Polymer-modified bituminous binders formulated with SINOPEC Baling Hunan SBS YH-815 are produced by preheating a 60/70 penetration-grade asphalt to 160–170 °C in a jacketed vertical tank, then transferring it to a high-shear mixer equipped with a rotor-stator head operating at 3,000–4,000 rpm. The oil-extended linear styrene-butadiene-styrene copolymer is added at 3.0–5.5 wt% of the total binder mass; lower dosages are associated with penetration-grade retention in dense-graded mixtures, while the 5.0–5.5 wt% range is typically reserved for highly stressed stone mastic asphalt and porous asphalt where elastic recovery under EN 14023 or ASTM D5976 must exceed the specification threshold for rutting resistance. Because YH-815 contains extender oil, the effective styrenic network concentration is lower than in a dry SBS grade at identical total mass addition, and formulators compensate by selecting the upper end of the dosage window or by reducing the separately added aromatic process oil by 1.0–2.0 wt%. Digestion at 175–185 °C under constant shearing is maintained for 45–90 min; the butadiene midblock swells selectively in the maltene phase, and the aromatic-to-saturate balance of the base asphalt controls the rate of swelling. If the base bitumen has a high asphaltene content above 8–10 wt%, a compatible aromatic extract is introduced at 1.0–3.0 wt% before the polymer to prevent phase inversion and flocculation that would otherwise appear as surface gel particles during drawdown testing. Post-mixing storage in a heated tank for 24 h under ASTM D7173 storage stability testing generally separates a polymer-rich top layer; if the softening point difference exceeds 2.5 °C under EN 13399, a stabilizer such as elemental sulfur at 0.10–0.25 wt% is introduced in the final 15–30 min of mixing to crosslink the vinyl units and anchor the polymer network, although excessive sulfur above 0.3 wt% can cause gelation of the entire binder. Temperature excursions above 200 °C are avoided because oxidative scission of the polybutadiene midblock produces an irreversible loss of elastic recovery even after the binder is cooled to application temperature. Terminal products include hot-mix dense-graded highway pavement, porous asphalt surfacing, stone mastic asphalt, and polymer-modified chip seal binders, with performance verified by penetration ASTM D5, softening point ASTM D36, elastic recovery ASTM D6084, and dynamic shear rheometer testing under ASTM D7175.

How Does YH-815 Affect Shear Hold Time in Styrenic Hot-Melt Pressure-Sensitive Adhesives?

In styrenic hot-melt pressure-sensitive adhesives, YH-815 is generally employed at 18–35 phr alongside a hydrogenated or C5/C9 aromatic tackifier at 50–70 phr, and the additional liquid plasticizer is limited because the extender oil already present in the grade contributes to compliance. Mixing is performed in a heated sigma-blade kneader at 160–180 °C under a nitrogen blanket; the ram air pressure and blade speed are set to avoid localized shear heating above 190 °C, where the butadiene segment may undergo chain scission and reduce cohesive strength. The molten adhesive is filtered through a 200-mesh screen pack and transferred to a slot die coater operating at 120–160 °C, with coat weights between 18 g/m² and 45 g/m² depending on the backing film. YH-815 reduces the low-shear melt viscosity relative to dry SBS of equivalent styrene content, which permits slot-die processing without excessive die pressure build-up on production lines where the pump speed is constrained by the backing web tension. The styrenic end-block content must be maintained above the minimum required for room-temperature shear resistance, because the extender oil increases the midblock free volume and shortens static shear time-to-failure if the tackifier loading is too high. Static shear adhesion is evaluated under ASTM D3654 on stainless steel panels at 1 kg load; 180° peel adhesion is measured by ASTM D3330 and loop tack by ASTM D6195. Terminal products include carton sealing tapes, difficult-to-bond low-surface-energy label stocks, hygiene construction films, and protective masking tapes. For indirect food-contact packaging, the finished adhesive is evaluated under 21 CFR 175.125 or the applicable EU framework regulation for migration; the release of the extender oil is the critical compliance variable because low molecular weight naphthenic oil may migrate into dry food matrices.

