Addition Silicone vs. Condensation Silicone

Attribute	Addition Silicone	Condensation Silicone
Curing Mechanism	Platinum-catalyzed addition reaction	Tin-catalyzed condensation reaction
Setting Time	Fast setting time	Relatively slower setting time
Shrinkage	Minimal shrinkage	Higher shrinkage compared to addition silicone
Viscosity	Low viscosity	Higher viscosity
Accuracy	Highly accurate	Less accurate compared to addition silicone
Tear Strength	High tear strength	Lower tear strength compared to addition silicone
Compatibility with Materials	Compatible with a wide range of materials	May have compatibility issues with certain materials
Odor	Odorless	May have a slight odor

Introduction

Silicone is a versatile material widely used in various industries, including healthcare, automotive, and construction. It is known for its excellent heat resistance, flexibility, and durability. Within the silicone family, there are different types, each with its own unique attributes and applications. In this article, we will compare two popular types of silicone: Addition Silicone and Condensation Silicone.

Chemical Composition

Addition Silicone, also known as Vinyl Polysiloxane (VPS), is a type of silicone rubber that cures through an addition reaction. It consists of a base polymer, a cross-linking agent, and a platinum catalyst. The base polymer provides the backbone structure, while the cross-linking agent and platinum catalyst facilitate the curing process.

On the other hand, Condensation Silicone, also known as Tin-Cured Silicone, cures through a condensation reaction. It contains a base polymer, a cross-linking agent, and a tin-based catalyst. The base polymer forms the main structure, while the cross-linking agent and tin-based catalyst enable the curing process.

Curing Process

Addition Silicone has a faster curing time compared to Condensation Silicone. It typically cures within a few minutes, allowing for quick production and reduced waiting time. The addition reaction occurs at room temperature, and the curing process is not affected by humidity or moisture in the environment.

Condensation Silicone, on the other hand, has a longer curing time. It usually takes several hours to fully cure, depending on the thickness of the silicone layer. The condensation reaction requires moisture to initiate the curing process, which means that humidity and moisture levels in the environment can affect the curing time.

Physical Properties

Both Addition Silicone and Condensation Silicone exhibit excellent flexibility and elasticity, making them suitable for applications that require movement or deformation. They have good tear strength and can withstand repeated stretching without tearing or losing their shape.

Addition Silicone has a higher dimensional stability compared to Condensation Silicone. It maintains its shape and size even under extreme temperature changes, making it ideal for applications that require precise measurements and accuracy.

Condensation Silicone, on the other hand, has a slightly lower dimensional stability. It may experience slight shrinkage or expansion when exposed to temperature variations, which can affect the accuracy of the final product.

Both types of silicone have excellent resistance to heat, chemicals, and UV radiation. They can withstand high temperatures without deforming or degrading, making them suitable for applications in harsh environments.

Applications

Addition Silicone is widely used in the dental industry for making impressions of teeth and gums. Its fast curing time allows for quick and accurate dental impressions, ensuring a comfortable fit for dental prosthetics such as crowns, bridges, and dentures.

Condensation Silicone is commonly used in mold making and casting applications. Its longer curing time allows for more intricate molds to be created, capturing fine details and producing high-quality replicas. It is also used in the production of silicone rubber products such as gaskets, seals, and O-rings.

Conclusion

In conclusion, Addition Silicone and Condensation Silicone are two popular types of silicone with their own unique attributes and applications. Addition Silicone offers fast curing time, excellent dimensional stability, and high accuracy, making it suitable for dental impressions. On the other hand, Condensation Silicone provides longer curing time, good flexibility, and is commonly used in mold making and casting applications. Both types of silicone exhibit excellent resistance to heat, chemicals, and UV radiation, making them versatile materials in various industries.