Influence of physical aging on the performance of corona-charged amorphous polymer electrets

• Published in: Journal of polymer science. Part B, Polymer physics Polymer physics, 2010-05, Vol.48 (9), p.990-997
• Main Authors: Erhard, Dominik P, Lovera, Deliani, Giesa, Reiner, Altstädt, Volker, Schmidt, Hans-werner
• Format: Article
• Language: English
• Subjects: amorphous polymers; Applied sciences; electret; Electrical engineering. Electrical power engineering; Electrical, magnetic and optical properties; Exact sciences and technology; high performance polymers; Materials; Organic polymers; physical aging; Physicochemistry of polymers; polymer blends; Properties and characterization
• ISSN: 0887-6266; 1099-0488; 1099-0488
• DOI: 10.1002/polb.21987

The influence of physical aging on the electret properties before corona charging of three amorphous polymers, polyetherimide (PEI), poly(phenylene ether) (PPE), and polystyrene (PS), as well as with blends of PPE and PS, was investigated. The degree of aging was monitored by determining the enthalpy relaxation Δh using differential scanning calorimetry (DSC). The electret performance was evaluated by isothermal potential decay (ITPD) at elevated temperatures and by thermal stimulated discharge (TSD) measurements. It was demonstrated that physical aging below the glass transition temperature substantially improves the electret performance of amorphous polymers by reducing the free volume and thus hindering charge motion. As an example, the performance of nonaged PEI was improved by physical aging at 200 °C for 4 days from 18 to 95% retained charge after 24 h at 120 °C. A similar beneficial influence of physical aging on the charge storage capability was achieved using blends of PPE with PS.