The tensile strength, which is characteristically important for the use of materials in design, varies considerably in polymers. If defined simply, tensile strength is the force applied to the last point at which the material elongates before breaking.

When pulled, some of the polymer materials (Polyethylene) can stretch up to 5 times their original length before breaking. This elongation is correlated with the molecular arrangement in the material. If the direction of the applied force is parallel to the molecular order, the strength will be different. If it is in the perpendicular direction, the breaking will be different. Therefore, this is a distinguishing property for materials. In general, tensile testing is the extension of the test sample by placing its both ends between the test jaws and moving the jaws at different speeds. The sample is placed vertically in the instrument and the speed is adjusted. The force value calculated against the elongation of the sample and the resistance of the sample is recorded by the machine. Testing takes place until the sample breaks.

Tensile test values vary depending on some factors, such as temperature during sample preparation or production by molding or machining. For this reason, the sample preparation methods stipulated by the standard are also important.