List Of Polyurethane Applications
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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 ...
products have many uses. Over three quarters of the global consumption of polyurethane products is in the form of foams, with flexible and rigid types being roughly equal in market size. In both cases, the foam is usually behind other materials: flexible foams are behind upholstery fabrics in commercial and domestic furniture; rigid foams are between metal, or plastic walls/sheets of most
refrigerator A refrigerator, commonly shortened to fridge, is a commercial and home appliance consisting of a thermal insulation, thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to ...
s and freezers, or other surface materials in the case of thermal insulation panels in the construction sector. Its use in garments is growing: for example, in lining the cups of brassieres. Polyurethane is also used for moldings which include door frames, columns, balusters, window headers, pediments, medallions and rosettes. Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. These materials include: * Low-density flexible
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 ...
used in
upholstery Upholstery is the work of providing furniture, especially seats, with padding, springs, webbing, and fabric or leather covers. The word also refers to the materials used to upholster something. ''Upholstery'' comes from the Middle English wor ...
, bedding, automotive and truck seating, and novel inorganic plant substrates for roof or wall gardens * Low density
elastomers An elastomer is a polymer with viscoelasticity (i.e. both viscosity and Elasticity (physics), elasticity) and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a ...
used in footwear * Hard solid plastics used as electronic instrument bezels and structural parts * Flexible plastics used as straps and bands * Cast and injection molded components for various markets – i.e., agriculture, military, automotive, industrial, etc. Polyurethane foam is widely used in high resiliency flexible foam seating, rigid foam insulation panels, microcellular foam seals and
gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to c ...
s, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, seals, gaskets,
carpet A carpet is a textile floor covering typically consisting of an upper layer of Pile (textile), pile attached to a backing. The pile was traditionally made from wool, but since the 20th century synthetic fiber, synthetic fibres such as polyprop ...
underlay, and hard plastic parts (such as for electronic instruments).


Usage per application

The following table shows an example how polyurethanes were used in one country over a dozen years ago (US data from 2004):


Cleaning products

Open-cell flexible polyurethane foam is used to make many kitchen and bathroom
sponges Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and ar ...
. The combination of low cost, high flexibility and high abrasion and tear resistance make polyurethanes excellent materials for scrubbing applications. Polyurethane sponges have been shown to reduce the risk of spreading certain bacteria.


Industrial Insulation

Rigid polyurethane foam is used in various industries to provide thermal insulation to installations and pipes. In particular, the piping for district heating systems in Europe is primarily insulated using a pre-insulated pipes sandwich assembly composed of a steel heat service pipe, an insulating layer (polyurethane foam) and a polyethylene (PE) casing, which are bonded by the insulating material. One of the main advantages of rigid polyurethane foam is that it offers a very low thermal conductivity (with values as low as 23mW/m⋅K) while offering enough structural strength to withstand the loads that buried pipe systems are subjected to. Due to the closed-cell nature of rigid polyurethane foams, PUR insulation has minimal water absorption, which coupled with an appropriate cover, makes it a particularly suitable in applications where bacterial growth is a concern. Polyurethane insulation is suitable for insulating pipes with surface temperatures ranging from -196°C to 148°C.


Furniture

Open cell flexible polyurethane foam (FPF) is made by mixing
polyols In organic chemistry, a polyol is an organic compound containing multiple hydroxyl groups (). The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, thre ...
, diisocyanates, catalysts, auxiliary blowing agents and other additives and allowing the resulting foam to rise freely. Most FPF is manufactured using continuous processing technology and also can be produced in batches where relatively small blocks of foam are made in open-topped molds, boxes, or other suitable enclosurers. The foam is then cut to the desired shape and size for use in a variety of furniture and furnishings applications. Applications for flexible polyurethane foam include upholstered
furniture Furniture refers to objects intended to support various human activities such as seating (e.g., Stool (seat), stools, chairs, and sofas), eating (table (furniture), tables), storing items, working, and sleeping (e.g., beds and hammocks). Furnitur ...
cushions, automotive seat cushions and interior trim, carpet cushion, and
mattress A mattress is a large, usually rectangular pad for supporting a person Lying (position), lying down, especially for sleeping. It is designed to be used as a bed, or on a bed frame as part of a bed. Mattresses may consist of a Quilting, quilted o ...
padding and solid-core mattress cores. Flexible polyurethane foam is a recyclable product.


