How Are Plastics Made?
Plastics are manufactured from chemicals that come from such materials as coal and petroleum. Petroleum, for example, is the source for different liquids and gases. One of the liquids that comes from petroleum is benzene. One of the gases is ethylene. To make plastic, the benzene and ethylene are mixed together with certain other chemicals.
When the mixture is heated, it turns into a hard plastic known as polystyrene. Heating these chemicals causes them to break down into molecules. Scientists then join these molecules into chains. These chains make up plastics. Different combinations of molecules form different kinds of plastic.
Plastics are easily shaped and molded. Plastics can be made into almost any shape by heating them at a high temperature. The heat softens the plastic, which can then be poured into a mold. As the softened plastic cools, it hardens. When reheated, some types of plastic will soften again. The plastic can then be made into new shapes. Other types of plastic will stay hard even when reheated. Some plastics have the hardness of steel. Others bend at the touch of a finger.
Most plastics are strong, long-lasting, and lightweight. They resist damage by water, heat, chemicals, and electricity. In addition, plastics can be made in many colors. There are about 50 main types of plastic. They have countless uses. Manufacturers often use plastics in place of more expensive materials. In nylon stockings, for example, plastic takes the place of silk. In vinyl house siding, plastic takes the place of wood. In many automobile body parts, plastic takes the place of metal.
In 1869 John Wesley Hyatt, a U.S. inventor, made the first plastic. He called it celluloid because he made it from a plant material called cellulose. In 1909 a U.S. chemist named Leo H. Baekeland developed the first plastic made completely from synthetic (human-made) materials. Baekeland named the new material Bakelite. Scientists developed many more plastics from the 1920s through the 1940s. Later scientists invented stronger plastics and blended plastics with other materials.