Where does Silicone Rubber Come from?

Imagine a material that is somewhat stretchy and very durable, especially at high and low temperatures. Knowing different types of silicone rubber and their particular properties is essential in selecting the best material for different applications.

What is Silicone Rubber?

Think of a material that you can stretch and squish, but it bounces back—that’s silicone rubber! Flexible as it is, it’s not brittle, and it comes in handy in hostile environments. Silicon rubber, a remarkable elastomer, is an artificially made compound that is mainly built out of silicon, oxygen, carbon, and hydrogen atoms.

Silicone Baby Spoon
Silicone Baby Spoon

Raw Materials

· Silicon

Silicon, the main component of silicone rubber, is not found in its pure form in nature. You can extract silica, colloquially called silicon dioxide. This element is an abundant natural compound available to you in sand and rocks.

During the purification process, you isolate the material the material from impurities to ensure its high quality and suitability for silicone rubber manufacturing. The low availability of silicon in silica-rich materials makes the production of silicone rubber complicated.

Silicon
Silicon – Photo courtesy: BRITANNICA

· Oxygen

You can get oxygen from various sources as it is abundantly available both in air and you can purify it easily. This makes it easier from you to manufacture silicon rubber despite the main material (silicon) might be hard to purify.

Manufacturing Process for Silicone Rubber

Manufacturing silicone involve involves many steps:

Processing Silicon
Processing Silicon

· Obtaining Silicon from Silica (High Heat)

Silicon, which is essential for silicone rubber, is obtained from silica, which is easily available in sand and rocks. When you heat silica in a high-temperature process, silicon is peeled away from the impurities, producing silica of the highest quality.

The extraction of silicon is usually achieved by heating silica at near-extreme temperatures in an atmosphere rich in reducing agents such as carbon or magnesium.

In this way, the silicon is separated from silica, and a molten mass is formed, which can be further processed to obtain pure silicon. These silicon molecules become the basic units used in creating silicone rubber, hence its widespread use in different industries.

· Combining Silicon with Methyl Chloride

You then purify silicon by combining it with methyl chloride to start a very important chemical reaction. Your added methyl chloride acts as a methylating agent, accelerating the addition of methyl groups (CH3) to the silicon atoms.

That reaction turns silicon into stylish methylchlorosilanes, which are crucial intermediates in the manufacturing of silicone polymers.

The methyl groups that are attached to the silicon atoms change the chemical structure of the silicone rubber; hence, it gets the desired properties like flexibility. This step forms a base for the formation of the elastomer, which is commercially known as silicone rubber.

· Creating Siloxane Polymers

Siloxane Polymers
Siloxane Polymers

After a silicon reaction with methyl chloride, the manufacturing of silicone rubber consists of forming siloxane polymers. This happens through a condensation reaction called hydrolysis, where the methylchlorosilanes produced earlier react with water.

Through the process of hydrolysis, the chlorine atoms are replaced by the hydroxyl groups (OH), leading to the formation of siloxane bonds (-Si-O-Si-).

These bonds that link silicon atoms to each other create long chains of siloxane polymers. These polymers act as the backbone of silicone rubber, which gives it its characteristic flexibility, durability, and thermal stability.

· Fillers and Curing Agents are Added for the needed Features

When the siloxane polymers are ready, the next step in creating silicone rubber involves the addition of fillers and curing agents to adjust the desired properties.

Fillers like silica or carbon black are added to improve certain properties like mechanical strength, abrasion resistance, or thermal conductivity. Their functions involve controlling the viscosity and processing properties of the silicone rubber formulation.

Different types of silicone rubber

  • High-Temperature Vulcanized (HTV) Silicone Rubber: Needs high heat (generally from 150°C to 300°C) to cure. It is well-known for its heat resistance, high tensile strength, and flame retardancy. More importantly, it is resistant to many chemicals and oils.
  • Room Temperature Vulcanized (RTV) Silicone Rubber: Cured quickly at room temperature that allows to skip ovens or complicated equipment. It is often used for caulking, sealing, potting electronics, mold making, and hobby projects because of its simplicity and versatility.
  • Liquid Silicon Rubber: Utilizes a two-stage process of injection molding coupled with a fast cure time at high temperatures. It has exceptional flowability, so the part geometry can be more intricate.

It has good heat resistance, chemical resistance, and an excellent surface finish. It is applied to high-volume medical products, baby products, food-grade components, and electronic devices because of its biocompatibility, accuracy, and safety.

Conclusion

Silicone rubber proves to be an excellent substance, having a wide range of uses and advantages in many industries. Its roots are in silica extraction, and now it has a wide range of formulations that make it both versatile, durable, and reliable. Exploring the diverse applications of silicon rubber illustrates how it can cover a wide range of requirements and problems.

More resources:

What are the Different Processing Methods for Silicone Rubber – Source: LEGENDAY

Understanding UL94v-0: Silicone Rubber – Source: LEGENDAY

Polyurethane vs Silicone Rubber – Source: LEGENDAY

Are Silicone Rubber Buttons Good for You? – Source: LEGENDAY

Liquid Silicone Rubber Overmolding – Source: LEGENDAY

What is Silicone Rubber Calendering – Source: LEGENDAY

What Is Medical Grade Liquid Silicone Rubber? – Source: LEGENDAY

Step-by-step Liquid Silicone Rubber Injection Molding Process – Source: LEGENDAY

Top 10 Liquid Silicone Rubber Manufacturers in the World – Source: LEGENDAY

What Is the Difference between Silicone Resin and Silicone Rubber – Source: LEGENDAY

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