Mechanical Properties of Material

Again, for many polymeric materials you will observe a dichotomy of nature depending on whether you are testing them below a temperature known as glass-transition temperature Tg when it will behave more like a brittle material (Glassy Phase); whereas, the same material above Tg (Rubbery Phase) will behave more like a ductile material. The modulus of elasticity in the Glassy phase is quite higher than the rubbery phase. Typical Stress-Strain diagrams for a polymeric material are shown below.

Stress-Strain Diagram for Polymeric Materials (Upper Curves typical of the Glassy Phase and Lower Curves typical of Rubbery Phase