scholarly journals The influence of the characteristics of polyethylene on thermoelectric properties of their composites with black carbon

2021 ◽  
pp. 18-23
Author(s):  
A. V. Markov ◽  
V. A. Markov ◽  
A. S. Chizhov

The work is devoted to the study of the effect of characteristics (melt flow and density) of various grades of polyethylene on the electrical resistance of polyethylene composites with carbon black at normal and elevated temperatures. Such polyethylene composites are characterized by abnormally high values of the positive temperature coefficient of electrical resistance in the melting temperature range of the polyethylene matrix. This causes the effect of power self-regulation of such heaters (selfregulating polymer heaters). It has been established that the content of carbon black, which provides a stable and clear effect of self-regulation of such heaters, is located in a concentration region approaching the region of the second concentration-structural percolation transition, which for all investigated polyethylene composites was about 12 vol% of carbon black. The growth rate of electrical resistance at these carbon-black contents is influenced by crystallinity of the polyethylene matrix.

2014 ◽  
Vol 778-780 ◽  
pp. 461-466 ◽  
Author(s):  
Hiroki Niwa ◽  
Jun Suda ◽  
Tsunenobu Kimoto

Impact ionization coefficients of 4H-SiC were measured at room temperature and at elevated temperatures up to 200°C. Photomultiplication measurement was done in two complementary photodiodes to measure the multiplication factors of holes (Mp) and electrons (Mn), and ionization coefficients were extracted. Calculated breakdown voltage using the obtained ionization coefficients showed good agreement with the measured values in this study, and also in other reported PiN diodes and MOSFETs. In high-temperature measurement, breakdown voltage exhibited a positive temperature coefficient and multiplication factors showed a negative temperature coefficient. Therefore, extracted ionization coefficient has decreased which can be explained by the increase of phonon scattering. The calculated temperature dependence of breakdown voltage agreed well with the measured values not only for the diodes in this study, but also in PiN diode in other literature.


Sign in / Sign up

Export Citation Format

Share Document