In the posts on “The Chemical Nature of Plastics,” various methods of synthesizing polymers were briefly discussed. This chapter will delve into the physical states of aggregation of these polymers, while the three subsequent chapters will explore the effect of molecular structure on the properties of polymers.

Simple molecules, such as water, ethyl alcohol, and sodium chloride, can exist in any of three physical states: solid, liquid, and gaseous, depending on ambient conditions. While achieving the gaseous state or even the liquid state might be challenging for some materials due to thermal decomposition, these three phases generally have sharply defined boundaries. For instance, pure water occurs at specific temperatures.

In polymers, changes of state are less precisely defined and may occur over a finite temperature range. The behavior of linear amorphous polymers, crystalline polymers, and thermosetting structures will be discussed in turn.

Generally, we will go ahead with the followings:

(1) LINEAR AMORPHOUS POLYMERS

(2) CRYSTALLINE POLYMERS

(3) CROSS-LINKED STRUCTURES

(4) POLYBLENDS