RUSS Shuiskaya SBS 1385 is introduced as a styrene-butadiene-styrene block copolymer supplied in porous pellet or crumb form. The designation places the material within the linear SBS class, in which polystyrene end blocks are coupled through a polybutadiene midblock. The numerical suffix 1385 distinguishes the grade from SBS 1301, SBS 1305, and similar materials on the basis of nominal bound-styrene content, melt mass-flow rate, and coupling efficiency. Product-specific values for this Shuiskaya grade are not fully itemized in the present source; consequently, the physical-property discussion below uses standard test methods and class-typical ranges for linear SBS with approximately 30 wt% bound styrene, unless a supplier certificate is explicitly referenced. The material is characterized under ISO 1133-1:2022 for melt mass-flow rate, ASTM D1238 for melt flow indexing, ISO 2781 or ASTM D792 for density, ISO 37 or ASTM D638 for tensile properties, and ASTM D2240 for hardness. In use, RUSS Shuiskaya SBS 1385 is directed toward bitumen modification, polymer compounding, hot-melt adhesives, and footwear soling compounds. The butadiene midblock imparts elastomeric recovery; the styrene end blocks provide physical crosslinks that melt above the glass transition of polystyrene, permitting reprocessing without sulfur cure. The grade should be stored below 35°C and protected from direct UV exposure to minimize oxidative degradation of the unsaturated polybutadiene segment.

What Processing Constraints Govern Twin-Screw Extrusion of SBS 1385?

Compounding of RUSS Shuiskaya SBS 1385 in co-rotating twin-screw extruders is governed by the shear sensitivity of the polybutadiene midblock and the thermal stability limit of the styrene domains. A processing range for linear SBS grades of this class is 130–190°C across feed, barrel, and die zones, with the feed throat held below 50°C to prevent pellet bridging. Extruders with L/D ratios of 32:1 to 44:1 and segmented screw elements are suitable; distributive mixing elements should dominate dispersive kneading blocks because excessive shear at 180–200°C can initiate chain scission and increase diblock content. Specific energy input for unfilled SBS is typically 0.15–0.25 kWh/kg; a melt temperature above 210°C is not recommended for extended residence periods. Published rheological data for linear SBS grades with approximately 30 wt% styrene report apparent melt viscosities in the range of 500–2000 Pa·s at 190°C and 100 s⁻¹. Radial SBS grades may exceed 3000 Pa·s under identical conditions, which is one reason grade substitution is not a direct viscosity swap. Pre-drying is required when surface moisture exceeds 0.1 wt%; porous SBS crumb exposed to air at RH above 60% should be dried at 70–80°C for 2–4 h in a dehumidifying hopper dryer. For oil-extended formulations, paraffinic or naphthenic extender oil is introduced through liquid injection at the first downstream vent after the melt seal; oil addition of 20–60 phr is typical for sealant and footwear compounds, while asphalt modification may use the neat polymer at 3–5 wt% of binder. Grade-specific optimization is required because RUSS Shuiskaya SBS 1385 certificates may differentiate melt-flow characteristics from class averages.

Bituminous binder modification with RUSS Shuiskaya SBS 1385 proceeds through high-shear mixing at binder temperatures that balance dissolution and oxidative aging. Addition at 3–5 wt% of total binder is common for paving-grade penetration grades, with mixing at 180–190°C for 60–120 min using a rotor-stator high-shear mixer or low-speed paddle after initial swelling. The polymer network forms only after the polybutadiene midblock absorbs maltene fractions and the polystyrene end blocks retain a physically crosslinked domain structure. When the grade contains a low diblock fraction, elastic recovery and storage stability tend to improve; high diblock content may reduce mixing time but can lower elasticity and increase temperature susceptibility. Phase inversion and network formation are monitored by softening point, elastic recovery, and fluorescence microscopy. Binder performance is evaluated under EN 14023 framework specifications, with softening point determined by EN 1427, penetration by EN 1426, elastic recovery by ASTM D6084, and storage stability by EN 13399. In vertical storage tanks, the modified binder should remain agitated at 160–170°C and under nitrogen blanketing if storage exceeds 48 h to limit surface skinning and oxidative age hardening. Comparison of SBS grades in this application is primarily based on hot-storage separation values; a difference of 2°C in softening-point top-bottom separation can determine whether a tank recirculation system is required. Published product-specific values for Shuiskaya 1385 in this configuration are limited; plant trials against a reference SBS grade are recommended before full substitution on a production line.

