Influence of corona charging in cellular polyethylene film

[En] Cellular polymers have recently attracted attention for their property of exhibiting a 
\npiezoelectric constant when they are electrically charged. The electrostatic charge generated in the 
\nvoids by the internal discharges creates and internal macrodipole which is responsible for the 
\npiezoelectric effect. Charging by corona discharge is the most used method for cellular polymers. 
\nMany works has been published on polypropylene and polyethylene films mainly focused on the 
\nrequired expansion process or on the results obtained for raw cellular materials electrically 
\nactivated. Our work is based on commercial polyethylene cellular films which have been 
\nphysically characterized and electrically activated. The effect of thermal treatment, physical 
\nuniaxial or biaxial stretching and corona charging was investigated. The new method of corona 
\ncharging improved the piezoelectric constant under other activation conditions.