TY  - JOUR
A1  - Frübing, Peter
A1  - Blischke, D.
A1  - Salah Khalil, M.
A1  - Gerhard, Reimund
T1  - Dielectric relaxations in titanium-dioxide-filled polyethylene: Filler-induced chemical modifications of the polymer provide the dipolar response
Y1  - 2001
SN  - 0-7803-7053-8
ER  - 
TY  - JOUR
A1  - Frübing, Peter
A1  - Kremmer, Alexander
A1  - Neumann, Werner
A1  - Gerhard, Reimund
A1  - Guy, I. L.
T1  - Dielectric relaxation in piezo-, pyro- and ferroelectric polyamide 11
N2  - Ferroelectric polyamide 11 films were prepared by melt-quenching, cold-drawing and electrical poling. Their ferroelectricity was studied by means of dielectric-hysteresis measurements. A remnant polarisation of up to 35 mC/m(2) and a coercive field of 75 MV/m were obtained. The piezoelectric d(33) coefficient and the pyroelectric coefficient of the films are reduced by annealing just below the melting region, but remain at about 3 pC/N and 8 muC/(m(2)K), respectively, during further heat treatment. Differential scanning calorimetry (DSC), dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarisation (TSD) were applied for investigating the conformational changes induced by melt-quenching, cold-drawing and annealing. The results indicate that the cold-drawn film mainly consists of a rigid amorphous phase which exhibits considerably lower conductivity, no glass transition and consequently no dielectric a relaxation. Instead, an a, relaxation is found, which is related to chain motions in regions of the rigid amorphous phase where the amide-group dipoles are not perfectly ordered. Annealing removes imperfectly ordered structures, but does not affect the ferroelectric polarisation. Therefore, it may be concluded that essentially the a, relaxation causes the thermally non-stable part of the piezo- and pyroelectricity in polyamide 11
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Ganesan, Lakshmi Meena
A1  - Frübing, Peter
A1  - Mellinger, Axel
A1  - Gerhard, Reimund
T1  - Dielectric relaxation behaviour of nematic liquid crystals dispersed in poly(vinylidene fluoride- trifluoroethylene)
N2  - Polymer-dispersed liquid crystals (PDLCs) are prepared from poly(vinylidene fluoride-trifluoroethylene) (P(VDF- TrFE)) and a nematic liquid-crystal (LC). The anchoring effect was studied using dielectric relaxation spectroscopy. Two dispersion regions are observed in the dielectric spectra of the pure P(VDF-TrFE) film. They are related to the glass transition and to a space-charge relaxation. In PDLC films containing 10 wt% of LC, an additional, bias field-dependent relaxation peak is found that can be attributed to the motion of LC molecules. Due to the hindered movement of the LC molecules, this relaxation process is considerably slowed down, compared with the related process in the pure LC.
Y1  - 2009
UR  - http://iopscience.iop.org/0022-3727/
U6  - https://doi.org/10.1088/0022-3727/42/9/092006
SN  - 0022-3727
ER  - 
TY  - JOUR
A1  - Frübing, Peter
A1  - Blischke, D.
A1  - Salah Khalil, M.
A1  - Gerhard, Reimund
T1  - Complete relaxation map of polyethylene : filler-induced chemical modifications as dielectric probes
Y1  - 2001
ER  -