Master Bond EP21NS is a two-part epoxy that may be used for bonding, coating, sealing, and potting/encapsulating. It has a nanosilica filler that imparts dimensional stability and offers abrasion resistance.
When measured according to the ASTM D4060 — the standard test method for abrasion resistance — with the CS-17 wheel for 1,000 cycles, EP21NS exhibits a very low weight loss (only 25 mg).
This formulation is a reliable, electrical insulation with a volume resistivity of greater than 1015 ohm-cm, an outstanding dielectric constant of 2.6 at 16.4 GHz, and a dielectric strength of 450 volts/mil at 75° F. This is for a 1/8-inch thick specimen. It’s serviceable over the temperature range of -80° to +250° F.
This system has a long working life and good flow properties with a moderately mixed viscosity of 50,000 to 90,000 cps. The mix ratio of EP21NS is a 1-to-1 by weight and its optimal cure schedule is overnight at room-temperature, followed by 4 to 5 hours at 150° F.
It also features a very low shrinkage upon curing, a low coefficient of thermal expansion (30-35 x 10-6 x in/in/° C), as well as a compressive strength of 16,000 to 18,000 psi.
This compound bonds well to a variety of substrates including metals, composites, glass, ceramics, rubbers, and several types of plastics. EP21NS is resistant to water and salts. It’s packaged in ounce kits, one-half pint kits, pint kits, and quart kits. The color of Part A is translucent and Part B is amber.