Tyvek

Tyvek house wrap

Tyvek /taɪˈvɛk/ is a brand of flashspun high-density polyethylene fibers, a synthetic material; the name is a registered trademark of DuPont. It is often seen used as housewrap, a synthetic material used to protect buildings during construction. The material is very strong; it 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 spunbond olefin fiber. It was first discovered in 1955 by DuPont researcher Jim White who saw polyethylene fluff coming out of a pipe in a DuPont experimental lab.^[1] It was trademarked in 1965 and was first introduced for commercial purposes in April 1967.^[2]

According to DuPont's website, the fibers are 0.5–10 µm (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.^[3]

Tyvek is manufactured at the Spruance plant in Richmond, Virginia, and in Sandweiler-Contern, Luxembourg.

Properties

Tyvek USPS Express Mail envelope

Among Tyvek's properties are:

• Light weight
• Class A flammability rating.
• Chemical resistance
• Dimensional stability
• Opacity
• Neutral pH
• Tear resistance

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 sealing.^[4]

Uses

• 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.^[5]
• 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,.^[6]
• Costa Rica,^[7] the Isle of Man,^[8] and Haiti^[9] have made banknotes from it. These banknotes are no longer in circulation and have become collectors' items.

Tyvek coveralls

• 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.^[10]
• In 1976, fashion house Fiorucci made an entire collection out of Tyvek.^[11] More recently fashion retailer and manufacturer American Apparel has included white Tyvek shorts as part of its range.^[12] 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^[13] introduced a Tyvek wallet made from a single sheet of Tyvek. The ultralight backpacking community has begun to use Tyvek for the construction of extremely light yet durable backpacks.^[14] In 2012, The Open Company released a foldable city map made of one of the stiffer variants of Tyvek.^[15]
• Increasingly, reused Tyvek material is being used by home crafters. Protective sleeves for Compact Discs and DVDs, tote bags,^[16] and origami wallets ^[17] also use Tyvek-containing materials.
• Tyvek is also used as a durable fabric in shoes.^[18][19][20]
• Tyvek is used in archery to construct waterproof target faces, replacing paper.
• Tyvek is also extensively used for packaging in laboratory and medical equipment as the material withstands conditions used to sterilize equipment.
• Tyvek wristbands are used at festivals, conventions, and events where admission and security are concerns,^[21] as well as hospitals, resorts, nightclubs, schools, and reunions.
• 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.^[22] 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.^[23]
• Tyvek based materials are used as a protective layer for sterile packaging including syringes, disposable medical instruments and catheters. Tyvek packaging allows packaging to be highly breathable yet completely sterile. Packaging is applied using Tyvek-based printers.^[24]
• Tyvek is often used in garment and other textile labeling due to high durability and washability. ^[25]

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,^[26] medical packaging and other non-hazardous Tyvek disposable garments can be recycled, as well as providing a mail-in recycling program for envelopes.^[27]

Recently, plastic bag recycling has become more prevalent. According to the American Chemistry Council, these plastic film drop-off locations accept Tyvek.^[28]

References

External links

Wikimedia Commons has media related to Tyvek.

• Tyvek at DuPont
• Tyvek at Doranix
• Tyvek FAQ at DuPont
• Browse our Tyvek® FAQs to learn more about the product
• Tyvek Envelope Recycling Program
• Tyvek Hard Structure and Soft Structure — What’s the difference?
• FAQ on how to recycle Tyvek coveralls and disposable clothing.
• FAQ on Tyvek chemical protection coveralls and recycling disposable coveralls.
• American Chemistry Council site stating Tyvek is OK at common plastic film drop-off locations
• Typar, A Tyvek alternative