Crosslinking effect of borax additive on the thermal properties of polymer-based 1D and 2D nanocomposites used as thermal interface materials

Recently, polymer-based materials have been used in various filed of applications, but their low thermal conductivity restricts their uses due to the high interfacial thermal resistance. Therefore, in this study, one-dimensional thin-walled carbon nanotube (1D-TWCNT) and two-dimensional boron nitride nanosheet (2D-BNNS) fillers were used to enhance the thermal properties of polyvinyl alcohol (PVA). An important factor to be considered in enhancing the thermal properties of PVA is the interfacial configuration strategy, which provides sufficient pathways for phonon transport and the controlled loss of the intrinsic thermal properties of the filler nanomaterial. In this study, the effect of sodium tetraborate (borax) additive on the thermal properties of 1D-TWCNT/PVA and 2D-BNNS/PVA nanocomposites was explored. Borax is a well-known crosslinking additive that can be used with PVA. The crosslink density of the PVA-borax nanocomposite was controlled by changing its borate ion concentration. The addition of borax into nanocomposites improves the conductivity of 1D-TWCNT/PVA nanocomposites up to 14.5% (4 wt.% borax) and of 2D-BNNS/PVA nanocomposite up to 30.6% for BNNS (2 wt.% borax). Thus, when borax was added, the 2D-BNNS/PVA nanocomposite showed better results than the 1D-TWCNT/PVA nanocomposite.