SINOPEC Baling SEBS YH-610 is a linear triblock copolymer comprising polystyrene end blocks and a hydrogenated ethylene/butylene midblock. The grade is supplied without process oil extension and is specified for compounding and melt-processing operations where a Shore A hardness in the 60–65 range and a measurable melt flow under ISO 1133-1:2022 are required. Because the midblock is catalytically hydrogenated, residual olefinic unsaturation is reduced relative to unhydrogenated SBS; this contributes to higher resistance to thermo-oxidative chain scission under repeated melt processing. Manufacturer-published typical data for YH-610 are reproduced in Table 1. The certificate of analysis for the specific production batch should govern specification limits.

In comparison with oil-extended SEBS grades, YH-610 contains no pre-added paraffinic oil. The effective polymer fraction per unit mass is therefore higher, and the low-shear melt viscosity is higher than an oil-extended grade of the same nominal hardness would be. On a 32:1 to 48:1 L/D co-rotating twin-screw extruder, the polymer is typically processed with barrel set points of 150–200 °C and die temperature of 190–210 °C. Actual melt temperature should be measured at the die adapter and kept below 230 °C; residence time above 210 °C should not exceed 120 s. Pre-drying at 80 °C for 2–4 h is required when the material has been exposed to relative humidity above 60%, because moisture in the feed can generate surface splay in injection-molded parts.

What Distinguishes YH-610 from SBS and Oil-Extended SEBS Grades Under Tensile Loading?

Under ISO 37:2017, YH-610 develops tensile strength in the 15–20 MPa range with elongation at break of 450–550%. Unhydrogenated SBS grades of similar styrene content may show comparable or higher initial tensile values, but their unsaturated midblock is more susceptible to chain scission and crosslinking during ageing. Oil-extended SEBS grades containing 30–50 phr paraffinic oil show Shore A hardness values in the 35–50 range and lower tensile strength. The comparison in Table 2 is based on typical ranges for the material classes, not on a single ISO plaque preparation.

When Melt Temperature Exceeds 230 °C in High-Shear Compounding

High-shear compounding of YH-610 creates a process conflict between dispersion and thermal stability. At screw speeds above 500 rpm on a 40:1 L/D co-rotating twin-screw extruder, viscous dissipation can raise the actual melt temperature 20–30 °C above the barrel set point. If the melt temperature crosses 230 °C, degradation may appear as gel specks in transparent or lightly filled compounds and as an increase in melt flow rate due to chain scission. The appropriate countermeasure is to lower the melting-zone barrel setpoint to 160–180 °C while retaining die temperature at 190–200 °C. Oil injection should be split so that 60–70% of the total paraffinic oil is added downstream of the first kneading block; if all oil is injected at the feed throat, early viscosity reduction can reduce shear heating but may also reduce distributive mixing quality and filler wetting. The torque limit of the extruder gearbox should not be regarded as the only constraint; melt-temperature measurement by immersion thermocouple or infrared thermometer at the die adapter is required for a stable process.

High-Pressure Capillary Rheometry and Melt Viscosity Scaling

At processing shear rates of 100–1,000 s⁻¹, YH-610 follows shear-thinning behaviour typical of symmetric styrenic block copolymers. Capillary rheometry at 200 °C with a die length-to-diameter ratio of 30:1 shows apparent viscosity reductions of approximately 50–70% as shear rate increases from 100 s⁻¹ to 1,000 s⁻¹. The exact power-law index varies with styrene content and temperature; when the styrenic domains are insufficiently softened below 160 °C, the material can exhibit plug-like flow and pressure fluctuations. For stable single-screw extrusion, the screw should be operated with a compression ratio of 2.5:1 to 3.5:1 and a melt temperature not lower than 180 °C at the screw tip. In injection moulding, a shot weight occupying 50–80% of the barrel capacity is preferred to limit residence time at elevated temperature.

Soft-touch and grip compounds formulated with YH-610 usually include polypropylene homopolymer and a paraffinic white oil. A starting point is 100 phr YH-610, 20–30 phr PP homopolymer with melt mass-flow rate of 12 g/10 min per ISO 1133-1:2022, and 60–80 phr paraffinic oil, yielding Shore A hardness of 45–55 when injection molded at 190–210 °C and tested per ISO 868:2003. Raising oil above 90 phr commonly reduces tensile strength below 5 MPa and can produce oil exudation after storage at 70 °C for 7 days; the actual threshold depends on oil molecular weight and aromatic content. Because compounding and moulding conditions affect these values, published data for this specific formulation configuration is limited, and a design-of-experiments evaluation is required for production qualification.

Hot-melt pressure-sensitive adhesives based on YH-610 are processed with tackifier resin and white oil in sigma-blade mixers or twin-screw extruders. Viscosity at 180 °C is measured by ASTM D3236-15 and is typically adjusted to 2,000–8,000 mPa·s by changing tackifier loading. The hydrogenated midblock permits lower stabilizer loading than SBS-based hot melts, but a phenolic antioxidant at 0.2–0.5 phr remains a common starting point. Specific peel, loop tack, and shear adhesion performance should be tested by the finished adhesive manufacturer using FINAT or PSTC methods; these values are formulation-dependent and cannot be assigned to the base polymer alone.

Bitumen modification with YH-610 is performed by high-shear mixing at 170–190 °C using a rotor-stator mixer. Addition levels of 3–7 wt% based on bitumen mass are common when increased softening point and low-temperature flexibility are required; softening point is assessed by EN 1427, penetration by ASTM D5/D5M-21, and storage stability by EN 13399. The mixing time should be limited below 4 h to avoid excessive thermal history, and the blend should be transferred under agitation because phase separation can occur in static storage. Published data for this specific configuration is limited; end-use performance remains dependent on base bitumen source.

Wire and cable insulation compounds are a lower-viscosity application for YH-610 when combined with polypropylene and flame-retardant masterbatch. Formulations containing 30–50 phr YH-610, 20–40 phr PP, and 10–20 phr flame-retardant masterbatch are typically processed on a 24:1 single-screw extruder with a barrier screw and 40/80/120 screen pack. Tensile behaviour after ageing for 168 h at 100 °C is evaluated by IEC 60811-501; flame retardancy class is determined by the masterbatch system, not by YH-610 alone. The grade’s high melt viscosity relative to oil-extended products may require elevated barrel temperatures in thin-wall insulation, but melt temperature must remain below 230 °C.

Medical tubing and film applications may be developed from YH-610 when combined with polyolefins and white oils that meet the applicable pharmacopoeial or ISO 10993 extractables requirements. The base polymer’s high tensile strength relative to softer SEBS grades supports thin-wall extrusion at wall thicknesses below 0.5 mm when processed on a 24:1 single-screw extruder with a temperature profile of 170–200 °C. Dimensional stability and kink resistance must be evaluated per product-specific test methods; no claim of medical compliance arises solely from the use of YH-610.

Regulatory documentation for YH-610 is formulation-dependent. The base polymer can be evaluated under REACH EC 1907/2006 and RoHS 2011/65/EU as amended by EU 2015/863; heavy-metal content in the supplied material is commonly reported by IEC 62321-5:2013. Food-contact status must be validated on the finished article under FDA 21 CFR 177.1810 or the relevant regional regulation, including migration testing, because additives, processing aids, and colourants alter the compliance profile. Medical or pharmaceutical applications requiring USP Class VI or ISO 10993 biological evaluation demand compound-specific extractables, cytotoxicity, and sensitisation data; no bulk polymer certificate alone satisfies those requirements.