In our This vs. That series, we compare two similar products to make their differences more clear. In this post, we look at the similarities and differences between Thermoplastics and Thermoset. When we browse cable spec sheets, we see the words thermoset and thermoplastic countless times. That’s because both are common cable insulation and jacket materials. But what do these words mean? What are the real differences between the two materials?

What is Thermoplastic?

Thermoplastic materials are composed of chains of molecules that separate when the heat is applied. This construction gives thermoplastics the ability to melt and be remolded repeatedly.

PVC, polyurethane, polypropylene, TFE, and FEP are all common thermoplastics. This type of insulation and jacketing is often used in automated equipment and high volume applications. Thermoplastic can be easy to work with, especially if the cable needs to be stripped.

What is Thermoset? 

Thermoset materials are composed of polymer structures that are cured or vulcanized-- often by irradiation, heat, or chemicals-- to form natural or synthetic rubber materials. During the curing process, the polymer chains are cross-linked with other molecules, making thermoset a cross-linked material.

Cross-linked materials are labeled with “XL” (e.g. XLPE = cross-linked polyethylene). Common thermoset materials include natural rubber, SBR, EPDM, silicone rubber, neoprene, and Hypalon. Thermoset materials don’t melt, so they are often used in high-temperature applications or in circuits at risk of overload.

How Do They Compare?

While thermosets function better at higher temperatures than thermoplastic, temperature performance isn’t the only factor to consider. Thermosets are much more flexible, even at low temperatures, and can lay flat. Thermoplastics, however, are generally more economical, lighter in weight, easier to color, and tend to have better electrical properties.

For more information on different insulation and jacketing materials, visit the technical information section of the Allied website.