Oxidative Embrittlement Control in Torch-Applied Bituminous Waterproofing Membranes

Compounds for torch-applied waterproofing membranes use YH-815 at 8–18 wt%, oxidized bitumen or an oxidized/polymer-grade non-oxidized bitumen blend at 40–50 wt%, atactic polypropylene at 10–15 wt%, and mineral filler at 25–35 wt%. The compound is prepared in a heavy-duty kneader or a twin-screw extruder with a cooled feed throat at 170–190 °C; the polymer is added after the bitumen and filler have formed a homogeneous melt to avoid encapsulating undispersed SBS particles in the mineral phase. The molten compound is calendered onto a nonwoven polyester reinforcement at 0.8–1.5 mm total thickness and surfaced with sand, mineral granulate, or PE film. The oil-extended grade contributes low-temperature flexibility and improves dimensional stability at torch application temperatures; however, the extender oil reduces indentation resistance and the formulator must rebalance filler loading to maintain a minimum ring-and-ball softening point above 95 °C when tested under ASTM D36. Long-term aging is assessed by heat aging at 70 °C for 28 days under ASTM D5147 or the corresponding EN 13707 specification, with embrittlement evaluated by low-temperature flexibility testing at -20 °C and tear resistance under ASTM D4073. The maximum melt temperature is 200 °C; above this limit the polybutadiene midblock reacts with atmospheric oxygen in the mixer headspace, generating polar oxygenated species that raise melt viscosity and produce surface cracking after thermal cycling. Terminal products include bridge deck membranes, below-grade waterproofing, plaza deck systems, and tunnel lining sheets, where the membrane is torched in place and must retain adhesion to primed concrete under wet conditions.

Impact modification of polypropylene homopolymer with YH-815 is carried out by pre-blending the oil-extended SBS pellets with polypropylene powder or pellets at 5–15 wt% SBS, then feeding the mixture into a co-rotating twin-screw extruder with a 40:1 or 44:1 length-to-diameter ratio. The barrel temperature profile is set from 180 °C in the feeding zone to 210 °C at the die, and screw speed is held at 250–400 rpm; a side stuffer is not required at this low rubber loading, but downstream addition of reinforcing talc or calcium carbonate at 10–20 wt% may be used to restore flexural modulus after the rubber phase reduces stiffness. The butadiene segment of YH-815 forms dispersed elastomer domains in the polypropylene matrix, while the styrene end blocks provide interfacial tension reduction and prevent gross coalescence during strand pelletizing. During injection molding, a clamp force of 120–180 t for multi-cavity tooling and a melt temperature of 200–220 °C are typical; mold surfaces are cooled to 20–40 °C to minimize post-molding shrinkage. Notched impact strength under ASTM D256 or ISO 180 is the primary critical-to-quality parameter, and results at equivalent rubber content are influenced by the oil phase, which plasticizes the polypropylene and raises elongation at break under ASTM D638 without necessarily increasing notched impact energy. Terminal products include injection-molded automotive interior trim, battery cases, appliance housings, and industrial storage containers. Compliance with REACH and EU RoHS recast 2011/65/EU is managed through the supplier’s material certification rather than through post-compounding testing, because the melt compounding process does not introduce heavy metals; however, the volatile oil fraction may condense on vacuum vent lines, and production-scale extruders require periodic vent cleaning to maintain residual volatiles below the threshold specified by the end-user for odour-sensitive automotive interiors.

