PLASTICS
Plastics are organic substances that consist of natural or artificial binders or resins.
Plastics are essential compounds of carbon with other elements such as hydrogen, nitrogen, and oxygen.
The characteristic feature of carbon to combine with itself, forming long chains gives rise to plastics.
The form and behavior of plastics depend on the temperature and pressure acting in them. As a final product, at normal temperature plastics are rigid and stable.
POLYMERIZATION
- Plastic is a polymer consisting of a large number of small identical or different units called monomers.
- A polymer is made up of thousands of monomers joined in different ways to give different polymers.
- The process of combining (synthesizing) these monomer units into a large single unit is called polymerization.
- Polymerization results in an increase in the overall strength, rigidity, and elasticity as compared to a single monomer.
Depending on the orientation of the joining of the monomer units, polymers structures can be classified into the following types.
(a) Linear structure: Linear structure is obtained when the monomer units join in a simple linear fashion. It is the most simple and fundamental type of structure formed.(b) Branched-chain structure: This structure is obtained when several monomers or another linear polymer unit combines with a linear structure in a random way appearing as a branch from a main line.
(c) Cross linked structure: This structure is formed when the adjacent chains combine with each other. Such a linking restricts the relative movement of chains and therefore greatly increase the strength of the structure.
(d) Network structure: It is a very complex structure formed by joining several individual monomers(units) forming a 3-dimnesional structure. In a network structure, it is difficult to identify or separate single individual chains.