Master Bond EP21ND-LP was created for structural bonding applications involving large surface areas. It has an advantageously long working life of 2-4 hours at 75°F for a 100 gram mass. Its smooth paste consistency makes it convenient to apply and use. Shore D hardness is 70-80 when mixed in a one to one mix ratio by weight or volume. Moreover, certain properties of the epoxy can be altered by adjusting the mix ratio. For example, adding more of Part A to obtain a 2:1 mix ratio will produce a formulation with a more rigid cure. Conversely, adding more of Part B in a 1:2 mix ratio will provide the epoxy with a more forgiving cure. EP21ND-LP cures at room temperature or more rapidly at elevated temperatures.
EP21ND-LP achieves high strength, durable bonds and has excellent gap filling properties. Its tensile strength ranges between 6,000 to 7,000 psi. It withstands thermal cycling and has a coefficient of thermal expansion of 50-55 x 10-6/in/in/°C. This dimensionally stable epoxy also offers reliable electrical insulation with a volume resistivity greater than 1014 ohm-cm.
The standard color of Part A is gray and Part B amber, although the epoxy can be formulated in a wide array of colors. It can be used in the electronic, electrical, computer, appliance, chemical, aerospace and specialty OEM industries. It is available in ½ pint, pint, quart and gallon kits