Product identification for Ningbo Changhong SBS CH1302-1HE places the material within a linear styrene-butadiene-styrene block copolymer series produced by sequential anionic polymerisation. The catalogue position of CH1302-1HE in the CH1302 series indicates a high-elongation variant; the base CH1302 designation is used for general-purpose SBS, while the HE suffix denotes modified elastomer performance. The product is supplied as porous or dense pellets depending on finishing-line configuration. Porous pellet morphology accelerates solvent dissolution in adhesive manufacturing but increases surface area for moisture and oxygen uptake.

Two-phase morphology governs the mechanical behaviour. The polystyrene end-blocks have a glass transition temperature near 95 °C, while the polybutadiene midblock has a glass transition temperature near -80 °C. This thermal asymmetry provides physical crosslinking at service temperatures and melt flow above 160 °C. Because the polybutadiene midblock is unsaturated, continuous exposure to air above 80 °C without antioxidant protection causes embrittlement.

Table 1 consolidates typical physical property ranges used for compounding and quality-control calculations for CH1302-1HE. These values are not lot-certificate guarantees; lot-specific certification should be obtained from the manufacturer. Published data for this specific configuration is limited for some measurements, and values below are representative of the CH1302 series rather than universal specifications.

Which Shear and Temperature Windows Govern Twin-Screw Compounding?

On a co-rotating twin-screw extruder with L/D 40:1 to 52:1, CH1302-1HE is processed with feed-zone barrel settings of 150 °C to 180 °C and mixing-zone settings of 180 °C to 210 °C. The melt temperature at the die is controlled within ±5 °C of set point; excursions above 230 °C for more than 2 min initiate degradation of the unsaturated midblock, producing cross-linked gel particles and rising screen-pack pressure. Specific energy input for a 70 mm diameter machine at 300–500 rpm is maintained below 0.20 kWh/kg; above that value, gel formation accelerates and the filtered-pressure rise rate exceeds 0.15 MPa/min.

Production-scale feed observations indicate that porous pellets begin to agglomerate at the hopper throat when pellet surface temperature exceeds 40 °C. Chilling conveying air to 10–15 °C and limiting hopper residence time to 20 min reduces bridging. Pre-drying at 60–70 °C for 2 h is required when ambient RH exceeds 60 %; desiccant dryers with a dew point below -30 °C are preferred. Drying above 80 °C causes pellet surface fusion and feed clumping.

Screw configuration for CH1302-1HE in a 70 mm co-rotating extruder typically uses two to three kneading-block zones with forward conveying elements and one vacuum devolatilisation port at -0.08 MPa. Reverse screw elements upstream of the vent increase melt seal and improve devolatilisation of low-volatile hydrocarbons. Atmospheric venting is insufficient when oil addition exceeds 15 phr; without vacuum, surface porosity appears in extruded profiles.

Paraffinic or naphthenic oils are used to reduce hardness and compound cost. Oil addition above 20 phr lowers Shore A hardness below 45 and increases plate-out on downstream calender rolls; below 5 phr, viscosity modification is marginal. Aromatic process oils are avoided because they plasticise the polystyrene end-block domains and reduce the upper service temperature. Addition of 2.5 wt% of a lubricant package reduces screw torque without measurable loss of tensile strength; addition above 4.0 wt% causes mould release but can reduce interlayer adhesion in shoe-sole assemblies.

Industrial Use in Footwear, Adhesive, and Bitumen Modification

Footwear sole compounds containing CH1302-1HE are blended at 70–85 phr with general-purpose polystyrene or high-flow polystyrene at 15–30 phr and naphthenic oil at 5–20 phr. Injection-moulding nozzles are held at 170–190 °C and mould temperatures at 20–40 °C. Compounds with polystyrene addition beyond 30 phr show a hardness increase above 85 Shore A but elongation falls below 300 %; this is a property cliff-edge for flexible sole designs requiring repeated flexural strain. Tensile properties of compounded footwear materials are evaluated according to ISO 37:2017 or ASTM D412-16, Test Method A. Flex fatigue of sole materials is evaluated under ISO 17707:2005 or ASTM D1052-09; published data for CH1302-1HE in this specific test is limited.

Injection moulding of CH1302-1HE compounds requires clamp force of 0.30–0.45 kN/cm² of projected part area, depending on wall thickness and gate design. Mould venting gaps of 0.010–0.015 mm prevent burning of unsaturated polymer at flow-front convergence. A cushion of 3–5 mm and screw back pressure of 0.5–1.0 MPa assist uniform density; excessive back pressure raises melt temperature and accelerates gel formation.

