LCY Chemical Globalprene® SBS 1477 is a linear styrene-butadiene-styrene block copolymer supplied as a non-oil-extended pellet. The grade is specified with a nominal bound styrene content of 33 wt% and a density of 0.94 g/cm³ measured under ISO 1183-1. The polybutadiene midblock retains residual unsaturation that contributes high elongation, good bitumen compatibility, and a reactive site for sulfur crosslinking. The polystyrene end-blocks form glassy domains that behave as physical crosslinks below approximately 95 °C. Because the styrene content is below the lamellar threshold, the morphology is dominated by spherical or cylindrical polystyrene domains. This architecture produces Shore A hardness below 80 without external plasticizer and retains tensile recovery after repeated strain. Representative manufacturer-published values for unfilled compression-molded test specimens are shown in the following table; they are typical data, not guaranteed specification limits.

The melt flow value under 190 °C/5 kg is not a complete viscosity fingerprint because the melt is strongly shear-thinning and temperature-sensitive. Above 200 °C, the polystyrene domains lose network strength and apparent viscosity drops sharply. This behavior must be considered in processes that require holding a preformed shape before cooling.

What Limits the Processing Envelope in Twin-Screw Compounding?

In twin-screw extrusion, the practical melt-temperature ceiling is determined by thermo-oxidative stability of the polybutadiene midblock rather than by barrel set point alone. Co-rotating twin-screw extruders with L/D ratios from 32:1 to 44:1 and segmented conveying/kneading blocks are suitable. A barrel profile of 130–140 °C in the feed zone, 170–190 °C in the mixing zone, and 180–200 °C at the die provides adequate dispersion without excessive degradation. Viscous dissipation can raise melt temperature by 10–25 °C above the barrel set point when screw speed exceeds 350–400 rpm. The upper melt temperature should be held below 230 °C; above this threshold, gel particles and surface roughness appear in the extrudate.

The shear-heating effect is non-uniform across the screw profile. In kneading blocks with 45° forward staggering, local melt temperature can exceed the barrel set point by 15–25 °C, while neutral 90° kneading blocks generate even higher shear. The barrel profile alone therefore does not define actual melt temperature. Screw designs with two or three mixing zones should position temperature probes downstream of the last kneading block. A melt temperature above 230 °C leads to crosslinking and gel, while below 160 °C high melt elasticity causes surging and poor strand pelletization. The practical operating window for SBS 1477 in a 40:1 L/D corotating twin-screw extruder is 170–200 °C at the die, 250–400 rpm screw speed, and feed rates that maintain specific energy input near 0.15–0.25 kWh/kg. Die pressure fluctuations greater than 10% indicate feed instability or melt fracture.

In injection molding of shoe soles, a general-purpose screw with compression ratio 2.5:1 to 3.5:1 and a check-ring non-return valve is recommended. Barrel settings of 150–165 °C rear, 170–185 °C mid, and 175–190 °C nozzle are typical for 10 mm thick soles. Mold temperatures of 10–40 °C and cooling times of 25–40 s for 10 mm sections reduce sink marks and shrinkage. Holding pressure of 40–70 MPa hydraulic pressure and back pressure of 0.5–1.5 MPa are common for multi-cavity footwear molds. Pellets sealed below 60% relative humidity require no pre-drying. Exposed pellets should be dried at 70–80 °C for 2 h in a desiccant dryer to keep surface moisture below 0.05 wt% and avoid surface defects.

Compounding with paraffinic or naphthenic oil from 10 phr to 50 phr lowers melt viscosity and permits higher filler loadings. A two-roll mill at 160 °C is used for laboratory evaluation; the SBS is banded first, then one-third of the oil is added, followed by filler and stabilizer in increments. Calcium carbonate at 50 phr with paraffinic oil at 30 phr disperses to a surface roughness below 5 µm after 10 min of mastication when measured by optical profilometry. Addition of 5–15 phr crystal polystyrene raises Shore A hardness by 3–7 points but increases melt-temperature sensitivity. In transparent polystyrene modification, 5–15 wt% SBS 1477 added to general-purpose polystyrene raises notched Izod impact strength from approximately 15 J/m to 25 J/m under ASTM D256 when dispersed domains remain below 1 µm. Published data for optical haze after long-term aging of this specific configuration is limited. Amine-based antiozonants should be avoided where residual phenolic stabilizers are present because discoloration can occur under fluorescent light exposure.

