Join us at the International Thermal Conductivity Conference (ITCC) and the International Thermal Expansion Symposium (ITES).
Aerogels are ultra-light, insulative, porous materials that have a wide variety of applications. The aim of this study was to synthesize resorcinol/formaldehyde (RF) cross-linked silica aerogels in one pot by acid catalysis. A thermal constant analyzer measured the thermal conductivity of the RF/SiO2 aerogels using the transient plane source (TPS) method. Results showed that although the RF/SiO2 aerogels had a lower density, their thermal conductivities resembled those of glass wool, and increased slightly after the carbonization process. Overall, the aerogels were highly efficient, and synthesizing other RF/oxide aerogels by one pot acid catalysis should be examined in the future.
The thermal conductivity of nanoporous glass alumina films (NGAFs) were theoretically and experimentally studied in this paper. The thermal conductivity of pristine NGAFs and silver nanowire-infused NGAFs of various pore sizes and porosities were measured with a thermal constants analyser based on the transient plane source (TPS) method. Theoretical and experimental results were consistent with one another, and indicated that the pore radius and porosity of the films influenced thermal conductivity. Additionally, the Ag nanowires that were added to the NGAF matrix had no impact on thermal conductivity.
The transient technique is the commercial method used to test the thermal conductivity, thermal diffusivity, and specific heat of solids. With the instrument, a double spiral nickel sensor is sandwiched between two homogenous samples, and as the sensor pulses electrical currents through the sample, it simultaneously measures how long it takes for the temperature of the sample to increase. This method is typically used on glasses, insulating materials, and polymer composites.
The authors have developed a method for the functionalization of single-walled carbon nanotubes (SWCNTs). The functionalization of the SWCNTs is useful in helping to produce a better dispersion of nanotubes throughout a polymer matrix. Better dispersion of nanotubes was thought to result in an improvement in the mechanical, electrical, and thermal properties of nanocomposite polymers. It was determined that the method produced effective surface modification of the nanotubes. The elastic modulus and thermal conductivities of the nanocomposites seemed to be unaffected by the functionalization of the SWCNTs; however, the flexural strength of the nanocomposites was reduced.
Phase change materials (PCMs) store large amounts of latent heat over small temperature ranges, so their application in the thermal regulation of buildings is becoming more popular. However, PCMs have low thermal conductivities, so micro-encapsulated PCMs (micro-PCMs) are being incorporated into PCMs to enhance their performance and improve thermal conductivity. In this study, micro-PCMs were mixed with thermally conductive, inorganic gypsum powder and glass fiber to produce gypsum boards. The thermal properties of the gypsum boards were analyzed as the proportion of micro-PCMs in the composites increased. A thermal constant analyzer was used to measure the thermal conductivity of the samples using the transient plane source (TPS) method. Results showed that the thermal conductivities of the samples decreased as the weight percentages of the gypsum matrix increased. At lower weight percentages, the micro-PCMs did not accumulate in the gypsum board and increased thermal transfer. It was found that the thermal characteristics of the composites is largely affected by the concentration of micro-PCMs, but overall, micro-PCMs as additives to building materials would improve the thermal capacities of the structures.