When YH-815 Enters a Mixed SBS/PS Outsole Compound at 35 phr

Footwear outsole compounds often use YH-815 at 25–45 phr as the primary elastomer in a blend with general-purpose polystyrene at 10–25 phr, silica filler at 20–35 phr, and extender oil added as a separate plasticizer only when the oil included in YH-815 does not meet the target Shore A hardness range of 55–65. Initial dispersion is performed in an internal mixer with a fill factor of 0.70–0.80, rotor speed 50–70 rpm, and drop temperature 90–110 °C; the batch is then milled at 60–80 °C to form a continuous sheet before granulation for injection molding machines. Injection molding of the outsole is performed at 160–190 °C melt temperature with screw back pressure of 0.5–1.5 MPa and an injection speed adjusted to prevent jetting; mold temperature is maintained at 20–40 °C. The styrene domains of YH-815 provide thermoplastic processability and allow recycling of runner scrap at up to 20–30 wt% of the total shot mass without an unacceptable loss of tear strength. Tear strength under ISO 34-1 and abrasion resistance under DIN 53516 are more sensitive to silica dispersion than to the polymer ratio; insufficient dispersion of silica agglomerates above 50 µm creates tear initiation sites that reduce trouser tear strength by as much as the difference between YH-815 and a dry SBS of equivalent styrene content. The terminal product range includes casual shoe unit soles, slipper outsoles, and injected midsoles. Compliance for the finished footwear article is verified against REACH Annex XVII restrictions on polycyclic aromatic hydrocarbons and the applicable ASTM consumer safety specification, with the primary risk originating from extender oil quality rather than from the SBS backbone.

Sealant formulations based on YH-815 are processed in a planetary double-arm mixer at 120–140 °C under vacuum to remove volatile low molecular weight oil fractions before the compound is discharged into aluminium cartridges or sausages. A representative formulation loads YH-815 at 10–20 wt%, a hydrogenated hydrocarbon tackifier at 15–25 wt%, polyisobutylene or butyl rubber at 5–10 wt% when low gas permeability is required, calcium carbonate filler at 30–45 wt%, and a hindered phenolic antioxidant at 0.3–0.5 wt%. The extender oil in YH-815 lowers mixing torque and permits higher filler loading than dry SBS, but it also increases surface tack and dirt pick-up; formulators reduce the tackifier fraction and increase the filler volume to control the cured sealant’s compression set and weatherability. Joint movement accommodation is characterized under ISO 11600 for construction sealants or ASTM C920 for elastomeric joint sealants; tensile adhesion is measured under ISO 8339 on concrete and aluminium substrates after immersion, heat aging, and UV conditioning. The terminal end uses include exterior building expansion joints, roof penetration sealing, window perimeter sealing, and cold-applied concrete joint fillers. A critical processing boundary is the maximum mixing temperature of 140 °C; above this limit the hindered phenolic antioxidant is consumed rapidly and the polybutadiene midblock oxidizes, resulting in a measurable increase in low-frequency rheological loss factor and a reduction in tensile retention after thermal aging.

Tuning Loss Factor in Automotive Acoustic Damping Laminates

YH-815 is compounded with blown bitumen, mica, and barium sulfate to produce acoustic damping sheets in which the temperature-dependent loss factor is matched to the 20–80 °C cabin temperature range. The compound formulation uses bitumen at 50–65 wt%, YH-815 at 5–15 wt%, mica at 10–20 wt%, barium sulfate at 10–25 wt%, and graphite or mineral filler to achieve a sheet density of 1.8–2.2 g/cm³. Compounding is carried out in a twin-screw extruder with barrel temperatures of 160–190 °C and a vacuum devolatilization port; the melt is calendered to 0.5–3.0 mm thickness and laminated with aluminium foil or polyethylene release liner. The flexural loss factor is determined by the Oberst beam method under ISO 6721-3 or the equivalent SAE J1637 test, and the peak loss factor is shifted by altering the ratio of YH-815 to bitumen and the extender oil content. Higher YH-815 content raises the damping peak temperature and broadens the tan δ curve, while excess mica above 20 wt% produces a brittle composite that cracks during die-cutting of complex floor panel shapes. Terminal applications include automotive floor panel damping sheets, door inner skin patches, and heavy equipment cab insulation, where the composite must resist sag at 90 °C and maintain adhesion to the metal substrate after heat aging.