Properties That Distinguish 1477 from Oil-Extended SBS and High-Styrene Grades

The absence of extender oil in SBS 1477 permits independent selection of plasticizer type and loading in shoe compounds. This raises neat tensile strength compared with oil-extended SBS grades of similar styrene content while also increasing melt viscosity and elastic memory. High-styrene SBS grades with 40–45 wt% styrene shift morphology toward more continuous styrene domains, increasing hardness and tensile modulus but reducing rebound and low-temperature flexibility. The following representative comparison is based on unfilled polymer categories and is not a specification.

Compared with high-styrene SBS grades, SBS 1477 provides lower hardness and lower modulus, which improves cold flex and reduces crack propagation in thin-walled footwear sidewalls. Against SEBS, the saturated midblock gives SEBS superior ozone and ultraviolet resistance. SBS 1477 is preferred in asphalt modification, pressure-sensitive adhesives, and rubber toughening where higher unsaturation improves compatibility and radical reactivity.

When 1477 Is Used in Bitumen Modification and Hot-Melt Adhesives

In polymer-modified bitumen, SBS 1477 is added at 3–6 wt% based on bitumen weight. The polybutadiene midblock swells in maltenes and forms an elastic network. Softening point increases by 15–30 °C under ASTM D36, and elastic recovery improves under EN 13398. High-shear rotor-stator mixing at 170–190 °C is required. Low-shear mixing below 200 rpm can leave visible SBS-rich particles and produce a storage instability exceeding the 2.5 °C softening point difference limit in ASTM D7173. For a 70/100 pen bitumen, a 4.5 wt% addition typically forms a continuous polymer network when sheared at 3,000–5,000 rpm for 60–120 min. Dispersion should be confirmed by fluorescence microscopy at 400× because the polymer phase fluoresces under blue light.

For hot-melt adhesives, blends with 30–50 phr of hydrogenated rosin ester or C5 hydrocarbon resin and 10–30 phr of naphthenic oil provide pressure-sensitive tack. Loop tack on stainless steel under ASTM D6195 is typically 15–25 N/25 mm, and peel adhesion under ASTM D3330 exceeds 10 N/25 mm for optimized formulations. Tackifier compatibility with the polybutadiene midblock should be checked by differential scanning calorimetry; a single mixed glass transition between the midblock and tackifier is required for high tack. Zinc stearate above 0.5 phr should be avoided where migration to the substrate reduces peel adhesion.

Solvent Compatibility, Cure Response, and Service Boundaries

SBS 1477 dissolves in toluene, cyclohexane, tetrahydrofuran, and chlorinated hydrocarbons. It is insoluble in methanol, ethanol, and water. Solution viscosity rises rapidly above 20 wt% solids in toluene at 25 °C; higher solids require heated high-shear mixing. The solubility parameter difference between the polybutadiene midblock and polystyrene end-block drives selective solvent absorption, which should be considered when selecting adhesive solvents or cleaning agents. MEK and ethyl acetate attack the styrene domains and can reduce physical crosslink density.

The unsaturated polybutadiene midblock permits sulfur vulcanization. In a 50/50 blend with natural rubber, a sulfur donor system with MBTS and TMTD at 1.0–2.0 phr reaches tc90 in 6–9 min at 170 °C under ASTM D5289. Peroxide cure is possible with dicumyl peroxide at 1.5–2.0 phr; higher temperatures can degrade the polystyrene domains. For outdoor service, the unsaturated midblock requires stabilization with 0.2–0.5 phr of a hindered phenolic antioxidant and 0.2–0.8 phr of a phosphite processing stabilizer. Continuous service in air above 90 °C requires oven-aging validation under ASTM D573 or ISO 188.

Regulatory documentation should be verified against the current LCY Safety Data Sheet. The product is supplied as a non-food-contact grade unless confirmed otherwise. European Union obligations under REACH apply to the polymer registration at tonnage levels specified by the manufacturer. For electrical and electronic applications, the grade is not formulated with lead, cadmium, mercury, hexavalent chromium, PBB, or PBDE above the thresholds in 2011/65/EU. Warehousing at ambient temperature below 35 °C in sealed, opaque packaging minimizes oxidative surface skin formation. Under ultraviolet exposure in warm climates, unprotected pellets can develop surface chalking within 4–8 weeks. The product should be added to compounding operations under inert gas or with local exhaust ventilation where melt temperatures exceed 200 °C to limit volatile emissions.