Definition
Emulsion polymerization is an industrial method for making a Polymer in which Monomer droplets are dispersed in water with a surfactant (soap) and polymerized inside tiny surfactant micelles, producing a milky latex of fine polymer particles. It is one of the upstream routes that creates the Resin a molder later buys — not something done in the molding shop, but it shapes the grade's properties.
How it works
- Water carries the heat away and stays low-viscosity even as polymer forms, so the reaction is easy to control and can run fast to high molecular weight.
- Surfactant micelles are the reaction sites; an initiator in the water phase starts the chains, which grow inside the micelles into nanoscale particles suspended as latex.
- The latex is then used directly (paints, adhesives, coatings) or the polymer is coagulated, washed and dried into powder or Pellets for molding.
What it makes for molders
Emulsion polymerization (and the related suspension process) produces several resins a molder uses: ABS (and its rubber phase), PVC paste/emulsion grades, PVDF, acrylics and SBR/latex rubbers. The route gives high molecular weight, controlled particle size and good impact modification — which is why emulsion-made ABS has its toughness.
Why it matters
The polymerization route is set long before molding, but it determines the resin's molecular weight, purity, residual surfactant and particle structure — all of which affect how the Resin flows, melts and performs. Knowing a grade is emulsion-made explains traits like its impact strength or, in PVC, its paste/plastisol behavior.
Related terms
- See also: Polymer, Monomer, Resin, Plastic, Depolymerization
What is emulsion polymerization?
A way of making polymers by dispersing monomer in water with surfactant and polymerizing inside micelles, yielding a latex of fine polymer particles — used to produce resins like ABS, emulsion PVC and acrylics.
Which plastics are made by emulsion polymerization?
ABS (and its rubber phase), PVC paste/emulsion grades, PVDF, acrylic polymers and synthetic latex rubbers (SBR) are commonly made this way, which gives high molecular weight and good impact properties.
How is emulsion polymerization different from depolymerization?
Emulsion polymerization builds a polymer from monomers (it makes the resin); depolymerization breaks a polymer back into monomers (it recycles the resin). They are opposite directions of the same chain chemistry.