RUBBER RESILIENCE

Geschriben am 29-01-2013

The great majority of the rubber parts is intended for dynamic applications; it is in particular the case of the bellows of transmission, engines’supports and elastic articulations. This is why all of these parts must be rigorously controlled, which required the development and the standardization of many testing methods.
Concerning the resilience of an unspecified material (and thus of a vulcanized rubber), it should be known that this parameter represents the link between the energy restored by this material  after being deformated and the energy which had been provided to ensure this deformation .
This parameter will be fundamental since it will represent the aptitude of a material to absorb a shock
what is crucial for different parts produced by our company. The ductility of a material can be obtained
by various ways

• From the hysteresis loops obtained by successive tractions and relaxations of a sample using a dynamometer. Let us keep in mind that at the time of this test, it is necessary to wait some cycles to be freed from MULLINS’ effect.

• It is also possible to determine the ductility by subjecting a sample (generally spherical shaped and of a few millimetres thickness) to a shock thanks to a system of beam. The height reached by the arm after rebounding directly gives the resilience of bounce of the material (Standard NF T 46 012). One of the apparatuses mostly used for this determination is the LUPKE reboundimeter.

• Lastly, the RPA 2000 (Rubber Process Analyzer), present within our laboratory, enables us to carry out tests of post-cure giving us access with the viscoelastic properties such as the resilience of the compounds cured in the testing chamber. Then, various tests were developed such as frequency sweeps, deformation sweeps and simulations of tests called strain/relaxation, whose operational limits are directly linked to the use of the finished products.