Problems in examining thermal properties of insulating composite materials designed for technical means of transport
Andrzej Posmyk, Krzysztof Hodor
Quarterly No. 1, 2019 pages 14-17
DOI:
keywords: technical means of transport, thermal conductivity, insulating materials, measurement inaccuracy
abstract The paper presents problems that accompany measuring the thermal conductivity of composite insulating materials with a matrix of polymer resins filled with hollow microspheres used in means of short and long-distance transport. To measure the thermal conductivity with measuring apparatuses available on the market, samples with a specific shape, dimensions and accuracy of workmanship are required. During the drying of water-soluble resins, bubbles and surface deformation develop as a result of water evaporation. Machining the samples to obtain flat and parallel surfaces is not recommended due to the possibility of damage to the microspheres. Moreover, pressing the sample plates with a force that exceeds the permissible pressure for the spheres (3÷5 MPa) in order to reduce air-filled gaps, is not recommended due to the possibility of damaging the coating. Inaccuracy in producing the samples significantly affects the accuracy of the thermal conductivity measurement results by direct methods using the heat flow conducted by the test sample.