Automobile seats

Flexible and semi-flexible polyurethane foams are used extensively for interior components of
automobile A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, peopl ...
s, in seats, headrests, armrests, roof liners,
dashboard A dashboard (also called dash, instrument panel or IP, or fascia) is a control panel (engineering), control panel set within the central console of a vehicle, boat, or cockpit of an aircraft or spacecraft. Usually located directly ahead of the ...
s and instrument panels. Polyurethanes are used to make automobile seats in a remarkable manner. The seat manufacturer has a
mold A mold () or mould () is one of the structures that certain fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal ...
for each seat model. The mold is a closeable "clamshell" sort of structure that will allow quick casting of the seat cushion, so-called molded flexible foam, which is then upholstered after removal from the mold. It is possible to combine these two steps, so-called ''in-situ'', foam-in-fabric or direct moulding. A complete, fully assembled seat cover is placed in the mold and held in place by vacuum drawn through small holes in the mold. Sometimes a thin pliable plastic film backing on the fabric is used to help the vacuum work more effectively. The metal seat frame is placed into the mold and the mold closed. At this point the mold contains what could be visualized as a "hollow seat", a seat fabric held in the correct position by the vacuum and containing a space with the metal frame in place. Polyurethane chemicals are injected by a mixing head into the mold cavity. Then the mold is held at a preset reaction temperature until the chemical mixture has foamed, filled the mold, and formed a stable soft foam. The time required is two to three minutes, depending on the size of the seat and the precise formulation and operating conditions. Then the mold is usually opened slightly for a minute or two for an additional cure time, before the fully upholstered seat is removed.


Houses, sculptures, and decorations

The walls and ceiling (not just the insulation) of the futuristic Xanadu House in Florida, USA, were built out of polyurethane foam. Domed ceilings and other odd shapes are easier to make with foam than with wood. Foam was used to build oddly shaped buildings, statues, and decorations in the Seuss Landing section of the Islands of Adventure (USA) theme park. Rigid foam manufacturers sell foam that replace wood in carved sign and 3D-topography industries. PU foam is also used as a
thermal insulator Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...
in many houses. Polyurethane resin is used as an aesthetic flooring material. Being seamless and water resistant, it is gaining interest for use in (modern) interiors, especially in Western Europe. Polyurethane is also used in some domestic and commercial capacities to waterproof areas that have leaks, such a
shower leaks
and balcony leaks. Image:Polyurethane insulator.jpg, Polyurethane being used as an insulator in house construction (yellow layer). File:Polyurethane the new Wattle and Daub, Brookend, Welland. - geograph.org.uk - 5811.jpg, Polyurethane foam as a wall insulation File:Xanadu - lily pads.jpg, Xanadu House with polyurethane foam walls and ceiling Image:Puf shrinkage over time 002.png, Polyurethane foam used as joist cavity insulation at a restaurant near
Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...
, not in direct sunlight, exhibiting shrinkage at the bond interface. File:Flame Retardant Research - LDH materials (16241017250).jpg, Flame test. Top, untreated polyurethane foam burns vigorously. Bottom, with fire-retardant.


Filling of spaces and cavities

Two binary liquids, one of which is a polyurethane (either T6 or 16), when mixed and aerated, expand into a hard, space-filling aerosolid.


Construction sealants and firestopping

Approved polyurethane sealants (which is different from foam) are available in one, two and three part systems, and in cartridges, buckets or drums. Polyurethane sealants (such as EZ-Poly) are used to fill gaps thereby preventing air and water leakage. They are also used in conjunction with inorganic insulation, such as rockwool or ceramic fibres, for
firestop A firestop or fire-stopping is a form of passive fire protection that is used to seal around openings and between joints in a fire-resistance-rated wall or floor assembly. Firestops are designed to maintain the fire-resistance rating of a wall ...
ping. Firestops can thwart
smoke Smoke is an aerosol (a suspension of airborne particulates and gases) emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwante ...
and hose-stream passage. The Browns Ferry Nuclear Power Plant used flammable polyurethane foam as a firestop, which was accidentally ignited and caused a major fire.


Water vessels

Polyurethane foam is widely used in the marine world in many applications:


Inflatable boats

Some raft manufacturers use urethane for the construction of inflatable boats. AIRE uses urethane membrane material as an air-retentive bladder inside a PVC shell, whereas SOTAR uses urethane membrane materials as a coating on some boats. Maravia uses a liquid urethane material which is spray-coated over PVC to enhance air retention and increase abrasion resistance.


Surfboards

Some surfboards are made with a rigid polyurethane core. A rigid foam blank is molded, shaped to specification, then covered with fiberglass cloth and polyester resin.


