Various techniques can be used to measure the toughness, or energy absorption, of a polymer sample. Two of these methods are the Izod Test, and the Charpy Test.

These methods are based on the principle of the application of the load using a high rate, measuring the amount of energy (Kg/m or Joule) absorbed during the impact of the load onto the sample. Key differences between these two tests involve the:

• Sample shape and size;
• Method of stabilizing the sample and;
• The peak energy content of the pendulum used that hits the sample during testing

Most engineering components are equipped with stress and notch raisers, making it imperative to understand the behavior of a specific material with notch once it undergoes impact loading.

• The test is commonly conducted with notched samples
• Un-notched samples can be used as well; with the results expressed accordingly to this.

Both of these tests can be utilized as a method of quality control, determining whether or not the material meets a measure of impact property. It can also be used to compare sets of materials for their general toughness.

The toughness of a material is not directly used in design purposes, as they only indicate the resistance of a material to the effects’ shock or load. These are used for the comparison of different materials as regards their resistance to deformation during impact load, or in measuring the resistance of one material to different conditions such as heat treatment, mechanical procedure, and others.

The polymer’s toughness, or its resistance to shock/load, is varied by their:

• Molecular structure;
• Surrounding Temperature;
• Type of stress applied to the polymer

Great care must be exercised when relating the polymers flexibility to its toughness. Generally, more rubbery polymers give a higher amount of elongation, as well as better resistance values. These, however, commonly have less stiffness.