HomeProducts

Methyl ethyl ketone peroxide

CAS Number
1338-23-4
EC Number
215-661-2
Molecular Weight
210.22 g/mol

Description

Methyl ethyl ketone peroxide (CAS 1338-23-4 ), commonly known as MEKP, is an organic peroxide used as a free-radical initiator in polymer curing and crosslinking systems. Supplied as a solution rather than in pure form, it activates resin systems at room temperature without requiring elevated heat. Formulators and compounders rely on it to control cure speed and crosslink density across a range of thermoset applications. MEKP is the standard initiator for curing unsaturated polyester and vinyl ester resins in fiberglass-reinforced composites. This includes marine hulls, automotive panels, and construction laminates. In combination with cobalt-based accelerators, it enables ambient-temperature cure cycles that are critical for open-mold and hand lay-up fabrication. Rubber compounders use it as a crosslinking agent to improve heat resistance and mechanical performance in elastomeric profiles and molded parts. It also initiates polymerization in gel coats and casting resins. In these applications, cure uniformity directly affects surface quality and product yield. MEKP is supplied as a liquid solution, typically diluted in plasticizers or inert carriers to reduce reactivity hazards during handling and transport. Standard commercial concentrations range from approximately 33% to 60% active oxygen content, with grades varying by reactivity profile to suit different resin systems and processing conditions. Technical-grade material is the norm for most industrial uses. Buyers should confirm active oxygen percentage and dilution carrier with suppliers when qualifying for specific applications to ensure compatibility. Contact us for supply of Methyl ethyl ketone peroxide Request Quote

Other Names (Synonyms)

methyl ethyl ketone hydroperoxide | MEKP | MEK peroxide | ethyl methyl ketone peroxide | butan-2-one peroxide | 2-butanone peroxide | Ketonox | Mepox

Key Technical Features

  • High Purity Grade standard
  • Consistent Batch Quality
  • Full Regulatory & REACH Support
  • Global Logistics Network enabled

Physical Properties

Melting Point<25 °C
Boiling Point19 °C
Density1.18 g/cm³
Flash Point190 °F
AppearanceMEKP, an organic peroxide, is a colorless liquid.
FormLiquid
Water Solubility0.1-0.5 g/100 mL at 22 ºC
Vapor Pressure0.644-73.6Pa at 25℃
Refractive Indexn 20/D 1.455
Log P0.3 at 25℃

Safety & Handling

Danger
GHS02· FlammableGHS05· CorrosiveGHS07· IrritantGHS01· ExplosiveGHS06· ToxicGHS08· Health Hazard

Hazard Statements

H227Combustible liquid
H241Heating may cause a fire or explosion
H242Heating may cause a fire
H302Harmful if swallowed
H312Harmful in contact with skin
H313May be harmful in contact with skin
H314Causes severe skin burns and eye damage
H315Causes skin irritation
H318Causes serious eye damage
H330Fatal if inhaled
H332Harmful if inhaled
H335May cause respiratory irritation
H336May cause drowsiness or dizziness
H341Suspected of causing genetic defects
H370Causes damage to organs
H373May causes damage to organs through prolonged or repeated exposure
H401Toxic to aquatic life H302+
H332Harmful if swallowed or if inhaled

Precautionary Statements

P203Obtain, consult and follow expert instructions for use.
P210Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
P234Keep only in original packaging.
P235Keep cool.
P240Ground and bond container and receiving equipment.
P260Do not breathe dust/fume/gas/mist/vapours/spray.
P261Avoid breathing dust/fume/gas/mist/vapours/spray.
P264Wash … thoroughly after handling.
P270Do not eat, drink or smoke when using this product.
P271Use only outdoors or in a well-ventilated area.
P273Avoid release to the environment.
P280Wear protective gloves/protective clothing/eye protection/face protection.
P284In case of inadequate ventilation wear respiratory protection.
P316Get emergency medical help immediately.
P317Get emergency medical help.
P318IF exposed or concerned, get medical advice.
P319Get medical advice/attention if you feel unwell.
P320Specific treatment is urgent (see … on this label).
P321Specific treatment (see … on this label).
P330Rinse mouth.
P363Wash contaminated clothing before reuse.
P378Use … for extinction.
P403Store in a well-ventilated place.
P405Store locked up.
P410Protect from sunlight.
P411Store at temperatures not exceeding … °C/…°F.
P420Store away from other materials.
P501Dispose of contents/container in accordance with local regulations.
P265Wash … thoroughly after handling.
P317Get emergency medical help.
P317Get emergency medical help.
P352IF ON SKIN: Wash with plenty of water.
P340IF INHALED: Remove person to fresh air and keep comfortable for breathing.
P316Get emergency medical help immediately.
P317Get emergency medical help.
P364Take off contaminated clothing and wash it before reuse.
P378Use … for extinction.
P233Store in a well-ventilated place. Keep container tightly closed.
P331Rinse mouth. Do NOT induce vomiting.
P354IF ON SKIN: Take off immediately all contaminated clothing. Rinse skin with water/shower.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P375Evacuate area.

Trade & Regulatory

UN Number3105
ADR Class5.2
Storage Class5.2 - Organic peroxides and self-reacting hazardous materials
WGK (Germany)1