Brominated Polystyrene (BPS) — CAS 88497-56-7, 66.33% Bromine

Brominated Polystyrene (BPS) - CAS 88497-56-7

Bromine 66.33% · TGA 1% loss 334 °C · 320 °C calcination qualified · Whiteness 84.40 · YI 9.96 · MFR 49.85 g/10min

📌 Why buyers are moving to BPS right now: the DBDPE problem

On 5 November 2025 the European Chemicals Agency added decabromodiphenyl ethane (DBDPE, CAS 84852-53-9) to the REACH SVHC Candidate List as very persistent and very bioaccumulative under Article 57(e). ECHA describes DBDPE as the most widely used aromatic brominated flame retardant on the European market. Articles containing more than 0.1% w/w carried an ECHA notification obligation with a deadline of 5 May 2026, plus SCIP entry and downstream safe-use disclosure - and Candidate List entries can later move to the Authorisation List.

A restriction dossier is also in preparation. ECHA's call for evidence in early 2026 and the restriction work that followed are scoped to non-polymeric aromatic brominated flame retardants in electrical and electronic products, construction products and textiles, naming DBDPE, bis(2-ethylhexyl) tetrabromophthalate and BTBPE. A draft restriction dossier is expected around December 2026.

Brominated polystyrene is polymeric. It is not on the Candidate List and does not fall within the named non-polymeric scope. That is the practical reason a PBT or PA66 compounder switches - not marketing, a supply-chain disclosure obligation with a date attached. See the honest caveats in the regulatory section further down before you treat this as permanent.

ℹ️ An MFR figure without test conditions is not a specification. Ask us for the temperature and load used, and make sure any competitor figure you are comparing against was measured the same way - otherwise you are comparing two unrelated numbers. We will state the conditions on the COA.

🌡️ Use the 1% figure, not the headline "decomposition > 330 °C"

Every BPS datasheet quotes a decomposition temperature. The number that actually predicts trouble in your extruder is the TGA 1% weight loss at 334 °C, because that is where the first bromine starts leaving. Once it does, hydrogen bromide in the barrel corrodes screws and dies, accelerates hydrolytic degradation of PBT and polyamide chains, and shows up as splay, discolouration and dropped impact strength.

Glass-filled PA66 typically runs a 280–300 °C melt, and shear heating in a high-glass, aggressive-screw compounding line can push actual melt well above the setpoint. 334 °C onset gives you roughly 35–50 °C of real headroom - comfortable, but not unlimited. If you are running hot PA66 at 45–50% glass, measure your melt temperature with a probe rather than trusting the controller display.

The shape of the curve matters as much as the onset. From 1% to 15% spans just 52 °C (334 → 386 °C), which means the material holds and then goes, rather than bleeding volatiles slowly across your whole processing window. A retardant with a high nominal onset but a shallow early curve is the worse buy.

⚖️ MFR 49.85 - a high-flow grade, and here is what it costs you

BPS is sold in high-flow and high-molecular-weight versions, and they are not interchangeable. An MFR of 49.85 puts this at the high-flow end - lower molecular weight, lower melt viscosity.

What you gain: easy dispersion in glass-filled compounds, no melt-viscosity spike, better filling of thin-wall connectors and long flow paths, and lower torque on the compounding line.

What you give up: lower molecular weight means marginally greater migration tendency over long thermal ageing, and slightly less thermal margin than the high-MW grades. For a thin-wall 5G connector or a small automotive sensor housing, high flow is the right call. For thick sections held at 150 °C for thousands of hours, ask us about the high-MW grade instead - we would rather sell you the correct one than the one on this page.

🧮 Working out your loading from the 66.33% bromine figure

Glass-filled PBT and PA66 typically need roughly 10–13% bromine in the finished compound to reach UL 94 V-0 at common wall thicknesses. At 66.33% Br that translates to about 15–20% BPS, plus antimony trioxide at a bromine-to-antimony ratio near 3:1, so roughly 4–6% Sb₂O₃.

