Solidification of Polymers

Solidification is the process during which a material undergoes a phase change and hardens. The phase change occurs as a result of either a reduction in material temperature or a chemical curing reaction. As discussed in previous chapters, a thermoplastic polymer hardens as the temperature of the material is lowered below either the melting temperature for a semi-crystalline polymer or the glass transition temperature for an amorphous thermoplastic. A thermoplastic has the ability to soften again as the temperature of the material is raised above the solidification temperature. On the other hand, the solidification of a thermosetting polymer leads to crosslinking of molecules. The effects of crosslinking are irreversible and lead to a network that hinders the free movement of the polymer chains, independent of the material temperature.