TSRC Taipol® SEBS 3150 is a linear styrene-ethylene/butylene-styrene triblock copolymer supplied as a free-flowing pellet. The nominal bound styrene content is 30 wt%. The ethylene/butylene midblock is fully saturated, which removes the main-chain unsaturation present in styrene-butadiene-styrene block copolymers and reduces oxidative chain scission during melt recycling and outdoor exposure. The polymer is registered under CAS 66070-58-4 and is used in thermoplastic elastomer compounding, hot-melt pressure-sensitive adhesive systems, polymer modification, and injection-molded or extruded articles requiring re-processability. Typical physical property data collated from TSRC technical documentation are shown in Table 1.

The stated values are lot-to-lot representative data, not specification limits. They are obtained from compression-molded test plaques after conditioning under 23 °C and 50% relative humidity. The grade is supplied with an antioxidant package that is active under normal melt-processing conditions but can be depleted by prolonged hold times above 230 °C.

What Distinguishes SEBS 3150 from SEPS and Higher-Styrene SEBS Grades?

The primary structural difference between TSRC Taipol® SEBS 3150 and SBS elastomers is the hydrogenated midblock. The ethylene/butylene segment has no unsaturated butadiene double bonds, which reduces thermal oxidation and permits sustained use in hot-melt formulations that would otherwise cross-link or embrittle. Relative to styrene-ethylene/propylene-styrene block copolymers, the ethylene/butylene midblock produces a different low-temperature flexibility and oil-extension response. SEPS grades often exhibit a lower midblock glass transition and can require different tackifier resin selection for equivalent pressure-sensitive adhesion.

Within the SEBS family, higher bound styrene levels above 30 wt% raise the polystyrene domain volume and increase modulus and hardness. Grades with lower melt flow rates typically provide higher tensile strength and lower melt processability, while higher melt flow rates improve low-viscosity wetting in sprayable hot-melt systems but reduce tensile recovery. The linear architecture of SEBS 3150 differentiates it from branched grades, which may exhibit higher melt strength, lower die swell, and different shear-thinning behavior in profile extrusion.

Melt Rheology and Barrel Temperature Limits in Twin-Screw Compounding

Compounding of TSRC Taipol® SEBS 3150 on a co-rotating twin-screw extruder with an L/D ratio between 25:1 and 40:1 is typically performed with a rising barrel profile from 180 °C to 210 °C and a die temperature of 200 °C. The melt temperature should not exceed 230 °C. At temperatures above 230 °C, the antioxidant package can be consumed rapidly, and the polymer may show yellowing, surface roughness, or lot-to-lot tensile loss. Pellets should be pre-dried at 80 °C for 2 h to 4 h when storage has occurred at relative humidity above 60%; while SEBS itself is not hydrolytically unstable, surface moisture can generate porosity in extruded profiles.

Oil extension with paraffinic white oil is the most common route for hardness adjustment. In a typical formulation sequence, the polymer is fed at the main throat, oil is injected after polymer plastication, and polypropylene or hydrocarbon resin is introduced through a downstream side feeder. When the oil loading exceeds 80 phr, split oil injection is recommended because a single injection before complete melting can cause wall slip, lower output stability, and inconsistent oil dispersion. Specific energy input in a 40:1 twin-screw extruder operating at 400 rpm with 80 phr oil typically falls in the range of 0.18 kWh/kg to 0.25 kWh/kg. Higher filler loadings of calcium carbonate above 40 wt% may require screw configurations with increased distributive mixing elements to prevent filler agglomeration and die-pressure fluctuations.

In injection molding, TSRC Taipol® SEBS 3150 can be processed at melt temperatures from 190 °C to 220 °C with mold temperatures between 20 °C and 60 °C. Mold temperature affects surface gloss and weld line strength. For parts with wall thickness below 1.5 mm, faster injection speeds are preferred to minimize premature solidification of the polystyrene end blocks, which can otherwise cause flow marks and poor knitting at weld lines. Published data for part-specific shrinkage are limited; mold shrinkage must be determined on the actual tool geometry.

When Hot-Melt PSA Formulations Require Saturated Midblock Stability

Hot-melt pressure-sensitive adhesive formulations based on TSRC Taipol® SEBS 3150 generally use a hydrocarbon tackifier, medium-viscosity naphthenic or paraffinic oil, and optionally a polypropylene homopolymer for elevated shear adhesion. The SEBS concentration commonly ranges from 15 wt% to 30 wt%. The saturated midblock prevents the rapid oxidative darkening and loss of peel strength observed with SBS-based systems in heated adhesive tanks. Open-tank aging under 180 °C for 24 h is a practical screening condition for pot-life stability. Loop tack and 180° peel strength can be evaluated under ASTM D6195-03 and ASTM D6864; shear adhesion failure temperature is tested under ASTM D4498 or ISO 19212:2006.

The low melt flow rate of SEBS 3150 relative to low-viscosity SEBS grades produces higher cohesive strength but requires higher adhesive application temperatures. In vertical non-woven lamination, viscosity at 180 °C often must be lowered by increasing oil content or by blending with a low-molecular-weight SEBS. Blending with more than 30 wt% of a low-viscosity SEBS can reduce peel strength and tensile set recovery, and the resulting adhesive may exhibit cohesive failure on polyethylene release liners if the coat weight is below 15 g/m².

