What do we mean by an internal or external antistat?
To lower the surface resistance of plastics (plastic itself is a non-conductive material), substances are added to them. These substances may be added by applying an extra layer onto the material or by mixing them into the material. Generally speaking a layer of antistat on the material can be expected to give better results than an internal antistat. However, disadvantages compared with an internal antistat are limited storage life and the loss of several decades during an operation. To give an example, an antistatic material of 109 ohms with an external antistat will fall to 1011 ohms after forming. • Can all materials be made antistatic? By no means all materials can be made into antistatic or conductive materials. Certainly for conductive materials only a few types (ABS and PS) are candidates. Carbon is added to these materials, acting as a conductor. Developments are currently taking place to make conductive other materials that can be formed using thermoforming technology.
