Products
Products
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| HS Code | 892630 |
| Chemical Name | Styrene |
| Cas Number | 100-42-5 |
| Chemical Formula | C8H8 |
| Molar Mass | 104.15 g/mol |
| Appearance | Colorless to yellowish oily liquid |
| Odor | Sweet, floral odor |
| Density | 0.906 g/cm3 at 25°C |
| Melting Point | -30°C |
| Boiling Point | 145°C |
| Flash Point | 31°C (closed cup) |
| Autoignition Temperature | 490°C |
| Solubility In Water | 0.03 g/100 mL at 20°C |
| Vapor Pressure | 6.4 mmHg at 20°C |
| Refractive Index | 1.5467 at 20°C |
As an accredited Styrene factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Styrene is supplied in 200 kg steel drums, 1000 kg IBC totes, or bulk tank containers, under inert gas. |
| Container Loading (20′ FCL) | 20' FCL: load styrene in sealed, grounded drums upright, with ventilation, no ignition sources, proper hazardous labels and securing. |
| Shipping | Styrene is shipped as a flammable, inhibited liquid (UN 2055, Class 3, PG III). Transport requires temperature control to prevent polymerization, proper grounding against static, and secure, compatible containers. Ensure adequate ventilation, avoid ignition sources, and follow hazardous materials regulations for safe handling. |
| Storage | Store styrene in tightly closed, approved containers away from heat, sparks, and direct sunlight. Maintain recommended storage temperature, usually below 20°C, to prevent polymerization. Ensure inhibitor is present and monitor concentration. Use explosion-proof equipment, bond and ground containers, and provide adequate ventilation. Separate from oxidizers, peroxides, and acids. Follow all local regulations. |
| Shelf Life | Store below 20°C, away from light/air, with polymerization inhibitor; typical shelf life is 6–12 months. |
In continuous bulk polymerization lines producing general-purpose polystyrene (GPPS) and high-impact polystyrene (HIPS), styrene monomer with minimum 99.8 wt% purity is mixed with 10–20 wt% ethylbenzene solvent and a low-cis polybutadiene rubber before thermal initiation. The HIPS prepolymerization stage operates at 120–150 °C with conversion held at 15–25% before phase inversion, where rubber dissolved in styrene transitions into a continuous rubber-rich phase containing SAN-grafted rubber particles. Typical HIPS grades contain 5–12 wt% polybutadiene rubber, median rubber particle diameter 0.8–3.5 µm, gel content 15–30%, and swelling index 10–20. A twin-screw devolatilizer with L/D ratio 36:1–48:1 is run at 230–260 °C and vacuum 20–50 mbar, reducing residual styrene to 200–500 ppm for food-contact grades. Melt volume-flow rate under ISO 1133-1:2022 at 200 °C/5 kg ranges from 1.5 cm³/10 min to 20 cm³/10 min, Vicat softening temperature under ISO 306/B50 from 95 °C to 105 °C, and notched Izod impact under ISO 180/A from 8 kJ/m² to 15 kJ/m² for HIPS. Increasing rubber loading beyond 14 wt% raises melt viscosity and reduces gloss without further impact improvement. Food-contact grades are evaluated under FDA 21 CFR 177.1640 and EU Regulation 10/2011, with overall migration below 10 mg/dm². Production failures are typically linked to rubber particle agglomeration when stirrer tip speed in the prepolymerizer falls below 0.8 m/s, or to devolatilizer vacuum degradation when stripping steam exceeds 0.5 wt% of melt throughput. Extruded sheet is thermoformed into refrigerator inner liners, coffee cup lids, dairy packaging, and single-use trays.
