Search Results (2)

The thermal conductivity of thermal insulation materials directly affects the building energy consumption. The types and constituents of thermal insulation materials in thermal insulation boards are the key to determining the insulation performance. By optimizing the material constituents and ratios, this paper proposes an improved graphite composite insulation board (GCIB), which has lower thermal conductivity and good fire resistance. Through theoretical derivation, it is found that the limit range of the thermal conductivity of the new GCIB is 0.042–0.064 W/(m · K). Combined with the results of theoretical value analysis, and according to the ratios of material components, the random distribution function of each material component is constructed, and the numerical model of GCIB is established. Through numerical analysis, the range of thermal conductivity of the new composite insulation board is 0.046–0.050 W/(m · K). Finally, we establish an experimental model of the new GCIB. Through the model test of six GCIBs, the thermal conductivity of the new GCIB is obtained as 0.046 W/(m · K), which is in good agreement with the results of theoretical analysis and numerical simulation. Through theoretical analysis, numerical simulation and a sample test, this paper verifies the better thermal insulation performance of the improved GCIB, providing theoretical and numerical simulation methods for the new GCIB, as well as a theoretical reference for the promotion and application of the GCIB. Full article

Biocomposite boards (BcBs) composed of hemp shives and corn starch are known as thermal insulating or structural building materials. Therefore, they must be stable during exploitation. However, BcBs are exposed to microorganisms present in the environment, and it is of great interest to investigate the biodegradation behaviour of these materials. This work identified microorganisms growing on BcBs that contain either Flovan CGN or expandable graphite as flame retardants and selected fungi such as Rhizopus oryzae and Aspergillus fumigatus to test the way they affect the materials of interest. For this purpose, the enzymatic activity of cellulases and amylases produced by these organisms were determined. In addition, the apparent density as well as compressive strength of the affected boards were evaluated. The results showed that apparent density and compressive strength deteriorated in BcB composition with the Flovan CGN flame retardant. At the same time, the level of deterioration was lower when the expandable graphite was used, suggesting that it also acts as an antimicrobial agent. A scanning electronic microscopy analysis was employed to monitor the growth of microorganisms in the BcBs. Such analysis demonstrated that, regardless of BcB composition, fungi easily penetrate into the middle layers of the material. Full article