Highly Thermally Conductive Polydimethylsiloxane Composites with Controllable 3D GO@f-CNTs Networks via Self-sacrificing Template Method

Constructing controllable thermal conduction networks is the key to efficiently improve thermal conductivities of polymer composites.In this work,graphite oxide(GO)and functionalized carbon nanotubes(f-CNTs)are combined to prepare“Line-Plane”-like hetero-structured thermally conductive GO@f-CNTs fillers,which are then performed to construct controllable 3D GO@f-CNTs thermal conduction networks via selfsacrificing template method based on oxalic acid.Subsequently,thermally conductive GO@f-CNTs/polydimethylsiloxane(PDMS)composites are fabricated via casting method.When the size of oxalic acid is 0.24 mm and the volume fraction of GO@f-CNTs is 60 vol%,GO@f-CNTs/PDMS composites present the optimal thermal conductivity coefficient(λ,4.00 W·m^(-1)·K^(-1)),about 20 times that of theλof neat PDMS(0.20 W·m^(-1)·K^(-1)),also much higher than theλ(2.44 W·m^(-1)·K^(-1))of GO/f-CNTs/PDMS composites with the same amount of randomly dispersed fillers.Meanwhile,the obtained GO@f-CNTs/PDMS composites have excellent thermal stability,whoseλdeviation is only about 3%after 500 thermal cycles(20-200℃).

Thermally Conductive and Insulating Epoxy Composites by Synchronously Incorporating Si-sol Functionalized Glass Fibers and Boron Nitride Fillers

Glass fibers(GFs)/epoxy laminated composites always present weak interlaminar shear strength(ILSS)and low cross-plane thermal conductivity coefficient(λ⊥).In this work,silica-sol,synthesized from tetraethyl orthosilicate(TEOS)and KH-560 via sol-gel method,was employed to functionalize the surface of GFs(Si-GFs).Together with a spherical boron nitride(BNN-30),the thermally conductive BNN-30/Si-GFs/epoxy laminated composites were then fabricated.Results demonstrate that Si-sol is beneficial to the improvement of mechanical properties for epoxy laminated composites(especially for ILSS).The BNN-30/Si-GFs/epoxy laminated composites with 15 wt%BNN-30 fillers display the optimal comprehensive properties.In-planeλ(λ//)andλ⊥reach the maximum of 2.37 and 1.07 W.m-1.K-1,146.9%and 132.6%higher than those of SiGFs/epoxy laminated composites(λ//=0.96 W.m-1.K-1 andλ⊥=0.46 W.m-1K-1),respectively,and also about 10.8 and 4.9 times those of pure epoxy resin(λ//=λ⊥,0.22 W.m-1.K-1).And the heat-resistance index(THRI),dielectric constant(ε),dielectric loss(tanδ),breakdown strength(E0),surface resistivity(ρs)as well as volume resistivity(ρv)are 197.3℃,4.95,0.0046,22.3 kV.mm-1,1.8×1014Ω,and 2.1×1014Ω.cm,respectively.