SBR
also Buna-S
SBR (Buna-S) is a styrene-butadiene copolymer and the highest-volume general-purpose synthetic rubber, supplied as emulsion (E-SBR), solution (S-SBR), oil-extended and black-masterbatch compounds from 40 to 90 Shore A.
Reference datasheet — SBR is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SHA60 condition
SBR grades and fills
SBR is supplied in 14 conditions, soft to hard. SHA60 is the default FabDigit quotes; the values on this page are for it.
Compare all 14 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Sponge / closed-cell foamed SBR | Choose for low-force sealing, gasketing, padding and insulation where compressibility, not strength, is the requirement. | 2 | 200 | 20 Shore A | |
Shore A 40 | Pick for soft seals, low-closure-force gaskets and cushioning where high flexibility matters more than strength. | 9 | 550 | 6 Shore D | |
Flame-retardant SBR compound | Use for underground mining belts, cable jackets and transit parts requiring flame and smoke ratings. | 10 | 300 | 70 Shore A | |
Shore A 50 | Balanced softness and strength for flexible gaskets, diaphragms and vibration pads. | 12 | 480 | 8 Shore D | |
Oil-extended SBR | Pick when processing softness and cost per volume matter (tire treads, soft mats); oil lowers strength and increases extractables. | 13 | 480 | 55 Shore A | |
SHA60Default Shore A 60 | Default workhorse compound for mats, gaskets, hose covers and molded goods needing wear resistance at lowest cost. | 15 | 400 | 12 Shore D | |
Weather/ozone-protected SBR | Specify for outdoor-exposed mats, seals and covers; antiozonant/wax and high black loading slow cracking but SBR still ages faster than EPDM. | 15 | 380 | 65 Shore A | |
Emulsion-polymerized SBR | Default commodity raw polymer route: cheapest, easy mixing and extrusion, used in general rubber goods and truck-tire compounds. | 16 | 400 | 13 Shore D | |
Shore A 70 | Use where extrusion resistance and wear life dominate: tire treads, conveyor covers, wheels, bushings. | 18 | 350 | 20 Shore D | |
High-styrene SBR resin | Blended in to stiffen and harden compounds (shoe soles, hard rolls, hard mats); brittle and not elastomeric on its own. | 18 | 120 | 50 Shore D | |
Shore A 80 | For rollers, scraper blades, skirting and pads where high stiffness and abrasion resistance are needed. | 20 | 250 | 28 Shore D | |
SBR/NR blend compound | Blend NR in when higher tear strength, tack and lower heat build-up are needed while keeping SBR cost and wear resistance. | 20 | 450 | 60 Shore A | |
Shore A 90 | Chosen for hard wheels, mallet faces and stiff pads; elongation and tear resistance are sacrificed. | 21 | 170 | 38 Shore D | |
Solution-polymerized SBR | Choose for low-rolling-resistance / high-wet-grip tire treads and cleaner, more uniform compounds with silica reinforcement. | 22 | 450 | 15 Shore D |
Supply forms, finishes and certifications
Ways SBR is supplied — form, process route, surface or paperwork — without a datasheet of their own. A reinforced fill changes stiffness and elongation; the branded products above carry the filled values.
| Option | What it is | Type |
|---|---|---|
CB-MB | Carbon-black masterbatch SBR | Reinforcement |
FDA | Food-grade / FDA white SBR | Certification |
What is SBR?
SBR (Buna-S) is a styrene-butadiene copolymer and the highest-volume general-purpose synthetic rubber, supplied as emulsion (E-SBR), solution (S-SBR), oil-extended and black-masterbatch compounds from 40 to 90 Shore A. Engineers use it for abrasion resistance at low cost in moulded goods, extruded profiles, calendered sheet and sponge. Typical cured properties are 15 MPa tensile strength, 400 % elongation, about 5 MPa modulus and service to 100 °C; oil, fuel and ozone resistance are poor and building tack is lower than natural rubber, so use NBR for oil or EPDM for weathering. SBR has a density of 1.15 g/cm³ (0.0415 lb/in³), lighter than 57% of polymer grades. Its glass-transition temperature is -52°C (-62 °F). SBR has a tensile strength of 15 MPa (2.18 ksi), weaker than 74% of polymer grades. Elongation at break is 400% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi).
What is SBR used for?
- tire treads
- footwear soles
- belts
- gaskets
- flooring
Advantages
- Ductile — tolerates forming and impact — 400%, better than 86% of polymer grades
- Low embodied carbon — 3.2 kg CO₂/kg, better than 81% of polymer grades
Limitations
- Needs corrosion protection — 50/100, worse than 97% of polymer grades
- Difficult to machine — 25/100, worse than 93% of polymer grades
- Low stiffness — 0.01 GPa (7.25×10⁻⁴ Msi), worse than 89% of polymer grades
- Absorbs moisture — dry before molding — 1%, worse than 84% of polymer grades
- High mold shrinkage — 2%, worse than 81% of polymer grades
SBR properties
Typical room-temperature values for SBR-SHA60; bars are the position among polymer grades.
