What are the Advantages of Silicone Foam Over Polyurethane Foam?

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From car seats to batteries to your home’s insulation, foams are found everywhere; but which type is the best for the purpose you’re looking for? In this article we explore where foams are used throughout various industries, alongside a comparison of the advantages of silicone foam to those of polyurethane foam.

polyurethane seats
Car seats are made more comfortable using a variant of polyurethane foam

What are Polyurethane Foams & Silicone Foams?

Polyurethane Foams

When it comes to polyurethane foams, it can be easy to look past or completely miss the vast number of products that polyurethane foams are involved with. From mattresses and sofas to washing up sponges and sound proofing equipment, polyurethane foams have virtually endless applications throughout daily life.

Polyurethane foams can come in both a solid form and in a foam liquid, which can also come in different levels of viscosity and strength.

Silicone Foams

Silicone foams can also come in different levels of thickness, strength and solidity. Although the applications for silicone foams are not as universal as those of polyurethane foams, they are still widely applicable in applications such as gaskets, insulation and lowering the effects of vibrations.

Where are Silicone & Polyurethane Foams Used?

Foams are used extensively in many industries around the world for applications in kitchen and bathroom appliances; automobile parts; cable, pipe and house insulation; construction sealants and firestopping; gasket sealants; and vibrational dampening. Thermal insulation is a particularly significant use of foams as it plays a key role in the reduction of carbon dioxide emissions, leading to a reduction of human impacts on global warming.

Silicone Foam

Silicone foams are ideal for gaskets, insulation, seals and vibration dampening, especially in applications where the sealing surface is not smooth and the temperatures vary widely, due to silicone’s excellent versatility. Here we explore a range of silicone foam’s unique advantages:

Advantages of Silicone Foam

  • Silicone foam is available in both open-cell or closed-cell foam structure
    • Open cell foam structure allows high absorption of water, moisture and dust – making it ideal in a typical sponge used for washing cars.
    • Closed cell foam structure doesn’t accommodate for the absorption of water, moisture or dust – making it ideal in sealing applications where water and dust need to be kept out. This type is inherently hydrophobic (repels water).
  • Low flammability – enabling uses in anti-fire measures and glazing seals (UL94 rated)
  • Low density – reducing overall weight and improving dimensional stability
  • Excellent compression set resistance – rebound to original thickness quickly
  • Mechanical properties remain virtually constant between -60°C to 230°C
  • Retain full flexibility over a large temperature range
  • Good sound and heat insulation
  • Highly resistant to harsh chemicals and UV light – leading to excellent weathering properties
  • No release of toxic chemicals during thermal decomposition
  • Great dielectric properties – enabling uses in electrical insulation or conduction
thermal insulation foam
Foams being used for thermal insulation of electronic equipment

Polyurethane Foam

Polyurethane foams are used in many applications where comfort is a priority, including car seat cushions, mattresses and the general furniture industry. It is a durable and cheap material, although upon its decomposition, it is prone to emitting harmful chemicals that could irritate breathing. Here we explore a range of polyurethane foam’s unique advantages:

Advantages of Polyurethane Foam

  • Polyurethanes are harder than rubber and more flexible than plastics – leading to a high strength and impact resistance
  • Superb abrasion resistance
  • Extremely lightweight – aids in reducing emissions in transport applications
  • Highly resistant to harsh chemicals and oils – minimal swelling
  • One of the softest foams that can be used in the furniture industry
  • Excellent shock resistance due to high vibration frequency
  • Structurally stable
memory foam
A memory foam cushion made up of a variant of polyurethane

Comparison of Silicone and Polyurethane Foam

When it comes to engineering comfort in the furniture industry, polyurethane foams have the advantage of being soft, impact resistant, tough, and lightweight – leading to products such as the memory foam mattress. However, due to polyurethane’s tendency to emit volatile organic compounds that can cause respiratory problems, it is slowly being phased out of the mattress and cushioning industries and being replaced by more environmentally friendly materials.

When considering insulation and anti-fire measures, closed-cell silicone foams certainly have the upper hand due to being fully flexible throughout a very wide temperature range and being a fire retardant. As a result, they have proven useful in battery thermal management in electric aircraft. Additionally, they can be used on any surfaces regardless of the environment they are in, due to silicone’s extreme weatherability and resistance to harsh chemicals and UV. Furthermore, open-cell silicone foams can also be used for use in sponges for washing.

Overall, silicone foams can be used in a wider range of applications than polyurethane foams, without having the adverse health benefits of polyurethanes.

A Silicone Foam to Consider

DOWSIL 3-6548 RTV Silicone Foam is a two-part, medium density foam that is ideal for sealing fire rated penetrations in systems containing cables and pipes. It is able to prevent smoke and gas penetrating through seals by forming irregular and complex shapes around the components it is protecting. It is composed of two liquids that mix in a 1:1 ratio, expanding and curing to a formed elastomer at room temperature. As with all silicone foams, it is non-corrosive, fire-resistant, and resistant to UV radiation and extreme temperatures. Additionally, it also meets the HL3/R22 of the EN45545 rail regulation, making it a great choice for use in the railway industry.

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everything you should know about the EN 45545
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EN 45545 Railway Applications

This white paper examines the european standard EN 45545 Fire protection for passenger railway vehicles.