Bakelite - Properties

Properties

Phenolics are seldom used in general consumer products today, due to the cost and complexity of production and their brittle nature. An exception to their overall decline is their use in small precision-shaped components where their specific properties are required, such as molded disc brake cylinders, saucepan handles, electrical plugs and switches and parts for electrical irons. Today, Bakelite is manufactured and produced in sheet, rod and tube form for hundreds of industrial applications in the electronics, power generation and aerospace industries, and under a variety of commercial brand names.

Phenolic sheet is a hard, dense material made by applying heat and pressure to layers of paper or glass cloth impregnated with synthetic resin. These layers of laminations are usually of cellulose paper, cotton fabrics, synthetic yarn fabrics, glass fabrics or unwoven fabrics. When heat and pressure are applied to the layers, a chemical reaction (polymerization) transforms the layers into a high-pressure thermosetting industrial laminated plastic. When rubbed, original Bakelite has a tell-tale odor.

Bakelite Phenolic sheet is produced in dozens of commercial grades and with various additives to meet diverse mechanical, electrical and thermal requirements. Some common types include:

  • Paper reinforced NEMA XX per MIL-I-24768 PBG Normal electrical applications, moderate mechanical strength, continuous operating temperature of 250 °F (121 °C).
  • Canvas reinforced NEMA C per MIL-I-24768 TYPE FBM NEMA CE per MIL-I-24768 TYPE FBG Good mechanical and impact strength with continuous operating temperature of 250 °F (121 °C).
  • Linen reinforced NEMA L per MIL-I-24768 TYPE FBI NEMA LE per MIL-I-24768 TYPE FEI Good mechanical and electrical strength. Recommended for intricate high strength parts. Continuous operating temperature 250 °F (121 °C).
  • Nylon reinforced NEMA N-1 per MIL-I-24768 TYPE NPG Superior electrical properties under humid conditions, fungus resistant, continuous operating temperature of 160 °F (71 °C).

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