Delrin vs Acetal : Homopolymer vs Copolymer

13 Aug

“Delrin” is a brand name owned by Dupont representing a plastic they invented about 50 years ago based on the acetal molecule.

Delrin could easily be called the workhorse of plastics in that it is so dimensionally stable, resistant to chemcials, physically tough, cosmetically appealing, and, for all intents and purposes, waterproof. You find it throughout automobiles, especially where people push and pull on knobs or handles. What would the rock and roll industry be without it, no one asks? Delrin is what most guitar picks are made of. It’s found in the crank gears and components of fishing rods. It’s the plastic casing that many metal tools are formed into.

In the sheet, rod, & tube world it’s uses are wide and varied – equipment buttons, equipment cases, connectors, gears, idlers, conveyor components such as rollers, pumps, impellers, timing screws, and pulleys. It’s chemical inertness and non-conductive properties make it an excellent candidate for replacing metal parts that exposed to the element such as water and corrosives.

There are many grades of acetal. What you’ll find on the shelves of your local plastics distributor will probably include the Delrin Homopolymer, the Acetal Copolymer, and Delrin AF – a blend of Delrin and Teflon.

According to the MATWEB database, the homopolymer:

  • Absorbs less water than the copolymer;
  • Has a similar Rockwell (R) & (D) hardness rating;
  • Offers a greater tensile strenght;
  • More stable flexural yield and compressive strength offers a list of where one grade is used over another.

As a general statement, copolymer grades tend to be more resistant against hydrolysis, strong alkalis and thermal-oxidative degredation than the homopolymer grades. Homopolymer grades have a higher mechanical strength, stiffness, hardness and creep resistance as well as a lower thermal expansion rate and often it also presents a better wear resistance.

Delrin medical components

Should you have a need for Delrin/Acetal then consider calling Warehoused Plastic Sales for a quote.

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Posted by on August 13, 2007 in General Knowledge, Mechanical Plastics


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