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5 Main Components to Build Flexible Closed Cell Elastomeric NBR Foam Sheets

NBR foam sheets, also known as Nitrile Butadiene Rubber foam sheets, are renowned for their versatility and wide range of applications. These sheets offer excellent insulation, cushioning, and sealing properties, making them a preferred choice in various industries. In this blog post, we will explore the key components that make up an NBR foam sheet, shedding light on the materials that contribute to its exceptional characteristics.

1. Nitrile Butadiene Rubber (NBR):

The primary component of an NBR foam sheet is nitrile butadiene rubber, a synthetic elastomer. NBR is derived from the copolymerization of butadiene and acrylonitrile. This rubber exhibits excellent resistance to oils, fuels, chemicals, and other substances, making it highly suitable for applications where exposure to such elements is common. NBR provides the foundation for the foam sheet's physical properties, including its flexibility, durability, and resistance.

2. Blowing Agents:

Blowing agents play a crucial role in the manufacturing process of NBR foam sheets. These agents are responsible for creating the foam's cellular structure, which contributes to its unique properties. Common blowing agents used include physical blowing agents like hydrocarbons or low-boiling-point liquids. During the foaming process, these agents vaporize, forming closed cells within the rubber matrix, resulting in a flexible and lightweight foam sheet.

3. Fillers:

Fillers are additives incorporated into NBR foam sheets to enhance specific properties and improve overall performance. Fillers commonly used include materials like calcium carbonate, talc, clay, or other minerals. These fillers contribute to the foam's mechanical strength, reducing material costs and enhancing resistance to aging, tearing, and abrasion. The type and concentration of fillers can be tailored to achieve desired characteristics such as hardness, density, and resilience.

4. Crosslinking Agents:

Crosslinking agents are essential components that promote the formation of chemical bonds between polymer chains in the NBR foam sheet. These agents enhance the foam's overall stability, resistance to heat and aging, and mechanical strength. Commonly used crosslinking agents include organic peroxides or sulfur-based compounds. Through crosslinking, a three-dimensional network structure is created within the foam, providing it with enhanced performance and durability.

5. Vulcanizing Agents:

Vulcanizing agents work in conjunction with crosslinking agents to complete the crosslinking process and strengthen the NBR foam sheet. These agents help create strong, flexible bonds within the foam's structure, improving its ability to withstand environmental conditions and maintain its properties over time. Common vulcanizing agents include sulfur-based compounds or organic peroxides.


NBR foam sheets owe their exceptional properties to a combination of key components. Nitrile butadiene rubber serves as the foundation, providing the sheet with flexibility, durability, and resistance to various substances. Blowing agents create the foam's cellular structure, while fillers enhance mechanical strength and other desired characteristics. Crosslinking agents and vulcanizing agents work together to strengthen the foam, ensuring long-term performance. Understanding the components that make up an NBR foam sheet helps us appreciate the complexity and engineering behind this versatile material, enabling its successful application in industries such as thermal insulation, cushioning, and sealing.

View our NBR Foam Sheet and NBR Clad Sheet here:

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