Dynasol Calprene® SBS 484 is a linear styrene-butadiene-styrene block copolymer supplied as porous pellets for compounding operations requiring high hardness, elevated tensile strength, and controlled oil absorption. The nominal bound styrene content is 48 wt%; diblock content is below 1 wt%, which preserves the physical network formed by polystyrene domains. Specific gravity is listed as 0.96 under ISO 1183-1:2019. Representative tensile properties determined on compression-molded specimens are 31.0 MPa tensile strength and 700% elongation at break under ISO 37:2017. Hardness is reported as 90 Shore A under ISO 7619-1:2010. The 48 wt% styrene content differentiates the grade from Calprene® SBS 446, a 44 wt% styrene linear SBS, by raising hardness and tensile modulus while reducing low-temperature flexural compliance and tolerance for high loadings of extender oil.

At production scale, the grade is compounded on high-shear continuous mixers or twin-screw extruders. Typical barrel settings of 160–190 °C are used with 40:1 L/D co-rotating screws; viscous dissipation generated by the high-styrene backbone is sufficient to trigger torque-limited drive alarms if screw speed is not reduced during transition from 44 wt% styrene material. The difference in apparent shear viscosity is measurable by capillary rheometry following ISO 11443:2021, where the 48 wt% styrene grade exhibits higher pressure drop at 190 °C and 100 s⁻¹ than lower-styrene linear grades. Published data for this specific configuration is limited; fixed conditions must be validated on the target production line.

How Does the 48 wt% Styrene Level Alter the Mechanical Performance Envelope?

In styrenic block copolymers, bound styrene content controls the volume fraction of glassy polystyrene domains that act as physical crosslinks. At 48 wt%, the domain volume fraction is sufficiently high to raise the 300% tensile modulus to approximately 3.9 MPa under ISO 37:2017, while elongation at break remains approximately 700%. The same test on 44 wt% styrene linear grades typically reports lower modulus and higher elongation because the polybutadiene soft phase is more continuous. The increase in styrene content also raises Shore A hardness by approximately 6–8 points under ISO 7619-1:2010. This shift is advantageous in injection-molded footwear units and rigid plastic modification, but it compromises low-temperature flexibility and increases melt viscosity. In dynamic mechanical analysis between −80 °C and 100 °C under ISO 6721-1:2019, the polybutadiene glass transition remains near −85 °C, while the polystyrene domain transition broadens and shifts toward higher temperatures for the 48 wt% grade relative to 44 wt% material.

Specification Conformance and Test Method Cross-Reference

The values in Table 1 are typical lot-to-lot data reported by the manufacturer; they are not maximum or minimum specification limits unless explicitly marked.

Footwear soling compounds based on Dynasol Calprene® SBS 484 are typically formulated with 20–50 phr paraffinic or naphthenic oil, 10–25 phr polystyrene or high-styrene resin, and 5–15 phr filler. In injection molding on a 100-ton clamp force machine with 28 mm screw diameter, melt temperatures of 170–190 °C and mold temperatures of 25–40 °C produce molded soling with Shore A hardness above 70, depending on oil loading. Abrasion resistance measured under DIN ISO 4649:2021 is typically better than that of 44 wt% styrene compounds at equal hardness because the higher styrene domain volume supports the surface against repetitive shear. Flex resistance under ISO 4643:2008 at 23 °C is generally acceptable for casual footwear; at −20 °C crack initiation occurs earlier than in lower-styrene grades. Grade selection therefore depends on whether abrasion and dimensional stability or low-temperature flex fatigue is the limiting service requirement.

Compared with radial SBS grades of similar styrene content, the linear architecture of Dynasol Calprene® SBS 484 produces lower melt elasticity and lower die swell in capillary flow under ISO 11443:2021. This reduces dimensional variation in profile extrusion dies. In single-screw extrusion with a 24:1 L/D screw and 2.0 mm sheet die, the linear grade typically requires lower head pressure than a radial 48 wt% styrene SBS at equal throughput. The trade-off is lower green strength in uncured compounds and lower resistance to creep under sustained load, as measured by compression set under ISO 815-1:2019. Published comparative data for this specific configuration is limited; direct side-by-side extrusion trials are required to establish tool-specific pressure and swell constants.

