الفهرس | Only 14 pages are availabe for public view |
Abstract The carried out in this worle allows us to conclude the following. The electrical conductivit o , of car bon blacJc loaded butyl rubber increases by adding 20 phr BaTiOs-ceramic to rubber mixtures. In case temperature coefficient. of conductivity (TCC] of’ corresponding samples decreases. 2. The decrease in due to Joule heating effect occurs as a result. of’ the thermal expansion of’ the hopping paths between carbon black particles and/or aggregates and is comparable with the changes occured in due text rnal heating. 3. Theoretical analysis of’ the obtained data allows to calculate reasonable values of’ the specific heat of carbon black-loaded butyl rubber composites. 4. The values of the time constants Tg and Td due sample heaing and cooling respecively are characerisic consanLs for each ype and concenLraion of carbon black and varies from 2 LO 5 min. 5. By using ~he ftash method technique the value of the specific heat of the composi~es are in good agreement with that which obtained from time-temperature It-TJ characteristic curves. 6. Each ~ype of invest.igaLed carbon black possesses a criticat concentration aL which a maximum value of heat produced by Joule effect. was obtained; namely, HAY [80 phr J, GPF I60 phr J, SRF I100 phr J and LAMP I70 phr J , 7. The heat capacity of bULyl rubber composites decreases as the carbon black concentration increases. 8. Both the heat produced by Joule effect and the values of ~he specific heat were found to bet markedly affected by the ambient temperature. 9. The heat. produced by Joule heating effect. increases as surface area to volume [S/¥) ratio of the sample increases. 10. The heat capacity of the investigated rubber composite is equal to the summation of the heat capacities of individual intredients and is governed by the rule of addi ti vty 11. The electrical and thermal parameters of composites containing 100 phr HAF. GPF. and SRF were not. markedly affected after 6 months of continuous power onset operation using the mains acpower source [50 Hz). |