Development of Thermoplastic Polyurethane-Hexagonal Boron Nitride Composite Foams with Enhanced Effective Thermal Conductivity

Thermoplastic polyurethane (TPU)-hexagonal boron nitride (hBN) composites fabricated by batch foaming were studied in this study. The results of this research demonstrated that by CO2 foaming it was possible to produce TPU foams at relatively low temperatures (60C). The results indicated that the cell size and cell density range are significantly wider at lower saturation pressures to varying foaming temperatures. While TPU foams usually yield extremely high cell population density and small cell size, by applying the appropriate foaming conditions, we prepared foams with a wide range of cell sizes, from 21 to 170 m, and cell population density from 105 to 108 pore/cm3. These conditions have been used to investigate the foaming-assisted filler alignment in TPU composite and nanocomposite foams for tailoring the thermal conductivity. Foamed samples at lower saturation temperatures (i.e. 20 and 40C) yielded higher thermal conductivity than solid counterparts.