Properties and uses of Cork (material)

The elasticity of cork combined with its near impermeability makes it suitable as a cork material, especially for wine bottles.Cork makes up about 60% of all cork products.Cork has a nearly zero Poisson's ratio, which means the cork's radius does not change significantly when squeezed or pulled.Cork is an excellent gasket material.For example, some carburetor bowl washers are made of cork.Cork is also an essential element in badminton production.Cork's cell-like structure and natural flame retardants make it suitable for sound and thermal insulation of walls, floors, ceilings and facades of houses.Cork, a by-product of more profitable stopper production, is gaining popularity as a non-allergenic, easy-to-dispose and safe alternative to petrochemical insulation.Cork chips are also often a by-product of cork production and are used to make bulletin boards as well as floor and wall tiles.Cork's low density makes it a suitable material for fishing buoys and buoys, as well as fishing rod handles (as an alternative to neoprene).

Cork particles can also be mixed into concrete.Composite materials made of cork particles mixed with cement have low thermal conductivity, low density and good energy absorption. Some ranges of properties for composites are density (400–1500 kg/m3), compressive strength (1–26 MPa) and flexural strength (0.5–4.0 MPa).

For wine bottling

Until the mid-17th century,French vintners did not use corks, but instead used oil-soaked rags to stuff the necks of their bottles.Wine corks can be made from a single piece of cork, or they can be composed of granules, as in Champagne corks; corks made of granulated granules are known as "agglomerated corks".Of the 20 billion bottles of wine produced each year, around 80% use natural corks.After declining in use due to increased use of synthetic alternatives, cork is making a comeback and now accounts for around 60% of wine stoppers in 2016.Due to the cork's honeycomb structure, it is easily compressed when inserted into the bottle and expands to form a tight seal.The inside diameter of glass bottle necks is often inconsistent, making this ability to seal through variable shrinkage and expansion an important attribute.However, the inevitable natural imperfections, channels and cracks in the bark make the cork itself highly inconsistent.In a 2005 closure study, 45% of corks showed gas leakage from the sides of the cork and through the cork body itself during pressure testing.

Since the mid-1990s, many wine brands have switched to other wine closures such as plastic stoppers, screw caps, or other closures. During 1972, more than half of Australian bottled wine was spoiled by corks.Much anger and suspicion has been directed at Portuguese and Spanish cork suppliers who are suspected of knowingly supplying non-EEA winemakers with inferior corks to help prevent cheap imports.Cheaper winemakers developed aluminum "Stelvin" caps with polypropylene stoppers.More expensive wines and carbonated varieties continue to use corks, despite increased focus on quality.Even so, some high-end brewers prefer Stelvin because it guarantees that the wine will hold up well even after decades of aging.Due to their cheap price, some consumers may perceive screw caps as indicative of lower quality wines; however, in Australia, for example, many non-sparkling wine producers now use these Stelvin caps as a cork replacement, although some have recently been criticized for their use Problem with the screw cap and switched back to cork.

Alternatives to cork have both advantages and disadvantages.For example, screw caps are often thought to provide a trichloroanisole (TCA)-free seal, but they also reduce the rate of oxygen transmission between the bottle and the atmosphere to almost zero, which can lead to poor wine quality.TCA is the main documented cause of cork taint in wine.However, some in the wine industry say that natural corks are important because they allow oxygen to interact with the wine for proper aging, and are best for buying wine with aging intent.By separating the suberin component of cork from unwanted lignin, it is possible to make stoppers very similar to natural cork, It is mixed with the same substances used in contact lenses and adhesives, and molded into standardized products free of TCA or other undesirable substances.Composite corks with real cork veneers are used for cheaper wines.Leading Australian wine writer and critic James Halliday wrote that since placing the cork inside the neck of a wine bottle is a 350-year-old technique, exploring other, more modern and precise.The approach to ensuring wine safety is logical.The study 'Life cycle analysis of cork, aluminum and plastic wine bottle caps', conducted by PricewaterhouseCoopers and commissioned by major cork manufacturer Amorim, concluded in a one-year life cycle analysis comparison that cork was the most environmentally friendly cork belt Plastic stopper and aluminum screw cap.