1 - Characteristics
- Synonyms: styrene monomer, Ethenylbenzene, Phenylethylene, Styrol, Vinylbenzene
- Chemical formula: C6H5-CH=CH2 · Molecular weight: 104.14 · MARPOL category: B
- UN n°: 2055 · CAS n°: 100-42-5 · IMDG class: 3.3
- Appearance at ambient temperature (20°C): colourless to pale yellow
- Relative density (water = 1): 0.906 · Relative vapour density (air = 1): 3.6
- Melting point: -30.6°C · Boiling point: 145.2°C
- Flash point: 31°C · Vapour pressure: 670 Pa at 20°C
- Solubility in water: 40 mg in 1 L of distilled water at 13°C, 20 mg in 1 L of seawater at 13°C (Cedre data)
- IDLH / TWA: 700 ppm / 50 ppm · Viscosity: 0.7 mPa.s at 25°C
2 - Physico-chemical behaviour
- Stability: stability is ensured by adding a polymerisation inhibitor (e.g. 4-tert-Butylcatechol) at a concentration of 10 at 15 ppm.
- In air: highly volatile, explosive mixture in air (LEL: 1.1% - UEL: 6.1% vol.), auto-ignition temperature: 490°C, vapours heavier than air with an odour threshold of 0.1 ppm.
- in water: insoluble but can polymerise when exposed to sunlight.
- reactivity with other products: can react violently with strong oxidising agents such as peroxides as well as with bases, acids and halides.
3 - Spill response techniques
- Emergency measures:
- Issue shelter-in-place orders within a radius of around 500 m around the spill
- In case of fire, styrene may mass explode: evacuate within a radius of 1 km (distance dependent on quantities involved)
- Stay upwind
- Avoid depressions
- Ventilate before entering a confined space
- Prevent infiltration into sewer system (seal drains) and confined spaces (explosion risk).
- Spill on platform area or quayside: evacuate 500 m strip downwind, drain and contain to recover or absorb at lower point. Prevent run-off into water bodies by building bunds or dykes made of earth or sand.
- Spill into water: if possible, prevent spill from reaching the bank or shore by deploying floating booms, then consider containment before recovering or absorbing the product.
4 - Risks for responders
- Response limits: major risk = flammability/explosion, propagation of vapours making it difficult to conduct response operations on the water.
- Intoxication risks: product classified as irritating to the eyes; inhalation into the lungs beyond a certain threshold can cause chemical pneumonia. Repeated exposure can cause liver damage as well as affecting the nervous system.
- Measuring devices: readings using explosimeter, photoionisation detector (PID equipped with appropriate lamp for styrene) as well as Dräger detector tubes:
- Monostyrolene 10/a n°6723301 from 10 to 200 ppm;
- Monostyrolene 10/b n°6733141 from 10 to 250 ppm;
- Monostyrolene 10/c n°CH27601 from 50 to 400 ppm.
- Choice of protection equipment: wear a splash suit resistant to liquid chemicals and organic vapours (type 3) and a full-facepiece respirator (covering eyes, mouth and chin) equipped with a filter protecting against gases and organic vapours (type A2). Laminate polyethylene and ethyl vinyl alcohol gloves.
Warning: butyl rubber, neoprene and polyvinyl chloride have a protection time of less than 1 hour.
5 - Risks for the environment
- Immediate effects: product considered toxic (acute toxicity of 1 to 10 mg/l) with a predicted no-effect concentration of 41 micro-g/l. In seawater, the toxicity varies between 2 and 100 mg/l according to the organisms involved.
- Persistence: low bioaccumulation potential, estimated persistence at around 1 week.