Shandong Jusage SBS 1301H is a linear styrene-butadiene-styrene block copolymer supplied as a non-oil-extended thermoplastic elastomer with a nominal bound styrene content of 30 wt% and a corresponding butadiene fraction of 70 wt%. The polymer is identified by CAS registry number 9003-55-8 and consists of a triblock architecture in which glassy polystyrene end blocks, with a glass transition temperature near 95 °C, are separated by a continuous polybutadiene rubber midblock having a glass transition temperature below -80 °C. This microphase-separated morphology produces the elastomeric recovery and thermoplastic processability expected of an SBS grade. The suffix “H” in the supplier nomenclature denotes a high-molecular-weight or high-viscosity variant relative to standard 1301; however, published data for this specific configuration is limited, and raw-material release values should be confirmed against a retained certificate of analysis.

Industrial applications typically select 1301H when low melt flow, elevated mechanical strength, and resistance to cold flow are required. The grade is supplied as white to off-white porous pellets, and pellet bulk density must be verified by ASTM D1895 Method A because loose-fill density can vary with pellet geometry and fines content. Since SBS 1301H is not oil-extended, its hardness and tensile properties remain higher after melt compounding than oil-extended grades with equivalent styrene content. That distinction is operationally significant in asphalt modification, roofing membranes, impact modification of polyolefins, and hot-melt adhesive compounding.

What Distinguishes 1301H from Standard 1301 and Oil-Extended 4303 Grades?

The primary difference is melt-viscosity class and oil content. Standard 1301 is a linear, non-oil-extended SBS with a similar 30 wt% styrene content, but it exhibits higher melt flow and lower molecular weight. Oil-extended 4303 contains aliphatic or naphthenic process oil at 10–15 wt%, reducing hardness and low-temperature stiffness while also reducing tensile strength. 1301H, in contrast, is selected where high-torque processing equipment can accept the lower melt flow in exchange for higher tensile strength and better elastic recovery. This trade-off is predictable from molecular weight: a higher molecular weight increases chain entanglement density and low-shear viscosity, but it also raises the specific energy required in a twin-screw extruder or high-shear bitumen mill.

Moisture uptake during warehouse storage in coastal Shandong can raise pellet surface moisture above 0.1 wt% when relative humidity exceeds 60%. Such moisture is not chemically bound, but it can generate surface defects and melt-line porosity if not removed before extrusion. Pre-drying in a desiccant hot-air dryer at 70–80 °C for 2–4 h is standard for moisture-sensitive operations; the actual value must be set by using ISO 787-2 or ASTM D5668 loss-on-drying measurements on incoming lots. Storage is specified below 40 °C in closed, UV-shielded containers because conjugated diene segments are susceptible to photo-oxidative chain scission and gel formation. Pellet surfaces should be protected from direct sunlight even when the warehouse is ventilated.

On a production-scale conveying system, pellet fragmentation can increase fines content and create dust explosion sensitivity. The minimum ignition energy of SBS dust is not typically published for this grade, but standard practice is to ground pneumatic conveying lines, maintain transfer velocities below 15 m/s, and use explosion venting in silos handling combustible polymer dust. Published data for this specific configuration is limited; therefore, process safety parameters should be evaluated by ASTM E2019 or equivalent dust-cloud testing before pneumatic transfer is commissioned.

Rheology, Hardness, and Tensile Data Obtained under ISO and ASTM Protocols

The following typical values are reproduced from supplier technical literature for SBS 1301H; they are not batch-release guarantees. Verification should be performed on the actual retained sample using the same standard designations and specimen conditioning at 23 ± 2 °C and 50 ± 5% relative humidity for 40 h according to ISO 23529.

A 65 mm co-rotating twin-screw extruder with an L/D ratio of 40:1 and a side-fed downstream addition port can be used to disperse 1301H into polypropylene at levels of 15–30 wt%. Barrel temperatures in zones 2 through 6 are typically maintained between 180 °C and 200 °C, with the die at 200 °C. Screw speeds in the range of 250–350 rpm are used to achieve fine SBS domain sizes below 5 µm; lower screw speeds can produce large agglomerates that reduce impact strength. Torque may increase by 10–20% when the melt flow rate of 1301H is at the low end of its specification, and the extruder drive should be sized for specific energy inputs of 0.25–0.35 kWh/kg.

When the compound is injection molded into test plaques on a 120-ton clamp force machine, melt temperature at the nozzle should be 190–210 °C, mold temperature 20–40 °C, and back pressure 3–6 bar. Excessive residence time above 220 °C causes polybutadiene segment degradation, yellowing, and release of butadiene-related volatiles; the molding machine should therefore be purged after 15 min of interruption. Field data from production-scale trials show that cold-flow resistance of 1301H compounds is superior to oil-extended grades, but the lower melt flow reduces throughput in hot-runner molds with gates smaller than 0.8 mm.

