Origins of the secondary dielectric losses in polycarbonate

Author(s):  
E. Sacher
Keyword(s):  
2018 ◽  
Vol 69 (8) ◽  
pp. 2040-2044
Author(s):  
Georgeta Velciu ◽  
Virgil Marinescu ◽  
Adriana Moanta ◽  
Ladislau Radermacher ◽  
Adriana Mariana Bors

The influence of fly ash adittion (90 % fraction [ 100 mm) on the cement mortar characteristics was studied. The XRD, XRF, SEM and FTIR determinations indicated that fly ash used has a hollow microstructure of microsphere and cenosphere whose total content in SiO2, Al2O3 and Fe2O3 is 88.63 % and that of CaO and MgO of 8.55 %. The mechanical, thermal and dielectric determinations made on mortar samples with content of fly ash in the 0-40 % range have highlighted fact that the mechanical strength of cement mortars is maximal at 20 %, the increase in fly ash content leads to a decrease in relative density and thermal conductivity as well as and to increased dielectric losses tgd.


1992 ◽  
Vol 247 ◽  
Author(s):  
Sergey A. Tishin ◽  
Mihail I. Tsapovestsky ◽  
Vladimir A. Tishin ◽  
Vladimir N. Kestelman

ABSTRACTThe relaxation of polyimid films after the axial tension has been investigated by measuring life-time of positrons and angular correlation of annihilation photons. The nonmonotonic change of mean life-time while relaxing the free film has been found. Two range of changes of positron-sensitive properties can be seen: “rapid” relaxation for 4–5 hours (characterized by reducing life-time of short-lived component) and “slow” relaxation (characterized by reducing the intensity of long-lived component). The results of this investigation have been compared with those of measuring of sample density and dielectric losses. The possible explanations and the- changes of mechanizms of relaxation with the conditions of deformation and “the rest” of polymers are analyzed.


1969 ◽  
Vol 20 (165) ◽  
pp. 455-466 ◽  
Author(s):  
C. Weaver ◽  
S. Lorenzoni

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