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= Tyvek = Tyvek is a brand of flashspun high-density polyethylene fibers, a synthetic material; the name is a registered trademark of the DuPont company, well known for their production of chemicals and textiles. Tyvek is often used as housewrap, a synthetic material used to protect buildings during construction. The material is difficult to tear but can easily be cut with scissors or a knife. Water vapor can pass through Tyvek, but liquid water cannot. All of these properties make Tyvek useful in a variety of applications.

History
Tyvek is a nonwoven product consisting of spun bond olefin fiber. It was first discovered in 1955 by a researcher for the DuPont textile company, named Jim White. While working in an experimental lab, Jim noticed a type of white fluff coming out of a pipe in a DuPont experimental lab. That fluff was a product known as polyethylene, which DuPont requested a patent for within a year of the discovery. After technologies improved during the next few years, in 1959 DuPont discovered that when the fluff was spun at high speeds it produced a durable fabric with the ability to be cut with a blade. While the product Tyvek was used since 1959, DuPont did not trademark the actual brand until 1965, making it available for commercial purposes in April 1967. As of 1970, Tyvek had reached the mainstream construction industry on both a national and global scale, and is often used for the construction of houses due to its unique ability to keep out liquid, while allowing vapor through.

In 2017, the DuPont company merged with another chemical company, Dow Chemicals to form DowDuPont. The net worth of this newly merged company is over $150 billion as of 2017. While the DuPont company still makes Tyvek, it also produces products such as Kevlar and cellophane, among numerous other chemical products. Tyvek is currently manufactured at the Spruance plant in Richmond, Virginia, and in Sandweiler-Contern, Luxembourg.

Adhesion and Bonding
DuPont recommends starch, dextrin, casein, and animal-based adhesives over most synthetic-based adhesives, emphasizing the effectiveness of water-based and quick-drying glues as the best for bonding Tyvek both to itself and to a variety of substrates. DuPont also claims that the following adhesives are highly effective:


 * Water-based synthetic lattices
 * Ethylene/vinyl acetate
 * Acrylic pressure-sensitive tape
 * Solvent-based single-component polyurethane
 * Hot glue

Heat sealing can be used to melt Tyvek and cause it to bond to itself, but this form of bonding tends to create puckers in the otherwise flat material. Dielectric bonding can be effective in some circumstances, as is ultrasonic welding.

Recycling
Though Tyvek superficially resembles paper (for example, it can be written and printed on), it is plastic, and it cannot be recycled with paper. Some Tyvek products are marked with the #2 resin-code for HDPE, and can be collected with plastic bottles as part of some municipal curbside recycling programs. DuPont runs a program in the United States where disposable clothing, coveralls, lab coats, medical packaging and other non-hazardous Tyvek disposable garments can be recycled, as well as providing a mail-in recycling program for envelopes.

Recently, plastic bag recycling has become more prevalent. According to the American Chemistry Council, these plastic film drop-off locations accept Tyvek.

Properties of Tyvek
According to DuPont's Web site, the fibers are 0.5–10 &#xB5;m (compared to 75 µm for a human hair). The nondirectional fibers (plexifilaments) are first spun and then bonded together by heat and pressure, without binders.

Tyvek is also:


 * Light weight
 * Class 1 flammability rating.
 * Chemical resistance
 * Dimensional stability
 * Opacity
 * Neutral pH
 * Tear resistance

Construction/Engineering

 * Large sheets of Tyvek are frequently used as "housewrap," to provide an air barrier between the outer cladding of a structure and the frame, insulation, etc., allowing water vapor to pass yet restricting air infiltration.
 * Tyvek is used in archery to construct waterproof target faces, replacing paper.
 * Tyvek was used to cover and protect the Reaction Control System (RCS) thruster ports from water and debris while the shuttle stack was exposed on the launchpad during the latter years of the Space Shuttle program. The Tyvek covers were dislodged shortly after ignition and before the shuttle cleared the tower, posing no strike risk as the shuttle was travelling below 100 MPH.
 * Tom Sachs used Tyvek for the outer shell of the spacesuits used in his Space Program series of artworks. Newone - FedEx Tyvek envelope.jpg

Government Use

 * Tyvek is used by the United States Postal Service for some of its Priority Mail and Express Mail envelopes


 * FedEx also uses it for some of its document envelopes.
 * New Zealand used it for its driver's licenses from 1986 to 1999.
 * Costa Rica (solely their 1000 colones bank note), the Isle of Man, and Haiti have made banknotes from it. These banknotes are no longer in circulation and have become collectors' items.

Fashion/Personal Use

 * Race bibs, or race numbers are often produced on Tyvek paper, so they are less likely to rip during competition.
 * Tyvek is often used in garment and other textile labeling due to high durability and washability.
 * Tyvek wristbands are used at festivals, conventions, and events where admission and security are concerns, as well as hospitals, resorts, nightclubs, schools, and reunions.
 * More recently fashion retailer and manufacturer American Apparel has included white Tyvek shorts as part of its range.
 * In 1976, fashion house Fiorucci made an entire collection out of Tyvek.
 * Rock band Devo is known for wearing large, two-piece Tyvek suits with black elastic belts and 3-D glasses. In 1979, Devo appeared with Tyvek leisure suits and shirts made specifically for the band, with the band's own designs and images. In 2005 Dynomighty Design introduced stitchless Tyvek wallets which can be customized with whatever imagery the customer chooses.
 * The ultralight backpacking community has begun to use Tyvek for the construction of extremely light yet durable backpacks. In 2012, The Open Company released a foldable city map made of one of the stiffer variants of Tyvek.
 * Increasingly, reused Tyvek material is being used by home crafters. Protective sleeves for Compact Discs and DVDs, tote bags, and origami wallets also use Tyvek-containing materials.
 * Tyvek is also used as a durable fabric in shoes.



Medical

 * Tyvek coveralls are one-piece garments, usually white, commonly worn by mechanics, oil industry workers, painters, insulation installers, and laboratory and cleanroom workers where a disposable, one-time use coverall is needed. They are also used for some light HAZMAT applications, such as asbestos and radiation work, but do not provide the protection of a full hazmat suit. Tychem is a sub-brand of Tyvek rated for a higher level of liquid protection, especially from chemicals. DuPont makes Tyvek clothing in different styles from laboratory coats and aprons to complete head-to-toe coveralls with hoods and booties. The latter was notably used by the Japan Ground Self-Defense Force as emergency limited CBRN gear during the Fukushima nuclear incident.
 * Tyvek is also extensively used for packaging in laboratory and medical equipment as the material withstands conditions used to sterilize equipment.
 * NSW Police, Australia uses Tyvek overalls to keep the integrity of alleged criminals' bodies at a crime scene, until they have had a chance to do body swabs.