In hot-melt adhesive formulation, 1301H is compounded with tackifying resins and stabilizers in a sigma-blade mixer at 170–180 °C. The low melt flow raises cohesive strength but limits sprayability through narrow nozzle orifices. A typical formulation uses 20–30 wt% SBS 1301H, 40–60 wt% C5/C9 tackifier, 20–30 wt% naphthenic oil, and 1 wt% hindered phenolic stabilizer. Viscosity at 180 °C measured by a Brookfield Thermosel is controlled between 5,000 mPa·s and 20,000 mPa·s; if viscosity exceeds 20,000 mPa·s, coating weight uniformity deteriorates. Published data for this specific formulation configuration is limited, so pilot-scale viscometry is required before specifying spray equipment.

When SBS 1301H Is Dispersed in Bitumen at 185 °C, What Processing Limits Emerge?

Asphalt modification is the largest application class for low-melt-flow SBS grades. A production batch using a 20 m³ vertical high-shear mixer operating at 1,500–3,000 rpm typically disperses 3–5 wt% SBS into penetration-grade bitumen at 180–190 °C. The process passes through a phase-inversion regime in which SBS becomes the continuous network phase; this occurs only when rotor-stator shear is sustained for 2–4 h and when base bitumen aromatic content is sufficient to solvate the polybutadiene midblock. If mixer speed falls below 1,000 rpm or temperature drops below 170 °C, the SBS particles remain as discrete island domains and elastic recovery remains below specification.

Modified binder properties are typically evaluated by ASTM D5 penetration at 25 °C, ASTM D36 softening point, ASTM D6084 elastic recovery at 25 °C, and dynamic shear rheometry by ASTM D7175. For paving-grade binders, AASHTO M320 performance grading is used, and the SBS dosage is adjusted to meet the required high-temperature performance grade, typically PG 76-22 or PG 82-22. The key processing limit is thermal degradation: above 200 °C, the butadiene segments undergo thermo-oxidative chain scission and gel formation, which is observed as a sudden rise in mixing torque and a drop in ductility. Therefore, the temperature control band is typically 180–190 °C with a tolerance of ±5 °C. This narrow window is the main reason 1301H is specified for plants with jacketed high-shear mixers, temperature-controlled asphalt tanks, and in-line viscosity monitoring.

In storage-stability tests according to ASTM D7173 or EN 13399, a 48 h oven aging at 163 °C can reveal phase separation. Formulations with 1301H usually require a compatible base bitumen or a reactive compatibilizer to maintain a softening-point difference between top and bottom sections below 2.5 °C. Published data for this specific configuration is limited, and plant trials are required to determine the exact dosage for a given bitumen source because crude source and refinery cut affect aromaticity and wax content.

SBS 1301H also differs from hydrogenated SEBS in oxidative stability and processing temperature. SEBS can withstand processing at 230–250 °C, while SBS 1301H should not exceed 200–210 °C. The unsaturated polybutadiene segment gives SBS higher resilience and lower viscosity at a given molecular weight, but SEBS is selected for UV-stable and high-temperature applications. For outdoor exposed roofing membrane compounds, 1301H requires carbon black or UV stabilizer loading of 1–2 wt% to survive accelerated QUV weathering of 1,000 h per ASTM G154, whereas SEBS may pass with lower stabilizer levels. This difference must be considered when designing exposure specifications for exposed geomembrane or roofing sheet applications.

Formulation chemists should note the solubility parameter limits of SBS 1301H. The polybutadiene midblock is swollen by aliphatic and naphthenic oils but is poorly compatible with highly polar ester solvents, ketones, and high concentrations of aromatic solvents. Strong oxidizing acids, chlorine, ozone, and long-term UV exposure attack the unsaturation in the butadiene segment, causing chain scission, yellowing, and loss of elastomeric recovery. Amine-based additives are generally not used as primary stabilizers in SBS 1301H compounds because certain aliphatic amines can accelerate oxidative degradation of unsaturated diene polymers; hindered phenolic antioxidants and phosphite secondary stabilizers are preferred.

Regulatory compliance for the supplied pellet is typically supported by REACH (EC 1907/2006) polymer registration requirements, RoHS Directive 2011/65/EU restrictions on lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE, and ASTM D6400 if compostability is not claimed. Since SBS 1301H is not food-contact approved as a standalone resin, applications involving food contact require evaluation under FDA 21 CFR 177.2600 or the relevant national food-contact standard. The grade is combustible and should be kept away from open flame; burning may release carbon monoxide, styrene, and butadiene. These limitations define the boundary of operation; they do not preclude use in industrial asphalt, roofing, or compounding, but they require process engineering controls, particularly in enclosed plants.