Polymers have been with us from the beginning of time; they form the very basis (building blocks) of life. Animals, plants all classes of living organisms are composed of polymers. Polymers can be classified according to origin: synthetic macromolecules made of fossil raw materials (such as petrochemicals produced by cracking or refining of crude oil), or naturally occurring polymers from various vegetable or animal sources or other sources. Polymers can also be classified according to differences in: preparation chemistry, molecular structures, properties (mechanical, physical, chemical, geological, biological), processing, or use in different fields. Most polymers can be classified according …show more content…
This process has several distinct advantages. Besides being easy to control the thermal and viscosity problems of the other techniques, large decreases in the molecular weight of a polymer can be made without altering the polymerization rate by using chain transfer agents. However, large increases in molecular weight can only be made by decreasing the polymerization rate, by lowering the initiator concentration or lowering the reaction temperature. Emulsion polymerization is a unique process in that it affords a means of increasing the polymer molecular weight without decreasing the polymerization rate. The difficulty of removing all impurities such as surfactant residues from the polymer is the only disadvantage of this