ABSTRACT
Early humans used a variety of naturally occurring polymers to meet their material needs. They used them not with the perception of the chemistry and physics of modern high polymers, but for their survival, food, shelter, and clothing. A variety of materials made from wood, bark, animal skins, cotton, wool, silk, natural rubber, etc. were essentially playing key roles in early civilizations [1]. They could mechanically modify materials into useful tools (stone axes; wood carvings; animal skins; the twisting of cotton, wool, and flax to form threads; weaving; preparation of thin-skinned papyrus and vegetable tissues for writing, etc). Embalming of corpses was one of the earliest practices that involved chemical modification (crosslinking of proteins by formaldehyde). With the growth of human civilizations, the use and applications of materials extended to metals and ceramics, and, by the nineteenth century, there were eight classical materials-metals, stones, woods, ceramics, glass, skins, horns, and fibers-of which woods, skins, horns, and fibers are organic polymers. During the past one and one half centuries, two more materials were added to the list, rubber and plastics, both of which are polymeric in nature. However, by 1900, there were only a few plastics in use, e.g., shellac, gutta percha, ebonite, and celluloid [2]. Although a variety of chemical modifications came into vogue, four great discoveries formed the foundation of the industrial use of natural polymers, which even today form the basis of continued support and maintenance of these industries against stiff competition from synthetics. They are: the vulcanization of natural
rubber; the mercerizing of cotton, hemp, and flax; the tanning of leather; and the loading of silk [ 1 ,3]. Even today, these discoveries are the basis of many modem industries based on natural polymers that produce standard materials with a definite specification.
