Calprene® SBS 413 is a linear styrene-butadiene-styrene block copolymer produced by Dynasol through anionic solution polymerisation and supplied as a free-flowing porous pellet. The grade designation 413 identifies a medium-to-high solution-viscosity SBS within the Calprene range. The molecular architecture consists of two terminal polystyrene blocks and a central polybutadiene block; the bound styrene content is 30% by weight under ISO 2453. The polybutadiene midblock retains unsaturation, which contributes to solubility in hydrocarbon solvents, thermo-oxidative degradation sensitivity, and sulphur crosslinkability when used in polymer-modified bitumen. The polystyrene blocks provide physical crosslinks that soften near 95–100 °C; below this temperature the domains act as reinforcing nodes. Published data for the exact 1,2-vinyl microstructure of this specific product configuration is limited.

How does the specification profile of Calprene® SBS 413 compare with adjacent Calprene SBS grades?

The following table lists manufacturer-reported typical data for compression-moulded sheet prepared at 150 °C and conditioned at 23 °C and 50% relative humidity for 24 h before testing. The values are not production release limits; lot-to-lot variance should be checked against the certificate of analysis.

The medium-viscosity profile separates Calprene® SBS 413 from lower-viscosity linear grades such as Calprene® SBS 412, which is reported to dissolve faster in solvent-borne adhesives but generates less high-shear melt strength in extrusion. Calprene® SBS 411 is described in the available product literature as a radial SBS; radial architectures typically exhibit stronger shear thinning and higher zero-shear viscosity at equivalent molecular weight compared with linear architectures. Direct substitution among these grades without rebalancing solvent solids, mixer residence time, or screw speed can shift Brookfield solution viscosity, dispersion quality in bitumen, and melt pressure upstream of the die.

When bitumen mixing temperatures exceed 180°C under high-shear dispersion

In polymer-modified asphalt, Calprene® SBS 413 is typically metered into paving-grade bitumen at 3–7% by weight of the finished binder. The bitumen is preheated to 160–180 °C in an agitated tank, and the polymer is dispersed with a rotor-stator high-shear mixer or an inline colloid mill operating at 12–20 m/s tip speed. Batch records from polymer-modified bitumen lines show that the dissolution window is controlled by the balance between polymer swelling and thermo-oxidative chain scission. A sustained temperature excursion above 190 °C for more than 4 h can reduce elastic recovery under ASTM D6084 and ring-and-ball softening point under ASTM D36. Operators commonly cap mixing temperature at 185 °C and apply a nitrogen blanket or antioxidant top-up when storage time exceeds 24 h. Published data for the exact oxidative induction time of this grade in bitumen is limited.

Storage stability is evaluated by ASTM D7173 at 163 °C for 48 h. A top-bottom softening point difference above 2.5 °C indicates phase separation or incomplete dispersion. The grade does not inherently provide storage-stable high-loading binders; formulations may require sulphur or reactive stabilisation at 0.05–0.15%. Excessive crosslinker dosing can create a gelled binder that fails ductility testing under ASTM D113. The required crosslinker level is binder-dependent and must be established by pilot trials because published data for this specific configuration is limited.

In solvent-borne adhesive compounding, Calprene® SBS 413 is dissolved in toluene, cyclohexane, or mixed aliphatic/aromatic solvent systems at solids contents of 20–30%. A low-speed disperser with a sawtooth blade is used, and the polymer is added as a slow stream to avoid fisheye formation. Once solvated, the solution can be let down with additional solvent for roll, brush, or spray application. Tackifier selection follows the polystyrene endblock solubility; aromatic-modified aliphatic resins and rosin ester resins with softening points of 85–105 °C are common. Peel adhesion is measured under ASTM D3330/D3330M at 180° angle on stainless steel panels after a 24 h dwell at 23 °C. Published data for this exact grade and adhesive formulation is limited, so compounding trials are required to establish tackifier ratio, open time, and solvent release.

