Chapter 3: The Vulcanization Process of LSR

What is the Vulcanization Process Used by SIMTEC Silicone Parts?

Vulcanization is the chemical process of converting rubber into durable materials using heat. While extreme temperatures often melt materials, in this case, heat triggers the chemical reaction between component A and B. As a result, LSR becomes a solid and cannot be altered otherwise. The vulcanization method also involves heating rubber and sulfur or other curatives to adjust the polymer to create cross-links.


Liquid Silicone Rubber vs. Solid Silicone Rubber

Liquid and solid silicone rubber exist, and while each has the same basic structure, the curing process is what sets them apart from one another. LSR is a two-component material. Component A is the catalyst solution, and component B is methyl hydrogen siloxane. Component B acts as a cross-linker and inhibitor during the vulcanization process. Both materials arrive separately at the SIMTEC facility, but we mix them during the LSR process using cold runner equipment to prevent the chemical reaction from occurring before the LSR enters the mold.

Cross-linking during vulcanization is when elastomer chains chemically cross-link. It releases energy to form an exothermic reaction. A 3D matrix develops because a catalyst bonds the long chains of the elastomer together. The intricate network of the silicone rubber improves the material’s mechanical properties.

Vulcanization Cross-Linking Benefits for Medical Grade Silicone Injections

Cross-linking of components A and B creates a stronger LSR that has durability unlike any other material in the healthcare industry. Vulcanized rubber can withstand more damage and stress from various environmental factors compared to non-vulcanized materials.

The advantages of using vulcanized rubber can surpass your expectations, and the only disadvantage is that if burned or melted, the material becomes toxic and cools quickly, which can create a hazard when people are handling it.

How Vulcanized Rubber Impacts the Medical Market

The vulcanization process for silicone rubber medical devices creates resilient and thermally stable rubber for any project. It’s a procedure that develops superior performance products that can last a lifetime regardless of exterior conditions. When our experts mix the silicone catalyst with the methyl chloride, the curing reaction takes place. We release the heat as soon as the chemical bonds form which boosts the temperature of the system. The viscosity of the material decreases as the temperature of the resin increases, which also releases air bubbles and permits better flow.

Even though the heat during the vulcanization process increases — up surging the temperature — the viscosity of the material rises. When the LSR reaches its gel point, the resin stops. This means we reached the viscosity and temperature limit. As curing proceeds, cross-linking stops since the viscosity increases, and the diffusion rate declines.

When it comes to medical-grade devices, tools, and instruments, rely on SIMTEC’s detailed vulcanization process to receive superior products. If you want a more in-depth view of SIMTEC’s LSR vulcanization process, see how it’s done here.

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