Ningbo Changhong SEBS CH1310 is supplied by Ningbo Changhong Polymer Materials Co., Ltd. as a styrene-ethylene-butylene-styrene block copolymer in pellet form. The model is a linear triblock elastomer with a saturated ethylene-butylene midblock, which removes the main-chain unsaturation present in SBS. CH1310 is specified for thermoplastic elastomer compounding, hot-melt adhesive modification, polymer modification, and sealant applications. Published grade-specific data for CH1310 is limited; therefore, lot-specific certificates of analysis should be obtained from the manufacturer before setting processing limits.

The polymer obtains room-temperature elastomeric behaviour from phase separation of polystyrene endblocks. The polystyrene domains act as physical crosslinks below the glass transition, while the ethylene-butylene midblock provides rubbery recovery. Because no sulfur vulcanization is required, in-plant scrap can be reworked and the material can be processed on standard thermoplastic equipment. The hydrogenated midblock gives CH1310 improved resistance to ultraviolet irradiation and oxidative embrittlement relative to SBS, but it also raises melt processing temperatures and may reduce adhesion to polar substrates compared with unsaturated block copolymers.

How Does CH1310 Differ from SBS and Other SEBS Grades?

Compared with a linear SBS of similar molecular weight, CH1310 exhibits a wider thermal-oxidative service window and lower main-chain unsaturation. The saturated midblock allows higher upper service temperatures but narrows compatibility with unsaturated tackifiers such as rosin esters and low-molecular-weight polybutadiene. Within the SEBS class, CH1310 is generally positioned between low-styrene soft grades and high-styrene stiff grades. Medium-styrene SEBS materials in this viscosity band typically exhibit hardness values in the 55–80 Shore A range, while low-styrene grades can fall below 40 Shore A and high-styrene grades can exceed 90 Shore A. The same nominal styrene content does not produce identical adhesive shear behaviour; the diblock-to-triblock ratio and melt mass-flow rate must be compared.

Specification Limits and Certificate-of-Analysis Testing

A certificate of analysis for CH1310 typically includes melt mass-flow rate, density, ash, Shore A hardness, tensile strength, elongation at break, and bound styrene content. The melt mass-flow rate is measured by ISO 1133-1:2022 at 230 °C under a 5 kg load. Hardness is measured by ASTM D2240 on a 6 mm compression-moulded plaque conditioned at 23 °C ± 2 °C for 24 h. Tensile strength and elongation at break are determined using ISO 37:2017 at 500 mm/min. Density is measured by ISO 1183-1:2019 at 23 °C. Ash is determined by GB/T 9345.1-2008 or ISO 3451-1:2019. The certificate should report both the measured value and the acceptance band; changes in diblock content are not visible in standard tensile data and require gel permeation chromatography.

Bound styrene content can be measured by nuclear magnetic resonance or Fourier transform infrared spectroscopy calibrated against the manufacturer’s reference samples. Gel permeation chromatography in tetrahydrofuran against polystyrene standards gives apparent molecular weight and the diblock content; the latter is a critical specification for adhesives. Melt viscosity is also measured by dynamic oscillatory rheometry at 200 °C and 1% strain, because single-point melt flow rate does not capture shear-thinning differences between SEBS grades. For compounds, oscillatory rheometry at 0.1–100 rad/s can identify structural differences caused by chain extension or coupling agent residues.

Incoming granulate is not normally classified as hygroscopic, but surface moisture from high-humidity storage can produce bubbles in extrudate. When storage relative humidity exceeds 60%, drying at 70–80 °C for 2–4 h in a desiccant dryer is applied. Metal contamination is removed by rare-earth magnets and screen packs downstream of the extruder. A 40 mesh or finer breaker plate is used to trap gel particles that may form if melt temperature exceeds 250 °C for extended residence time. On production lines, the most common processing bottleneck is not the SEBS melting point but the transition from starve-fed solids conveying to fully filled screw sections. In a 65 mm co-rotating twin-screw extruder with an L/D ratio of 40:1, a CH1310/polypropylene compound containing 30 wt% oil may require a side-stuffer downstream to prevent oil flooding into the feed throat. Feeder consistency is influenced by pellet bulk density; a shift from 0.55 g/cm³ to 0.60 g/cm³ can alter gravimetric feed output by several weight percent at constant screw speed. Screen packs are changed when head pressure increases by more than 2 MPa above baseline.

When CH1310 Is Compounded into Polypropylene, Cooling Rate Determines Impact Transition

In polypropylene impact modification, CH1310 is added at 5–20 wt% to shift the ductile-brittle transition to lower temperatures without eliminating the matrix modulus. Compounding is performed on a co-rotating twin-screw extruder with an L/D ratio of not less than 40:1 and a vacuum port maintained at -0.08 MPa gauge pressure during devolatilization. The die-face pelletizer is operated with an underwater cutter speed of 2500–3500 rpm for 3 mm pellets; actual settings scale with die hole count and throughput. Notched Izod specimens are injection moulded under ISO 1874-2 conditions and tested by ISO 180/A; instrumented puncture is measured using ISO 6603-2. Increasing the cooling rate from 10 °C/min to 50 °C/min decreases the dispersed SEBS domain size and shifts the impact transition downward. In-line rheometry at 1 s⁻¹ and 100 s⁻¹ shows that dispersion quality correlates with melt viscosity changes; formulations with poorly dispersed SEBS domains show more pronounced non-Newtonian response and batch-to-batch variability in notched impact energy.