Screw plastication and predrying requirements for injection moulding of Calprene® SBS 413

Injection moulding of Calprene® SBS 413 is performed on a reciprocating screw machine with a general-purpose screw having an L/D ratio of 20:1–24:1 and a compression ratio of 2.5:1–3.0:1. Barrel zone settings are typically 160 °C rear, 175 °C centre, 190 °C front, and 190–200 °C nozzle. Mould temperatures from 20 °C to 50 °C are sufficient for solidification because the polystyrene domains vitrify quickly. Pellets stored at relative humidity above 60% require predrying at 70 °C for 2 h in a desiccant dryer with a dew point no higher than -40 °C. Moisture passing through the barrel without drying can cause surface splay and reduce weld-line tensile strength. Hot-runner systems should operate below 200 °C; above this temperature, the butadiene midblock may form gel unless residence time is limited to 5 min and the manifold is blanketed with nitrogen.

Experience on production-scale moulding machines indicates that uncontrolled screw backpressure above 10 bar can raise melt temperature beyond set point because of viscous dissipation. Start-up purging with a general-purpose polyethylene or polypropylene is recommended to displace degraded material after heater soak periods longer than 30 min.

Extrusion of Calprene® SBS 413 for sheet and profile is performed on a single-screw extruder with an L/D ratio of 24:1–30:1, a barrier screw with a compression ratio of 2.5:1, and barrel temperatures from 150 °C to 190 °C. The melt temperature at the die should not exceed 200 °C. A screen pack with 60/80/100 mesh protects the die from gel particles. Calendering and thermoforming require the sheet to be cooled below 60 °C before winding to avoid blocking. The unsaturated polybutadiene sequence makes the melt sensitive to oxygen; therefore long heat-up cycles in the extruder should be purged before production.

Polypropylene impact modification with Calprene® SBS 413 is carried out in a co-rotating twin-screw extruder with an L/D ratio of 40:1 and barrel temperatures of 180–210 °C. The SBS concentration is typically 5–20% by weight. Screw speed is set between 250 rpm and 500 rpm; higher screw speeds increase melt temperature through viscous dissipation and can degrade the unsaturated butadiene segments. The viscosity ratio between the dispersed SBS phase and the polypropylene matrix controls particle size; when the ratio exceeds approximately 4:1, coalescence and coarse morphology reduce notched Izod impact strength measured under ISO 180:2023. Twin-screw compounding lines produce more uniform dispersion when a flat temperature profile and distributive mixing elements are used instead of aggressive kneading blocks. Published data for the exact viscosity ratio of this grade against specific polypropylene melt flow rates is limited.

Blends with general-purpose polystyrene are prepared at 10–30% SBS content to improve impact strength while maintaining flexural modulus. Melt mixing below 180 °C may leave unmelted SBS domains; mixing above 210 °C risks yellowing. Notched impact is assessed under ISO 179-1:2020 or ASTM D256-23, depending on the final specification.

Footwear compound formulations use Calprene® SBS 413 in blends with polystyrene and hydrocarbon resins. Typical formulations contain 50–70% SBS, 20–40% polystyrene, and 5–15% plasticiser oil. Mixing is performed in an internal mixer with a fill factor of 0.75–0.85 and cooling water at 40–60 °C. The compound is then granulated and injection moulded into soles. Slip resistance and abrasion are measured under ASTM D5963-22 or ISO 4649:2021. Published data for specific compound values in this configuration is limited.

Finished articles based on Calprene® SBS 413 should not be exposed continuously to aromatic hydrocarbon fluids, ketones, or strong oxidising acids because the polystyrene domains swell and the unsaturated butadiene midblock undergoes chain scission. Outdoor applications require ultraviolet stabilisers and antiozonants; unprotected compression-moulded sheet crazes and loses tensile strength under ISO 1431-1:2022 ozone exposure. Processing above 220 °C is permissible only for very short residence times below 5 min; otherwise gel particles can form and appear as surface defects in extruded profiles or moulded soles. These incompatibilities define the operating envelope for compounding, moulding, and bitumen modification.