Certain Relevant Information on Thermoplastics

An elementary introduction to thermoplastics is given in this section. Readers wishing to get an exposure to a more comprehensive treatment should consult some of the standard references [1-4] on the subject. Thermoplastics are high-molecular-weight organic substances that have been usually synthesized from low-molecular-weight compounds through the process of polymerization. 

Broadly speaking, the two possible routes for synthesizing thermoplastics are based on the mechanism of the formation reaction of the polymer, namely, addition reaction and condensation reaction. Each of these can be subcategorized as shown in Table 1.1 however, the details of the subcategories are not discussed below, as they are considered to be outside the scope of this book. 

In addition polymerization, the reaction is initiated by a free radical which is usually formed due to the decomposition of a relatively unstable component in the reacting species. In this reaction, repeating units add one at a time to the radical chain, thereby causing an increase in the molecular weight as shown in Fig. 1.1. Reasonably high-molecular-weight polymers can be formed in a short 

Cationic Anionic Bulk Solution Emulsion Suspensioa 

In condensation polymerization, the reaction takes place between two polyfunctional molecules to produce one larger polyfunctional molecule with the possible 

The molecular weight (il/i) of a polymer chain is calculated by multiplying the molecular mass (nii) a( tte repeating unit by the number of times it rqreats itself, namely, the degree of polymerization (pi). Thus, 

The lengths of the polymer dudns formed during the polymerizatirm process are not the same and, tence, it results in a mixture of polymer drains of different 

---