1. A large range of mechanical properties

2. Elastic properties

3. Elastic return

4. Fatigue resistance

5. Outstanding properties at low temperature

6. Dynamic Mechanical Analysis (DMA)

3. Elastic return

3.1 Energy return or hysteresis measurement

The area covered by the charge and discharge curves applied to the material under tensile cycled solicitation (hysteresis curve) is an important data to take in consideration. It represents the mechanical energy not released by the material and is dissipated by self-internal heating during the solicitation.

Tensile Cycled Test (from 0 to 100% with a step change of 5% and a speed of 500 mm/min) for pebax^® 2533

The hysteresis measurement or energy return can be performed under different solicitations, not only using a tensile cycled test but also when using a dynamic cycled compression test. The speed, as well as the amplitude of the deformation, are important parameters. The following graph illustrates that the hysteresis of pebax^® 2533 is poorly dependent on the applied deformation.

3.2 Damping test

Arkema has set up a test aiming at reproducing in a controlled and instrumented way, the nervousness property of pebax^®. This property is usually felt by pebax^® users described in the subsequent example: bending a plate on the edge of a table and then observing the way the material recovers the deformation after being released. One generally observes the frequency of the oscillations and the time needed to absorb these oscillations. The higher the frequency, the smaller the dampening is. In this situation, the material is generally considered to be nervous.

When performing this experiment, it allows one to plot the position of the extremity of the sample versus time. This generally translates into a sinusoidal curve with decreasing amplitude with time. This curve and the associated calculation described hereafter enables one to quantify the nervousness of the material.

By properly treating the damping test curves, on can determine for each material, a nervousness factor N, which is the ratio of the modulus of the material compared to its amortization property obtained from DMA measurements (see corresponding paragraph). The nervousness N is defined as:

The curve also enables to determine for each material, the frequency f, the pulsation ω, the modulus E, the dampening-factor a, and the amortization tan δ .

The following graph illustrates the pebax^® nervousness factor of different grades and stresses their intrinsic excellent nervousness property when compared to other elastomers.

Nervosité - Damping test