Treat those as starting points for your own bar testing, not as a formulation. Actual requirement moves with wall thickness, glass loading, polymer grade, pigment package and whether you need V-0 at 0.4 mm or 1.6 mm. Higher bromine content in the retardant is worth real money here: every point of additive you avoid is a point of glass or polymer you keep, which is mechanical property you do not have to give away.

🎨 Whiteness 84.40 and YI 9.96 - why colour is a cost line

Brominated polystyrene can come out anywhere from near-white to distinctly straw-coloured depending on how it was made and purified. That colour does not disappear in your compound - it sets the floor on what white you can reach, and every point of yellow you have to correct costs titanium dioxide and pigment. At 15–20% loading the retardant is a major colour contributor, so for white and pastel connectors, sockets and appliance housings, ask every supplier for whiteness and YI figures and not just "white powder" on the datasheet.

🔌 1. Electrical & Electronic - connectors, sockets, switchgear

Glass-filled PBT and PA66 connector bodies, relay housings, sockets, circuit breaker components and terminal blocks. This is where BPS earns its position: the parts are thin-walled, must survive reflow or high service temperature, need a UL 94 V-0 rating with a comparative tracking index that does not collapse, and are frequently moulded in white or light grey. Non-blooming behaviour matters because a bloomed surface degrades contact reliability and looks like a defect.

🚗 2. Automotive & New Energy Vehicles - harnesses, sensors, busbar parts

Wire harness components, sensor housings, connector systems and battery-adjacent structural parts. NEV architecture has increased both the count of electrical connections and their voltage, which raises the flame rating burden on every polymer part in the path. The long thermal ageing requirements typical of under-bonnet and battery-pack specifications are exactly where a non-blooming polymeric retardant beats a small-molecule one.

🔗 For the cable insulation side of the same assembly: TOPM - 125 °C-plus wire and cable plasticiser

📡 3. 5G Communications - base station and router components

Base station housings and internal structural parts, router and antenna components, and PPO/PPE-based dielectric parts where low dielectric loss matters alongside the flame rating. BPS's electrical performance and its compatibility with PPO blends are the reason it appears here rather than a cheaper general-purpose retardant.

🏠 4. High-End Appliances & Engineering Compounds

Appliance internal components, motor end caps, pump and fan housings, and glass-filled PET and PCT compounds generally. Also used in polyamide and polyester fibres and films where a thermally stable, non-migrating flame retardant is needed and halogen-free chemistry cannot reach the required rating at acceptable loading.

✅ Where BPS currently stands

Not on the REACH SVHC Candidate List. Not a PBB or PBDE, so not affected by the RoHS entries for those groups, and not a Stockholm Convention POP. Outside the named non-polymeric scope of the current ECHA aromatic-BFR restriction work. Polymeric structure gives low bioavailability, low migration and low extractability relative to small-molecule brominated retardants.

For a compounder facing a DBDPE notification obligation and a customer asking for an SVHC-free declaration, that combination is the practical answer available today.

⚠️ Three things we are not going to pretend

1. RoHS compliance is not REACH clearance. RoHS names PBBs and PBDEs; the SVHC Candidate List is far broader and independent of it. A supplier certificate saying "RoHS compliant" tells you nothing about SVHC status. Ask for both, separately.

2. The direction of travel for brominated chemistry is one way. ECHA has said explicitly that the DBDPE listing supports future restriction work on brominated flame retardants as a group, and is assessing whether other substances in the aromatic BFR family show PBT or vPvB properties. BPS is not in scope today. We are not going to tell you it is guaranteed to stay outside scope forever. If your product platform has a ten-year life, put a halogen-free evaluation on the roadmap in parallel - that is what a serious supplier says.

3. End-of-life is a real issue. Brominated retardants complicate mechanical recycling of engineering plastics and make recycled-content targets harder to hit. Like all brominated aromatics, BPS must not be openly burned; controlled incineration with proper flue gas treatment is required. Its structure lacks the diphenyl ether linkage of the PBDE generation, which places it in a better position on brominated dioxin formation, but that is not a reason to be casual about disposal.