Suspension polymerization of styrene for expandable polystyrene (EPS) is carried out in a stirred autoclave with water as continuous phase, tricalcium phosphate or polyvinyl alcohol as suspending agent, and a dual initiator package of benzoyl peroxide and tert-butyl peroxybenzoate. The blowing agent n-pentane or iso-pentane is added at 5–7 wt% after monomer conversion reaches 60–80%. Bead diameter after classification is controlled in cuts from 0.3 mm to 1.6 mm, and residual styrene is held below 1000 ppm for insulation grades. Pre-expansion with saturated steam at 90–105 °C produces bulk density between 12 kg/m³ and 35 kg/m³; the pre-expanded beads are aged at 20–25 °C for 6–24 h so pentane pressure equilibrates and air diffuses into the foam cells. Block moulding uses steam pressure 0.7–1.5 bar for 20–60 s; final block density is determined by shot weight and steam enthalpy. Bead fusion strength is tested by tensile separation across a moulded interface, with values below 100 kPa indicating either overaged beads or insufficient steam penetration at the core. Thermal conductivity after 90 days of aging is measured under EN 12667 or ISO 8301 at 10 °C mean temperature and ranges from 0.031 W/m·K to 0.038 W/m·K. Compressive stress at 10% deformation under EN 826 is 70–250 kPa depending on density. Product compliance is governed by EN 13163 and ASTM C578; untreated EPS is classified Euroclass E under EN 13501-1, and EU flame-retardant grades no longer rely on hexabromocyclododecane due to REACH Annex XVII restrictions. End products include exterior insulation boards, foundation void formers, fish boxes, and cold chain packaging.
Mass polymerization of acrylonitrile-butadiene-styrene (ABS) begins by dissolving polybutadiene rubber in a styrene-acrylonitrile mixture. The first reactor maintains rubber content between 8 wt% and 14 wt% to reach phase inversion, after which the rubber-rich continuous phase occludes styrene-acrylonitrile graft copolymer. Final ABS composition is 40–60 wt% styrene, 15–25 wt% acrylonitrile, and 10–30 wt% butadiene rubber depending on grade. Prepolymerization temperature is staged between 90 °C and 130 °C, and devolatilization runs at 230–260 °C and 20–40 mbar. Injection moulding demands pre-drying at 80 °C for 2–4 h to below 0.02% moisture; if ambient relative humidity exceeds 60%, dry-air hoppers must be used to prevent surface splay. Melt temperature is 220–260 °C, and mould temperature is 40–80 °C. Notched Izod impact under ISO 180/A ranges from 20 kJ/m² to 35 kJ/m² for high-impact grades. Melt volume rate under ISO 1133-1:2022 at 220 °C/10 kg is 5–30 cm³/10 min. The material is specified under ISO 2580-2; automotive interior grades are additionally screened for volatile organic compound emissions. Process instability occurs when stirrer tip speed in the phase inversion reactor drops below 0.5 m/s, producing coarse rubber particles and non-uniform extrudate. Terminal products include instrument panel substrates, door trim, electronic equipment housings, and appliance control panels.
| ABS grade class | Butadiene rubber content (wt%) | Melt volume rate ISO 1133-1 (cm³/10 min) | Notched Izod impact ISO 180/A (kJ/m²) | Vicat softening ISO 306/B50 (°C) |
|---|---|---|---|---|
| General-purpose injection moulding | 10–15 | 15–25 | 18–25 | 98–103 |
| High-impact extrusion | 18–25 | 5–12 | 30–40 | 95–100 |
| High-heat injection moulding | 12–18 | 8–15 | 15–22 | 106–112 |
In continuous bulk copolymerization of styrene-acrylonitrile resin, the azeotropic feed composition is approximately 76 wt% styrene and 24 wt% acrylonitrile, which suppresses compositional drift and yields a transparent random copolymer with residual monomer below 300 ppm after devolatilization. Reactor temperature is staged from 120 °C to 180 °C, and polymer melt is discharged through a twin-screw devolatilizer at 20–40 mbar and 230–250 °C. Glass transition temperature is 100–105 °C, and Vicat softening temperature under ISO 306/B50 is 101–108 °C. Tensile strength under ISO 527-2 is 65–75 MPa, tensile modulus 3,300–3,800 MPa, and light transmission across a 3 mm plaque is 88–90%. Moulding requires pre-drying at 80 °C for 3–4 h to below 0.05% moisture; melt temperature is 200–260 °C, and mould temperature is 30–60 °C. The resin resists aliphatic solvents, edible oils, and dilute acids, but is incompatible with ketones, esters, aromatic solvents, and concentrated strong acids. Materials are specified under ISO 4894-1, with food-contact grades evaluated under EU Regulation 10/2011. End products include transparent kitchen appliance bowls, cosmetic packaging, battery cases, and diagnostic device housings.
