Polyurethane (PUR and PU) is a polymer composed of a chain of organic units joined by carbamate (urethane) links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available.

Polyurethane polymers are traditionally and most commonly formed by reacting a di- or polyisocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain on average two or more functional groups per molecule.

Some noteworthy recent efforts have been dedicated to minimizing the use of isocyanates to synthesize polyurethanes, because the isocyanates raise severe toxicity issues. Non-isocyanate based polyurethanes (NIPUs) have recently been developed as a new class of polyurethane polymers to mitigate health and environmental concerns.

Polyurethane products often are simply called “urethanes”, but should not be confused with ethyl carbamate, which is also called urethane. Polyurethanes neither contain nor are produced from ethyl carbamate.

Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires (such as roller coaster and escalator wheels); automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; hard-plastic parts (e.g., for electronic instruments); hoses and skateboard wheels.

Polyurethanes are produced by mixing two or more liquid streams. The polyol stream contains catalysts, surfactants, blowing agents and so on. The two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the 'A-side' or just the 'iso'. The blend of polyols and other additives is commonly referred to as the 'B-side' or as the 'poly'. This mixture might also be called a 'resin' or 'resin blend'. In Europe the meanings for 'A-side' and 'B-side' are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers. Polyurethane can be made in a variety of densities and hardnesses by varying the isocyanate, polyol or additives.

Fully reacted polyurethane polymer is chemically inert. No exposure limits have been established in the U.S. by OSHA (Occupational Safety and Health Administration) or ACGIH (American Conference of Governmental Industrial Hygienists). It is not regulated by OSHA for carcinogenicity. Polyurethane polymer is a combustible solid and can be ignited if exposed to an open flame. Decomposition from fire can produce mainly carbon monoxide, and trace nitrogen oxides and hydrogen cyanide.

Liquid resin blends and isocyanates may contain hazardous or regulated components. Isocyanates are known skin and respiratory sensitizers. Additionally, amines, glycols, and phosphate present in spray polyurethane foams present risks.[32]

In the United States, additional health and safety information can be found through organizations such as the Polyurethane Manufacturers Association (PMA) and the Center for the Polyurethanes Industry (CPI), as well as from polyurethane system and raw material manufacturers. Regulatory information can be found in the Code of Federal Regulations Title 21 (Food and Drugs) and Title 40 (Protection of the Environment). In Europe, health and safety information is available from ISOPA,[33] the European Diisocyanate and Polyol Producers Association.

The methods of manufacturing polyurethane finished goods range from small, hand pour piece-part operations to large, high-volume bunstock and boardstock production lines. Regardless of the end-product, the manufacturing principle is the same: to meter the liquid isocyanate and resin blend at a specified stoichiometric ratio, mix them together until a homogeneous blend is obtained, dispense the reacting liquid into a mold or on to a surface, wait until it cures, then demold the finished part.

Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.

It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, low-temperature toughness, stress-crack resistance, hot-melt adhesive waterproof properties, and resistance to UV radiation. EVA has a distinctive "vinegar" odor and is competitive with rubber and vinyl products in many electrical applications.

Hot melt adhesives, hot glue sticks, and top of the line soccer cleats are usually made from EVA, usually with additives like wax and resin. EVA is also used as a clinginess-enhancing additive in plastic wraps. Craft foam sheets are made of EVA and these foam sheets are popularly used for children's foam stickers.

EVA is also used in biomedical engineering applications as a drug delivery device. The polymer is dissolved in an organic solvent (e.g., dichloromethane). Powdered drug and filler (typically an inert sugar) are added to the liquid solution and rapidly mixed to obtain a homogeneous mixture. The drug-filler-polymer mixture is then cast into a mold at −80 °C and freeze dried until solid. These devices are used in drug delivery research to slowly release a compound. While the polymer is not biodegradable within the body, it is quite inert and causes little or no reaction following implantation.

EVA is one of the materials popularly known as expanded rubber or foam rubber. EVA foam is used as padding in equipment for various sports such as ski boots, bicycle saddles, hockey pads, boxing and mixed martial arts gloves and helmets, wakeboard boots, waterski boots, fishing rods and fishing reel handles. It is typically used as a shock absorber in sports shoes, for example. It is used for the manufacture of floats for commercial fishing gear such as purse seine (seine fishing) and gillnets. In addition, because of its buoyancy, EVA has made its way into non-traditional products such as floating eyewear. It is also used in the photovoltaics industry as an encapsulation material for silicon cells in the manufacture of photovoltaic modules. EVA slippers and sandals are currently very popular because of their properties like light weight, easy to form, odorless, glossy finish, and cheaper compared to natural rubber. In fishing rods, it is used to construct handles on the rod-butt end. EVA can be used as a substitute for cork in many applications.

