ABSTRACT
Polymers are modern materials in material science and are often termed as “materials of 21st century.” Based on the origin, polymers can be classified as natural, synthetic, and semisynthetic. Synthetic polymers are tailored for various commercial applications in order to cater to the industrial and defense requirements. Two examples of synthetic polymers are styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) having good abrasion resistance and oil resistance property, respectively. Synthetic form of natural rubber prepared in the laboratory is called polyisoprene. Semisynthetic polymers are prepared in the laboratory from the naturally existing polymer derivatives, for example, cellulose acetate prepared from the acetylation of cellulose. Naturally existing polymers are in the form of biological macromolecules such as proteins, polysaccharides, deoxyribonucleic acids (DNA), shellac, cotton (cellulose), wool (collagen), silk (fibroin), and many more. The melting behavior of the polymer varies based on the nature of the polymers. Most of the naturally occurring polymers are amorphous in nature and lack a distinct melting point whereas thermoplastic materials undergo melting. We will discuss natural and synthetic polymers more in detail in the following sections.
