Plastic are called 'plastic' because of their flexibility. They can be shaped and molded easily.
Thermoplastics are plastics that are easy to mold and shape when they are hot. They can even melt when hot enough.
Material that can be molded and shaped when heated.
Among thermoplastic are:
When heated up to a certain temperature, all plastics become soft and may change shape. When cooling down, plastics become hard and brittle.
The temperature threashold is called glass transition temperature or Tg.
There is different Tg for each plastic. At room temperature some plastics are already above their Tg and are soft enough to be bended. Others are below their Tg and are not bendable.
Sometimes additives can also be added to plastic to make it softer, more deformable, and to alter their Tg. These additives are called plasticizers.
The PVC ( Polychlorure de Vinyle )
PVC is useful because it resists two things that hate each other: water and fire.
Because of its resistance to water is used to make raincoats, shower curtains, and of course water hoses.
It resists fire because it contains chlorine atoms. When trying to burn PVC, chlorine atoms are released and inhibit combustion.
Structurally, the PVC is a vinyl polymer.
It is similar to polyethylene, but some carbon atoms of the main chain, one of the hydrogens is replaced by a chlorine atom.
PVC is manufactured by radical polymerization of vinyl chloride.
Le PVC est l'une de ces découvertes étranges qui en réalité doivent être faites deux fois.
Il semble qu'il y a une centaine d'années, quelques industriels allemands avaient décidé de faire fortune en équipant les maisons avec des lampes à acétylène.
Malheureusement pour eux juste au moment où ils ont fabriqué des tonnes d'acétylène pour le vendre à tous ceux qui achèteraient leurs lampes,
de nouveaux générateurs électriques très efficaces ont été développés, ce qui a rendu le prix de l'éclairage électrique si bas que les lampes à acétylène
ne se sont plus vendues. Et l'acétylène est resté là.
Then in 1912 a German chemist, Fritz Klatte decided to try to do something, and reacted some acetylene with hydrochloric acid (HCl).
This reaction produces vinyl chloride, but at that time no one knew what to do, so he put it on a shelf where it polymerized over time.
Not knowing what to do, he told his bosses at his company, Greisheim Electron, who deposited a patent on the material in Germany.
They could not find a use for PVC, and in 1925 the patent expired.
And just a year later, in 1926, an American chemist, Waldo Semon was working at BF Goodrich when he independently invented PVC.
But unlike its predecessors it seemed to him that this material would make a very good shower curtain.
He and his bosses at BF Goodrich deposited a patent on PVC in the US
(Klatte's bosses apparently had never applied for a patent outside Germany).
Tons of new applications were found for this wonderful waterproof material, and PVC was this time a great success.