A study on electric charge behaviors in polymeric materials using “direct current integrated charge method”

The space charge accumulation in polymeric materials is one of the important behaviors of pre-ageing phenomena in electrical insulations. The Pulsed electro-acoustic (PEA) method is an appropriate method to understand the space charge behavior, but some kind of charges such as charges with high speed are hardly detected by the method. To understand the whole information of charges, that is Q(t) behaviors, we have been trying the direct current integrated charge (DCIC-Q(t)) method, which is using a measuring capacitor directly connected to a sample, and measuring from the starting point of applying voltage to the end point of grounding. The basic technologies of the method and some investigation results of generally used polymers, low- and high-density polyethylene (LDPE and HDPE), and polyethylene terephthalate (PET) are described in this article. Even concluded in same category of polyethylene, LDPE and HDPE show a different behavior, and PET which contains aromatic groups in the molecular chain shows excellent ability to control charges.