Reticulated foam
Encyclopedia
Reticulated foam is a very porous
, low density solid foam
. 'Reticulated' means like a net
. 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 is composed solely of intact (fully enclosed) bubbles. In a reticulated foam only the linear boundaries where the bubbles meet remain.
The solid component of a reticulated foam may be an organic polymer like polyurethane
, a ceramic
or a metal
. These materials are used in a wide range of applications where the high porosity and large surface area
are needed, including filters
, catalyst
supports, fuel tank
inserts, and loudspeaker
covers.
A description of the structure of reticulated foams is still being developed. While Plateau's 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 is the most recent. In a reticulated foam only the edges
of the polyhedra remain; the faces
are missing. In commercial reticulated foam, up to 98% of the faces are removed. The dodecahedron 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
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.
. Producing reticulated polyurethane foam is a two step procedure: a conventional flexible polyurethane foam is produced then the windows or faces of the foam are removed. The high surface area of the windows makes them more susceptible to either combustion or chemical degradation than the cell struts (edges). Filling the closed-cell foam with a combustible gas like hydrogen
and igniting it under carefully controlled conditions, or exposing the foam to a sodium hydroxide solution, again with careful control, removes the windows and leaves the edges.
Reticulated ceramic
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 metal
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.
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
, low density solid foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
. 'Reticulated' means like a net
Net (device)
A net, in its primary meaning, comprises fibers woven in a grid-like structure, and is very infrequently mentioned in discussions of philosophy. It blocks the passage of large items, while letting small items and fluids pass...
. 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 is composed solely of intact (fully enclosed) bubbles. In a reticulated foam only the linear boundaries where the bubbles meet remain.
The solid component of a reticulated foam may be an organic polymer like polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
, a ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
or a metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
. These materials are used in a wide range of applications where the high porosity and large surface area
Surface area
Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra the surface area is the sum of the areas of its faces...
are needed, including filters
Filtration
Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium through which only the fluid can pass...
, catalyst
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....
supports, fuel tank
Fuel tank
A fuel tank is safe container for flammable fluids. Though any storage tank for fuel may be so called, the term is typically applied to part of an engine system in which the fuel is stored and propelled or released into an engine...
inserts, and loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
covers.
Structure and properties
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.Plateau's laws state:# Soap films are made of entire smooth surfaces....
, 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 is the most recent. In a reticulated foam only the edges
Edge (geometry)
In geometry, an edge is a one-dimensional line segment joining two adjacent zero-dimensional vertices in a polygon. Thus applied, an edge is a connector for a one-dimensional line segment and two zero-dimensional objects....
of the polyhedra remain; the faces
Face (geometry)
In geometry, a face of a polyhedron is any of the polygons that make up its boundaries. For example, any of the squares that bound a cube is a face of the cube...
are missing. In commercial reticulated foam, up to 98% of the faces are removed. The dodecahedron 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
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
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 CompanyScott Paper Company
The Scott Paper Company is a USA-based corporation which manufactures mostly paper based consumer products.Scott Paper was founded in 1879 in Philadelphia, Pennsylvania by brothers E. Irvin and Clarence Scott, and is often credited as being the first to market toilet paper sold on a roll...
. Producing reticulated polyurethane foam is a two step procedure: a conventional flexible polyurethane foam is produced then the windows or faces of the foam are removed. The high surface area of the windows makes them more susceptible to either combustion or chemical degradation than the cell struts (edges). Filling the closed-cell foam with a combustible gas like hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
and igniting it under carefully controlled conditions, or exposing the foam to a sodium hydroxide solution, again with careful control, removes the windows and leaves the edges.
Reticulated ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
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 metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
foam can also be made using polyurethane foam as a template similar to its use in ceramic foams. Metals can be vapor deposited
Physical vapor deposition
Physical vapor deposition is a variety of vacuum deposition and is a general term used to describe any of a variety of methods to deposit thin films by the condensation of a vaporized form of the desired film material onto various workpiece surfaces...
onto the polyurethane foam and then the organic polymer burned off.
Applications
Reticulated foams are used where porosity, surface area, low density are important.- HumidifierHumidifierA humidifier is a household appliance that increases humidity in a single room or in the entire house. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the...
pads - Air conditioner filters
- Scrubbers
- Ceramic filters for filtering molten metal
- Vehicle and bacteria filters
- SpeakerLoudspeakerA loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
grills - Face mask and pads
- Shoe polishShoe polishShoe polish , usually a waxy paste or a cream, is a consumer product used to polish, shine, waterproof, and restore the appearance of leather shoes or boots, thereby extending the footwear's life...
and cosmetic applicators - Ink jet cartridgesInk cartridgeAn ink cartridge or inkjet cartridge is a replaceable component of an inkjet printer that contains the ink that is deposited onto paper during printing....
- AquacultureAquacultureAquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
(water purification) - Fuel tanks for aircraft and race cars For example: A-10 Thunderbolt IIA-10 Thunderbolt IIThe Fairchild Republic A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support for ground forces by attacking tanks,...