When people talk about rubber materials used in various applications, foam rubber, and sponge rubber may sound interchangeable. They are both a type of material known for their flexible and cushioning nature, commonly used across various industries for cushioning, insulation, and sealing applications. Although their functions are similar, there are significant differences in their material composition, structure, and properties. Therefore, it is important to understand and correctly differentiate between sponge vs foam rubber. It also helps to choose the right rubber material for your specific application.
How is foam rubber made?
Foam rubber can be made from a variety of polymers, including natural latex, polyurethane, neoprene, nitrile rubber, etc. Foam rubber production typically involves incorporating air bubbles into the rubber compound. This can be done mechanically by beating air into the material, or chemically by adding a blowing agent that releases gas when heated.
Foam rubber has a cell structure that may be either open-cell or closed-cell. In open-cell foam rubber, the cells are interconnected, creating a softer, more breathable material. Closed-cell foam rubber has individual cells that are not connected, making it denser, more water-resistant, and better at insulation. so the key properties of foam rubber include flexibility, cushioning capability, shock absorption, thermal insulation, and acoustic insulation.
How is Sponge Rubbers Made?
Sponge rubber manufacturing is similar to foam rubber, both use a liquid mix of polymers, water, and colorants (optional). The key difference lies in the blowing agent, sponge rubber uses a decomposing blowing agent to create interconnected air pockets and has different densities (soft, medium, and hard). Sponge rubber is featured by its cellular structure. The manufacturing process introduces gases into the rubber compound, creating a cellular structure that is mainly closed-cell but can also have open-cell cellular depending on the application requirement.
In open-cell sponge rubber, the cells are interconnected, allowing air, moisture, and other chemicals to pass through. On the other hand, closed-cell sponge rubber contains distinct, unconnected air pockets that do not allow the gaseous and liquid substance, making it more water-resistant and denser. Sponge rubber can be made from various synthetic rubber materials, including neoprene, silicone, EPDM (ethylene propylene diene monomer), and nitrile offering distinct advantages regarding chemical resistance, temperature stability, and durability.
Uses of Foam rubber And Sponge RubberBoth foam rubber and sponge rubber are used for their cushioning properties. Foam rubber with its soft and cushiony structure, finds numerous applications across various sectors due to its unique properties, such as its ability to absorb impacts, insulate against heat and sound, provide comfort, and seal against air or moisture. Here are some of the common uses of foam rubber:
Foam rubber, especially open-cell foam rubber, can compress more easily, making it suitable for applications that require softer cushioning. Closed-cell foam rubber also performs well in sealing but is more commonly chosen for thermal and acoustic insulation applications due to its denser structure. Foam rubber is used in various products, including mattresses and cushions, automotive weatherproofing, gaskets and seals, footwear, thermal insulation materials, athletic equipment, insulation, and acoustic panels.
Air pockets within sponge rubber provide excellent thermal and sound insulation and absorb shock and vibration, which is ideal for automotive, aerospace, and industrial applications. Due to its excellent compression set and resilience, sponge rubber is widely used in seals and gaskets in automotive, marine, aerospace, and industrial applications to protect against the effects of air, water, dust, and other environmental factors. Closed-cell sponge rubber is ideal for sealing applications such as gaskets, weatherstripping, or seals in automobiles, outdoor applications, or construction.
Common Types Of Foam Rubber and Sponge Rubber
Foam and sponge rubber come in lots of different kinds! Each type has special characteristics based on its material composition that cater to specialized applications. Knowing which kind is best helps you pick the right one for what you need. Common types are as follows:
Polyurethane Foam (PU): widely known as PU foam, One of the most common types is known for its excellent rigidity, shock absorption, and sound insulation. There are Open-cell polyurethane foam and closed-cell polyurethane foam two structures. Often used in high-performance applications like industrial machinery components, shock absorbers, vibration isolators, and hood gaskets.
Ethylene-Vinyl Acetate (EVA) Foam: Known for its rubber-like softness and flexibility, EVA foam is widely used in sports equipment, footwear, toys, and packing materials.
Polyethylene foam (PE), also known as PE foam or polyfoam, is a versatile closed-cell foam rubber material, with flexibility, lightweight, resilience, water resistance, and chemical resistance. It is widely used in packaging, thermal insulation, and various other applications.