When Substituting Calprene SBS 484 for Calprene SBS 446 in Plastic Modification

In general-purpose polystyrene modification, the higher styrene content of Dynasol Calprene® SBS 484 improves interfacial compatibility relative to 44 wt% styrene linear SBS. Notched impact resistance must be verified under ISO 180:2023 or ASTM D256-23 at the intended addition level, typically 5–15 wt%. The contribution to impact is processing-history dependent; dispersion on a co-rotating twin-screw extruder with a 13:1 L/D mixing zone and 300 rpm screw speed yields a different rubber particle size distribution than single-screw compounding. Melt mass-flow rate of the neat polymer is approximately 3.0 g/10 min at 200 °C/5 kg under ISO 1133-1:2022, lower than many lower-styrene linear triblocks. This requires higher melt temperature or slower screw speed during blending to avoid excessive shear heating. Published data for this specific blend combination is limited; the optimum dispersive mixing intensity should be determined by scanning electron microscopy with 5 kV acceleration voltage and image analysis of rubber particles in etched surfaces.

Hot-melt pressure-sensitive adhesive formulations based on Dynasol Calprene® SBS 484 use tackifying resins compatible with the styrene domains. Because the high styrene content raises cohesive strength, the grade is selected when shear adhesion failure temperature must be increased. Loop tack under FINAT FTM 9 is lower than that of low-styrene SBS at equal tackifier loading, while shear resistance under FINAT FTM 8 improves. Formulators compensate by raising midblock-compatible tackifier content by 5–10 phr or reducing aromatic resin loading to maintain tack. Open time on low-energy substrates must be validated because the high styrene content increases melt viscosity and may reduce wet-out on untreated polyethylene.

For dry blending prior to extrusion, 0.5–1.0 phr of processing aid is sometimes added to reduce adhesion to screw flights. The porous pellet morphology absorbs liquid process oils; a soak time of 20–30 min in a heated ribbon blender at 60 °C improves oil dispersion and reduces free-oil carryover into the feed throat. Free oil at the feed throat is monitored by visual inspection and can cause feed instability greater than ±5% in throughput as measured by loss-in-weight feeder output. This operational detail is more critical for Dynasol Calprene® SBS 484 than for lower-styrene grades because the high polystyrene domain volume reduces the rate of oil diffusion into the pellet core.

Asphalt modification uses Dynasol Calprene® SBS 484 when a harder polymer-rich binder is required at low polymer addition. Laboratory binder formulations with 4–6 wt% polymer in a 70/100 penetration-grade base bitumen are prepared in a high-shear rotor-stator mixer at 180 °C for 45 min. The high styrene content raises the softening point under ASTM D36 and increases the complex shear modulus measured with a dynamic shear rheometer under EN 14770:2023. Low-temperature flexibility measured by Fraass breaking point under EN 12593:2015 is less favorable than that of lower-styrene SBS because the high polystyrene domain content stiffens the binder. For applications requiring compliance with EN 14023:2013, the final binder must be tested against the exact performance-graded specification of the road agency; published data for this specific formulation is limited.

Operational boundaries apply to thermal history and compounding additives. Barrel temperatures above 200 °C for residence times exceeding 8 min can produce non-reversible viscosity loss under ISO 11443:2021 because of chain scission. Porous pellets stored at relative humidity above 60% may require drying at 60–70 °C for 2 h before extrusion. Aromatic process oils above approximately 30 phr plasticize the polystyrene domains and can reduce Shore A hardness by more than 10 points under ISO 7619-1:2010. Amine-based additives above 2 phr may interact with the thermal stabilizer package; oxidative induction time under ISO 11357-6:2018 must confirm stability before lot approval. Food-contact suitability is application-specific and must be validated under 21 CFR 177.1810 or EU Regulation 10/2011 for the finished article. For industrial use, compliance with REACH registration obligations applies; the product is not intended for use in finished electrical and electronic equipment unless assessed against RoHS Directive 2011/65/EU.