Drainpipe

Rigid PVC extruded into a hollow pipe.

Drainpipe, illustrative image

Material

Pipe wall: PVC

Material selection rationale

Rigid profile
Keeps an open channel for drainage.
Continuous shaping
Extrusion makes long lengths with a consistent cross-section.
Cross-section stiffness
A circular wall carries loads around its circumference; diameter, wall thickness and support spacing matter alongside resin stiffness.

How it becomes a product

  1. Prepare the rigid blend: PVC resin is combined with the stabilisers and processing aids needed for a pipe formulation.
  2. Extrude and cut: The blend passes through an annular die, then is sized, cooled and cut into pipe lengths. The extruded tube is calibrated and cooled to keep its diameter and roundness before cutting.

Preparation routes

Vinyl chloride route

Free-radical addition polymerisation. Vinyl chloride molecules link into PVC chains. The resin is then formulated differently for rigid pipes and flexible coverings. The original double bond is consumed, while the C–Cl bonds remain in the repeat unit. Flexible and rigid PVC can therefore have the same polymer origin.

An initiator starts chain growth. Stabilising additives and, for flexible formulations, plasticisers are separate from the monomer. Plasticiser acts mainly by altering chain mobility; it is not a second polymerising feedstock.

  1. PVC: monomer production, polymerisation and usesChemical Industry Education Centre, University of York

From ethene to vinyl chloride

  1. Ethene + Chlorine → 1,2-Dichloroethane

    Direct chlorination adds chlorine across ethene's double bond.

  2. 1,2-Dichloroethane → Chloroethene

    Industrial cracking removes hydrogen chloride, leaving the double bond in vinyl chloride.

  1. PVC: monomer production, polymerisation and usesChemical Industry Education Centre, University of York

Sources

  1. PVC: monomer production, polymerisation and usesChemical Industry Education Centre, University of York