Cold emulsion styrene-butadiene rubber (E-SBR) is polymerized at 5–10 °C using a redox initiation system of cumene hydroperoxide, ferrous sulfate, and sodium formaldehyde sulfoxylate. Styrene is charged at 23.0–24.5 wt% in the monomer feed for tire tread grades; the bound styrene controls the glass transition near −52 °C and influences Mooney viscosity. Polymerization is short-stopped at 60–70% conversion to limit branching and gel; unreacted styrene and butadiene are stripped under vacuum and recovered. Coagulation with sodium chloride and sulfuric acid produces crumb rubber with residual volatile content below 0.75 wt%. Mooney viscosity ML(1+4) at 100 °C for general tire tread grades is 45–55. Increasing bound styrene from 23.5 wt% to 30 wt% raises the glass transition by approximately 5–8 °C and reduces resilience; this improves wet-grip tread compounds but may impair low-temperature flexibility. The rubber is tested under ASTM D3185 and ISO 2322. In a conventional tread formulation with 50 phr N330 carbon black, 2 phr sulfur, and 1 phr N-cyclohexyl-2-benzothiazolesulfenamide, tensile strength is 20–25 MPa and elongation at break is 400–500% under ISO 37. Carboxylated styrene-butadiene latex grades use styrene between 45 wt% and 65 wt%, carboxylic acid 1–4 wt%, and total solids 48–52%; these are applied to coated paperboard, carpet backing, and nonwoven binders. Coated paperboard latex is assessed under FDA 21 CFR 176.170. Latex shear stability is critical; viscosity rises sharply when shear exceeds 500 s⁻¹ in high-solids compounding. End products include tire treads, conveyor belts, shoe soles, coated paperboard, and carpet backing.
In unsaturated polyester resin systems, styrene performs dual roles as crosslinking monomer and viscosity-reducing diluent. Commercial laminating resins contain 30–50 wt% styrene, with base resin solids 50–70 wt% and viscosity at 25 °C between 200 mPa·s and 800 mPa·s. Free-radical initiation uses methyl ethyl ketone peroxide at 1.0–1.5 phr and a cobalt accelerator solution at 0.2–0.5 phr. Gel time at 25 °C is 15–40 min, and the curing exotherm peak is 120–170 °C depending on thickness. Glass-fibre-reinforced laminates produced by hand lay-up or vacuum infusion show tensile strength under ISO 527-4 of 60–90 MPa, flexural strength under ISO 14125 of 100–150 MPa, and Barcol hardness under ASTM D2583 of 40–50. Styrene vapor is a volatile organic compound; open-mould workshops maintain workplace exposure below 20 ppm and install extraction at 0.5–1.0 m/s air velocity across the mould surface. Low-styrene-emission resins use wax additives that bloom during cure to form a surface barrier, reducing styrene release by 30–60% compared with unmodified laminating resins. Amine-based additives are incompatible because they interfere with peroxide initiation and can cause premature gelation. End products include boat hulls, chemical storage tanks, pipe liners, and architectural panels.
