University of Alicante

The Spanish researcher has developed a new method to obtain cellular materials that overcomes all the disadvantages of the methods currently used.

The raw material is mixed with a liquid compound (hydrogen peroxide, H2O2). This liquid breaks down generating water and oxygen gas. The decomposition can be spontaneous or assisted. The generated oxygen is trapped in independent cavities in the material matrix, changing its physical structure without variation in its chemical composition. This change in the material structure changes the mechanical properties too.

The infiltration of the hydrogen peroxide in the material can be made in several ways. The cheapest and fastest one is simple diffusion in water. If the hydrogen peroxide doesn’t break down spontaneously, the decomposition can be assisted by light and heat. For this purpose, sunlight has enough power to produce H2O2 decomposition and is cheap and ecofriendly. In the same way, sunlight can be used to dry the material after the process, unless a fast drying is needed. In that case autoclave can be used.

Cellular materials can be polymeric, ceramic, cement or glassy nature, but in every case the process to obtain them is the same. Oxygen bubbles are formed inside the material by hydrogen peroxide decomposition. These bubbles create independent cavities. The variables of the process can be modified attending to the customer requirements to obtain materials with specific properties.

Example:

Method to obtain cellular concrete to be used in buildings, maintaining the original chemical composition of the concrete. Fistly, water is introduced into the mould to wet the walls. Hydrogen peroxide is added and after this, the concrete. The mixture must be stirred during one minute. A variation in the stirring time can modify the volume and the mechanical resistance, so it can be optimized to obtain the desired properties. Finally, the mixture must be setted for 3 hours. With this method the surface has cellular appearance. This can be avoided impregnating the mold previously with no cellular concrete, to create a no cellular film on the surface on the cellular concrete. With 400 g of concrete, 500 mL of water and 15 mL of H2O2, one liter of cellular concrete can be obtained.

The described process can be applied to different materials optimizing the variables to obtain the amount, shape and size of porous needed in each case.

• The resultant porous material doesn’t change its original chemical composition but changes its physical structure.

• Very low production cost.

• Lightweight materials are obtained.

• Insulating materials can be obtained.

• Porous can be used to introduce some chemicals in the material to give it certain properties (for example, flameproof).

• The obtained materials can float in water.

• Special machinery in NOT needed to process the materials.

• The cellular material can be produced in situ.

• Easy manufacturing process without dangerous chemicals involved.

• This technology can be applied to a lot of material like polymers, concrete, gel, composites, etc.

Cellular materials are a new and attractive materials class with interesting applications in different sectors.

The first prototypes of cellular concrete have been manufactured at laboratory scale. To scale up the process to industrial production is viable, but nowadays there isn’t any production line running. The conditions of the process will be different according with the specific needs of the sector which the cellular material will be applied for.

With this kind of materials can be satisfied the new requests of the market in new engineering and technological applications like:

BUILDING:

- Cellular materials for building and thermal and acoustic insulations.

- Cellular concrete for buildings with different shapes and sizes and with the original chemical composition of the concrete.

TECHNOLOGY:

- Cellular materials to thin layer processes. Thin layers can be obtained between the cellular structures of the matrix.

This technology is protected by patent.

• Application Number: P200701648

• Application Date: 14/06/2007