The effect of foam pore size, density and the use of MXene on the thermal conductivity and flexural strength of PU-foam roofing panel samples

This study investigated the effect of polyurethane (PU) foam pore size and density and the application of MXene nanoplates to enhance heat insulation and flexural strength. Results show that the thermal conductivity decreases at an average rate of 0.01803 W/m-K per unit increase in pore density (No. of pores/mm2) while it is enhanced with pore size increase at a rate of 0.0168 (W/m-K)/mm. Mechanical characterization has revealed that an improvement in flexural strength corresponds to the decrease in pore size and increase in density with values of 0.776 MPa/mm and 0.445 MPa/(No. of pores/mm2) respectively. Adding a layer of adhesive with MXene is also reported to have a beneficial effect vis a vis reduction in thermal conductivity and elevating flexural strength. On a per gram basis, the effectivity factor of MXene has been determined to be in the order of 103 validating these materials exceptional capabilities to transform material properties. The work also derived empirical mathematical expressions for the thermal conductivity, flexural strength, and the effect of MXene as a function of pores size and density which can be used for PU foam/roof panel design and fabrication, and building energy modeling. Error analysis indicates that these equations have an average normality plot correlation score of 0.9036 at the 95 % confidence level verifying their accuracy and applicability.