ABSTRACT
The chemical modication of cellulose and its derivatives by graft copolymerization has generated interest among researchers, because few comonomer molecules signicantly change a number of characteristics of the original natural polymer. In the polymeric age, it is essential to modify the properties of a polymer according to tailor-made specications designed for target applications. There are several means to modify the properties of a polymer, viz., blending, curing, grafting, and derivatization. Blending is the physical mixture of two (or more) polymers to obtain the requisite properties. In curing, the polymerization of an oligomer mixture forms a coating that adheres to the substrate by physical forces, whereas in grafting, the monomers are covalently bonded and polymerized onto the polymer chain. The process of grafting can take minutes, hours, or even days for completion, whereas curing is a very rapid process and occurs in a fraction of second. In derivatization, simple molecules are substituted with the reactive groups of the polymer chain. The most common derivatization reactions of cellulose are esterication and etherication. The schematic presentation of the polymer modication is presented in Figure 17.1.