Rigid-hulled boats

Some boat hulls have a rigid polyurethane foam core sandwiched between fiberglass skins. The foam provides strength,
buoyancy Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...
, and sound deadening.


Boat decks and outdoor marine surface areas

Some boat decks including U.S Navy and Pakistani fishing vessels use specialized polyurethane sealants to protect from constant moisture and harsh oceanic elements. As an example, Durabak-M26 uses a custom single-part polyurethane to prevent water seepage to unwanted areas.


Water tanks

Some water tanks are insulated with polyurethane chemicals (polyol and isocyanates) to maintain water temperature for long periods of time.


Flexible plastics


Tennis grips

Polyurethane has been used to make several Tennis Overgrips such as Yonex Super Grap, Wilson Pro Overgrip and many other grips. These grips are highly stretchable to ensure the grip wraps neatly around the racquet's handle.


Watch-band wrapping

Polyurethane is used as a black wrapping for timepiece bracelets over the main material which is generally stainless steel. It is used for comfort, style, and durability.


Textiles

A thin film of polyurethane finish is added to a polyester weave to create polyurethane laminate (PUL), which is used for its waterproof and windproof properties in outerwear, diapers, shower curtains, and so forth. PU is used in some cutting-edge swimsuits to provide buoyancy for competitive swimmers. There are restrictions as the buoyancy enhances swimming performance. A still more popular use of polyurethane in textiles is in the form of
spandex Spandex, Lycra, or elastane is a synthetic fiber known for its exceptional elasticity. It is a polyether- polyurea copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont. Name The name ''spandex'', which is an anagram of t ...
, also known as elastane or by DuPont's brand name Lycra. Polyurethane
fiber Fiber (spelled fibre in British English; from ) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often inco ...
s in the form of spandex can stretch up to 600% and still return to their original shape. Spandex is spun with other fibers, such as cotton, nylon, or polyester, to create stretchable fibers essential for clothing for both sports and fashion.


Varnish

Polyurethane materials are commonly formulated as
paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...
s and
varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmente ...
es for finishing coats to protect or seal wood. This use results in a hard, abrasion-resistant, and durable coating that is popular for
hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...
floors, but considered by some to be difficult or unsuitable for finishing furniture or other detailed pieces. Relative to oil or shellac varnishes, polyurethane varnish forms a harder film which tends to de-laminate if subjected to heat or shock, fracturing the film and leaving white patches. This tendency increases when it is applied over softer woods like
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
. This is also in part due to polyurethane's lesser penetration into the wood. Various priming techniques are employed to overcome this problem, including the use of certain oil varnishes, specified "dewaxed"
shellac Shellac () is a resin secreted by the female Kerria lacca, lac bug on trees in the forests of India and Thailand. Chemically, it is mainly composed of aleuritic acid, jalaric acid, shellolic acid, and other natural waxes. It is processed and s ...
, clear penetrating
epoxy Epoxy is the family of basic components or Curing (chemistry), cured end products of epoxy Resin, resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide fun ...
, or "oil-modified" polyurethane designed for the purpose. Polyurethane varnish may also lack the "hand-rubbed" lustre of
drying oil Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be conside ...
s such as linseed or tung oil; in contrast, however, it is capable of a much faster and higher "build" of film, accomplishing in two coats what may require many applications of oil. Polyurethane may also be applied over a straight oil finish, but because of the relatively slow curing time of oils, the presence of volatile byproducts of curing, and the need for extended exposure of the oil to oxygen, care must be taken that the oils are sufficiently cured to accept the polyurethane. Unlike
drying oil Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be conside ...
s and alkyds which
cure A cure is a substance or procedure that resolves a medical condition. This may include a medication, a surgery, surgical operation, a lifestyle change, or even a philosophical shift that alleviates a person's suffering or achieves a state of heali ...
, after evaporation of the solvent, upon reaction with
oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
from the air, polyurethane coatings cure after
evaporation Evaporation is a type of vaporization that occurs on the Interface (chemistry), surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evapora ...
of the
solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...
by a variety of reactions of
chemical A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...
s within the original mix, or by reaction with
moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Moisture is defined as water in the adsorbed or absorbed phase. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some comme ...
from the air. Certain products are "hybrids" and combine different aspects of their parent components. "Oil-modified" polyurethanes, whether water-borne or solvent-borne, are currently the most widely used wood floor finishes. Exterior use of polyurethane varnish may be problematic due to its susceptibility to deterioration through ultra-violet (UV) light exposure. All clear or translucent varnishes, and indeed all
film A film, also known as a movie or motion picture, is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are generally, sinc ...
-
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
coatings (i.e.,
paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...
,
stain A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Accidental staining may make materials app ...
,
epoxy Epoxy is the family of basic components or Curing (chemistry), cured end products of epoxy Resin, resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide fun ...
, synthetic
plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
, etc.) are susceptible to this damage in varying degrees.
Pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
s in paints and stains protect against UV damage, while UV-absorbers are added to polyurethane and other varnishes (in particular " spar" varnish) to work against UV damage. Polyurethanes are typically the most resistant to water exposure, high humidity, temperature extremes, and fungus or mildew, which also adversely affect varnish and paint performance.


