Improved asbestos-reinforced laminates

Asbestos-reinforced plastics, rigid shapes and pre-pregs, are widely accepted for high temperature service. These materials are being used, for example, as missile parts because they have good ablation characteristics at burn-out temperatures, and good physical strength and stability up to the thermal decomposition temperatures. On the other hand, rigid asbestos laminates have traditionally been held in low esteem by the electrical industry, primarily because of poor electrical properties. This is exemplified in the NEMA Standard for Industrial Laminated Thermosetting Products which states for Grade A, Asbestos Paper Base Laminates: More resistant to flame and slightly more resistant to heat than cellulosic laminated grades because of high inorganic content. Not recommended for primary insulation for electrical applications involving commercial power frequencies in excess of 250 volts. Small dimensional changes when exposed to moisture.