Antistatic Agents

Abstract

Many organic macromolecular compounds behave as dielectrics. Usually, electrons involved in chemical bonds are localized and the specific conductance of polymers generally varies from 10⁻⁹ to 10⁻² S cm⁻¹ at room temperature. The electric conductance depends greatly on the temperature. It is possible to notice an important increase in the specific conductance of polymers above their T _g value. Below T _g , the specific conductance may vary from 10⁻¹² to 10⁻¹⁹ S cm⁻¹, and above T _g , it may increase up to 10⁻⁶ S cm⁻¹ [1]. The values of the specific conductance of many well-known polymers are given in Table 7.1 [1]. These polymeric materials have a tendency to develop electrical charges under repeated deformations and friction. The superficial electrical potential may reach values up to a few tens of kilovolts, and this presents serious difficulties for practical applications and to users. The electrical charges accumulated on the surfaces of plastic materials may produce sparks that become fire hazards in an inflammable atmosphere. For these reasons plastic containers are not recommended for transportation and storage of inflammable liquid materials, unless the plastic material has been treated against charge accumulation. These charges also cause serious problems in many other cases; for instance, they are produced on aircraft during takeoffs and landings. They may then interfere seriously with the undercarriage mechanism and with radio communications between the aircraft and ground stations.