Monday, February 23, 2009


The word “plastic”comes from the Greek word “plastikos” meaning “to form.”

In more technical terms, a plastic is a material that can be heated and molded so that it keeps its molded shape after it cools.

When we talk of a substance being “plastic”most people would agree on its meaning. It can flow or be moulded, it is ductile or it can be shaped, but when we turn to defining “plastics” we have problems. Almost any simple definition will exclude materials which everyone would agree should be included so we have to turn to scientific terms and start with the comment that plastics are all polymers.

Monday, February 16, 2009


The turban (from Persian dulband via the Turkish dulbant) is a headdress consisting of a long scarf-like single piece of cloth wound around either the head itself or an inner hat. The word "turban" is a common umbrella term, loosely used in English to refer to several sorts of head wrap.

In Western countries, men wearing turbans in public are likely to be Sikhs, whose religion requires them to cover their long uncut hair.

* Middle Eastern, Central Asian, South Asian, and Sikh turban wearers usually wind their turban anew for each wearing, using long strips of cloth. The cloth is usually five meters or less. However, some elaborate South Asian turbans may be permanently formed and sewn to a foundation. Turbans can be very large or quite modest dependent upon region, culture, and religion.

* Turbans are worn as women's hats in Western countries. They are usually sewn to a foundation, so that they can be donned or removed easily. Now that fewer Western women wear hats they are less common. However, turbans are still worn by female cancer patients who have lost their hair to chemotherapy and wish to cover their heads. Some women use wigs; others prefer scarves and turbans.

Monday, February 09, 2009

Carbonated water

Carbonated water, also known as sparkling water, fizzy water and seltzer, is plain water into which carbon dioxide gas has been dissolved, and is the major and defining component of most soft drinks. The process of dissolving carbon dioxide gas is called carbonation. It results in the formation of carbonic acid (which has the chemical formula H2CO3).

In the past, carbonated water, also known as soda water, was produced in the home by "charging" a refillable seltzer bottle by filling it with water and then adding carbon dioxide. Club soda may be identical to plain carbonated water or it may contain a small amount of table salt, sodium citrate, sodium bicarbonate, potassium bicarbonate, potassium citrate, potassium sulfate, or disodium phosphate, depending on the bottler. These additives are included to emulate the slightly salty taste of homemade soda water. The process can also occur naturally to produce carbonated mineral water, such as in Mihalkovo in the Bulgarian Rhodopes.

Monday, February 02, 2009


A polymer is a large molecule (macromolecule) composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties and purposes.

Well-known examples of polymers include plastics and proteins. A simple example is polypropylene, whose repeating unit structure is shown at the right. However, polymers are not just limited to having predominantly carbon backbones, elements such as silicon form familiar materials such as silicones, examples being silly putty and waterproof plumbing sealant. The backbone of DNA is in fact based on a phosphodiester bond.

Natural polymer materials such as shellac and amber have been in use for centuries. Biopolymers such as proteins and nucleic acids play crucial roles in biological processes. A variety of other natural polymers exist, such as cellulose, which is the main constituent of wood and paper.