RUSS Shuiskaya SBS 1375 is introduced in supplier documentation as a linear styrene-butadiene-styrene block copolymer supplied under the RUSS trade designation for thermoplastic modification, bitumen waterproofing, adhesive compounding, and footwear compounds. The grade is produced by anionic solution polymerization; the styrene end-blocks form glassy domains that act as physical crosslinks in the solid state, while the unsaturated polybutadiene midblock provides ambient and low-temperature flexibility. Incoming inspection is usually structured around bound styrene content by ISO 21561-1, melt mass-flow rate by ISO 1133-1:2022 at 190 °C/5 kg, tensile properties by ISO 37:2017, and Shore A hardness by ASTM D2240-15. The numerical suffix 1375 is a producer-specific grade identifier and does not replace the certificate of analysis; processors should derive drying, mixing, and screw-speed settings from the supplied lot data rather than from nominal grade tables.

How does the linear triblock architecture control tensile set and melt-phase separation?

In a linear SBS such as RUSS Shuiskaya SBS 1375, the styrene mass fraction is understood to be in the 30 wt% class. At this composition, the polystyrene domains are discrete in the polybutadiene matrix when quiescent, giving elastomeric recovery without chemical crosslinking. Compared with random styrene-butadiene copolymers of similar comonomer ratio, the block structure produces higher tensile strength and lower compression set because the glassy domains reorganize only above the styrene glass transition at approximately 95 °C. The polybutadiene midblock exhibits a glass transition near −85 °C, which supports low-temperature flexibility but also contributes oxidative sensitivity. Published data for this specific grade are limited; consequently, the certificate of analysis and gel-permeation chromatography data for molecular weight distribution, diblock content, and coupling efficiency are the authoritative lot-level inputs for compounding.

The linear triblock architecture also affects melt rheology. Under shear, the polystyrene domains soften and the melt becomes pseudoplastic; shear viscosity declines with increasing shear rate more strongly than that of a random SBR. This behavior is exploited in high-shear bitumen mixing, where a rotor-stator mill can disperse the polymer without excessive molecular weight breakdown if the thermal boundary is maintained. In melt-processed articles, the same pseudoplasticity reduces pressure drop through dies but may produce lower melt strength than branched or radial SBS grades.

Microphase separation in RUSS Shuiskaya SBS 1375 is thermally reversible. During high-shear melt processing above the order-disorder transition, the styrene domains dissolve into a transient homogeneous melt; subsequent cooling restores the physical network. If cooling is too rapid or the melt is diluted with certain oils, the domain morphology may become co-continuous or ill-defined, lowering tensile strength and elastic recovery. The order-disorder transition temperature depends on molecular weight and styrene volume fraction; published data for this specific grade are limited, so dynamic mechanical analysis of the cooled compound is used to confirm phase separation. In injection-molded parts, a mold temperature of 30–50 °C is typical to allow the styrene domains to re-form before ejecting.

Solution viscosity is a sensitive lot-consistency parameter. In toluene at 25 °C, linear SBS of the 30 wt% styrene class usually shows lower solution viscosity than radial SBS of equal bound styrene because the branched architecture of radial grades generates higher hydrodynamic volume. Melt viscosity is tested by ISO 1133-1:2022 or by capillary rheometry; the exact load and temperature are defined on the certificate of analysis. A significant increase in solution viscosity at constant concentration can indicate gel, high coupling residue, or crosslinked contamination. The same information is used to set solvent dilution sequences in adhesive manufacture, where a polymer solution of 20–30 wt% solids may exhibit paste-like viscosity and require anchor or helical ribbon agitation.

Bitumen modification with RUSS Shuiskaya SBS 1375 is concentrated in paving-grade polymer-modified bitumen and in waterproofing membranes. High-shear mixing is normally performed at 3,000–5,000 min⁻¹ in a rotor-stator mill, with bitumen preheated to 160–170 °C and mixing maintained at 175–185 °C. The polymer charge is typically added in staged increments of 0.5–1.0 wt%; full dispersion may require 45–120 min depending on batch size and mill geometry. At polymer contents of 3–7 wt%, the modified binder typically shows a measurable increase in softening point and elastic recovery, while contents below 3 wt% may leave phase inversion incomplete and yield poor storage stability. Above 190 °C or at residence times exceeding 120 min, thermal-oxidative attack on the unsaturated midblock reduces elastic recovery even if the binder remains visually homogeneous. The finished PMB is conventionally evaluated under EN 14023:2010 framework specifications using ASTM D36 softening point, ASTM D5 penetration, ASTM D6084 elastic recovery, and EN 13399 storage stability. On production-scale rotor-stator mills of 25–30 m³ capacity, the addition rate must be controlled to avoid fish-eye agglomerates; this is a field-observed constraint that can appear before the mill motor load reaches its maximum.