Comparative Behaviour of Linear SBS 1385 and Radial Coupled Grades Under Tensile Protocols

Material selection between RUSS Shuiskaya SBS 1385 and competing SBS grades is driven by melt-flow rate, coupling architecture, and tensile response. The following matrix presents standard test methods and class-typical ranges for linear SBS grades with near 30 wt% bound styrene; these values are not certificates for Shuiskaya 1385 and must be confirmed against lot-specific analysis.

Property	Test method	Class-typical range for linear SBS
Melt mass-flow rate	ISO 1133-1:2022 at 200°C, 5 kg	0.5–5 g/10 min
Density	ISO 2781	0.93–0.95 g/cm³
Tensile strength	ISO 37 Type 1A	12–20 MPa
Elongation at break	ISO 37 Type 1A	500–800%
Shore A hardness	ASTM D2240	60–80
Bound styrene	ISO 21561 or FTIR	28–33 wt%

Radial SBS grades, in contrast, provide higher melt viscosity and often higher tensile strength at lower addition levels because the star-shaped architecture imposes greater chain entanglement density. This translates into a lower melt mass-flow rate under identical test conditions and a more pronounced shear-thinning response. For compounding operations that demand fast flow and lower torque, linear grades such as the 1385 designation are generally preferred; for bitumen modification requiring high softening-point elevation at minimal polymer content, radial grades may be selected. The difference in processability is measurable in injection-molded footwear soles: linear SBS fills thin-wall sections at lower injection pressure, whereas radial SBS may produce better abrasion resistance and lower tensile set. The choice of RUSS Shuiskaya SBS 1385 over SBS 1301, SBS 1401, or radial grades is therefore a trade-off between melt flow, elasticity, and compounding energy, not a uniform substitution. Diblock content and coupling efficiency should be obtained by GPC or supplier certificate, because two grades with similar styrene content can differ substantially in hot-storage stability and tensile recovery if the diblock fraction differs by more than 5 wt%.

When Moisture and Long-Term Storage Become Process Risks

Because SBS crumb is porous, moisture uptake in humid climates can generate melt-phase volatiles that cause foaming at die exit and reduced tensile strength in extruded profiles. Moisture concentrations above 0.1 wt% are sufficient to produce visible surface defects in thin-gauge compounds. Storage silos should be purged with dehumidified air at -20°C dew point or lower. Bags should be kept unopened until use; if partially used, re-sealing under nitrogen is required to limit oxidation of the unsaturated polybutadiene segment. The material is sensitive to ozone and UV exposure, so storage areas should not contain ozone-generating equipment or high-intensity fluorescent lighting without UV-filtering covers. Contact with copper, manganese, or iron stearates should be avoided because these species accelerate oxidative chain scission of the polybutadiene midblock. RUSS Shuiskaya SBS 1385 should not be compounded with strong oxidizing agents or chlorinated solvents; ketone and ester plasticizers are generally less compatible than paraffinic or naphthenic extender oils. Product-specific shelf life should be confirmed on the supplier certificate; typical SBS shelf life in sealed bags is 24 months from production date when stored below 25°C.

Hot-melt adhesive formulations based on RUSS Shuiskaya SBS 1385 are compounded with styrenic or hydrogenated tackifier resins and paraffinic/naphthenic oils. Typical tackifier loading ranges from 40–100 phr; oil loading from 20–60 phr; and antioxidant addition from 0.1–0.3 phr of a hindered phenolic stabilizer. Mixing is performed in a sigma-blade or planetary mixer at 150–170°C under nitrogen. Viscosity at 180°C depends on the oil-to-tackifier ratio; formulations requiring low viscosity benefit from a low diblock SBS grade, while high cohesive strength is obtained with higher diblock-free triblock content. In footwear soling compounds, SBS 1385 is blended with general-purpose polystyrene at 10–30 phr, calcium carbonate filler at 20–50 phr, and antioxidant at 0.2–0.5 phr. The resulting compound is extruded or injection-molded with melt temperatures at 160–190°C and mold temperatures below 60°C to prevent styrene domain softening before ejection. Compared with styrene-isoprene-styrene and styrene-ethylene-butylene-styrene block copolymers, SBS grades typically exhibit better hydrocarbon tack and lower compound cost, but lower oxidation resistance and lower service temperature capability. The 1385 grade is therefore positioned for applications where melt flow and solubility in bitumen or hydrocarbon tackifiers matter more than long-term UV stability.