📁 Supplied with every consignment:

📄 EU CLP-format SDS, 16 sections

📄 Batch COA from a CNAS-accredited laboratory, with MFR test conditions stated

📄 RoHS compliance statement and a separate REACH SVHC declaration - not one document doing both jobs

📄 Full TGA curve rather than single-point figures, on request

📄 Halogen content and heavy metal analysis for your material declaration

Q1. Can I drop BPS straight into a formulation that currently uses DBDPE?

Not as a one-for-one swap. DBDPE runs around 82% bromine against BPS at 66.33%, so you need roughly a quarter more BPS by weight to deliver the same bromine to the compound - which changes your filler balance and mechanical properties, not just your cost line. BPS also behaves differently in the melt: it is polymeric, so it raises viscosity more than a small molecule at equal loading, though this high-flow grade minimises that. Rebalance the formulation, re-run your UL 94 bars at your actual wall thickness, and re-check heat ageing. Budget a proper trial, not a substitution memo.

Q2. Do I still need antimony trioxide?

Yes. BPS is a bromine source, and bromine flame retardancy in engineering plastics relies on antimony synergy - the antimony forms volatile antimony halides that carry the halogen into the flame zone where radical scavenging happens. Without Sb₂O₃ you will need a great deal more BPS and probably still miss V-0. Start near a 3:1 bromine-to-antimony weight ratio. If your customer restricts antimony, tell us at the enquiry stage, because that changes the whole system design and BPS alone will not solve it.

Q3. Is BPS a PBDE? Is it banned anywhere?

No, and no. PBDEs (penta-, octa- and decaBDE) are diphenyl ethers and are POPs-restricted under the Stockholm Convention and named in RoHS. Brominated polystyrene is a brominated polystyrene backbone with no ether linkage, is a different substance entirely, and is not on the SVHC Candidate List or any current restriction list. Buyers do sometimes conflate all brominated retardants into one bucket - if your customer's specification bans "brominated flame retardants" as a blanket category, that is a commercial conversation about their spec, not a regulatory fact.

Q4. My moulded parts show black specks. Is it the flame retardant?

Possibly, but check the easy causes first. Degraded polymer from excessive residence time, contamination in the regrind stream, and screw or hot-runner deposits account for most speck complaints. If the retardant is genuinely at fault it will usually correlate with melt temperature - this grade passes a 320 °C calcination test, so specks appearing at a 280 °C melt point somewhere else. Send us the lot number, your measured melt temperature and residence time and we will help work through it.

Q5. Should I be moving to halogen-free instead?

Honestly, it depends on your part and your timeline. Phosphorus-based systems have made real progress in glass-filled polyamide, but they generally require higher loadings, can hurt electrical tracking performance and hydrolytic stability, and in some thin-wall applications still cannot reach V-0 without unacceptable property loss. Where halogen-free works, use it. Where it does not yet, BPS is the polymeric brominated option with the cleanest current regulatory position - and it buys you time to qualify a halogen-free system properly rather than in a panic. We would rather you plan that transition than be forced into it.

Q6. What sample and lead time can you offer?

Trial quantities are available for compounding qualification, with the full COA and TGA curve. Tell us your substrate (PBT, PET, PA6, PA66, PPO), glass loading, target UL 94 rating and wall thickness, colour requirement, annual volume and destination port. We reply within 24 hours with pricing, documentation and a starting loading recommendation - and if the high-MW grade is the better fit for your part, we will say so.

📩 Request BPS Price, Trial Sample & Full TGA Curve

Tell us your substrate and glass loading, target UL 94 rating and wall thickness, colour requirement, annual volume and destination port. We reply within 24 hours with pricing, batch COA with MFR conditions stated, EU CLP SDS, separate RoHS and REACH SVHC declarations, and a starting loading recommendation for your system. If a different BPS molecular weight suits your part better, we will tell you.