Well you'll need some way to measure the reactance or phase angle.  In RF we usually use S-parameters and if the angle is positive, then we know it's inductive and capacitive if negative.  Depends on how you're measuring it. 

Depending on the configuration of the load a high voltage ac may be reacted to by the polymer as a capacitor and a high frequency ac as an inductor?

I agree wit Mr. Hakim Sellaoui. Generally we are able to measure an impedance. It is no problem.

Suraya,

Adding to what has been said by the colleagues, you have to supply the polymer specimen with two metallic electrode. The best electrodes may be the parallel palte electrodes. Then you can measure the impedance of the specimen by an RLC meter.

You can measure the it resistance and reactance. That is Z= R+jX,,

If the reactance is positive, the specimen behaves inductive. And if it is negative the specimen behaves captive. 

However, i would like to expect that the polymer as an insulator behaves capacitive,

Magnetic materials behaves inductive. In this case, it i ad viable to make a coil and use the specimen as it core. One can then measure the inductance with and without the core. If there is no appreciable difference the material will be nonmagnetic.

There are other method depending in observing the phase between the voltage on the specimen and the current passing through it. The inductive current lag behind the voltage while it lead the voltage if the specimen is capacitive.

The latter method is simpler and need only a sine wave generator and two channel oscilloscope.

wish you success

Thank you very much ,Hakim Sellaoui,Sudha Balagopalan,Josef Punčochář,Abdelhalim Zekry  for deatiled and encouraging reply.

Regards,

Surya.