Polystyrene foam, also commonly known as Styrofoam, is a type of closed-cell foam rubber that is lightweight, excellent Insulator, moisture resistant, water resistant, and has shock-absorbing properties. It is widely used in packaging, insulation, and various other applications.
Polyvinyl Chloride (PVC) Foam: closed-cell structure, that provides good chemical resistance, flame retardancy, and sound insulation. It is commonly used in various applications like flooring underlayment, gaskets, and marine flotation devices.
EPDM Foam Rubber vs. EPDM Sponge RubberEPDM, which stands for Ethylene Propylene Diene Monomer, is a remarkable rubber material renowned for its exceptional weather resistance. EPDM has impressive resistance to weather, UV rays (sunlight), and ozone, and offers excellent flexibility and longevity. While both EPDM foam and sponge rubber seals share the core benefits of EPDM materials, their porous structures have unique properties that make them suitable for different applications.
EPDM Foam features a closed-cell structure, which can provide weather resistance, water repellent, and some thermal insulation properties. so EPDM foam seal finds favor in various applications, including Roofing membranes, Gaskets, seals, automotive weather stripping, and other applications. On the other hand, the Open-cell EPDM sponge rubber seal is used in cushioning, absorbing shocks, and vibrations applications, including Weatherstripping, Gaskets, seals, and vibration isolators.
Neoprene Foam Rubber VS Neoprene Sponge RubberNeoprene, a synthetic rubber is known for its exceptional durability and flexibility. It excels in demanding applications due to its withstand resistance to wear and tear, weather, and even some chemicals. This makes it a reliable choice for outdoor use like gaskets, hoses, and weather stripping.
Neoprene foam, a form of neoprene with a closed-cell structure, offers moderate water resistance and some thermal insulation. Neoprene Foam rubber seals are perfect for weatherstripping. Neoprene sponge's superior absorption, exceptional cushioning, and impact absorption capabilities make it fit for padding and industrial applications.
Silicone Rubber Foam VS Silicone Sponge RubberSilicone rubber, a versatile and widely used synthetic elastomer, is known for its high-temperature resistance, low compression set, and impressive flexibility. Specific types of silicone rubber are formulated to be flame retardant. This combination makes it fit for sealing in extreme applications.
silicone foam rubber provides reliable sealing and insulation thanks to its closed-cell structure. it is ideal for industrial and demanding aerospace applications, including gaskets and seals requiring high-temperature performance and weatherproofing. Silicone Sponge Rubber, open-cell structure allows for superior absorption, cushioning, and compression resilience, making it ideal for various industrial needs, including effective sealing and vibration dampening.
Neoprene/EPDM Rubber blendsNeoprene and EPDM can be blended to create specialized rubber compounds that combine the beneficial properties of both materials. This ingenious blend combines the strengths of neoprene, renowned for its durability and flexibility, with EPDM's exceptional resistance to UV rays, ozone, and oil. This EPDM Neoprene blend excels in harsh weather conditions while offering excellent oil and chemical resistance. it is Ideal for manufacturing gaskets, seals, and weather stripping in the automotive, marine, and manufacturing industries.
Neoprene/EPDM rubber: More than just a blended material, it's an innovative solution. Manufacturers often create these blends with specific applications in mind and may not always disclose the exact ratios.
Summary of Foam and Sponge RubberThis article provided a foundational understanding of foam and sponge rubber, covering their material composition, cellular structure (closed-cell vs. open-cell), common types (e.g., neoprene foam, silicone sponge), and various applications.
Closed-cell foam rubber features sealed bubbles, offering excellent weather resistance, thermal insulation, and effective sealing. Open-cell sponge rubber boasts interconnected air pockets, making it ideal for superior cushioning, shock absorption, and some breathability. Due to their diverse properties, foam and sponge rubber find applications in a wide range of industries, including automotive, construction, medical, and food and beverage.
Guangdong Zhongxiang New Materials Co., Ltd. specializes in custom-made, high-quality closed-cell silicone sponge rubber profiles in various sizes, shapes, and colors. We offer foam/sponge gaskets, extruded strips, and sheets. Visit www.zyxrubber.com for more information on their products and applications across diverse sectors like railway, aerospace, and construction. We collaborate with clients to select the most suitable rubber material and provide excellent customer service.
