www射-国产免费一级-欧美福利-亚洲成人福利-成人一区在线观看-亚州成人

National

Regional

Taiwan, HK, Macao

Special Coverage

Focus

Society

Profiles

What is melamine?

(wisegeek.com)
Updated: 2008-09-12 12:32

Melamine is an organic compound that is often combined with formaldehyde to produce melamine resin, a synthetic polymer which is fire resistant and heat tolerant. Melamine resin is a very versatile material with a highly stable structure. Uses for melamine include whiteboards, floor tiles, kitchenware, fire retardant fabrics, and commercial filters. Melamine can be easily molded while warm, but will set into a fixed form. This property makes it ideally suited to certain industrial applications.

Melamine resin is manufactured by mixing urea with formaldehyde under heat and pressure. The substances begin to polymerize and are forced into a mold which will create the desired shape. Under pressure, melamine releases water, which could make the plastic unstable if it is not removed. The materials finish polymerizing and create a finished product, melamine resin.

Melamine resin is known as a thermoset plastic, because the plastic is fixed after molding. If exposed to enough heat, melamine will melt. For this reason, melamine dishware should not be exposed to high temperatures like those in the oven and microwave. However, the plastic is able to withstand higher temperatures than other plastics. Because it is a thermoset plastic, melamine resin is difficult to recycle.

Melamine can be made into a foam product. Melamine foam has a distinctive structure composed of stacked bubble shapes, which are extremely hard and therefore can easily clean a wide variety of substances. Melamine foam is marketed under a variety of commercial names including Magic Eraser, a cleaning tool well known for removing scuffs and dirt from a wide range of surfaces.

Melamine resin is used in Formica and similar construction products made from composite materials. Formica is made using melamine resin, which is used to coat the fibers in the upper layer of the construction product. The melamine resin makes the end result heat resistant, so that hot objects can be set on the counter without concern. The surface of the material is designed to be easily wiped and cleaned, creating a long lived household product.

Melamine also plays a role in a wide range of flame resistant materials. These include textiles used in upholstery and the uniforms worn by firemen. Thermal liners, heat resistant gloves, and aprons to protect from splashback of hot substances are made using melamine. Melamine will protect a wearer from heat hazards, and will help to resist the spread of fire in aircraft and buses by providing a fire blocker.

Melamine is also used in the manufacture of some filters. The material is porous and will admit substances to pass through, but can be used to filter out particles of a particular size. Melamine filters are capable of handling a high capacity and can be used in hot environments due to the heat resistance of melamine. Melamine filters are also extremely efficient.

Aside from common commercial uses, melamine became a topic of much discussion in early 2007, when veterinary scientists determined it to be the cause of hundreds of pet deaths, because of pet food contamination. Prior to these reports, melamine had been regarded as non-toxic or minimally toxic. However, because of the unexplained presence of melamine in wheat gluten added to mass-produced dog and cat foods, it is the most likely cause. Pet owners report symptoms that are commonly associated with renal failure, which could be explained by the ammonia that may result from the digestion of the melamine.