Key takeaways
- Process (S-PVC or E-PVC — never just "PVC")
- K-value for S-PVC; viscosity in mPa·s for E-PVC paste resin
- Pipe class or end-application context
- Stabiliser system tolerance — the EU has moved off lead, parts of Asia have not
- Origin preference and Incoterms
Most other commodity polymers are described first by their molecular structure. PVC is described first by how it was made. Suspension PVC (S-PVC) and emulsion PVC (E-PVC) are chemically the same polymer, but the particle morphology that comes out of the reactor is so different that the two cannot substitute for each other in their main applications.
Suspension PVC is polymerised in droplets of monomer suspended in water. The result is a porous granule, typically 100–150 microns across. That porosity matters: it lets the granule absorb plasticiser and stabiliser quickly during dry-blending, which is why S-PVC dominates the rigid extrusion segment — window profiles, pipe, fittings, siding — and most of the flexible compound segment too.
S-PVC is graded by K-value, which is a measurement of average molecular weight. K65–67 is typical for pipe; K57–60 for injection mouldings; K70+ for cable insulation. Different K-values are not interchangeable. A pipe extruder set up for K67 will not run K57 cleanly.
Emulsion PVC is polymerised in much smaller droplets stabilised by surfactant. The dried particles are 0.1–2 microns. Those tiny particles disperse easily in plasticiser to form a plastisol — a paste that can be spread, dipped, sprayed, or rotationally cast and then heated to fuse.
Plastisols are how vinyl flooring is made. They are also how dipped automotive parts, artificial leather, and the soft-touch coating on wallpaper are made. None of those processes work with S-PVC. The particles are too large to disperse cleanly.
- Process (S-PVC or E-PVC — never just "PVC")
- K-value for S-PVC; viscosity in mPa·s for E-PVC paste resin
- Pipe class or end-application context
- Stabiliser system tolerance — the EU has moved off lead, parts of Asia have not
- Origin preference and Incoterms
Many global producers run both processes side-by-side. Most regional producers run only one. That is why pricing for S-PVC and E-PVC drifts in different directions during tight markets, and why a substitution offer from one process to the other is almost always a sign of a confused supplier.