When YH-796 Is Fed into a 170–190°C Bitumen Carrier

High-shear blending of 40/60 or 60/70 paving-grade bitumen with SINOPEC Baling Hunan SBS YH-796 is conducted in a rotor-stator mill at 4,000–5,000 rpm, equivalent to a rotor tip speed of 15–25 m/s, after the base binder has been preheated to 165–175°C. YH-796 is added at 3.5–5.0 wt% for dense-graded surface-course binders and at 5.0–7.0 wt% for open-graded or stone-mastic asphalt binders. The addition is made in portions over 10–15 min to prevent lump formation; high-shear dispersion is continued for 45–90 min until a uniform swollen elastomer phase is developed. In the 170–190°C mixing window, the polystyrene end-blocks soften sufficiently to allow molecular-scale dispersion, while the polybutadiene midblock absorbs maltenes from the asphalt phase. Upon cooling, the styrene domains reharden and form a physically crosslinked network that increases ring-and-ball softening point, elastic recovery, and resistance to permanent deformation. After high-shear mixing, the blend is transferred to a maturation tank with low-shear agitation at 160–165°C for 2–4 h. If the processing temperature exceeds 190°C, oxidative chain scission of the polybutadiene segment causes viscosity loss and gel formation; below 160°C, the high-viscosity bitumen prevents homogeneous dispersion. Production terminals apply nitrogen blanketing when the matured binder is held for more than 8 h before truck loading.

The plant-scale release testing matrix for a 40/60 asphalt modified with YH-796 includes the following methods and operational screening windows; actual values are base-binder dependent.

Base bitumen chemistry controls the SBS swelling equilibrium and the final storage stability. In low-aromatic binders, YH-796 develops a co-continuous phase only at higher addition levels; in highly aromatic binders, the SBS swells rapidly but can over-swell and reduce elastic recovery if the dosage exceeds 5.5 wt%. Asphaltene-rich binders compete for maltene fractions and can produce storage instability when SBS content reaches 5.5–7.0 wt% without additional reactive compatibilisation. Storage stability is checked by EN 13399 on a vertically split cylinder after 72 h at 165°C; a top-bottom softening point difference above 2–3°C indicates phase separation risk. Terminal finished binders are supplied as PG 70-22 or PG 76-22 products for stone-mastic asphalt, open-graded porous asphalt, and stress-absorbing membrane interlayers. In hot-mix plants, the modified binder is held at 160–170°C under agitation and pumped through heated jacket lines; binder film thickness on aggregate is controlled at 8–12 µm to avoid draindown during SMA-13 production.

A pre-applied polymer-modified bituminous membrane compound is manufactured by loading YH-796 at 10–14 wt%, isotactic polypropylene or amorphous poly-alpha-olefin at 4–8 wt%, and calcium carbonate filler at 20–30 wt% into a continuous planetary mixer at 160–180°C. The SBS phase imparts low-temperature flexibility and reduces filler-filler friction during calendering; the polyolefin phase raises the cone penetration and reduces cold flow at membrane storage temperatures. The compound is discharged through an 80–120 mesh screen and calendered onto a polyethylene release film at a line speed of 1.2–1.5 m/min, with a finished sheet thickness of 1.5–2.0 mm. Calendering above 190°C produces surface pre-gel and release-film heat shrinkage; moisture in ground calcium carbonate above 0.2 wt% generates micro-voids that appear as pinholing in the finished membrane. Final products are installed as pre-applied wet-installed membranes for basement slabs and cut-and-cover tunnels; adhesion to post-poured concrete is tested under GB/T 23457-2017. Peel strength after heat ageing at 70°C for 7 days is typically specified above 2.5 N/mm in project specifications; low-temperature flexibility is verified at -25°C according to GB/T 328.14.

Can YH-796 Replace Solution-Polymerised SBS in Injection-Moulded Unit Soles?

Injection moulding of thermoplastic rubber unit soles does not require a sulphur or peroxide curing step, so YH-796 compounds are processed on standard reciprocating-screw injection moulding machines with general-purpose screws having L/D ratios between 18:1 and 22:1. A production compound is built on 100 phr YH-796, 25–50 phr naphthenic process oil, 10–20 phr general-purpose polystyrene, 20–40 phr fumed silica or carbon black, 5–15 phr high-density polyethylene, 0.3–1.0 phr hindered phenolic antioxidant, and 0.5–1.5 phr processing lubricant. Mixing is carried out in an internal mixer at 130–150°C for 8–12 min, followed by a two-roll mill at 120–130°C for pigment and filler dispersion. The material is granulated and fed to an injection moulding barrel with zone temperatures from hopper to nozzle of 160–190°C; mould temperature is maintained at 25–40°C, injection pressure is set at 60–90 MPa, and hold pressure is typically 30–50 MPa. Naphthenic oil is preferred over paraffinic oil because of its compatibility with the polybutadiene midblock; paraffinic oil can reduce tensile strength and cause surface exudation at addition levels above 35 phr. Fumed silica improves tear strength but raises melt viscosity; carbon black provides UV resistance but increases mixing torque. The process window is limited above 150°C in the mixing stage because oil flash-off and polybutadiene oxidation reduce mechanical properties.

