Ningbo Changhong SBS CH1401HE is a linear styrene-butadiene-styrene block copolymer supplied as a porous pellet. The grade designation 1401 corresponds to a nominal bound styrene content of 40 wt% in the SBS 1401 series. Melt flow rate is typically reported in the range 0.5–3.0 g/10 min when measured at 200 °C under 5 kg load in accordance with ISO 1133-1:2022; published data for this specific configuration is limited, and incoming lots should be verified against the manufacturer’s certificate of analysis. The product is used primarily in asphalt modification, solvent-borne adhesive compounding, and general-purpose thermoplastic elastomer modification where the stiffness, tensile strength, and hardness of a 40 wt% styrene network are needed. Because the butadiene midblock remains unsaturated, CH1401HE is not inherently oxidation-resistant; antioxidant packages and processing stabilizers are required for long-term thermal service.

What Distinguishes CH1401HE from Lower-Styrene and Star-Shaped SBS Grades?

With the styrene block fraction at 40 wt%, CH1401HE is positioned above a 30 wt% styrene SBS 1301 analogue in modulus, tensile strength, and Shore hardness. In a standard compression-molded sheet tested under ISO 37:2017, the higher styrene content raises the nominal tensile strength envelope from roughly 16–20 MPa for 30 wt% styrene grades to approximately 20–26 MPa, while elongation at break shifts downward as the glassy styrene domains restrict chain extension. The 300% modulus also increases because the larger styrene domain fraction raises physical crosslink density. The operational penalty is reduced low-temperature flexibility: a 40 wt% styrene SBS typically exhibits a brittle point approximately 10–15 °C higher than a 30 wt% styrene analogue.

Against a star-shaped SBS of equivalent styrene content, CH1401HE is a linear architecture. This lowers zero-shear melt viscosity and improves solution flow in solvent-borne adhesives and sealants. Star-shaped grades generally provide higher green strength and better high-temperature creep resistance after processing, whereas the linear CH1401HE is selected for controlled low-viscosity compounding and faster dissolution in aromatic and aliphatic solvent blends. The choice between linear and star-shaped SBS therefore depends on whether the manufacturing constraint is melt pressure and coating rheology or final-part creep resistance.

Incoming lot control for CH1401HE follows the property envelope shown below. The values are representative of SBS 1401-type linear block copolymers; lot-specific numbers must be taken from the certificate of analysis because published data for this specific configuration is limited.

Tensile specimens are compression molded and conditioned for 16 h at 23±2 °C and 50±5% RH according to ISO 23529:2016. The presence of diblock above 15 wt% reduces tensile strength and raises melt flow, so diblock content is a critical quality parameter for adhesive dissolution and low-viscosity processing. Volatile matter and ash limits are relevant for hot-melt and solvent-borne applications because excess volatiles generate bubble defects during coating or molding, while ash can interfere with optical clarity and downstream filtration.

Melt Processing Limits and Vacuum-Drying Requirements

On a co-rotating twin-screw extruder with an L/D ratio of 36:1 to 44:1, CH1401HE is compounded at barrel temperatures from 150 °C to 190 °C, with a melt temperature limit of 220 °C. At melt temperatures above 230 °C the unsaturated polybutadiene midblock is susceptible to gel formation and chain scission. In production-scale compounding of similar linear SBS grades, screw speed is typically limited to 250–350 rpm at 40–60% torque, and vacuum venting is maintained at -0.08 MPa or lower to strip residual moisture and low-molecular-weight volatiles. Porous pellets absorb moisture under high humidity; pre-drying at 70–80 °C for 2 h is required when storage relative humidity exceeds 60% or when visible surface condensation is present. Uncontrolled moisture in the feed throat produces porosity, melt-pressure fluctuation, and poor pellet-to-pellet lot uniformity.

For injection molding of CH1401HE compounds, barrel temperatures between 150 °C and 180 °C and mold temperatures between 20 °C and 40 °C are typical. Clamp force requirements scale with projected part area and are not exceptional for SBS; however, the higher styrene content increases melt viscosity relative to lower-styrene SBS and may require an increase in melt temperature or injection pressure of approximately 10–20% when a mold qualified for 30 wt% styrene SBS is reused. Operation above 220 °C should not be used to compensate for viscosity limitations because gel formation accumulates on screw flights, check rings, and hot-runner dead spots.

On a production-scale asphalt modification line, CH1401HE is added to bitumen at 170–185 °C in a rotor-stator mill. At addition levels of 3.0–5.0 wt%, the polymer phase swells and disperses as a continuous network only after shear is maintained for 45–90 min; a reduction in mixer tip speed below 15 m/s before phase inversion produces storage-unstable binder with polymer-rich domains that separate within 24 h. The critical processing threshold is not merely time-at-temperature but the transition from discrete swollen particles to a co-continuous polymer-rich phase. Softening point typically increases by 15–30 °C over the base bitumen, and elastic recovery at 25 °C reaches 70–90% when tested per ASTM D6084-21 or EN 13398. Storage stability is evaluated by the softening-point difference between top and bottom sections after 72 h at 163 °C; values below 2.5 °C are generally required for hot-storage tanks. Not every bitumen composition responds identically: high-asphaltene sources may require the upper dosage limit or longer pre-shear dwell to reach a stable network.

When Solvent-Borne Adhesive Compounding Requires Controlled Dissolution Viscosity

CH1401HE can be dissolved in toluene, cyclohexane, ethyl acetate, or blended aliphatic-aromatic solvent systems for contact adhesives and pressure-sensitive formulations. The linear architecture and controlled diblock content govern dissolution time and final viscosity. A 25 wt% solids solution in toluene at 25 °C typically exhibits a Brookfield viscosity in the range 800–2,500 mPa·s depending on diblock content and molecular weight distribution. Lower-diblock lots dissolve faster and produce lower solution viscosity; higher-diblock lots reduce solution clarity and increase tack but can depress cohesive strength. Production-scale mixing with a high-torque disperser at 300–600 rpm for 4–8 h is sufficient for full dissolution when pellets are added slowly to the vortex; undissolved gel-like centres remain if the pellets are charged too rapidly or if local solvent temperature falls below 15 °C.

Do not combine CH1401HE with amine-based organic additives that generate free radicals under high shear, as these can initiate premature crosslinking of the unsaturated butadiene block. For adhesive formulations requiring oxidation resistance, hindered phenolic or phosphite stabilizers are preferred. Finished adhesive viscosity should be measured after 24 h equilibration because solution viscosity can drift as the styrene domains fully solvate.

Blends of CH1401HE with general-purpose polystyrene or polypropylene are not molecularly miscible; however, they are compatible enough to produce useful co-continuous morphologies in footwear compound extrusion at polypropylene contents below 20 wt%. On a single-screw extruder with a compression ratio of 3:1 and die temperature 160–180 °C, the higher styrene content of CH1401HE improves dimensional stability relative to 30 wt% styrene SBS but increases melt pressure by approximately 15–25% at the same screw speed. This operational boundary should be considered when retrofitting a line qualified for lower-styrene SBS. The same compatibility limit applies to filler-modified compounds: calcium carbonate loadings above 30 phr increase viscosity and reduce elongation, but the higher modulus styrene network of CH1401HE retains more hardness and tear strength than lower-styrene SBS at equal filler loading.