Plastics; synthetic polymers

This topic belongs to "macromolecules". We will talk about them in the paragraph with biochemistry, toghether with the natural polymers.
Here we limit the words to some synthetic polymers made by men in factories:
plastic, nylon, artificial rubber, polyether, polyester, and poly-additie products (PVC for example)

some rules:
Structure of the polymers
    1. homopolymers: the macromolecule is built up of only one type of monomers.
    2. copolymers: the macromolecule is built up of two or more types of monomers.
    1. a macromolecule can have a linear structure; the product then is more flexible.
    2. a macromolecule can have a branched structure; the product is then harder, with little or no flexibility.
    1. Between the macromolecules can exist interconnections. Such products remain hard when heated. We call them "thermoharders". These substances can have a kind of lattice, a threedimensional structure with interconnections.
    2. If not,the structure has no clear threedimensional structure; there is no such thing as a lattice.
      At heating, the product becomes then softer and can sometimes even melt. We call them "thermoplasts".