Novel Process for Manufacturing Electret from Polypropylene Nonwoven Fabrics

In this work, a novel procedure for manufacturing an electret was designed, and the relationship between the surface voltage and other variables elucidated. The charge decay of the nonwoven electret over six weeks was also investigated. The new process quickly charges the dielectric to a voltage of between 10 and 30 kV at temperatures of 25°C to 90°C and various charging times. The parameters of the process, including the surface temperature of the nonwoven, the charging time and the charging voltage were varied. A novel electrical mechanism that can quickly charge the dielectric into an electret under a high electric field was designed to save energy and protect the environment. After the dielectric of polypropylene nonwoven was charged, the nonwoven exhibited a low pressure drop and high filtering efficiency. The manufacturing procedure was very easy to implement. Additionally, the power consumed by this electrical mechanism was almost 10% of that used by a traditional dust collector. Hence, this mechanism generated an electret filter that saved energy, had a low pressure drop and highly efficient filtration. The theoretical models were analyzed and the application of the process modified according to the experimental results. The surface voltage of the dielectric increased linearly with charging time. The optimal surface voltage was 19.99 kV when the charging voltage was 30 kV; the surface temperature was 50°C, and the charging time was 10 seconds.