What Is Liquid Silicone Rubber?

Over the last hundred years, material innovations in basic and specialty elastomers have led to a range of materials that are suitable for a broad range of applications and operating environments.

The materials vary in terms of key characteristics, such as elasticity, strength, hardness, compatibility, temperature range, environmental resistance and other properties.

One of these materials, LSR, which has been around since the 1970s, continues to make the transition to becoming the premier material for the manufacture of medical products and devices. LSR consists of a highly flexible thermosetting plastic that comes in a broad range of composition and hardness.

The variety of LSR materials allows product designers and engineers to select the material with the characteristics most appropriate for the application.

At room temperature, thermoplastic begins as solid material, which softens when you heat or reheat the material above its melting point.

In comparison, thermosetting materials start out in liquid form, and the heat cures the resin into a solid state. Once it cures, the part remains solid — a feature that helps make LSR the idea material choice for numerous medical applications.

The key attributes of LSR include:

Hardness
Tensile strength
Compression set
Fluid resistance

The benefits of medical-grade LSR over elastomeric materials include:

Bio-inert material in compliance with ISO 10993, USP Class VI and RoHS standards
Ability to be sterilized with a variety of methods such as Autoclave, ETO, E-beam and Gamma radiation processes
Low viscosity that allows flow to all parts of the mold
Excellent stability over a broad range of temperatures 150°F to 450°F
Low compression set
Self-adhesive LSR that chemically adheres to plastics without the need for priming
Ability to maintain its resiliency, flexibility and capability to transfer mechanical force at extreme temperatures

LSR has superior electrical insulating qualities even under the most severe environmental conditions. The manufacturer can acquire mold cavities specifically tailored to achieve different surface textures for parts and products.