TY  - GEN
A1  - Wang, Jingwen
A1  - Rychkov, Dmitry
A1  - Gerhard, Reimund
T1  - Influence of Charge Density on Charge Decay in Chemically Modified Polypropylene Films
T2  - 2018 IEEE 2nd International Conference on Dielectrics (ICD)
N2  - Previous work has shown that surface modification with orthophosphoric acid can significantly enhance the charge stability on polypropylene (PP) surface by generating deeper traps. In the present study, thermally stimulated potential-decay measurements revealed that the chemical treatment may also significantly increase the number of available trapping sites on the surface. Thus, as a consequence, the so-called "cross-over" phenomenon, which is observed on as-received and thermally treated PP electrets, may be overcome in a certain range of initial charge densities. Furthermore, the discharge behavior of chemically modified samples indicates that charges can be injected from the treated surface into the bulk, and/or charges of opposite polarity can be pulled from the rear electrode into the bulk at elevated temperatures and at the high electric fields that are caused by the deposited charges. In the bulk, a lack of deep traps causes rapid charge decay already in the temperature range around 95 degrees C.
KW  - polypropylene
KW  - surface charge stability
KW  - thermally stimulated discharge
KW  - cross-over effect
KW  - chemical modification
Y1  - 2018
SN  - 978-1-5386-6389-9
U6  - https://doi.org/10.1109/ICD.2018.8514718
PB  - IEEE
CY  - New York
ER  - 
TY  - GEN
A1  - Nguyen, Quyet Doan
A1  - Gerhard, Reimund
T1  - LDPE/MgO Nanocomposite Dielectrics for Electrical-Insulation and Ferroelectret-Transducer Applications
T2  - 2018 IEEE 2nd International Conference on Dielectrics (ICD)
N2  - Published results on LDPE/MgO nanocomposites (3wt%) show that they promise to be good electrical-insulation materials. In this work, the nanocomposites are examined as a potential (ferro-)electret material as well. Isothermal surface-potential decay measurements show that charged LDPE/MgO films still exhibit significant surface potentials after heating for 4 hours at 80 degrees C, which suggests good capabilities of LDPE/MgO nanocomposites to hold electric charges of both polarities. Open-tubular-channel ferroelectrets prepared from LDPE/MgO nanocomposite films show significant piezoelectricity with d(33) coefficients of about 20 pC/N after charging and are stable up to temperatures of at least 80 degrees C. Thus LDPE/MgO nanocomposites may become available as a new ferroelectret material. To increase their d(33) coefficients, it is desirable to optimize the charging conditions and the ferroelectret structure.
KW  - ferroelectrets
KW  - LDPE nanocomposites
KW  - electroacoustic probing
KW  - space-charge and polarization profiles
KW  - thermally stimulated discharge
Y1  - 2018
SN  - 978-1-5386-6389-9
SN  - 978-1-5386-6388-2
SN  - 978-1-5386-6390-5
PB  - IEEE
CY  - New York
ER  -