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)

2. Elastic properties

The elastic behavior of pebax^®, that is to say the ability of the material to recover its initial shape after a given deformation, can be measured of remanent deformation under tensile or compression conditions, or to an elastomeric limit test.

2.1 Remanent Deformation In Traction

The remanent deformation is obtained by measuring the deformation remaining constant after x% of elongation and relaxation to the initial state. The hard pebax^® grades lead to the highest remanent deformation. Measurement of the remanent deformation under tensile solicitation is typically performed at 23°C using ASTM D412 standard and samples, which have been conditioned for 15 days at 23°C and 50% relative humidity :

• Sample type: ASTM D638 type 4
• Experimental protocol :
  • Elongation of x% (x=5, 10, 15 and 20%) of deformation (speed = 500 mm/min)
  • Wait for 10 minutes
  • Initiate discharge
  • Remanent deformation measurement

The described protocol and speed are verified in ASTM D412.

 2.2 Elastomeric Limit

The elastomeric limit test has been developed by ARKEMA in the early 90’s. It consists of performing a cycling charge-discharge tensile solicitation to a sample. The deformation applied to each charging cycle is then increased. The sample is relaxed between each cycle until a null value of the force is achieved and at the same speed as the one applied during charging. The remanent deformation recorded at the end of each cycle is then plotted versus the applied deformation. This graphical representation enables one to illustrate that above a critical value of the applied deformation, the material behavior is not elastic any more and becomes plastic. This leads to a linear and important increase of the remanent deformation at a high elongation rate.

By plotting the line passing through the linear part of the (remanent deformation vs. applied deformation) curve, and by extrapolating to the equivalent null value of the remanent deformation, one can get the value of the elastomeric limit.

This determination method makes the elastomeric limit a relative data, as it can depend to some extent, on the way it is measured on the graph.