Physical4
SBR has a density of 1.15 g/cm³ (0.0415 lb/in³), lighter than 57% of polymer grades. Its glass-transition temperature is -52°C (-62 °F).
Mechanical9
SBR has a tensile strength of 15 MPa (2.18 ksi), weaker than 74% of polymer grades. Elongation at break is 400% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi).
Thermal8
SBR is rated for continuous service to 100°C (212 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 72% of polymer grades. Thermal expansion is 220 µm/m·K (122.2 µin/in·°F).
Electrical5
SBR is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10⁸ Ω·m.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 97% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of SBR takes about 95 MJ of energy and emits 3.2 kg of CO₂ — less than 70% of polymer grades. Typical recycled content is 5%.
Manufacturability5
SBR's machinability is poor (25/100, worse than 93% of polymer grades); weldability not recommended (12/100); formability very good (75/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. SBR is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SBR
Is SBR easy to machine?
Cured SBR is die-cut, waterjet-cut or ground rather than machined; use sharp knives with water/soap lubrication and freeze or backing plates for close tolerances.
Can SBR be welded?
Not weldable as a thermoplastic; join by uncured splicing and re-vulcanization, hot bonding to metal (Chemlok primers) or cyanoacrylate/contact adhesive for cured parts.
Can SBR be formed, bent or molded?
Mixed on two-roll mill/Banbury, then calendered, extruded, compression/transfer/injection molded and sulfur-cured at ~150–180 °C; good green strength and easy extrusion, but tack is lower than NR.
SBR chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| styrene (bound)23–24 % typical for E-SBR 1500/1502; ≥50 % in high-styrene resins | 15 – 40 | 23.5 |
| carbon black (N330/N550/N660)phr in the compound, not wt % of polymer | 0 – 80 | 50 |
| precipitated silicaphr; primary filler in S-SBR green-tire treads | 0 – 80 | 0 |
| process/extender oilphr; 37.5 phr in OE-SBR 1712 | 0 – 50 | 10 |
| sulfur + acceleratorsphr, sulfur cure system | 1.5 – 4 | 2 |
| zinc oxidephr activator | 3 – 5 | 4 |
| stearic acidphr activator | 1 – 3 | 2 |
| antioxidant / antiozonantphr, 6PPD/TMQ type | 0.5 – 3 | 1.5 |
| butadienebalance of the copolymer backbone | balance |
What surface finishes work on SBR?
Surfaces can be buffed, ground or texture-molded; use chlorination or plasma to improve paint/adhesive adhesion, and post-cure oven cycle to reduce blooming and volatiles.
Equivalent designations
Standards and trade names that resolve to SBR in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Buna-S
How much does SBR cost?
SBR is a standard-cost polymer ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SBR — frequently asked
What is SBR used for?
SBR is typically used for tire treads, footwear soles, belts, gaskets and flooring. In short: lowest-cost general-purpose rubber; better abrasion than NR; tire-tread workhorse.
What is the tensile strength of SBR?
SBR has a typical tensile strength of 15 MPa (2.18 ksi) — weaker than 74% of polymer grades. Strength varies by condition: see the 14 listed tempers.
Is SBR easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of polymer grades). Cured SBR is die-cut, waterjet-cut or ground rather than machined; use sharp knives with water/soap lubrication and freeze or backing plates for close tolerances.
Can SBR be welded?
Not readily — weldability is rated not recommended (12/100). Not weldable as a thermoplastic; join by uncured splicing and re-vulcanization, hot bonding to metal (Chemlok primers) or cyanoacrylate/contact adhesive for cured parts.
What surface finishes work on SBR?
Surfaces can be buffed, ground or texture-molded; use chlorination or plasma to improve paint/adhesive adhesion, and post-cure oven cycle to reduce blooming and volatiles.
Can SBR be formed, bent or molded?
Mixed on two-roll mill/Banbury, then calendered, extruded, compression/transfer/injection molded and sulfur-cured at ~150–180 °C; good green strength and easy extrusion, but tack is lower than NR.
What is the maximum service temperature of SBR?
SBR is rated for continuous use to about 100°C (212 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does SBR cost?
SBR is a standard-cost polymer ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM D2000 — Classification System for Rubber Products in Automotive Applications — ASTM (2020)
- ASTM D1418 — Rubber and Rubber Latices Nomenclature — ASTM (2017)
- Vanderbilt Rubber Handbook, 14th ed. — R.T. Vanderbilt (2010)
- The Rubber Formulary / Rubber Technology Handbook — Noyes / Hanser (1999)
- IISRP Synthetic Rubber Manual (SBR grade series) — IISRP (2012)
- Materials Selection in Mechanical Design (elastomer property/eco data) — Ashby / Elsevier (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.