Are Acetal Copolymer and Homopolymer Acetal the same?
This is one of our most common questions, and it is a bit involved of an answer.
There are two main versions of Acetal Resin
Homopolymer Acetal and Copolymer Acetal
The most popular name for a Homopolymer Acetal is the Dupont Delrin, which is a premium Homopolymer Acetal.
The second Acetal is a Copolymer acetal, and there are many suppliers of this resin.
Acetal is the generic, and not all Acetal is Delrin® Hompolymer, nor is it Acetal Copolymer. A distinction is required to determine which is best for your application. There are several manufacturers that produce Acetal Copolymer resin, including: Celanese®, BASF®, Ticona®, SABIC® and many more.
Acetal Copolymer compared to Delrin® Homopolymer Acetal
Delrin® is a premium homopolymer Acetal produced by Dupont. Many of the physical properties of the homopolymer exceed that of the copolymer Acetal. Dupont™ Delrin® is a popular acetal homopolymer brand name and the most commonly used acetal homopolymer.
The generic term ‘Acetal’ covers both the homopolymer from Dupont and the copolymer grades of resin. Both materials meet the ASTM-D-4181, ASTM-D-6100 or ASTM-D-6778 specification (an old call out is L-P-392). Homopolymer Acetal is POM111, and Copolymer Acetal is POM211.
Both are very tough and machinable, and have some similar properties.
An additional difference is the inherit problem of center-line porosity in some of the homopolymer grades. This is caused by out gassing during manufacturing, and can be found at the center or on the surface of all homo-polymer extrusions. This porosity can cause some problems with machining or moisture permeation through the material. The copolymer resin has little to no porosity issue.
Some of the other differences are in the physical properties of the resin. Review the chart for some of the most popular properties people ask for when looking at Acetal Copolymer or Homopolymer Acetal.
See Homopolymer and Copolymer Acetal properties chart below.
Tensile Modulus of Elasticity
Flexural Modulus of Elasticity
Heat Deflection Temp @ 264 psi – degrees F
Melting Point – degrees F
Coef. of Linear Thermal Expansion
6.8 x 10-5
5.4 x 10-5
Water Absorption @ Saturation
Material is available as both Acetal Copolymer or Acetal Homopolymer in Rod, Block, Sheet and Slabs.
Acetal is one of the most widely available plastics, especially on the West Coast (for some reason the East Coast seems to like the Nylon – Polyamide material more). Most commonly available in Natural (White) or Black, but can be produced in a wide range of colors with minimum orders. This enables material matching your product color or for easy identification of parts.
While these properties are similar, depending on your application, one material may be better suited than the other. Review our Delrin® Homopolymer and Acetal Copolymer page for additional information on the product availability and data sheets. We get calls for the premium Delrin® Homopolymer product, but some people may call it Delron, Delran, Delrun, Derlin and many other names, but it is still premium Delrin® Homopolymer Acetal to us.