TABLE OF CONTENTS Natural polymers constitute a wide class of important polymers with many commercial applications, including food packaging, fibres, fuel, coatings, automobile components, adhesives and genetic engineering materials among many others. The main categories of natural polymers are polysaccharides (starch, chitin, chitosan, cellulose and their derivatives), proteins (amino acids, enzymes and peptides) and polynucleotides (polyesters of phosphoric acid and nucleosides). Others include rubber, lignin, humus, coal, kerogen, asphaltenes, shellac and amber. With many diversified applications, natural polymers have attracted a lot of research interest, particularly in biochemisty and materials science engineering, thus making it prudent to discuss the thermal degradation of natural polymers. However, due to the wide scope of the topic, the thermal degradation of only starch, chitin, chitosan, cellulose, lignins, poly(3-hydroxyalkanoates) (PHA), proteins, natural rubber, poly(hydroxy acid)s and poly( p-dioxanone) (PPDO) are presented in this chapter.
Starch is one of the main polymers present in Nature; its structure and properties have been investigated extensively in the past century. Increasing environmental concerns in recent years have led to biodegradable materials replacing petrochemical polymers in many applications. Starch has shown advantages and superior characteristics over other natural and synthetic biodegradable polymers, especially because of the low cost of the raw materials. Its applications have been extended from traditional food, paper and textile industries to packaging, controlled drug delivery and many other areas in either its native or modified forms.
Along with temperature increases, the solid-state reactions of starch start with the combination of phase transitions such as melting, evaporation...
