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Liquid silicone rubber (LSR) has secured a vital position in modern industry due to its unique molecular structure and versatile processing capabilities. As a thermosetting material based on polyorganosiloxane, it combines the stability of inorganic materials with the elasticity of organic polymers. For end users, a thorough understanding of its curing mechanisms and selection criteria is key to maximizing its performance.
The core of LSR processing lies in curing—the transformation from a flowable liquid to an elastic solid. Based on curing conditions, it is broadly divided into room-temperature vulcanization (RTV) and high-temperature vulcanization (HTV/LSR injection molding). RTV silicones require no heating equipment; they cure at ambient temperature upon exposure to atmospheric moisture or the addition of a catalyst. This makes them ideal for small-batch production, on-site applications, or crafting complex-shaped mold patterns. In contrast, HTV LSR is primarily processed using injection molding machines, where heat rapidly crosslinks the material. This method offers high production efficiency and a high degree of automation, yielding parts with stable mechanical properties, and is widely used in precision components for medical, automotive, and consumer electronics industries.
When selecting a grade, customers typically focus on the following key parameters:
Viscosity: Determines flow behavior. Low-viscosity materials are suitable for filling tiny gaps or intricate molds, while high-viscosity materials are better for thick coatings or vertical applications.
Hardness: Expressed in Shore A, this directly affects the softness or firmness of the final part. Ranging from soft (20A) to firm (80A), different hardness levels serve applications such as sealing, keypads, and vibration damping.
Tensile and Tear Strength: Reflect the material's resistance to mechanical stress, making these properties particularly critical for seals that undergo repeated disassembly or operate under high stress.
Cure Time: Includes working time (pot life) and tack-free/full cure time. These must align with production cycle requirements.
A proper understanding of LSR curing principles and performance parameters not only helps mitigate potential risks in application but also enables manufacturers to optimize processes and develop more competitive end products.
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