Deltech Monomers para-Methylstyrene (PMS)

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Deltech para-Methylstyrene (PMS) is recommended for evaluation as a replacement for vinyltoluene and styrene monomers. It shares similar chemical properties and polymerization behavior with both vinyltoluene and styrene. When used as a partial or complete replacement for styrene monomer in unsaturated polyester resin applications, polymerized resin products exhibit lower vapor pressure at any temperature and a higher flashpoint. Additionally, PMS offers advantages such as lower shrinkage during molding, improved thermal properties, and greater tensile strength in glass-filled applications.

Chemical Name: 3-Methylstyrene, p-Methylstyrene

Chemical Family: Styrenics

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Identification & Functionality

Chemical Family
Base Chemicals Functions
Chemical Structure

Typical Isomer Distribution:
95% Para
5% Meta

Features & Benefits

Applications & Uses

  • In applications where vinyltoluene monomer is replaced by PMS monomer, property improvements related to the higher para-content and polymerizables are obtained. Direct substitution of PMS monomer for vinyltoluene can be made with minimal reformulation to obtain equal or improved performance when used in specialty coatings, sealants and adhesives.
  • Use of PMS monomer as a partial or complete replacement for styrene monomer in unsaturated polyester resin applications results in lower resin vapor pressure at any temperature and a higher flashpoint. Lower shrinkage during molding, higher thermal properties and greater tensile strength in glass-filled applications can be expected from polymerized resin products.
  • PMS monomer can replace styrene monomer in homopolymers, impact polymers, acrylonitrile-butadiene terpolymers, specialty copolymers, elastomers and thermosetting polyesters. Homo and copolymers prepared from PMS monomer have been found to possess lower specific gravity, higher flow properties and improved heat distortion than the corresponding styrene-based analogs. In thermosetting polyester applications, higher heat distortion, faster molding cycles, and better electrical properties have been demonstrated. Also, fire retarding properties can be obtained with lower dosages of flame retardant additives and the molecular structure of PMS polymers can be modified through radiation and chemical crosslinking.


Physical Form
Physical Properties
ValueUnitsTest Method / Conditions
Carbonyls10.0ppmASTM D-2119-82
Inhibitor TBC25.0ppmASTM D-4590
Sulfur Content25.0ppmXRF
Refractive Index (n25D)1.5408--
Density (at 25°C)0.892g.cm³-
Viscosity (at 25°C)0.79cps-
Surface Tension (at 25°C)34.0dynes-cm-¹-
Boiling Point (at 760mm Hg)170.0°C-
Flash Point-34.0°C-
Volume Concentration on Polymerization (at 25°C)12.0%-
Vapor Pressure (at 40°C)4.0mm.Hg-
Vapor Pressure (at 80°C)35.0mm.Hg-
Vapor Pressure (at 120°C)170.0mm.Hg-
Vapor Pressure (at 160°C)580.0mm.Hg-
Heat of Polymerization15 - 17Kcal mole-¹-
Copolymerization (Q Values)1.27--
Copolymerization (e Values)-0.98--
Heat of Vaporization (at 25°C)98.2cal/g-
Specific Heat (at 25°C)0.413cal/g °C-
Chemical Analysis
ValueUnitsTest Method / Conditions
Isomer Distribution (Para)95.0%GC
Isomer Distribution (Meta)5.0%GC
PolymerNegativeppmASTM D-2121-84

Regulatory & Compliance

Certifications & Compliance
Chemical Inventories

Nothing contained herein is to be construed as a recommendation to use any product in conflict with any patent. Deltech LLC makes no warranties as to the fitness of merchantability of any product referred to, no guarantee of satisfactory results from reliance upon contained information or recommendation, and disclaims all liability for any resulting loss or damage.

Storage & Handling

Storage & Handling

Typical precautions in handling PMS monomer include wearing protective clothing, the use of impermeable gloves and use in a well ventilated area. Do not store in direct sunlight. Maintain storage temperature below 75oF if extended storage is required. PMS monomer contains the polymerization inhibitor tertiary butylcatechol (TBC) to reduce polymer formation during storage. For other product safety and toxicological information, please consult the Material Safety Data Sheets for PMS monomer.