Wheels

Polyurethane is also used in making solid tires and
wheel A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machin ...
s. Industrial applications include
forklift A forklift (also called industrial truck, lift truck, jitney, hi-lo, fork truck, fork hoist, and forklift truck) is a powered industrial truck used to lift and move materials over short distances. The forklift was developed in the early 20th c ...
drive and load wheels, grocery and industrial carts, and roller coaster wheels. Modern roller blading and
skateboard A skateboard is a type of sports equipment used for skateboarding. It is usually made of a specially designed 7–8-ply maple plywood deck and has polyurethane wheels attached to the underside by a pair of skateboarding trucks. The skateboard ...
ing became economical only with the introduction of tough, abrasion-resistant polyurethane parts, helping to usher in the popularity of what had once been an obscure 1960s craze. The durability of polyurethane wheels allowed the range of tricks and stunts performed on
skateboards A skateboard is a type of sports equipment used for skateboarding. It is usually made of a specially designed 7–8-ply maple plywood deck and has polyurethane wheels attached to the underside by a pair of skateboarding trucks. The skateboard ...
to expand considerably. Polyurethane is also used to make small equipment tires in the lawn and garden industry for wheelbarrows, hand trucks, lawn mowers, carts, etc. They provide the bounce and feel of an air-filled tire with the benefit of no punctures. They weigh about the same as air-filled tires as well, even though they are solid polyurethane all the way through. Other constructions have been developed for pneumatic tires, and microcellular foam variants are widely used in tires on wheelchairs, bicycles and other uses. These latter foam types are also widely encountered in car steering wheels and other interior and exterior automotive parts, including bumpers and fenders.


Automotive parts

Polyurethane usage has increased over the past twenty years in the automotive industry. It is being used to replace traditional rubber bushings which are known to fail or wear out on road surfaces prone to large amounts of salt and chemical debris. Using polyurethane bushings can have many benefits like maintaining the right alignment of caster, camber and toe and thereby increasing the overall control and handling. It also increases the lifespan, provides more resistance to wear out and is less pervious to oil and similar road contaminants. Polyurethane (PU) is popularized in the manufacturing of some of the highest quality aerodynamic components /body kits ( body kits) for varying automobiles (car, truck, and SUV) on the market. These components include bumpers, side skirts, roll pans, and wiper cowls. Polyurethane allows production of durable components unlike the conventional fiberglass (FRP) that can easily break upon impact. Polyurethane is highly flexible therefore more resistant to damage. Including durability, these body kits when produced by a reputable manufacturer, exhibits less imperfections, are easy to install and maintain, and are affordable. When fiberglass body kits begin to show cracks, chips from usual wear and tear, a well manufactured polyurethane components have similar durability to a factory installed bumper. As mentioned above, when produced by a reputable manufacturer, tend to have less pinholes and casting imperfections. Flexibility of polyurethane makes them easy to work with. Installation can be completed individually as a "do-it-yourself" project. Maintenance is extremely simple. Concerning pricing, it may vary depending on the manufacturer but are kept between an affordable range. As good as it sounds, polyurethane body kits too have its downfalls. Fiberglass or carbon fiber components are lighter in weight than most polyurethane kits. Polyurethane, again is flexible but more material and thickness is most often needed to keep adequate stiffness for road use. For drivers seeking speed for their higher performance vehicle, this can become a problem. Also, unlike fiberglass, polyurethane cannot be patched or repaired. Though it is much harder to damage, if damage did occur, the entire component must be removed and replaced. There are varying options when purchasing polyurethane kits.


Electronic components

Often electronic circuit components and wires are protected from environmental influence and mechanical shock by enclosing them in polyurethane. Typically polyurethanes are selected for the excellent abrasion resistances, good electrical properties, excellent adhesion, impact strength, and low-temperature flexibility. The disadvantage of polyurethanes is the limited upper service temperature (typically 250 °F (121 °C)). The production the electronic circuit-board manufacture would use a two-part urethane (resin and catalyst) that would be mixed and poured onto the circuit assembly (see resin dispensing). In most cases, after the urethane cures, the completed circuit board would not be repairable. Because of its physical properties and low cost, polyurethane encapsulation (potting) is a popular option in the automotive manufacturing sector for automotive circuits and sensors.


