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CoolTherm® UR-389 Flame Retardant Urethane Encapsulant

Product Information

CoolTherm® UR-389 encapsulant is a two-component urethane system designed for encapsulating and casting applications. CoolTherm UR-389 encapsulant cures at room temperature to produce a flame retardant, semi-flexible material.

Shelf Life

Shelf life of each component is six months when stored in a clean, dry environment at 18-30°C in original, unopened container. CoolTherm UR-389 resin and hardener containers must be periodically inverted to prevent settling.

After opening, protect each component from excessive moisture by using dry nitrogen as an inert cover.

If stored or shipped at cooler temperatures, CoolTherm UR-389 hardener may crystallize. If crystals appear, gently warm hardener at 30-50°C to melt crystals before mixing with resin. Limit heating period to less than three hours as excessive heating will cause dimerization.

Features and Benefits

Low Stress – exhibits low shrinkage and stress on components as it cures.

Low Viscosity – maintains low viscosity for complete and void-free encapsulation.

Room Temperature Cure – suitable for curing at room temperature; may be mildly heat cured (65°C) to expedite cure.

Environmentally Resistant – provides excellent thermal shock resistance.

Uncured Typical Properties*

Mixed Appearance Black Liquid
Mixed Viscosity, cps @ 25°C 14,000
Mixed Specific Gravity 1.50
Working LIfe, minutes @ 25°C 5
Gel Time, minutes @ 25°C
100 grams

Cured Typical Properties*

Thermal Conductivity, W/m·K 0.7
Coefficient of Linear Thermal Expansion, ppm/°C alpha 1 = 70
alpha 2 = 145
Glass Transition Temperature (Tg), °C 26
Hardness, Shore D 45
Moisture Absorption, %
7 days
Volume Resistivity, ohm-cm @ 25°C 7 x 1014
Dielectric Strength, kV/mm (V/mil) @ 25°C 16 (406.4)

*Data is typical and not to be used for specification purposes.


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Download Technical Data Sheet CoolTherm UR-389 Flame Retardant Urethane Encapsulant

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