Thermal conductivity of densified borosilicate glasses

•We study the effect of hot compression on structure and thermal conductivity of soda lime borosilicate glasses.•We observe an increase in density, elastic moduli, fraction of four-fold boron, and thermal conductivity with increasing applied pressure.•Thermal conductivity is found to increase significantly for borate-rich glasses (>50%), but far less for silicate-rich glasses (~10%) upon hot compression at 2 GPa.•Thermal conductivity shows a positive correlation with topological constraint density.