Phenolic Materials Buying Guide

Phenolic, a composite resin material made from a combination of phenol and aldehyde, is a rigid material used in a wide range of consumer fitting applications. Because phenolic is easy to manufacture and relatively affordable, it is also frequently used as an acrylic alternative, as a binder, and as an insulator. Phenolic’s characteristics and properties vary depending on the type of aldehyde used, although formaldehyde is most common. To transform the aldehyde and phenol mixture into a phenolic sheet, paper, glass or cloth is impregnated with the synthetic mixture, then layered and pressed together using heat and pressure. As a result of the heat and pressure, polymerization occurs and the resin reacts with the paper, cloth, or glass to produce a hard, dense sheet of phenolic plastic.

Types of Phenolic Material

Phenolic material is typically available in a range of geometries, including sheets, tubes, rods, profiles, slabs, specific shapes and blocks. It is also available as foam, which is typically used in insulation applications. For information about the various compositions of phenolic foam and phenolic hybrids, consult article: http://www.thomasnet.com/articles/plastics-rubber/foam-phenolic-hybrid.

Basic types of phenolic resin include novolacs and resols, which are distinguished from one another by their aldehyde to phenol ratios. Typically, if the aldehyde to phenol ratio is 1 or greater, as is the case with resols, the phenol will cross-link and harden. However, if the aldehyde ratio is less than one, as is the case with novolacs, an additive is needed to induce hardening. With novolacs, hexamine is often added to assist in cross-linking.

Other Considerations

Phenolic is known by several trade names. Common names include:

• Bakelite: Made from wood flour and phenolic resin, this kind of plastic is often used as an electrical insulator and in other non-conductive heat-resistant applications.
• Novotext or Tufnol:This type of phenolic resin is reinforced with cotton or linen fibers and is often used in applications as a liner in loaded bearings, because it has low-friction. A similar product, Paxolin, is made from phenolic resin and paper.