| Formulation component | Dosage (phr) | Function | Critical parameter |
|---|---|---|---|
| Unsaturated polyester base resin in styrene | 100 | Matrix and reactive diluent | Styrene content 35–45 wt% |
| Methyl ethyl ketone peroxide | 1.0–1.5 | Free-radical initiator | Active oxygen 8.8–9.5% |
| Cobalt octoate solution | 0.2–0.5 | Accelerator | Cobalt content 6 wt% |
| Fumed silica | 1–3 | Thixotropy | BET surface area 130–200 m²/g |
Suspension copolymerization of styrene with technical divinylbenzene is the standard route to gel and macroporous ion exchange resin beads. Gel cation exchange resins use divinylbenzene crosslinker at 2–12 wt%, while macroporous resins incorporate 5–20 wt% divinylbenzene and a porogen such as isooctane or toluene at 30–60 wt% relative to monomer. Bead diameters after screening are 300–1200 µm, with uniformity coefficients below 1.6 for high-efficiency counter-current water softening. Sulfonation with concentrated sulfuric acid or oleum at 90–120 °C yields strong-acid cation exchange capacity of 1.8–2.2 eq/L in the hydrogen form. Resin quality is evaluated by total exchange capacity, moisture retention, and bead integrity under ASTM D2187. Iron fouling and oxidative attack from free chlorine above 1 ppm are common field failures; vinyl aromatic crosslinked resins are not resistant to strong oxidizing agents such as nitric acid or concentrated hydrogen peroxide. Terminal uses cover boiler feedwater softening, demineralization trains, and acid catalysis in esterification and hydration reactors.
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Styrene monomer, inhibited, polymer grade, CAS 100-42-5, is supplied as a clear liquid for free-radical polymerization, copolymerization, and reactive diluent service. The product designation most frequently encountered on supplier certificates is “styrene monomer, inhibited, polymer grade, ASTM D2827-20”; the nominal composition is C8H8 with molar mass 104.15 g/mol, density 0.906 g/cm³ at 20 °C, normal boiling point 145 °C, closed-cup flash point 31 °C, and vapor pressure 0.67 kPa at 20 °C. Industrial use is concentrated in continuous mass polystyrene, high-impact polystyrene, expandable polystyrene, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, styrene-butadiene rubber latex, and unsaturated polyester resin. In polymer-grade deliveries the monomer is inhibited with 4-tert-butylcatechol at 10–15 mg/kg to suppress thermal polymerization during bulk storage and transport.
Supplier certification for continuous polymerization plants usually includes polymer content, inhibitor concentration, water content, color, and purity. Technical-grade styrene is available with lower purity and is generally limited to noncritical resin applications, while polymer-grade material is required for food-contact polystyrene, optical-grade styrene-acrylonitrile, and high-clarity acrylonitrile-butadiene-styrene. Under GHS the monomer is classified as Flam. Liq. 3, Acute Tox. 4, Skin Irrit. 2, Eye Irrit. 2, and STOT SE 3; in the United States it is a hazardous air pollutant under 40 CFR 63, and in Europe it is registered under REACH. These regulatory properties drive vapor-recovery, tank-venting, and monomer-transfer engineering on production lines.
ASTM D2827-20 provides the consensus specification for polymer-grade styrene monomer. The critical control points are purity, inhibitor concentration, color, polymer content, water content, and impurity profile. Because downstream continuous mass polymerization is sensitive to chain transfer and crosslinking, minor deviations in polymer content or inhibitor carryover alter reactor viscosity and product molecular weight. The table below summarizes a typical polymer-grade commercial profile; individual suppliers may apply tighter internal limits.
| Property | Typical polymer-grade limit | Test method |
|---|---|---|
| Purity | ≥ 99.80 % by mass | ASTM D2827-20 gas chromatography |
| 4-tert-butylcatechol inhibitor | 10–15 mg/kg | ASTM D2827-20 |
| Color | ≤ 10 Pt-Co | ASTM D1209-19 |
| Polymer content | ≤ 10 mg/kg | ASTM D2827-20 turbidity |
| Water | ≤ 200 mg/kg | ASTM E203-21 Karl Fischer |
| Refractive index, n20/D | 1.5460–1.5470 | ASTM D1218-21 |
The polymer content limit is not solely a specification requirement. If styrene is heated in a pre-polymerizer above 100 °C, residual polymer nuclei can promote gel deposits on agitator blades and heat-transfer surfaces, reducing heat removal. A batch with polymer content above 10 mg/kg is sometimes diverted to dark-color resin or fuel-blending applications rather than optical-grade polymer lines. Water content above 200 mg/kg can contribute to hydrolysis side reactions in unsaturated polyester curing and to surface defects in cast sheet; it is managed by supplier drying or by azeotropic removal in the customer process.
