Definition of Plastics
Plastics comes from the Greek word plastikos, which means to form or to mold. However, plastics is not a uniformly defined term. Some people define plastics based on specific properties of the material, others take a broader approach that includes various manufacturing processes.
To start off, let’s look at plastics as a material.
Think about all the material available in this world. You will realize that all materials are classified as liquids, gases and solids. While noting that most materials can be converted from one state to another through heating or cooling, let’s narrow our scope on materials that remain solid in room temperature. You are left with metals (iron, copper, gold, etc.), ceramics (stones, clay, etc.) and polymers.
A polymer is a large molecule made up of smaller molecules that are joined together by chemical bonding. Polymers can be divided into natural polymers and synthetic polymers. In natural polymer, the selection of molecules and the process of chemical bonding occur naturally – thus giving us materials like wood, leather, cotton, rubber, hair – even your finger nails.
In synthetic polymers, the selection of molecules and the chemical bonding process is man-made. This gives us material like nylon, polyester and polyethylene. Some synthetic polymers can be “manufactured copies” of natural occurring materials – e.g. synthetic rubber is made in a lab by following the natural process of rubber. Modifying the chemical bonding process is another example of how celluloid or cellophane is synthetically modified to an extent that the whole natural polymer characteristic of cellulose is altered.
The 3 ways to classified synthetic polymers are:
• does not occur naturally
• occur naturally but made by non-natural processes
• modified natural processes
In short, all synthetic polymers are considered plastics .
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