Foam rubber (also known as cellular rubber, sponge rubber, or expanded rubber) refers to

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...

that has been manufactured with a

foaming agent A foaming agent is a material such as a surfactant or a blowing agent that facilitates the formation of foam. A surfactant, when present in small amounts, reduces surface tension of a liquid (reduces the work needed to create the foam) or increases ...

to create an air-filled matrix structure. Commercial foam rubbers are generally made of

synthetic rubber A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32-million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubbe ...

, natural

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well. In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...

polyurethane Polyurethane (; often abbreviated PUR and PU) refers to 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, polyurethan ...

. Latex foam rubber, used in mattresses, is well known for its endurance. Polyurethane is a thermosetting polymer that comes from combination of Methyl di-isocyanate and

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including bo ...

and some other chemical additives.

Manufacturing history

Foam rubber was first produced in 1929 by

Dunlop Rubber Dunlop Ltd. (formerly Dunlop Rubber) was a British multinational company involved in the manufacture of various natural rubber goods. Its business was founded in 1889 by Harvey du Cros and he involved John Boyd Dunlop who had re-invented and d ...

researcher chemists E. A. Murphy and

Eric Owen The given name Eric, Erich, Erikk, Erik, Erick, or Eirik is derived from the Old Norse name ''Eiríkr'' (or ''Eríkr'' in Old East Norse due to monophthongization). The first element, ''ei-'' may be derived from the older Proto-Norse ''* ain ...

using whipped

. In 1937 isocyanate based materials were first used for the formation of foam rubbers, after World War II

styrene-butadiene Styrene-butadiene or styrene-butadiene rubber (SBR) describe families of synthetic rubbers derived from styrene and butadiene (the version developed by Goodyear is called Neolite). These materials have good abrasion resistance and good aging st ...

rubber replaced many natural types of foam. Foam rubbers have been used commercially for a wide range of applications since around the 1940s. Polyether

rubber was discovered and patented in the 1950s by

Charles C. Price Charles C. Price (July 13, 1913 - February 11, 2001) was an American chemist and president of the American Chemical Society (1965). He taught at the University of Illinois at Chicago, the University of Notre Dame, and the University of Pennsyl ...

. Currently, polyurethane-based foams make up over 90%, by weight, of the entire market for polyurethanes. The largest amount of polyurethane is used by these industries: construction, transportation, home furniture, noise and vibration reduction, and carpet. Construction uses 27% of polyurethane, and transportation uses 21%. Flexible foam is the leading material usage at 44% total volume, and rigid foam material at 28% of the United States market.

Manufacturing process

Rates of polymerization can range from many minutes to just a few seconds. Fast reacting polymers feature short cycle periods and require the use of machinery to thoroughly mix the reacting agents. Slow polymers may be mixed by hand, but require long periods on mixing, as a result industrial application tends to use machinery to mix products. Product processing can range from a variety of techniques including, but not limited to spraying, open pouring, and molding. * Material preparation Liquid and solid material generally arrive on location via rail or truck, once unloaded liquid materials are stored in heated tanks. When producing slabstock typically two or more polymers streams are used. * Mixing Open pouring, better known as continuous dispensing is used primarily in the formation of rigid, low density foams. Specific amounts of chemicals are mixed into a mixing head, much like an industrial blender. The foam is poured onto a conveyor belt, where it then cures for cutting. * Curing and cutting After curing on the conveyor belt the foam is then forced through a horizontal band saw. This band saw cuts the pieces in a set size for the application. General contracting uses 4’x12’x2’’. * Further processing Once cut and cured the slabstock can either be sold or a lamination process can be applied. This process turns the slabstock into a rigid foam board known as boardstock. Boardstock is used for metal roof insulation, oven insulation, and many other durable goods.

Physical properties

The main physical properties of foam rubber are generalized as being “Lightweight, buoyant, cushioning performance, thermal and acoustic insulation, impact damping and cost reduction”. Crosslinking technology is used in the formation of

EVA Eva or EVA may refer to: * Eva (name), a feminine given name Arts, entertainment, and media Fictional characters * Eva (Dynamite Entertainment), a comic book character by Dynamite Entertainment * Eva (''Devil May Cry''), Dante's mother in t ...

based foams, including

LLDPE Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. Linear low-density polyethylene differs s ...

LDPE Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. Its ...

HDPE High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...

, PP, and TPE. Crosslinking is the most important characteristic in the production of foam rubber to obtain the best possible foam expansion and physical properties. Crosslinking is defined as chemical bonding between polymer chains, and is used for foam rubber manufacturing to stabilize bubble expansion, enhanced resistance to thermal collapse and improve physical properties.

Recycling

Due to the variety in polyurethane chemistries, it is difficult to recycle foam materials using a single method. Reusing slab stock foams for carpet backing is how the majority of recycling is done. This method involves shredding the scrap and bonding the small flakes together to form sheets. Other methods involve breaking the foam down into granules and dispersing them into a polyol blend to be molded into the same part as the original. The recycling process is still ever developing for foam rubber and the future will hopefully unveil new and easier ways for recycling.No Author
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References

:* http://www.pfa.org/intouch/new_pdf/lr_IntouchV.8.pdf :* http://www.madehow.com/Volume-5/Foam-Rubber.html {{DEFAULTSORT:Foam Rubber Rubber

Manufacturing history

Manufacturing process

Physical properties

Recycling

See also

References