ÅngströmLink™ AL-3241 Silicone Elastomer Encapsulation Gel, 1.41 Refractive Index, 1 Pint Kit

The ÅngströmLink™ AL-3241 Optically Clear Silicone Elastomer is a two-part encapsulation material designed to protect sensitive photonics and fiber optic assemblies from mechanical shock, thermal cycling, dust, and environmental exposure.

This room-temperature curing system provides approximately 4 hours of working time, allowing the material to flow easily into complex geometries and enable trapped air to escape. The AL-3241 cures to a flexible elastomer within 24 hours at ambient conditions, with no UV exposure or heat required.

AL-3241 is supplied in a ready-to-use cartridge that maintains a 10:1 mix ratio during dispensing. The cured material has a service temperature range of -40°C to +180°C, with short-term exposure up to +260°C for soldering operations

Features of AL-3241:

• Optically Clear
• Long pot life with room-temperature cure
• Ultra-clear formulation with excellent resistance to yellowing
• Refractive index of 1.41 for LED encapsulation and optical coupling

Applications:

• Designed for photonics and fiber optic applications
• LED encapsulation
• Elastomeric lens gap medium for UV lithography optics
• Matrix medium for suspension of photonically active powders, switch elements, etc.
• Clear low absorbance encapsulation for near UV, blue, or visible emitters or detector

Cure & Processing:

• Uncured Mixed Viscosity: 5,300 cP
• Pot Life: 4 hours
• Full Cure Time: 24 hours

Mechanical Properties (Cured):

• Physical State: Soft Rubber
• Shore A Hardness: 50
• Tensile Strength: 1,300 psi
• Tear Strength: 20 ppi
• Elongation: 100%
• Specific Gravity: 1.03

Thermal Properties (Cured):

• Glass Transition Temperature, Tg: < -40°C (est.)
• Thermal Expansion: 8 × 10^-4 cc/cc/°C (est.)
• Thermal Conductivity: 0.13 W/m·K (est.)

Electrical & Optical Properties (Cured):

• Appearance: Optically Clear
• Ionic Content (K, Na, P, Ag, Cu, Sn): < 10 ppm each (est.)
• Volume Resistivity: 10¹⁵ ohm·cm
• Dielectric Strength: 20 kV/mm
• Refractive Index (589 nm): 1.41
• Refractive Index Temp. Coefficient: -3.5 × 10^-4 /°C