectives and Study Overview

The primary goal of this application note is to demonstrate a fast, non-destructive approach for detecting and identifying brominated flame retardants in thermoplastic polymers. Key objectives include:

• Screening polymer samples for common BFRs such as Decabromodiphenylether, Tetrabromobisphenol A and other PBDEs.
• Establishing a robust FT-IR based identification workflow using ATR sampling.
• Assessing practical detection limits for routine QA/QC applications.

Methodology and Instrumentation

The approach combines attenuated total reflection Fourier‐transform infrared spectroscopy (ATR-FT-IR) with specialized identification software and X-ray fluorescence (XRF) analysis:

• ATR-FT-IR acquires spectra in the fingerprint region (2000–600 cm⁻¹) to capture characteristic absorption bands of both polymer matrix and flame retardant.
• OPUS IDENT software compares measured spectra against a curated library of polymer–flame retardant combinations, enabling rapid compliance checking.
• XRF quantifies total bromine and restricted heavy metals (Pb, Hg, Cd, Cr-VI) but cannot distinguish specific BFR species.

Instrumentation

• High-performance FT-IR spectrometer equipped with a diamond ATR crystal for robust sampling under high pressure.
• X-ray fluorescence analyzer for total element quantification.

Main Results and Discussion

Analysis of various polymer matrices (ABS, PC/ABS, PS, PE, PP, PVC, PBT, PA, SB) demonstrated:

• Clear differentiation of polymers with and without BFRs based on unique absorption bands.
• Reliable identification of flame retardant content above 5 % by weight; in certain polymers detection down to 3 % is achievable.
• Fast, straightforward sample preparation by pressing polymers onto the diamond ATR surface.

Benefits and Practical Applications

The combined FT-IR/ATR method offers:

• Rapid, non-destructive screening without complex extraction or chemical reagents.
• Minimal sample preparation, ideal for routine laboratory and on-site inspections.
• Automated reporting of polymer and flame retardant identity, supporting compliance and recycling workflows.

Future Trends and Potential Applications

Emerging developments may include:

• Expansion of spectral libraries to cover new flame retardant chemistries and polymer blends.
• Integration of chemometric models for enhanced detection at lower concentrations.
• Portable FT-IR instruments for in-field screening of electronic waste streams.
• Hybrid workflows combining FT-IR screening with targeted GC-MS for trace-level analysis.

Conclusion

ATR-FT-IR spectroscopy supported by a dedicated identification library provides a powerful, rapid and non-destructive tool for detecting brominated flame retardants in polymer materials. When paired with XRF for total bromine quantification, laboratories can achieve comprehensive compliance testing in line with RoHS and WEEE directives.