Incoming inspection matrix for RUSS Shuiskaya SBS 1375

The following test matrix is used for lot acceptance and for comparison with equivalent SBS grades. No single method is sufficient because hardness and melt flow alone do not capture the phase quality of the polymer.

Adhesive and sealant compounding uses RUSS Shuiskaya SBS 1375 as a thermoreversible network former. Hot-melt pressure-sensitive adhesives are prepared by combining the polymer with tackifier resins and naphthenic or paraffinic process oils in sigma-blade or twin-screw equipment at 150–180 °C. Oil extension in the range of 30–80 phr is common to lower hardness and shift the glass transition of the midblock, but high-aromatic oils are avoided because they plasticize the styrene domains and reduce upper service temperature. The unsaturated polybutadiene segment requires stabilization against ozone and ultraviolet attack; outdoor adhesive films are formulated with antioxidant and UV stabilizer packages. Peel and shear performance are tested under ISO 11339 or ASTM D1002 as applicable, and the compounded adhesive is characterized for Brookfield viscosity and softening point before coating. Because solvent-borne systems use hydrocarbon solvents, the polymer dissolution rate is controlled by crumb surface area and mixing intensity; pre-swelling in a portion of the solvent is sometimes used to prevent gel lumps.

Footwear compounds based on RUSS Shuiskaya SBS 1375 are typically mixed with polystyrene, hydrocarbon resin, and paraffinic oil in internal mixers or twin-screw extruders. Compound hardness is adjusted by oil and polystyrene content; Shore A hardness values in the range 55–85 are common for sole applications, but the specific compound recipe must be optimized. The unsaturated midblock gives good wet traction but limits solvent resistance; ester or ketone solvents can swell the compound. Abrasion is tested by ISO 4649 or ASTM D5963, and flex cracking by ISO 4643 or a corresponding application-specific method. The polymer alone does not define footwear performance; filler dispersion and processing history control the final physical properties.

When melt compounding with polystyrene or polyolefins requires thermal boundary control

Thermoplastic modification with RUSS Shuiskaya SBS 1375 is carried out on corotating twin-screw extruders with L/D 32:1 to 44:1. The preferred melt-temperature window is 160–200 °C; sustained operation at 220 °C and above can generate gel particles and reduce elongation at break because the polybutadiene midblock undergoes thermal-oxidative chain scission. A flat or mildly reverse temperature profile is employed, with only the feed-throat and side-stuffer zones held lower to control agglomerate formation. Feed moisture is maintained at ≤0.5 wt%; at ambient relative humidity above 60%, pre-drying at 60–70 °C for 2–3 h in a desiccant dryer is applied before extrusion unless the supplier’s drying advice states otherwise. When RUSS Shuiskaya SBS 1375 is melt-blended with general-purpose polystyrene at 10–20 wt%, impact performance improves while modulus falls; the exact balance is determined by ISO 37:2017 or ASTM D638-14 on injection-molded or compression-molded specimens. With polyolefins, compatibility is governed by the viscosity ratio and by the styrene block affinity to the polyolefin interface; a compatibilizer may be required for stable morphology at higher polyolefin contents.

RUSS Shuiskaya SBS 1375 is differentiated from other SBS products primarily by the producer-specific linear architecture, the styrene mass fraction, and the lot-level molecular-weight distribution. Compared with linear SBS grades of 40 wt% styrene, the 30 wt% class yields lower hardness and modulus but better low-temperature flexibility and lower melt viscosity. Compared with radial SBS of similar styrene content, the linear structure gives lower solution viscosity and lower zero-shear viscosity, which eases high-shear bitumen dispersion but may reduce tensile strength at equivalent molecular weight. Differences from series designations such as SBS 1301 or SBS 1401 cannot be assumed from nomenclature alone; each supplier uses different coding for diblock content, molecular weight, and coupling efficiency. A substitution should therefore be qualified by full re-testing of the end article against EN 14023:2010, ISO 37:2017, or the application-specific specification, not by nominal hardness or melt-flow match.

Regulatory and storage boundaries are lot-specific. Standard food-contact clearance cannot be inferred from polymer class; if direct food-contact use is proposed, the specific lot must be reviewed against 21 CFR 177.1810 and any migration testing required by the end-use legislation. For general industrial use, RoHS and REACH documentation is obtained from the supplier; the extended safety data sheet provides registration status and any hazardous constituents. Storage is recommended below 40 °C, away from direct sunlight, moisture, and sources of ignition. The unsaturated midblock is incompatible with strong oxidizing agents, chlorinated solvents at elevated temperatures, and certain amine-based additives that can accelerate oxidative degradation. Opened bags should be resealed or consumed promptly to prevent moisture uptake and surface contamination.