Solvent-borne adhesive formulations use CH1302-1HE at 20–30 wt% solids in toluene, cyclohexane, ethyl acetate, or aliphatic blends. Solution viscosity is measured with a Brookfield viscometer at 25 °C, spindle LV-4 at 60 rpm; because the linear architecture gives lower solution viscosity than radial SBS of equal solids, higher coating weights can be applied before exceeding the coating-head viscosity limit. The unsaturated midblock requires stabilisation with a hindered phenol antioxidant and a phosphite secondary antioxidant; without stabilisation, Brookfield viscosity can decrease during storage due to chain scission.

Bitumen modification is performed at 180–190 °C under high-shear mixing, with SBS content of 3–7 wt% of the bitumen. Storage stability depends on the density mismatch between the polystyrene-rich and polybutadiene-rich phases; without sulphur crosslinking or compatibilising additives, phase separation occurs in static storage. When sulphur crosslinking is used, the vulcanisation kinetics of the polybutadiene midblock control the storage-stability improvement; excessive sulphur produces gelation and pumping difficulties. Published data for this specific configuration is limited for CH1302-1HE in some modified bitumen systems.

Polymer modification uses CH1302-1HE at 2–10 wt% in polypropylene or polystyrene compounds to improve impact resistance. Notched impact strength of modified polypropylene is measured under ISO 180:2019; addition of CH1302-1HE improves low-temperature toughness, but the extent depends on dispersion and phase size. Tensile properties of modified polypropylene are tested under ASTM D638-14 or ISO 527-2:2012. Because low-molecular-weight constituents can migrate to the surface, extraction according to ISO 6427:2013 is used to control plasticiser and oligomer content.

When CH1302-1HE Replaces Radial SBS or SEBS in Injection-Moulded Goods

Relative to the base CH1302-1, CH1302-1HE is positioned as a higher-elongation grade. The HE suffix indicates a shift in the stress-strain curve; where CH1302-1 datasheets list elongation at break near 500 %, CH1302-1HE documentation places typical elongation at break near 650 %. This difference is relevant for vacuum-formed footwear components where local strain exceeds 300 % during lasting. The exact lot-specific elongation must be confirmed because batch-to-batch variation in coupling efficiency affects molecular weight distribution.

Table 2 differentiates CH1302-1HE from related grades on the basis of structural features and processing behaviour. The comparison is qualitative and should be supported by parallel melt flow and rheology checks before substitution.

Compared with radial SBS, the linear CH1302-1HE exhibits lower extrudate swell and narrower molecular weight distribution, which reduces die-swell variation in profile extrusion. Radial SBS grades of equivalent styrene content generally exhibit higher melt elasticity; CH1302-1HE may therefore require a shorter die land length to maintain identical profile dimensions. Against SEBS, the unsaturated midblock of CH1302-1HE gives inferior resistance to UV, ozone, and oxidative ageing. SEBS is specified where ISO 10993 biocompatibility, repeated steam sterilisation, or continuous outdoor weathering is required; CH1302-1HE is not a drop-in substitute in those applications.

Lot acceptance is based on melt flow rate according to ISO 1133-1:2022, tensile properties according to ISO 37:2017 or ASTM D412-16, and Shore A hardness according to ISO 868. For footwear compounds, abrasion loss is measured under ISO 4649:2017; unfilled CH1302-1HE exhibits higher abrasion loss than filled compounds, requiring filler loading of at least 20 phr of treated calcium carbonate or silica for sole specifications below 250 mm³. Tear strength is measured by ISO 34-1:2022, method B, procedure (a); the inherent tear strength of CH1302-1HE compounds is typically lower than polyurethane but improved by addition of 2–5 phr of high-styrene SBS resin.

Regulatory documentation for CH1302-1HE should be reviewed for RoHS Directive 2011/65/EU substance restrictions, REACH registration status, and FDA 21 CFR suitability where the grade is processed into food-contact articles. Under REACH, SBS polymers are generally exempt from registration as polymers, but monomers and additives used in production must be registered; supplier documentation should be requested for the specific monomer inventory. Storage of porous pellets should be in sealed containers at 20–30 °C and RH below 50 %. Open storage beyond 6 months can increase volatile matter and reduce melt stability; lot re-qualification is recommended if the volatile content exceeds 0.5 %.