In direct comparison with other vinyl monomers, styrene differs in radical stabilization, homopolymer glass transition, volatility, and copolymerization parameters. Compared with α-methylstyrene, styrene lacks the low ceiling temperature that limits α-methylstyrene homopolymerization near 61 °C. Vinyl toluene has a methyl-substituted aromatic ring that reduces volatility and modifies radical stability, but its higher cost and different copolymerization parameters limit drop-in use. Methyl methacrylate has a lower boiling point, higher vapor pressure, and superior outdoor gloss retention, but it produces a less aromatic network in unsaturated polyester resins. n-Butyl acrylate and vinyl acetate are chosen when flexibility or lower refractive index is required. In styrene–methyl methacrylate radical copolymerization, reported reactivity ratios are 0.52 and 0.46; the system approaches azeotropic behavior but does not eliminate monomer drift at all temperatures. The table below lists selected physical properties of these reference monomers; values are standard reference data and should be confirmed against the specific lot certificate.
| Property | Styrene | Methyl methacrylate | Vinyl acetate | n-Butyl acrylate |
|---|---|---|---|---|
| Molar mass | 104.15 g/mol | 100.12 g/mol | 86.09 g/mol | 128.17 g/mol |
| Boiling point at 101.3 kPa | 145 °C | 100 °C | 72.5 °C | 145 °C |
| Vapor pressure at 20 °C | 0.67 kPa | 3.85 kPa | 11.1 kPa | 0.44 kPa |
| Homopolymer Tg | 100 °C | 105 °C | 30 °C | -54 °C |
The selection of styrene over methacrylate or acrylate monomers depends on refractive index, homopolymer glass transition, reactivity ratio compatibility with fumarate or butadiene unsaturation, and regulatory limits on aromatic emissions. These are process variables rather than direct performance advantages.
Styrene undergoes thermal self-initiation through a Diels-Alder dimerization mechanism that generates radicals. The rate is strongly temperature-dependent; supplier bulk storage guidance commonly sets maximum tank temperature at 30 °C, with short-duration excursions to 38 °C permitted only when 4-tert-butylcatechol is present and dissolved oxygen is not depleted. The phenolic inhibitor functions as a radical trap only in the presence of oxygen; nitrogen blanketing of inhibited styrene must therefore be designed to avoid oxygen stripping. Tank vents should be pressure-vacuum conservation with flame arrestors, and recirculation lines with side-stream chillers are sometimes used to maintain bulk temperature. Weekly polymer content and inhibitor titrations are taken on terminal tanks; a rise in polymer content above 50 mg/kg or a drop in inhibitor below 5 mg/kg typically triggers repackaging or inhibitor adjustment. Exothermic polymerization in a confined storage tank can exceed 145 °C if monomer vapor reflux is suppressed; this condition is a serious process-safety hazard.
Published data for the minimum dissolved-oxygen concentration required to maintain inhibitor activity vary by supplier and oxygen-transfer geometry. Operations that combine oxygen-free blanketing with elevated steam tracing temperatures have repeatedly shown accelerated polymer formation. Transfer piping should be sloped to avoid dead legs, and pump mechanical seals should be specified for low-shear conditions to reduce local frictional heating.