Adhesives

Polyurethane can be used as an
adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advantage ...
, especially as a woodworking glue. Its main advantage over more traditional wood glues is its water resistance. It was introduced to the general North American market in the 1990s as '' Gorilla Glue'' and ''Excel'', but had been available in Europe much earlier. Polyurethane is the basis for some construction adhesives in a
caulking Caulk (also known as caulking and calking) is a material used to seal joints or seams against leakage in various structures and piping. The oldest form of caulk consisted of fibrous materials driven into the wedge-shaped seams between board ...
tube format. On the way to a new and better glue for bookbinders, a new adhesive system was introduced for the first time in 1985. The base for this system is polyether or polyester, whereas polyurethane (PUR) is used as prepolymer. Its special features are coagulation at room temperature and resistance to moisture. First generation (1988) * Low starting solidity * High viscosity * Cure time >3 days Second generation (1996) * Low starting solidity * High viscosity * Cure time <3 days Third generation (2000) * Good starting solidity * Low viscosity * Cure time between 6 and 16 hours Fourth generation (present) * Good starting solidity * Very low viscosity * Cure reached within a few seconds due to dual-core systems Advantages of polyurethane glue in the bookbinding industry: * PUR is better than hotmelt or cold glue for most applications. Because of the lack of moisture in the glue, paper with contrary grain direction can be glued without problems. Even printed and supercalendered paper can be bound without problems. It is the most economical glue, with a theoretical application thickness of 0.01 mm. However, in actual use, it is not practical to apply less than 0.03 mm. * PUR glue is weather-proof, and stable at temperatures from to .


Abrasion resistance

Thermoset polyurethanes are also used as a protective coating against abrasion. Cast polyurethane over materials such as steel will absorb particle impact more efficiently. Polyurethanes have been proven to last in excess of 25 years in abrasive environments where non-coated steel would erode in less than 8 years. Polyurethanes are used in industries such as: * Mining and mineral processing * Aggregate * Transportation * Concrete * Paper processing * Power * Inflatable boat manufacture Polyurethane is also used in the concrete construction industry to create formliners. Polyurethane formliners serves as a mold for concrete, creating a variety of textures and art.


Solid-fuel rockets

Polyurethane is used together with Ammonium perchlorate as solid fuel in the submarine launched
Polaris missile The UGM-27 Polaris missile was a two-stage solid-fuel rocket, solid-fueled nuclear warhead, nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980. In the mid-1950s the Navy ...
s.


Body armor

Polyurethane urea elastomers have been investigated by researchers from the U.S. Army Research Laboratory and the
Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...
for potential material for helmets, face shields, and ballistic vests for soldiers.


Inorganic plant substrates

Sheet and flaked semi-open cell hydrophilic polyurethane foams have found application in roof gardens and vertical green walls with commercial products now emerging on the market. Semi-open cell polyurethane foams substrates have much lower density and far greater water holding capacities than soil substrates. The semi-open cell structure facilitate the required plant root attachment for vertical wall gardens. Reductions in weight reduce building/wall supporting structure requirements, whilst increased water holding capacity reduces plant watering requirements.


Concrete raising

Closed cell polymers have been used to raise and support concrete roadways and bridge approaches since 1989. Originally developed in Europe an
patented
by Uretek, this method of concrete leveling is now widely used in residential, commercial and municipal applications. Common applications include repairing settled sidewalks, driveways, patios and garage floors. In the US it is sometimes known a
Slabjacking

Foam Supplies Incorporated
have developed the eco-friendl
FoamJack™
system.


Concrete substitute

Closed cell polyurethane foam can be used as backfill in applications where the high density and compression strength of concrete are not necessary. In addition to being considerably lighter than concrete, the closed cell nature of the material prevents the transfer of moisture to the structure being supported which can reduce the risk or rot or corrosion.


Seawall Repair

Environmental variables, natural wear and tear, and weather conditions, can all cause damage to concrete seawalls. These problems can erode the structure over time, rendering it more susceptible to further harm. Traditionally repair has required an in depth process using concrete, however geofoam is a lightweight and long-lasting substance that has become increasingly popular to repair damaged seawalls.


References

{{DEFAULTSORT:Polyurethane applications Polyurethanes Science-related lists