EVA emulsions are polyvinyl acetate (PVAc) copolymers based on vinyl acetate (VAM) internally plastized with vinyl acetate ethylene (VAE). PVAc copolymer are adhesives used in packaging, textile, bookbinding for bonding plastic films, metal surfaces, coated paper, as redispersible powder in plasters and cement renders

Vinyl acetate ethylene copolymer(VAE), is also used in coatings formulation of good quality interior water-borne paints at 53% Primary dispersant

Hydrolysis of EVA gives ethylene vinyl alcohol (EVOH) copolymer.

EVA is used in orthotics, fire safe cigarettes (FSC), surfboard and skimboard traction pads, and for the manufacturing of some artificial flowers. It is used as a cold flow improver for diesel fuel and a separater in HEPA filters. EVA can easily be cut from sheets and molded to shape. It is also used to make thermoplastic mouthguards that soften in boiling water for a user specific fit. It is also used for impregnation of leather. Additional uses are in the making of nicotine transdermal patches since the copolymer binds well with other agents to form gel like substances. EVA is also sometimes used for making body bags.

A gel (coined by 19th-century Scottish chemist Thomas Graham, by clipping from gelatine) is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are mostly liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid. It is the crosslinking within the fluid that give a gel its structure (hardness) and contribute to the adhesive stick (tack). In this way gels are a dispersion of molecules of a liquid within a solid in which the solid is the continuous phase and the liquid is the discontinuous phase.

Many gels display thixotropy – they become fluid when agitated, but resolidify when resting. In general, gels are apparently solid, jelly-like materials. By replacing the liquid with gas it is possible to prepare aerogels, materials with exceptional properties including very low density, high specific surface areas, and excellent thermal insulation properties.

Many substances can form gels when a suitable thickener or gelling agent is added to their formula. This approach is common in manufacture of wide range of products, from foods to paints and adhesives.

In fiber optics communications, a soft gel resembling "hair gel" in viscosity is used to fill the plastic tubes containing the fibers. The main purpose of the gel is to prevent water intrusion if the buffer tube is breached, but the gel also buffers the fibers against mechanical damage when the tube is bent around corners during installation, or flexed. Additionally, the gel acts as a processing aid when the cable is being constructed, keeping the fibers central whilst the tube material is extruded around it.

Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber (the Cork Oak), which is endemic to southwest Europe and northwest Africa. Cork is composed of suberin, a hydrophobic substance, and because of its impermeability, buoyancy, elasticity and fire retardant, it is used in a variety of products, the most common of which is for wine stoppers. The montado landscape of Portugal produces approximately 50% of cork harvested annually worldwide, with Corticeira Amorim being the leading company in the industry. Cork was examined microscopically by Robert Hooke, which led to his discovery and naming of the cell.

Cork is used in musical instruments, particularly woodwind instruments, where it is used to fasten together segments of the instrument, making the seams airtight. Conducting baton handles are also often made out of cork.

It is also used in shoes, especially those using Goodyear Welt Construction.

Cork can be used to make bricks for the outer walls of houses, as in Portugal's pavilion at Expo 2000.

On November 28, 2007, the Portuguese national postal service CTT issued the world's first postage stamp made of cork.

Cork is used as the core of both baseballs and cricket balls. A corked bat is made by replacing the interior of a baseball bat with cork—a practice known as "corking". It was historically a method of cheating at baseball; the efficacy of the practice is now discredited.

Cork is often used, in various forms, in spacecraft heat shields and fairings.

Cork can be used in the paper pick-up mechanisms in inkjet and laser printers.

Cork is also used inside footwear to improve climate control and comfort.

Corks are also hung from hats to keep insects away. See cork hat.

Cork has been used as a core material in sandwich composite construction.

Cork can be used as the friction lining material of an automatic transmission clutch, as designed in certain mopeds.

Cork can be used instead of wood or aluminium in automotive interiors.

Cork can also be used to make watch bands and faces as seen with Sprout Watches.

KUN HUANG developed the POLIYOU^® foam material independently. ThePOLIYOU^® foam material provides special properties, such as superior ventilation, well dampness absorption, and anti-bacteria & anti-fungus. It has not only obtained cross-countries patents, but also adopted by many famous global brands, including NIKE, ECCO, NEW BALANCE, PUMA, Reebok, Hotter, Florsheim, Dr. Martem, Clarks, Walmart, etc. On the strength of KUN HUANG's sales network across Europe, Asia, and America, the sales of POLIYOU^® insoles achieved tens of millions each year and earned a lot of foreign exchange for Taiwan as well. KUN HUANG, an insole corporation located at the Tunglo Industrial Park in Miaoli County, was introduced ISO-9002 international authentication to guarantee the quality, was accredited the international quality certificate by KEMA from Netherlands on February 23, 1999 and also accredited the ISO-9001 DNV by the International Organization for Standardization in 2001. The rigid internal management system, intelligent employee training programs, and agile improvement for quality management are the keystones for KUN HUANG Corp. 