The dispersed phase dimensions are measured by scanning electron microscopy after staining with ruthenium tetroxide; image analysis on 500 domains should be used. Differential scanning calorimetry at 10 °C/min is used to confirm the onset of the polystyrene endotherm and to detect co-crystallization with polypropylene. A shift in the polypropylene crystallization exotherm may indicate partial miscibility that reduces impact performance. In plant-scale injection moulding with a clamp force of 1300 kN, short shots have been observed when SEBS dosage exceeds 20 wt% and melt temperature is below 200 °C, because the added elastomer increases melt viscosity and reduces flow length under fixed machine conditions.

Hot-melt pressure-sensitive adhesives based on CH1310 are prepared by dispersing the polymer in a low-viscosity naphthenic oil at 160–180 °C, followed by addition of a hydrogenated C5 tackifier at 30–50 wt%. The molten adhesive is coated at 150–170 °C using slot-die or roller coating equipment. Final bonding properties are evaluated by loop tack using PSTC-101, 180° peel using ASTM D903-98, and shear adhesion failure temperature using a 500 g static load in a forced-air oven ramped at 0.5 °C/min. Higher diblock content in CH1310 can increase pressure-sensitive tack but reduce shear holding power; this trade-off is measured by dynamic mechanical analysis at 1 Hz. The saturated midblock supports reduced colour formation at 180 °C. Product-level food-contact approval must be confirmed for the final adhesive formulation and is not conferred by the raw material alone.

In footwear foam compounds, CH1310 is blended with ethylene-vinyl acetate and a chemical blowing agent such as azodicarbonamide. A typical pre-blend contains 10–30 wt% SEBS to improve resilience and abrasion resistance. Mixing is carried out at 90–110 °C in an internal mixer before adding the blowing agent at 80 °C to avoid premature decomposition. Foam expansion is evaluated by density reduction and rebound resilience; DIN 53512 rebound tests at 23 °C can distinguish SEBS-modified foams from unmodified EVA. Because CH1310 has a saturated midblock, stabilizer loading in outdoor footwear may be lower than for SBS-based foams, but yellowing can still occur without ultraviolet absorbers.

Thermal Degradation Pathways in High-Shear Processing Are Governed by Midblock Scission

During production of CH1310-based compounds on twin-screw extruders with an L/D ratio of 44:1, degradation is controlled by specific energy input rather than by barrel temperature alone. Specific mechanical energy above 0.25 kWh/kg can reduce melt viscosity and generate low-molecular-weight tails. The die melt temperature is held below 240 °C; when the die melt temperature exceeds 245 °C for more than 3 min, yellowing and a drop in tensile strength are observed. A nitrogen blanket on the feed hopper and a vacuum devolatilization zone at -0.09 MPa reduce oxidative chain scission. Head pressure is maintained between 8 MPa and 15 MPa; higher pressure indicates insufficient screen-pack open area or an undersized die. Screw configurations include kneading blocks after the oil injection point to ensure homogeneous oil distribution without excessive shear. Process water for pelletizing is controlled at 30–50 °C to prevent pellet agglomeration and to control the crystallization history of the polystyrene domains. The operational boundary for extended residence time is stricter than the short-term peak melt temperature; even brief exposure above 260 °C can induce localized gel formation in the presence of oxygen.

Evaluating Diblock Content and Rheological Match Before Substitution

Substitution of CH1310 for another SEBS grade cannot be based on Shore A hardness alone. Comparative trials include melt mass-flow rate by ISO 1133-1:2022, capillary rheometry at 200 °C over shear rates from 10 s⁻¹ to 1000 s⁻¹, and small-amplitude oscillatory shear at 180 °C with 1% strain. Because diblock content alters the balance between tack and cohesive strength, gel permeation chromatography data should be reviewed. Tensile hysteresis tests at 200% elongation and 50 mm/min detect differences in cyclic energy loss that are not captured by single-extension tensile data. Substitution should be validated at equal oil and tackifier loadings; otherwise, differences in oil absorption capacity can alter the adhesive continuous-phase glass transition and low-temperature flexibility. If the alternative SEBS grade has a melt mass-flow rate more than 3 g/10 min different from CH1310 under identical conditions, processing parameters should not be transferred without re-validation. Published data for this specific configuration is limited; laboratory-scale compounding on a 25 mm twin-screw extruder is recommended before converting to production-scale equipment.

Compliance statements for CH1310 are application-dependent. For repeated-use rubber articles, verification may be required under FDA 21 CFR 177.2600 or the relevant European Union plastics regulation. RoHS 2011/65/EU and REACH SVHC declarations are normally supplied by the manufacturer, but converters must confirm the status of the specific lot. Avoid combining CH1310 with unsaturated hydrocarbon resins that contain high levels of double bonds; such mixtures may show premature oxidative discolouration during prolonged high-temperature exposure. For outdoor applications, UV stabilizers and antioxidants are required because the base polymer alone does not provide complete protection against long-term ultraviolet degradation.