In continuous mass polystyrene production, the monomer is fed to a prepolymerizer stirred reactor operating at 110–150 °C with a target prepolymer solids level of 10–20 % by mass. The viscous solution then enters a plug-flow or tower reactor with staged heating from 130 °C to 180 °C; the rising viscosity imposes heat-transfer limitations and requires close control of wall temperature. Devolatilization is normally conducted under vacuum at 230–250 °C and 1.3–4.0 kPa absolute pressure using a devolatilizer or vented twin-screw extruder with L/D ratio typically in the range of 28:1 to 40:1. Styrene vapor removed from the devolatilizer is condensed and recycled; ethylbenzene and water must be purged to avoid accumulation. Ethylbenzene, often present in fresh styrene at 0.1–0.3 %, acts as a chain transfer agent; recycled streams with ethylbenzene levels above 1 % can reduce polystyrene molecular weight and require purge rate increases.
In emulsion styrene-butadiene rubber manufacture, styrene is fed as the hydrophobic comonomer with butadiene; its solubility in the micelle core and its reactivity ratio influence sequence distribution and latex particle morphology. In suspension expandable polystyrene lines, residual styrene after devolatilization is controlled according to Commission Regulation (EU) 10/2011 for food-contact applications. Production-scale failures in continuous mass plants are often associated with pre-polymerizer agitator seal leakage when polymer content in recycled monomer is not controlled, or with vent-line fouling when devolatilizer pressure is allowed to fall below design levels. These failure modes are minimized by installing side-stream filters and by limiting recycled monomer polymer content below 10 mg/kg.
In unsaturated polyester resins, styrene acts simultaneously as a reactive diluent and crosslinking monomer. Replacement of methyl methacrylate with styrene shifts the copolymerization rate because styrene and the fumarate or maleate unsaturation in the polyester backbone have a strong alternating copolymerization tendency. The practical result is higher crosslink density at equivalent monomer loading, increased aromatic content, and higher heat-distortion temperature in the cured cast, but reduced resistance to yellowing and surface erosion under weathering. Formulations containing styrene are typically adjusted with cobalt accelerators and methyl ethyl ketone peroxide or acetylacetone peroxide initiators; gel time is measured by ASTM D7029 or ISO 2535. Because styrene has a lower vapor pressure than methyl methacrylate but is classified as a hazardous air pollutant, open-mold laminating operations often suppress emissions through low-styrene resins, wax additives, or vapor capture. In closed-mold processes the lower vapor pressure reduces void formation; however, the aromatic monomer can soften gel coat layers more than methacrylate alternatives when over-sprayed, requiring scheduling controls for secondary coats.
Published data for styrene emission factors in hand lay-up and spray-up operations show wide variability depending on resin temperature, mold surface area, and film-forming additives. Emissions are reduced by lowering monomer content and increasing resin viscosity, but the trade-off is higher styrene consumption per unit of laminate mechanical strength if monomer is not fully incorporated during curing.
Styrene monomer is not compatible with amine-based additives that can neutralize or complex the phenolic inhibitor. Loss of 4-tert-butylcatechol activity can occur even when the amine is present at low concentration. Strong mineral acids and acidic ion-exchange resins may promote cationic dimerization or sulfonation of the aromatic ring, generating color bodies and reactive impurities. Oxidizing agents produce peroxides and benzaldehyde-type carbonyl impurities that alter polymerization kinetics. Storage tanks and transfer piping are normally fabricated from stainless steel or carbon steel; if copper-based alloys are present, published data indicate that inhibitor depletion may accelerate under certain conditions, so copper alloys are generally avoided. Purge lines should not be cross-connected to amine-containing monomer systems because vapor-phase contamination can deactivate inhibitor in the tank headspace.
Cleaning and maintenance procedures require removal of residual styrene before hot work. The closed-cup flash point of 31 °C places styrene in Class IC flammable liquid under NFPA 30, and transfer pumps should be equipped with mechanical seals and low-level interlocks to avoid dry-running that generates local heating. Static discharge control is required during loading because the liquid has low electrical conductivity; inerting of the tank headspace is not always sufficient if oxygen is needed for inhibitor function, so loading procedures must balance flammability control with inhibitor preservation.