The production technology of POLIYOU^® was also registered the worldwide patents more than 30 countries. After decades of export trade, KUN HUANG plans to introduce the POLIYOU^® insoles to the domestic market. The CEO of KUN HUANG wishes that all the domestic consumers would know “A pair of good shoes should have a pair of good insoles. Consumers should have the ability to choose shoes.” It infers “Having a pair of shoes with a pair of insoles which could keep shoes odor free is so called good shoes.”

POLIYOU^® shoe materials and insoles propounded the innovation of smell-less shoes.POLIYOU^® reversed the traditional notion that the odor smell is produced by the feet and consumers themselves. Through over 20 years of efforts, KUN HUANG obtained the breakthrough on the technology of POLIYOU^® insoles. The ISO-9001 also symbolizes the grand quality guarantee for consumers' health and comforts. KUN HUANG hopes that every consumer in the world would like to use POLIYOU^® insoles.

The final goal of KUN HUANG is to achieve the company's sustainable management and pursuing smell-free shoes.

Synthetic latex is a man-made molecular copy of natural latex. The scientific name for this compound is Styrene-Butadiene (SBR).

Styrene is named for “styrax”, the resin from a Turkish tree. Low levels of styrene occur naturally in many kinds of plants as well as a variety of foods such as fruits, vegetables & nuts.

Butadiene is produced by dehydration of butane obtained from petroleum. Butadiene is also used in the manufacture of latex paints and nylon fibers used in rope and clothing.

Synthetic Latex is extremely uniform at the molecular level, so sleep products will have greater durability than those made solely with Natural Latex. However, what you gain in durability you lose in feel and sleep benefits as compared to Natural Latex.

OrthoLite’s advanced proprietary polyurethane formula with recycled rubber content delivers a combination of benefits unmatched by any other insole manufacturer.

Long-Term Cushioning

Unlike traditional insoles, the compression set of OrthoLite insoles is less than 5% over time so the cushioning and fit never change inside the shoe, providing maximum comfort every time you put your shoes on.

High-Level Breathability

OrthoLite’s open-cell PU foam is 95% to 100% breathable, allowing air to circulate in and around the insole, keeping the foot cooler inside the shoe.

Moisture Management

The unique open-cell structure of OrthoLite insoles creates a moisture management system, helping to move moisture away from the foot to provide a cooler, drier, healthier shoe environment.

Antimicrobial Function

A patented salt-based antimicrobial is added to all OrthoLite foams to fight against the presence of fungus, bacteria and odor. The antimicrobial inhibits the buildup of the bacterial fungi associated with the cause of odor.

Washable

OrthoLite insoles are machine washable, coming out like new every time while maintaining all of their performance benefits after washing.

 Lightweight

OrthoLite insoles are lightweight, enhancing the performance of the shoes with airy comfort.

It is a patented foam, developed and patent belongs to RogersCorp, here is the official website for you if you want to know more details:

https://www.rogerscorp.com

Poron materials are more popular in electric industry, as it is soft and shock absorbent, can protect the electric devices safely without increasing too much space one package, and also it is very light.  

Some kind of materials are made in USA factory and some are made in Suzhou, China. Poron is used in shoe industry because its permanent elastic and outstanding shock absorbent properties. Beyond that, Poron is also very breathable materials. Should be noted that Poron is very expensive. 

This kind of material are often been seen on diabetic shoe inserts.

A wide range of polymer combinations is available to give increased stiffness, improved temperature resistance and improved mouldability. Plastazote® foams are engineered to offer superior performance and lighter weight. The absence of any chemical agents in the foam and a consistency of cell structure and density allows Zotefoams to offer the world’s lightest cross-linked foams.

Plastazote^® foams are available in:

• a range of densities from 15kg/m3 to 115kg/m3
• a variety of attractive colours
• Metallocene grades for easier thermo-compression behaviour
• special grades with increased flame-retarding properties, and/or conductive or static-dissipative characteristics

Plastazote^® foams are used in a variety of industries including:

• packaging
• automotive (thermoformed parts)
• aerospace
• electronics
• healthcare thanks to their inert qualities
• construction
• sport (protective padding)
• marine where buoyancy is crucial
• industrial (seals and gaskets)

D3O^® unique patented and proprietary technologies provide both enhanced protection, versatile and flexible materials for a host of shock absorption and impact protection applications.

This kind of new tech material not only can be applied in wearing protection, but also become popular in industry. 

D3O^® materials are categorised into five groups:

• Impact Additives (iA)
• Set Foams (SF)
• Formable Foams (FF)
• Set Elastomers (SE)
• Formable Elastomers (FE)

Check more information on the official website here

https://www.d3o.com/what-is-d3o/materials/