The comparative analysis of thermal effects in elastomers modified with MCNT at constant DC voltage

Abstract

The author carried out the comparative analysis of elastomers – polyurethane (NPC) and silicone compound (NCOC) modified with carbon nanotubes (MCNT) with a mass content of 1 to 9 %. MCNTs were synthetically produced by the CVD technology using Co-Mo/Al2O3-MgO (MCNT1) and Fe-Co/2,1Al2O3 (MCNT2) catalysts. The analysis of experimental study results showed that the lowest specific bulk electrical conductivity (5×10-10 Cm×cm-1) was typical for polyurethane elastomer (1 mass. % MCNT synthetically produced using Fe-Co/2,1Al2O3 catalyst). For the silicone elastomer modified with 9 mass. % MCNT1, the specific bulk electrical conductivity was 4×10-1 Cm×cm-1. The author identified the parameters of percolation of electrical conductivity model for NPC, NCOC with MCNT1 and MCNT2, taking into account the MCNT packing factor and electrical conductivity critical index. The maximum temperature field uniformity is typical for silicone elastomer with 7 mass. % MCNT2. Nonuniform temperature field in modified polyurethane-based elastomers can be caused by the local MCNT entanglement manifested in the creation of agglomerates or more dense electrically-conductive circuit packing, which, in its turn, results in the decrease in heat power. The heating temperature of nanomodified composites produced from NCOC 1 and NCOC 2 can vary from 32.9 to 102 °С. The author studied the modes of nanomodified elastomers heat generation in the range of 6 to 30 V, compared heat generation in the elastomer-based and ceramics-based samples. The study allowed identifying the best combination of the polymeric matrix and MCNT type. For the electric heater, it is the most efficient to apply silicone compound at the 7 % MCNT concentration and, depending on the feeding voltage level of 12 or 24 V, to use MCNT1 or MCNT2.