Reticulated foam is a very

porous Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

, low-density solid

foam Foams are two-phase materials science, material systems where a gas is dispersed in a second, non-gaseous material, specifically, in which gas cells are enclosed by a distinct liquid or solid material. Note, this source focuses only on liquid ...

. 'Reticulated' means like a

net NET may refer to: Broadcast media United States * National Educational Television, the predecessor of the Public Broadcasting Service (PBS) in the United States * National Empowerment Television, a politically conservative cable TV network ...

. Reticulated foams are extremely open foams i.e. there are few, if any, intact bubbles or cell windows. In contrast, the foam formed by

soap bubbles A soap bubble (commonly referred to as simply a bubble) is an extremely thin film of soap or detergent and water enclosing air that forms a hollow sphere with an iridescent surface. Soap bubbles usually last for only a few seconds before burs ...

is composed solely of intact (fully enclosed) bubbles. In a reticulated foam only the lineal boundaries where the bubbles meet ( Plateau borders) remain.

The solid component of a reticulated foam may be an

organic polymer A polymer () is a substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeating subunits derived from one or more species of monomers. Due to their broad spectrum of properties, bot ...

polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...

, a

ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...

, or a

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

. These materials are used in a wide range of applications where the high porosity and large

surface area The surface area (symbol ''A'') of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the d ...

are needed, including

filters Filtration is a physical process that separates solid matter and fluid from a mixture. Filter, filtering, filters or filtration may also refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Fil ...

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

supports,

fuel tank A fuel tank (also called a petrol tank or gas tank) is a safe container for Flammability, flammable fluids, often gasoline or diesel fuel. Though any storage tank for fuel may be so called, the term is typically applied to part of an engine sys ...

inserts, and

loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

covers.

Structure and properties

A description of the structure of reticulated foams is still being developed. While

Plateau's laws Plateau's laws describe the structure of soap films. These laws were formulated in the 19th century by the Belgian physicist Joseph Plateau from his experimental observations. Many patterns in nature are based on foams obeying these laws. Laws ...

, the rules governing the shape of soap films in foams were developed in the 19th century, a mathematical description of the structure is still debated. The computer-generated

Weaire–Phelan structure In geometry, the Weaire–Phelan structure is a three-dimensional structure representing an idealised foam of equal-sized bubbles, with two different shapes. In 1993, Denis Weaire and Robert Phelan found that this structure was a better solutio ...

is the most recent. In a reticulated foam only the

edges Enhanced Data rates for GSM Evolution (EDGE), also known as 2.75G and under various other names, is a 2G digital mobile phone technology for packet switched data transmission. It is a subset of General Packet Radio Service (GPRS) on the GS ...

of the

polyhedra In geometry, a polyhedron (: polyhedra or polyhedrons; ) is a three-dimensional figure with flat polygonal faces, straight edges and sharp corners or vertices. The term "polyhedron" may refer either to a solid figure or to its boundary su ...

remain; the

faces The face is the front of the head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affect the ...

are missing. In commercial reticulated foam, up to 98% of the faces are removed. The

dodecahedron In geometry, a dodecahedron (; ) or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagons as faces, which is a Platonic solid. There are also three Kepler–Po ...

is sometimes given as the basic unit for these foams, but the most representative shape is a polyhedron with 13 faces. Cell size and cell size distribution are critical parameters for most applications.

Porosity Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

is typically 95%, but can be as high as 98%. Reticulation affects many of the physical properties of a foam. Typically resistance to compression is decreased while tensile properties like elongation and resistance to tearing are increased.

Production

Robert A. Volz is credited with discovering the first process for making reticulated polyurethane foam in 1956 while working for the

Scott Paper Company The Scott Paper Company was a manufacturer and marketer of sanitary tissue products with operations in 22 countries. Its products were sold under a variety of well-known brand names, including ''Scott Tissue'', ''Cottonelle'', ''Baby Fresh'', ''S ...

. Production of reticulated

polyurethane foam Polyurethane foam is a solid polymeric foam based on polyurethane chemistry. As a specialist synthetic fibre, synthetic material with highly diverse applications, polyurethane foams are primarily used for thermal insulation and as a cushioning mat ...

is a two-step process that begins with the creation of conventional (closed-cell) polyurethane foam, after which cell faces (or "windows") are removed. To do so, the fact that the higher surface area and lower mass of cell faces compared with cell struts (or edges) makes them much more susceptible to both combustion and chemical degradation is exploited. Thus, closed-cell foam is either filled with a combustible gas like

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

and ignited under controlled conditions, or it is exposed to a

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

solution to chemically degrade the foam, which will remove cell windows whilst sparing the edges. Reticulated

foams are made by coating a reticulated polyurethane foam with an aqueous suspension of a ceramic powder then heating the material to first evaporate the water then fuse the ceramic particles and finally to burn off the organic polymer. Reticulated

foam can also be made using polyurethane foam as a template similar to its use in ceramic foams. Metals can be vapor deposited onto the polyurethane foam and then the organic polymer burned off.

Applications

Reticulated foams are used where porosity, surface area, and low density are important. * Puppets (such as the bodies/faces/hands of

The Muppets The Muppets are an American ensemble cast of puppet characters known for an surreal humor, absurdist, slapstick, burlesque, and self-referential humor, self-referential style of Musical theatre, musical Variety show, variety-sketch comedy. Cre ...

) *

Humidifier A humidifier is a household appliance or device designed to increase the moisture level in the air within a room or an enclosed space. It achieves this by emitting water droplets or steam into the surrounding air, thereby raising the humidity. ...

pads *

Air conditioner Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...

filters * Scrubbers * Ceramic filters for filtering molten metal * Vehicle and bacteria filters *

Speaker Speaker most commonly refers to: * Speaker, a person who produces speech * Loudspeaker, a device that produces sound ** Computer speakers Speaker, Speakers, or The Speaker may also refer to: Arts and entertainment * "Speaker" (song), by David ...

grills * Face mask and pads * Outdoor cushions * Marine seating *

Shoe polish Shoe polish, also known as boot polish and shoeshine, is a waxy paste (rheology), paste, cream (pharmaceutical), cream, or liquid that is used to polish, polishing, shine, and waterproofing, waterproof leather shoes or boots to extend the footwe ...

and cosmetic applicators * Ink jet cartridges *

Aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

(water purification) * Anti-slosh filling in fuel tanks for aircraft (such as the

A-10 Thunderbolt II The Fairchild Republic A-10 , also infamously known under the nickname , is a single-seat, twinjet, twin-turbofan, straight wing, straight-wing, Subsonic aircraft, subsonic attack aircraft developed by Fairchild Aircraft, Fairchild Republic ...

) and race cars

References

External links

Reticulation Process, FXI
{{Webarchive, url=https://web.archive.org/web/20150301215236/http://fxi.com/foam-technologies/processes/reticulation.php , date=2015-03-01 Ceramic materials Foams Materials science Plastics Polyurethanes