Table 3.

Summary of λ values (W·m⁻¹·K⁻¹) of polymer composites filled with hybrid fillers.

Filler 1	Filler 2	Matrix	Loading	$\mathit{\lambda }$	Ref.
Graphene, 0.35 to 12 nm (thickness) 2 to 8 μm (lateral)	Hexagonal boron nitride 0.35 to 12 nm (thickness) 3 to 8 μm (lateral)	Epoxy	21.8 vol% + 21.8 vol%	6.50	[135]
spherical α-Alumina, (∼30 nm)	Hexagonal boron nitride (∼10 μm)	Epoxy	22.5 wt% and 7.5 wt%	1.182	[114]
Alumina, d50: 12.5 ± 5.35 μm	Boron nitride d50: 8.3 ± 5.20 μm	Epoxy	52 wt% and 10 wt%	1.65	[136]
Spherical Alumina	Hexagonal boron nitride	poly(3-hydroxylbutyrate)	7wt% and 43 wt%	1.79	[137]
Alumina, 3 μm	Boron nitride platelets, 32.52 μm	polydimethylsiloxane	30 wt% and 5 wt%	3.64	[138]
Graphene nanoplatelets with 15 μm lateral size and 10 nm thickness	Boron nitride nanoparticles (nm-BNs, 110 nm)	Epoxy	16 vol% + 1 vol%	4.72	[139]
α-Alumina, average particle sizes of 0.7 and 5 μm	Graphite oxide	Silicone oil	63 vol% and 1 wt%	3.45	[140]
Alumina flake, average thickness of 372 nm and a diameter of 8.2 μm	Silver particle, 10–20 nm	Epoxy	50 wt% and 0.6 wt%	6.71	[121]
Alumina, 4.98 μm	Graphene nanosheets, the average lateral size is 4.96 μm	Epoxy	42.4 wt% and 12.1 wt%	33.4 in radial direction and 13.3 in axial direction	[141]
Multiwalled carbon nanotubes with a length of 10 μm and a diameter of 11 nm	Boron nitride with a particle size of 1–2 μm	Silicone rubber	0.25 vol% and 30 phr	0.279	[142]
Hexagonal boron nitride	Multiwalled carbon nanotubes with a length of 3–12 μm	Polydimethylsiloxane	30 wt%+2 wt%	4.28	[143]
Hexagonal boron nitride with a lateral size of approximately 70 nm and a normalized thickness of 7 nm	Graphene oxide nanosheets have a normalized lateral size of 860 nm and a normalized thickness value of 1.6 nm	Poly(vinyl alcohol)	less than 1 wt%	9.9, in-plane	[130]
Graphene nanoplatelets, diameter, 1–20 mm; thickness, 5–15 nm	Alumina fibers with diameters ranging from 1.6 mm to 2.3 mm, several centimeters in length	Epoxy	2 vol% and 50 vol%	1.62	[129]
Boron nitride, diameter: 12 μm	Graphene oxide	Poly(dimethylsiloxane)	30 wt% and 2 wt%	10.91 in-plane and 1.27 through-plane	[127]
Alumina, 1 μm	Carbon fiber, the diameter is 10 μm and mean length is 150 μm	Silicone rubber	5 vol% and 25 vol%	9.60	[144]