For UV-stable outdoor adhesive films, hindered amine light stabilizers and benzotriazole UV absorbers are commonly added at combined loadings from 0.2 wt% to 0.6 wt%. The saturated midblock reduces the addition rate required for retention of peel adhesion after xenon arc exposure under ASTM G155-21. Without UV stabilizers, surface chalking may still occur after extended exposure, particularly in low-oil formulations.

Compression Set Measurements Do Not Scale Linearly with Oil Extension

Compression set of unfilled TSRC Taipol® SEBS 3150 measured under ASTM D395-18, Method B, at 70 °C for 22 h is typically below 40%. The value increases with oil content, but the change is not linear. At oil loadings below 60 phr, the compression set remains below 60% in many formulations. Above 80 phr, softening of the continuous phase can raise compression set above 80%, especially when the compound is held at service temperatures above 70 °C. This threshold effect is attributed to the disruption of the polystyrene network and oil migration to the surface under sustained compressive load.

Compression set can be reduced by blending SEBS 3150 with polypropylene homopolymer or by adding endblock-compatible resins. Addition of 10 wt% to 20 wt% polypropylene raises hardness and service temperature but reduces elastic recovery and increases processing viscosity. For sealing applications with continuous service above 90 °C, the compound should be evaluated under ISO 815-1:2019 at the expected service temperature, because static set values are strongly temperature dependent. TSRC Taipol® SEBS 3150 should not be blended with unsaturated elastomer systems where residual sulfur or amine-based accelerators are present; sulfur-vulcanized SBR crumbs introduced as recycled filler can cause premature oxidation and odor at the SEBS processing temperature.

When the bound styrene content is raised above 30 wt% in rigid compounds, the formulation moves toward a semi-crystalline or glassy response at room temperature. TSRC Taipol® SEBS 3150 itself is not a high-modulus material; flexural modulus of neat pressed film remains below 50 MPa. For applications requiring flexural modulus above 150 MPa, blending with high-styrene SEBS, polypropylene, or polyphenylene ether is required. The use of high-styrene SEBS raises the styrene domain continuity and improves creep resistance but reduces low-temperature flexibility and increases melt viscosity.

For medical device components such as tubing connectors, grips, seals, and specimen container liners, TSRC Taipol® SEBS 3150 offers a non-vulcanized elastomeric option that can be autoclaved at 121 °C. Repeated autoclave cycles may increase compression set and surface tackiness, especially in oil-extended compounds. Cytotoxicity, irritation, and sensitization testing must be performed on the final sterilized article under ISO 10993-5 and ISO 10993-10. Product-specific FDA status for food-contact uses should be confirmed against 21 CFR 177.1810, which covers styrene block polymers. The supplier should be consulted for current regulatory datasheets, because the product may be manufactured with antioxidants that are not suitable for all medical or long-term implant applications.

In overmolding onto polypropylene substrates, TSRC Taipol® SEBS 3150 obtains acceptable adhesion when the substrate surface temperature exceeds 90 °C at the interface during melt contact. The adhesion mechanism is primarily physical chain entanglement at the polypropylene surface, not covalent bonding. For high peel strength overmolded parts, a thin tie layer of polypropylene homopolymer or a high-styrene SEBS is sometimes used to increase interfacial compatibility. In direct overmolding without a tie layer, adhesion is reduced when the polypropylene substrate contains high levels of nucleating agents or slip additives at levels above 0.2 wt%, because migration of low-molecular-weight additives can create a weak boundary layer.

In extrusion of flexible tubing and profiles, the low melt flow rate of SEBS 3150 provides adequate melt strength for thin-wall shapes. Die swell is generally higher than that of plasticized PVC and lower than that of high-molecular-weight SBS. A typical single-screw extruder with a 24:1 L/D barrier screw can be used at screw speeds from 20 rpm to 80 rpm. Higher screw speeds above 100 rpm may produce melt-pressure fluctuations and sharkskin if the die land length is below 10 mm. Adding 0.05 wt% to 0.15 wt% of an external lubricant such as erucamide reduces surface defects but may impair adhesive bonding in later overmolding steps.

Published data for this specific configuration is limited in some high-filler flame-retardant compounds. In polyolefin-based halogen-free flame-retardant formulations, SEBS 3150 is used as a char-matrix modifier with ammonium polyphosphate and melamine polyphosphate loadings between 20 wt% and 35 wt%. The saturated midblock provides a less flammable hydrocarbon profile than unsaturated SBS, but the final compound still requires flame-retardant screening under UL 94 or IEC 60695-11-10. Zinc borate may be added at 2 wt% to 5 wt% to reduce smoke, but high zinc concentrations above 8 wt% can degrade the antioxidant package and lower tensile strength after extrusion.

TSRC Taipol® SEBS 3150 should not be stored in direct sunlight or in unventilated areas above 40 °C. Prolonged storage beyond the supplier-designated shelf life can shift melt flow rate and yellowing index even when pellets remain free-flowing. Before use in clear or light-colored compounds, a lot-specific yellowness index test under ASTM E313-20 is recommended.