SEBS/SIS Thermoplastic Elastomers: Applications, Selection and Common Mistakes

Thermoplastic elastomers (TPE) combine the elasticity of rubber with the processability of plastic. Among them, SEBS (hydrogenated SBS) and SIS (styrene-isoprene-styrene) offer excellent ageing resistance, ozone resistance and low odour, making them important alternatives to traditional vulcanised rubber. SEBS is the hydrogenated form of SBS: the double bonds in the molecular chain become saturated, so yellowing and weather resistance improve dramatically, making it the preferred base for premium TPE modification, transparent elastomers and human-contact products.

Typical Application Areas

Adhesives: because its central polyisoprene segment is soft and its polystyrene end blocks increase tack, SIS is the core elastomer in hot melt pressure-sensitive adhesives (HMPSA), widely used in labels, hygiene products and courier sealing tapes. SEBS is used more in overmoulding (TPE overmoulding of PP/ABS), soft toys, medical catheters, food-contact products and cable sheathing. In shoe midsoles, sports equipment grips and automotive interior soft-touch layers, SEBS-based systems also dominate.

Selection Points

For procurement and formulation, watch: oil content and hardness (white oil filling lowers hardness and improves feel, but too much causes bloom), styrene content (determines strength and resilience), melt index (MI) (determines the injection/extrusion processing window) and whether it is oil-filled pellet. SEPS (hydrogenated SIS) is more advantageous in premium transparent adhesives and cosmetic thickeners. For grade comparisons or samples, see the Product Centre or submit an Online Inquiry directly.

Common Mistakes

Mistake one: using SBS where SEBS is required — SBS has poor weatherability and yellows easily, so it cannot be used outdoors or under long-term load. Mistake two: looking at hardness but ignoring oil content — at the same hardness, oil-filled and neat resin systems differ hugely in properties. Mistake three: ignoring overmoulding compatibility — SEBS bonds well to PP, but overmoulding PC/ABS requires special polar-modified grades. For overall synthetic rubber selection, see our Synthetic Rubber Selection in Practice article.

Procurement Advice

Define the application scenario (food contact / medical / general industrial), the hardness range and certification requirements, then ask the supplier for the corresponding grade COA and samples. Haiyu Zhonglong can provide specification sheets for SEBS/SIS/SEPS and other elastomers with samples from 1kg/25kg. Contact Us to get started.