Engineers are quickly growing to appreciate the cost, light weight and durability advantages of thermoplastics over metals in many applications, but not everyone is sure of the ideal thermoplastic for particular applications.

This learning curve is a hangover from the days when Australian engineering was almost exclusively metals-focussed in particular industry categories, preferring to stick with traditional metal engineering materials even as the rest of the world was switching to thermoplastics in important areas of industry, where they were ideal for mechanical, structural and chemical applications.

One such thermoplastic whose time has now come is Polypropylene PP or Polystone PP in the Dotmar range, which has a non-polar structure that gives it a high molecular mass.

This makes it highly resistant to chemicals and to aqueous solutions of salts, acids and alkalis. PP homopolymers have a high level of stiffness and toughness at room temperature.

This, together with their capacity to repel water, makes them a good choice for mechanical, structural and chemical applications including: food or corrosive storage vessels; cooling or scrubbing towers; pump bodies and components; wall cladding; pipe flanges; chemical storage tanks; electroplating barrels, tanks and hoods; fume cupboards and bench tops.

The Polystone PP (H), available from Dotmar Engineering Plastics , a division of Dotmar EPP, is a polyolefin, which is much stiffer and harder with high heat resistance and chemical resistance at elevated temperatures.

Faced with an abundance of materials to choose from, industries such as medical, food packaging and materials processing and handling, for example, are reaping the benefits of polypropylene (PP).

Typically available at a lower cost, PP boasts properties such as chemical and impact resistance that more than match more expensive resins and is eminently preferable over metals.

Produced by the polymerisation of propylene monomer with or without co-monomers, PP has low density of all the commodity thermoplastics and is available in a range of molecular weights depending on the production process and comonomer used.

Due to PP's low density and impact/stiffness balance, finished parts often require fewer raw materials than other resins, making it one among the most cost-effective commodity plastics available.

Key features and benefits:

  • Mechanical Strength - a hard, stiff readily workable material
  • Impact resistance - robust and tough
  • High chemical resistance
  • Higher scratch resistance than plastics such as HDPE
  • Moisture resistance – good food and chemical applications
  • Thermoformable
  • Weldable - suitable for fabrication
  • Available from Dotmar EPP in rod, sheet or as machined parts

Engineers should consult appropriate technical guidance for which engineering plastics suits particular applications. One advanced resource to determine particular products for particular properties is provided by the Dotmar website.

The more detail known on how and where the material will be used, the better chance users have of precisely matching the grade to the application.