Quantifying Water Vapor Diffusion across Elastomer Pressure Sensor Seals
Water vapor diffusion across elastomer seals causes reference cavity pressurization and dielectric drift, requiring coulometric ISO 15105-2 verification.
Liquid Silicone Rubber
Polymer Structure
Two-part platinum-cured liquid elastomers offer low viscosity processing and high thermal stability for precision sensor encapsulation and sealing. Component designers select liquid silicone rubber when complex seal geometries require high-precision injection molding with minimal flash formation. Addition-curing chemical structures yield no volatile reaction byproducts, maintaining dimensional stability across extended operating lifetimes.
Injection Molding
Liquid silicone rubber requires high-pressure liquid injection molding machines equipped with cold runner systems and heated mold cavities. Mixing components A and B in a one-to-one ratio initiates platinum-catalyzed hydrosilylation crosslinking upon exposure to elevated mold temperatures between one hundred and seventy and two hundred degrees Celsius. Short cure cycles under thirty seconds enable rapid mass production of intricate sensor seals with sub-millimetre wall thickness.
Low initial viscosity allows the polymer to fill micro-cavities before thermal crosslinking hardens the matrix.
Thermal Stability
Thermal stability spans from minus fifty to two hundred degrees Celsius without measurable change in durometer hardness or elasticity. Low compression set below twenty percent ensures long-term sealing force in environmental enclosure seals. Hydrophobic surface properties protect internal electronic assemblies from moisture ingress in outdoor transmitter housings.
Quality Inspection
Material batch testing verifies shore A hardness and tensile strength against ISO 37 testing standards. Standard compliance certificates document post-cure thermal conditioning parameters to confirm full polymer crosslinking.
Port Geometry and Gasket Seating on a Pressure Part
Controlled gland squeeze between 15% and 25% prevents mechanical die stress while isolating the pressure port against long-term fluid leakage.