Resinous Chemistry
Thermosetting polymers containing saturated ring structures offer high resistance to ultraviolet radiation and electrical tracking. Known as cycloaliphatic epoxy, these materials lack aromatic rings, which prevents the formation of conjugated double bonds that absorb light and initiate polymer degradation. Their low viscosity allows for high filler loading during manufacturing.
Dielectric Performance
Electrical insulation applications benefit from the low ionic content and high thermal stability of these materials. The cycloaliphatic epoxy formulations maintain low dielectric dissipation factors even at high frequencies and elevated operating temperatures. This performance makes them suitable for encapsulating outdoor high-voltage bushings, transformers, and optoelectronic sensors.
Humidity exposure can cause surface conductivity to increase, but hydrophobic additives are added to counter this effect.
Polymerization Process
Curing typically occurs through thermal or ultraviolet initiation. Curing agents like acid anhydrides react with the oxirane rings on the cycloaliphatic epoxy to form a dense, cross-linked network. This reaction produces low shrinkage, which protects delicate optical or electrical components from mechanical stresses during the curing phase.
Insulation Constraint
Formulators must balance the rigidity of the cured network with the required impact resistance. While the cycloaliphatic epoxy offers high compressive strength, it can be brittle unless modified with flexibilizers. Excessive moisture during storage of the uncured components leads to premature reactions and voids in the final casting.