Shore A hardness is measured under ISO 868 and typically falls between 60 and 70 for casual footwear. Tensile strength is tested according to ASTM D412 or ISO 37; abrasion loss is measured with DIN ISO 4649-A; flex fatigue is checked by ASTM D1052 at room temperature. Because YH-796 is a non-vulcanised TPR, 20–30 wt% of regrind from runner and sprue scrap can be added back without generating unacceptable crosslinked gel; this is an operational boundary of the compounding line. Service at sustained temperatures above 70°C leads to styrene-domain softening and compression set increase; applications requiring continuous upper service temperature above 90°C are better served by SEBS or vulcanised rubber.

Styrene Domain Reinforcement in HMPSA Slot-Die Coating

For hot-melt pressure-sensitive adhesives, YH-796 is dissolved into a molten tackifier system in a sigma-blade or planetary mixer at 150–170°C under an inert gas blanket. A stable hot-melt formulation comprises 25–30 wt% YH-796, 40–50 wt% C5 aliphatic hydrocarbon resin, 5–10 wt% aromatic C9 resin for styrene endblock reinforcement, 15–20 wt% naphthenic or paraffinic oil, and 0.5–1.0 wt% hindered phenolic antioxidant. The mixer runs at 30–50 rpm for 30–60 min until all YH-796 pellets are solvated; the final Brookfield viscosity at 150°C is controlled between 2,000 and 8,000 mPa·s to suit slot-die coating. Coating lines operate at 140–160°C with a web speed of 100–250 m/min, applying 18–25 g/m² dry adhesive weight to biaxially oriented polypropylene film or siliconised paper. If the residence time in the coating head exceeds 4 h at 170°C, oxidation of the polybutadiene midblock produces gel streaks that are visible under UV light after coating.

Pressure-sensitive performance is checked by ASTM D6195-22 loop tack, ASTM D3330/D3330M-02 180° peel, and ASTM D3654-19 static shear holding power. The aromatic C9 resin raises the glass-transition temperature of the polystyrene domains and improves cohesive strength; excess oil above 20 wt% reduces holding power and causes adhesive transfer on stainless steel test panels. YH-796-based hot melts are used in packaging tapes, label stock, and diaper side-tape applications where continuous use temperatures remain below 70°C; these systems are not recommended for prolonged contact with aliphatic solvents or for outdoor UV exposure without light stabilisers.

Twin-screw compounding of polypropylene regrind with YH-796 at a barrel profile of 190–220°C and a screw speed of 350–450 rpm produces a two-phase impact-modified morphology in which the SBS domain size is governed by the viscosity ratio of the dispersed SBS phase to the continuous PP melt. A practical compound for injection-moulded storage crates and logistics containers uses 80–85 wt% recycled PP, 10–15 wt% YH-796, and 3–5 wt% maleic anhydride-grafted PP as a compatibilising bridge. The PP-g-MAH reduces interfacial tension and shifts the SBS particle size below 1.5 µm; this is checked by scanning electron microscopy on cryo-fractured specimens. Notched Izod impact strength, tested under ASTM D256-23 at 23°C, is increased relative to unfilled recycled PP, although published data for this exact YH-796/recycled PP configuration is limited; plant trials are required to set lot-specific addition rates. Melt flow is measured by ISO 1133-1:2022 at 230°C/2.16 kg to maintain a moulding melt index above 10 g/10 min in thin-wall container tools. The compound is injection moulded at nozzle temperatures of 200–230°C, with mould temperatures of 25–50°C. Finished parts include produce crates, collapsible dunnage, and logistics pallets where low-temperature impact durability is required. The upper service temperature is limited by the polypropylene continuous phase, but the SBS dispersed phase should not be exposed to sustained temperatures above 80°C; oxidative degradation of the butadiene midblock is controlled with hindered phenolic and phosphite antioxidant packages at 0.15–0.30 wt%.

Asphalt-Based Automotive Damping Sheets Demand High Filler Acceptance

In body-in-white acoustic damping, SBS-modified bituminous sheets are produced by compounding YH-796 at 6–10 wt% with asphalt, barium sulfate or calcium carbonate filler at 60–75 wt%, and a minor polyolefin or rosin ester melt-flow aid, then calendering onto nonwoven felt or aluminium foil at 120–140°C. YH-796 improves cold flexibility and crack resistance of the highly filled mastic so that the sheet can be die-cut and adhered to vertical door inner panels without cracking at handling temperatures of 5–10°C. Damping loss factor is measured by SAE J1637 or ISO 6721; a typical composite loss factor target is above 0.10 at 20–25°C and 200 Hz. Plant-scale processing is conducted in a heated kneader or twin-screw extruder with a barrel profile of 100–140°C; wet filler above 0.2 wt% moisture causes steam pinholes and localised delamination at the felt interface. The finished sheets are applied in door panels, floor pans, and roof bows in passenger vehicles. Because filler particle-size distribution and oil absorption influence the damping modulus, rheological data for a specific YH-796-filled mastic is normally generated at plant scale rather than taken from published data for unfilled asphalt; this is a recognised operational limitation of the application.