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FR-130 vs Brominated SBS: Which Flame Retardant Is Suitable for EPS and XPS?

Expanded polystyrene (EPS) and extruded polystyrene (XPS) are widely used in thermal insulation applications, but both materials require an effective flame-retardant system when fire-performance requirements must be met.

Two brominated flame retardant options commonly considered for EPS and XPS are FR-130 and Brominated SBS. Although both are used in polystyrene foam applications, they differ significantly in chemical structure, molecular weight, thermal behavior and processing characteristics.

This article compares the main characteristics of FR-130 and Brominated SBS to help EPS and XPS manufacturers understand where each product may fit in their formulation.

What Is FR-130 Flame Retardant?

FR-130 is a brominated flame retardant used primarily in EPS and XPS foam systems.

The material has CAS No. 97416-84-7 and typically contains approximately 65% bromine. Commercial FR-130 products are generally supplied as white powder or granules and are designed to provide efficient flame-retardant performance in polystyrene foam. Senthos ST-130 has a specified bromine content of at least 65% and purity of at least 96%. Senthos Chem

FR-130 has been used as an HBCD-free flame retardant option for EPS and XPS where manufacturers require a conventional brominated additive with established processing characteristics.

For detailed specifications, see our FR-130 Flame Retardant – ST-130.

What Is Brominated SBS?

Brominated SBS is a polymeric brominated flame retardant produced from brominated styrene-butadiene block copolymer.

It has CAS No. 1195978-93-8 and is specifically used in EPS and XPS flame-retardant systems. Unlike conventional additive flame retardants, Brominated SBS has a high molecular weight polymeric structure.

Senthos ST-970 has approximately 65% bromine content, a molecular weight of around 100,000, and good thermal stability, with 1% weight loss occurring above 230°C according to its specification. Senthos Chem

The high molecular weight of Brominated SBS helps reduce migration and blooming compared with smaller-molecule brominated flame retardants, which can be beneficial in applications where long-term material stability is important. Senthos Chem

For technical details, see our Brominated SBS – ST-970.

FR-130 vs Brominated SBS: Key Differences

Both materials are commercially used in EPS and XPS flame-retardant applications. Independent supplier specifications also identify both FR-130 and Brominated SBS as flame retardants for EPS and XPS.

Thermal Stability and Processing

Thermal stability is one of the most important differences between the two products.

FR-130 is suitable for typical EPS and XPS flame-retardant formulations, but Brominated SBS was developed as a polymeric solution with particularly good stability during higher-temperature polymer processing.

Commercial Brominated SBS specifications commonly report processing stability above 230°C, making the material attractive for applications where the flame retardant is exposed to elevated temperatures during extrusion or foam production. Senthos Chem

The best choice therefore depends not only on flame-retardant efficiency, but also on the actual production process, processing temperature and formulation design.

Migration and Long-Term Stability

Because Brominated SBS has a high molecular weight, it has lower mobility within the polymer matrix than many conventional additive flame retardants.

This can help reduce migration, blooming or surface frosting over time. Senthos ST-970 is therefore positioned particularly for applications where low migration and long-term material stability are important. Senthos Chem

FR-130 remains a practical option where manufacturers already have established formulations and prioritize straightforward processing and cost efficiency.

Which One Should EPS Manufacturers Choose?

There is no single choice that is optimal for every EPS formulation.

FR-130 may be suitable when:

• The existing EPS formulation is already designed around FR-130.
• Cost efficiency is an important consideration.
• Conventional EPS processing conditions are used.
• The manufacturer wants a direct brominated flame-retardant solution for EPS/XPS.

Brominated SBS may be suitable when:

• A polymeric flame retardant is preferred.
• Higher thermal stability is required.
• Low migration or low blooming is important.
• The formulation is being designed around a polymeric HBCD-alternative system.

Final dosage and formulation should always be determined through production trials because flame-retardant performance can also depend on resin grade, density, processing conditions, synergists and the required fire-performance standard.

Flame Retardant Synergists in EPS Systems

In some EPS flame-retardant systems, organic peroxide synergists can be used together with brominated flame retardants to improve overall flame-retardant efficiency.

One example is Dicumyl Peroxide (DCP), which can be used as an EPS flame-retardant synergist in combination with brominated flame retardants. Senthos Chem

For more information, see Dicumyl Peroxide – ST-DCP.

Conclusion

FR-130 and Brominated SBS are both practical brominated flame retardants for EPS and XPS, but they serve somewhat different formulation priorities.

FR-130 provides an established and cost-effective solution for conventional EPS/XPS flame-retardant systems, while Brominated SBS offers the advantages of a high-molecular-weight polymeric structure, including strong thermal stability and reduced migration tendency.

For manufacturers evaluating a new formulation, the final selection should be based on processing temperature, target flame-retardant performance, material stability, cost and production trials.

Senthos supplies both FR-130 (ST-130) and Brominated SBS (ST-970) for EPS and XPS applications. Contact us for technical specifications, samples or formulation discussions.