SBS vs SEBS: Which TPE Base Polymer Your Part Needs
SEBS is SBS with the double bonds removed. That single chemical change - hydrogenation of the butadiene mid-block - is what gives SEBS its substantially better resistance to UV light, heat and oxidation, and it is the most consequential difference between two TPE grades that a hardness figure will never reveal.
Key takeaways
- SBS is styrene-butadiene-styrene; SEBS is styrene-ethylene-butylene-styrene, produced by hydrogenating SBS.
- The unsaturated double bonds in SBS butadiene are chemically reactive sites for UV and oxidative attack. Hydrogenation removes them.
- SBS is more economical and processes readily. SEBS holds up far better outdoors, at elevated temperature and over a long design life.
- Five grades in this catalogue are SBS-based, all carrying an S suffix in the grade code.
- A stabiliser package helps, but it does not convert an SBS compound into a SEBS one.
The chemistry, briefly
Both materials are styrenic block copolymers. Both have hard polystyrene end blocks that cluster into physical cross-links, and a soft rubbery mid-block that provides the elasticity. That architecture is what lets a thermoplastic elastomer behave like rubber while still melting and reflowing like a plastic.
The difference is the mid-block. In SBS it is polybutadiene, which retains carbon-carbon double bonds along the chain. Those double bonds are reactive: ultraviolet light and atmospheric oxygen attack them, and the result is chain scission or cross-linking that shows up as surface chalking, hardening, cracking and loss of elongation.
Hydrogenation saturates those bonds, converting the polybutadiene mid-block into an ethylene-butylene one. The elastic behaviour is largely preserved; the reactive sites are gone. That is SEBS.
What it means in service
| Property | SBS | SEBS |
|---|---|---|
| UV and weathering resistance | Limited | Substantially better |
| Thermal and oxidative stability | Lower | Higher |
| Relative cost | Lower | Higher |
| Processing | Easy | Easy |
| Typical use | Indoor, short life, cost-driven | Outdoor, warm service, long life |
Which FARRPRENE grades are SBS-based
Five of the 49 grades in this catalogue are SBS-based. They are identifiable by the S suffix on the grade code:
| Grade | Hardness | Tensile | Elongation | Stabilisation |
|---|---|---|---|---|
| FARRPRENE IF658AS | 65 Shore A | 5.5 MPa | >800% | Heat stabilised |
| FARRPRENE IF701AS | 70 Shore A | 5 MPa | >800% | Heat stabilised |
| FARRPRENE IF750AS | 75 Shore A | 3.5 MPa | >550% | UV and heat stabilised |
| FARRPRENE IF800AS | 80 Shore A | 6 MPa | >650% | Heat stabilised |
| FARRPRENE IF901AS | 90 Shore A | 5.5 MPa | >500% | UV and heat stabilised |
All five are injection, filled, natural-coloured grades. The remaining 44 grades in the catalogue are SEBS-based.
Choosing between them
Use an SBS grade when the part lives indoors, the service temperature is moderate, the design life is short to medium, and cost per part is the governing constraint. Interior components, short-life consumer items and cost-sensitive moulded parts are all reasonable candidates.
Use a SEBS grade when the part sees sunlight, warm air, or needs to still perform in several years. Every extrusion grade in this catalogue is SEBS-based, which is consistent with extruded profiles frequently ending up in exterior applications.
If you are replacing an SBS grade with a SEBS equivalent at the same hardness, check melt flow as well - the two are formulated independently, and matching hardness does not mean matching processability.
All values quoted are typical average values from a limited sample set, not a formal specification. Request the signed datasheet for current values.
Scope note. The guidance on this page is based on published mechanical properties - hardness, tensile strength, elongation, melt flow, specific gravity, base polymer and stabilisation. Food contact, skin contact, biocompatibility, flame retardancy, halogen-free formulation and electrical performance are not characterised in the public catalogue and require a separately qualified compound and testing. Contact us to qualify a grade against any of those.
Frequently Asked Questions
Is SEBS better than SBS?
Better for durability, not better in every respect. SEBS resists UV, heat and oxidation substantially better because hydrogenation removes the reactive double bonds in the butadiene mid-block. SBS is more economical and processes just as readily, so for an indoor, moderate-temperature, cost-driven part it can be the correct engineering choice.
How can I tell whether a TPE compound is SBS or SEBS based?
The datasheet or the supplier should state it. In the FARRPRENE range the base polymer is published in the grade notes and the SBS grades carry an S suffix on the code - IF658AS, IF701AS, IF750AS, IF800AS and IF901AS. If a supplier will not tell you the base polymer, treat that as a reason to ask harder, because it governs weathering behaviour.
Does a UV stabiliser make SBS as durable as SEBS?
No. A UV stabiliser package slows the degradation of an SBS compound and is worth having, but it does not remove the unsaturated double bonds that make the polymer susceptible in the first place. For sustained outdoor exposure a SEBS base is the more reliable starting point.
Can SBS and SEBS grades be recycled the same way?
Both are thermoplastic, so both can be re-melted and reprocessed without a curing step, and production scrap from either can be reground. They should not be mixed indiscriminately, though, because the blend inherits the weathering weakness of the SBS fraction.
Which base polymer is used for outdoor weatherstrip and seals?
SEBS, in almost all cases, and preferably with a UV stabiliser package as well. In this catalogue every extrusion grade is SEBS-based, and the UV-stabilised extrusion grades are the usual starting point for exterior sealing profiles. Service life still depends on exposure, colour and section geometry, so qualify against the real duty cycle.
Related guides
- How to Choose a TPE Grade: A Specifier's Guide
- UV and Heat Stabilised TPE: What the Callouts Mean
- Filled vs Unfilled TPE: What Specific Gravity Tells You
- TPE Melt Flow Index: Why Injection and Extrusion Grades Are Not Interchangeable
About the FARRPRENE range
FARRPRENE is the thermoplastic elastomer (TPE) compound range of Farr Polychem FZCO, a polymer compounder based in Jebel Ali Free Zone, Dubai, United Arab Emirates, supplying the UAE, the wider MENA region and Europe. The range covers injection moulding and extrusion compounds from soft gel-like Shore A grades through rigid Shore D grades, in unfilled translucent and filled natural variants, colour-matchable to a customer reference, with free samples and technical datasheets available on request. Browse the full grade catalogue, see every grade side by side on the comparison table, or request a sample.
FARRPRENE GRADES
Grades commonly specified for industrial applications
| GRADE | HARDNESS | TENSILE (MPa) | TYPICAL USE |
|---|---|---|---|
| IEU150AInjection / Extrusion / Unfilled | 15 Shore A | 3 | Vibration-damping pads and soft mounts |
| IF752AInjection / Filled | 75 Shore A | 5.5 | Bushings, spacers and wear components |
| IF900AInjection / Filled | 90 Shore A | 5.5 | Hard bushings and near-rigid flexible parts |
Typical average values from a limited sample set; not a formal specification. Request the signed datasheet for current values.
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