Re: How are Plastics made? What does their c

My answer to your question is a very simplistic explanation as the question covers such a vast topic. My main advice to you is to pick up an A-level chemistry book or any book titled Introduction to Polymers to get a more indepth explanation on the structure and manufacturing processes of plastics. You may also want to check out the following URL:

http://www.ems.psu.edu/academic/matsc259/polymer.html

First of all as way of a basic definition a plastic is defined as a solid material the primary ingredient of which is an organic polymer. Plastics may include additives such as fillers (eg colour dyes), plasticizers (to control the extent of the plasticity), flame retardants (if they are required to be flame proof) etc...

Polymers are essentially made up of many carbon atoms forming a chain. A Plastic may then be viewed as a jumble of carbon chains similar in appearance to a pot of pasta. Each carbon atom can form four covalent bonds of which at leat two are used in forming the polymer chains. On the remaining bonds two side groups are attached whose function is dependent on the type of monomer used. Also it is worth noting that side groups have a big influence on the final structure of the polymer, ie whether if will be amorphous, semi-crystalline or crystalline, because their structure controls inter-chain interaction that is being hydrogen-bonding, Van der Waals bonding, entanglement and chemical cross-linking.

A polymer is constituted of many monomers each of which is an organic molecule. There are two main ways which these monomers can attach themselves to each other to form a polymer.

1. Step Polymerisation - here the mutually reactive functional groups on monomers begin to react together forming polymers.
2. Free Radical Polymerisation - this process occurs in three steps. Initiation where free radical are created eg by radiating the monomers with UV light. Propagation, the polymer chain begins to grow by rapid sequential addition of monomers. Termination, the growth of the polymer chain is terminated as all the radical have combined.