The combination of AlN and h‐BN for enhancing the thermal conductivity of thermoplastic polyurethane composites prepared by selective laser sintering

Abstract

In recent years, with the rapid development of 5G communication technology and microelectronic chip integration technology, smart wearable devices with high thermal conductivity are becoming more and more important. The most common method to improve the thermal conductivity of polymers is to introduce fillers with high thermal conductivity for compounding and build a thermal conductivity network inside the system. At present, the main methods of preparing heat-conducting composites are hot pressing molding, injection molding, and casting molding, but these traditional molding processes are difficult to prepare heat-conducting composites with complex shapes and structures. Selective laser sintering (SLS) is a new 3D printing technology, which uses the energy provided by laser to melt polymer powder, then sinter layer by layer, stack layer by layer, and finally form printed products. Compared with the traditional molding process, the SLS process has the advantages of a simple manufacturing process, high molding precision, recyclable materials, and wide application, which can realize the design and development of complex structural parts. In this study, TPU composites were successfully prepared by using thermoplastic polyurethane (TPU) polymer as matrix material, AlN and h-BN as thermally conductive fillers, and SLS technology. When the content of AlN is 20 wt% and the content of h-BN is 15 wt%, the thermal conductivity of TPU composite is as high as 0.90 W/mK, which is 391% higher than that of pure TPU sintered parts. At this time, the tensile strength of the composite is 17.2 MPa and the elongation at break is 301%, and it still shows good mechanical properties. This work is devoted to proposing a preparation method of flexible and high thermal conductivity composite materials, which can be used to prepare thermal management materials with complex shapes and structures and carriers of smart wearable devices, and has broad application prospects.

Thermal Conductivity and Mechanical Properties of Polymer Composites with Hexagonal Boron Nitride—A Comparison of Three Processing Methods: Injection Moulding, Powder Bed Fusion and Casting

“…For PBF composites, refs. [ 12 , 13 ] achieved relatively higher thermal conductivities than in our study. This could be due to synergetic effects of using two filler types (hBN and Al 2 O 3 in ref.…”

“…Hon et al [ 33 ] examined the effects of processing parameters on the mechanical properties of the PBF composites containing PA12 and SiC. Zhang et al [ 13 ] combined AlN and hBN for enhancing the thermal conductivity of TPU composites processed by PBF.…”

Thermally Conductive Polymer Composites with Hexagonal Boron Nitride for Medical Device Thermal Management

“…Filler loading (filler size) Processing method Thermal conductivity hBN/epoxy [11] 95 wt% Compression moulding 21.3 W/m•K (in-plane) 7 W/m•K (through-plane) hBN/PU [14] 80 vol% Freeze drying & hot pressing 39 W/m•K (in-plane) 11.5 W/m•K (through-plane) hBN/polyimide [15] 60 vol% Spin-cast (film) 17.5 W/m•K (in-plane) 5.4 W/m•K (through-plane) hBN/epoxy [16] 57 vol% (5-11 µm) Casting 5.27 W/m•K (through-plane) hBN/PE [17] 50 vol% (4-5 µm) Injection moulding 3.66 W/m•K (through-plane) hBN/PEEK [18] 60 wt% (25-30 µm) Injection moulding 12.45 W/m•K (in-plane) 2.34 W/m•K (through-plane) hBN/TPU [19] 50 wt% Solution mixing & hot pressing 3.06 W/mK (through-plane) hBN/PA12 [20] 40 wt% Powder bed fusion 0.55 W/m•K (through-plane, 77% higher than PA12) hBN/Al2O3 /PA12 [21] 15 wt% hBN and 35 wt% Al2O 3 Powder bed fusion 1.05 W/m•K (through-plane, 275% higher than PA12) hBN/AlN/TPU [22] 15 wt% hBN and 20 wt% AlN Powder bed fusion 0.9 W/m•K (through-plane, 391% higher than TPU) hBN/TPU [23] 30 wt% Fused deposition modeling (material extrusion)…”