What is Silicone Rubber? Composition, Structure & Key Properties
Introduction
Silicone rubber is a high-performance synthetic elastomer engineered to combine flexibility, resilience, and durability under extreme conditions. Unlike organic rubbers made from carbon-based polymers, silicone rubber is built on a silicon–oxygen (Si–O) backbone, which gives it extraordinary thermal stability, weather resistance, and electrical insulation properties.
From automotive seals and electronic gaskets to medical devices and food-contact products, silicone rubber is valued for its ability to maintain elasticity and performance across a wide range of environments — from −60°C to +250°C and beyond.
Chemical Composition & Structure
At the molecular level, silicone rubber is composed of polysiloxane chains, featuring alternating silicon and oxygen atoms (Si–O–Si). These chains are connected by organic side groups such as methyl, vinyl, or phenyl, which influence the rubber’s flexibility, transparency, and chemical resistance.
During vulcanization (curing), these polymer chains form a three-dimensional crosslinked network, resulting in a material that is elastic yet extremely stable.
This unique combination of inorganic backbone + organic side groups is what distinguishes silicone rubber from all other elastomers:
- The Si–O bond is stronger than a carbon–carbon bond, giving silicone its exceptional heat resistance.
- The flexible molecular structure allows low-temperature performance without becoming brittle.
- The absence of double bonds ensures excellent ozone and UV resistance.
Main Types of Silicone Rubber
Silicone rubber comes in several forms depending on its viscosity, curing system, and processing method.
1. HTV (High-Temperature Vulcanizing) Silicone Rubber
A solid, heat-cured form supplied as sheets or blocks. HTV is typically reinforced with silica fillers and processed by extrusion, compression, or transfer molding. It is widely used in automotive, industrial, and electrical components.
2. LSR (Liquid Silicone Rubber)
A two-component, pumpable system cured by platinum catalysis. LSR is ideal for injection molding, offering high precision and repeatability. It is the preferred choice for medical-grade, optical, and consumer applications.
3. RTV (Room Temperature Vulcanizing) Silicone
Cures at ambient temperature and is commonly used in adhesives, sealants, and coatings. RTV formulations are suitable for construction, electronics encapsulation, and prototyping.
🔗 Explore our [HTV Silicone Compounds] and [LSR Materials] to find the right formulation for your application.
Key Properties of Silicone Rubber
Property | Description |
Temperature Resistance | Remains flexible from −60°C to +250°C; withstands peaks above 300°C in specialized grades. |
Chemical Stability | Resistant to oils, ozone, moisture, and many acids and alkalis. |
Electrical Insulation | Excellent dielectric strength, ideal for high-voltage insulation. |
Elastic Recovery | Retains flexibility and rebound even after long-term compression or exposure. |
Transparency & Colorability | Naturally translucent, can be easily pigmented or made optically clear. |
Biocompatibility | Safe for skin and tissue contact; widely used in medical and healthcare devices. |
These combined properties make silicone rubber suitable for critical applications where other materials would degrade, melt, or lose elasticity.
Applications of Silicone Rubber
Silicone rubber’s versatility allows it to serve across industries:
- Medical & Healthcare: Catheters, tubing, seals, baby products, and respiratory components
- Automotive: Spark plug boots, sensor seals, hoses, and vibration isolators
- Electronics: Cable insulation, gaskets, and connector seals
- Construction: Waterproof sealants, expansion joints, glazing profiles
- Food & Consumer Products: Bakeware, kitchen utensils, molds, and food-grade tubing
In each of these applications, the balance of thermal stability, chemical resistance, and biocompatibility ensures reliable long-term performance.
Why Choose Silicone Rubber
The enduring value of silicone rubber lies in its stability, versatility, and customizability. It can be formulated to meet diverse requirements — from ultra-soft LSR for delicate medical parts to reinforced HTV compounds for high-stress industrial environments.
At WICSilicone, we design and produce advanced HTV and LSR silicone compounds tailored to meet demanding performance and regulatory standards. Whether you need materials for medical molding, electrical insulation, or food-contact applications, our formulations deliver precision, reliability, and consistency.
WICSilicone — Engineering Silicone Solutions for the Future
👉 Contact our technical team to discuss your project or request a customized formulation.
