Abstract

The present work shows the development of temperature sensors based on flexible polymers reinforced with carbon nanoparticles. More specifically, they have been manufactured with polydymethysiloxane (PDMS) reinforced with graphene nanoplatelets (GNPs). The analysis of electrical properties reveal that an increase of the GNP contents promotes an enhancement of the electrical conductivity due to the higher number of conductive pathways inside the material. On the other hand, the electrical conductivity decreases with temperature because of the polymer expansion, as well as due to some scattering effects in the contacts between adjacent nanoparticles. This decrease is more significant at lower GNP contents as, in this case, the scattering effects inside the matrix are also very prevalent. The analysis of the proof-of-concept as temperature sensors shows an outstanding sensitivity, especially at low GNP contents, with a linear-exponential correlation of the electrical resistance with temperature. Their use as alarm sensors is proved due this excellent thermal sensitivity.

Abstract

Heat dissipation is an issue that is acquiring great importance to increase the efficiency in the utilization of the energy and extending the lifespan of the equipment. Traditionally, heat dissipation has been carried out using metals, but the increase in the requirements of equipment and devices, composites have gained importance. Graphite based composites have relevance in heat dissipation, particularly when the disperse material is a metal or metal carbide. The reason is the great value of thermal conductivity combined with good mechanical properties and lightness. Research has focused until nowadays on the composite graphite-MoC, although there are other composites with great potential, as that proposed in this manuscript: graphite- Cr3C2. The preparation of the composite graphite-Cr3C2 consisted in mechanical mixing of the staring powders, subsequent obtaining of the green compact of 40 mm in diameter and, finally, sintering at 2000 °C for 20 minutes under an applied pressure of 30 MPa in the Spark Plasma Sintering apparatus. The sintered material exhibited electrical and thermal conductivities in the in-plane direction of 1.08 MS/m and 215 W/m · °C, respectively, and a flexural strength of 113 MPa, which makes this material a suitable candidate for its application in heat dissipation.