Yogurt pot

A polystyrene sheet formed into a thin-walled pot.

Yogurt pot, illustrative image

Material

PS component of the pot: PS

Material selection rationale

Thin, self-supporting walls
Make a light pot that can stand on a shelf.
Thermoformable sheet
Allows many pot shapes to be formed from a continuous sheet.
Thin wall and flange
A light wall contains the yogurt while a relatively flat rim supports a lid seal. The lid and its sealant are separate materials.

How it becomes a product

  1. Make the sheet: Packaging-grade PS is extruded as a sheet; commercial grades may include rubber modification or blends.
  2. Form and finish: The warmed sheet is drawn into a mould, cooled and trimmed. Filling and sealing follow separately. The formed sheet is cut into pots; the remaining flange must suit the selected lid-sealing system.

Preparation routes

Styrene route

Addition polymerisation. The vinyl groups join into a carbon backbone carrying phenyl side groups. Making foam is a later processing choice, not a second polymerisation reaction. The benzene ring is retained as a side group rather than opened into the growing chain. Solid PS and expanded PS therefore share this molecular route.

Initiation and temperature control support chain growth. Expandable grades also contain a blowing agent, which is not a monomer; rubber-modified grades have additional polymer content. Rubber addition or bead expansion changes material structure beyond this simple backbone trace.

  1. Polystyrene: from benzene and ethene to solid and expanded productsChemical Industry Education Centre, University of York

From benzene and ethene to styrene

  1. Benzene + Ethene → Ethylbenzene

    Alkylation joins an ethyl group to the benzene ring. Both feedstocks belong to this step.

  2. Ethylbenzene → Styrene

    Dehydrogenation removes hydrogen and creates the vinyl double bond used in the next polymerisation step.

  1. Polystyrene: from benzene and ethene to solid and expanded productsChemical Industry Education Centre, University of York

Sources

  1. Polystyrene: from benzene and ethene to solid and expanded productsChemical Industry Education Centre, University of York
  2. Polystyrene for rigid food packagingINEOS Styrolution