Polymer Plastic Classification and History

Plastic are often divided into thermosetting, thermoplastic, oil soluble, and protein products as presented in the table below. On the basis of derivation, they may be grouped as natural resins, cellulose derivatives, protein products, and synthetic resins. In general, except where noted, synthetic resins formed by condensation polymerization are thermosetting (heat curing produces an infusible or insoluble product), and synthetic resins formed by addition polymerization are thermoplastic (heating soften and cooling hardens). These two polymerization reaction are fundamentally different.

Addition polymerization involves a series of conversions which produce a polymer having a recurring structural unit identical with that of the monomer from which it is formed. Condensation polymerization yields polymers whose recurring units lack certain atoms present in the original monomer. The reaction takes place by the combination of two or more units and the elimination of a small molecular such as water, methanol, or hydrogen chloride. During or after the original condensation polymerization, the long chain of polymerization, the long chain of polymer may react with each other to form a “cross linked” material which usually harder and tougher than the straight chain polymer. Properties can be varied for special purposes by regulating the amount of cross-linking.

Another variation in the type of final product is effected by the simultaneous polymerization of two or more type of monomers. By carefully regulating the relative amounts of the monomer and the reaction conditions and initiators, the properties of the final polymer can be controlled. This type of copolymer may be formed, depending upon conditions.

• Random Copolymer
• Alternating Copolymer
• Block Copolymer

Polymer Types and History:

1. Cellulose Nitrate, 1808
2. Cellulose Acetate, 1894
3. Phenol Formaldehyde, 1900
4. Cellulose Others, 1912
5. Vinyls, 1927
6. Urea Formaldehyde, 1929
7. Acrylates, 1931
8. Furans, 1934
9. Polystyrene, 1937
10. Polyamides, 1938
11. Melamine-Formaldehyde, 1939
12. Polyester, 1942
13. Silicones, 1942
14. Polyethylene, 1943
15. Epoxy, 1948
16. Crystalline Polypropylene, 1957
17. Phenoxy, 1962