RESUMO
Thermally conductive composites with self-healing ability can not only solve the heat dissipation problem of integrated electronic devices but also help improve their service life, thereby reducing electronic waste. In this study, a self-repairing thermally conductive composite with good electrical insulation, high thermal conductivity, high healing efficiency, and excellent mechanical strength was designed and prepared using a silicon vitrimer as the matrix and functionalized boron nitride nanosheets (fBNNS) as the thermally conductive filler. The tensile strength of the vitrimers with 10 wt% of octaglycidyl polyhedral oligomeric silsesquioxane (POSS) increased by 2.82 times to 8.4 ± 0.1 MPa with respect to that without POSS. In addition, the composites exhibited excellent thermal conductivity of 1.41 ± 0.05 W/mK with 66 wt% of fBNNS, which is more than 6 times higher than that of undoped elastomers. More importantly, the repair efficiency of undoped vitrimeric silicone can be as high as 98.8 ± 1.1%, which was slightly reduced to over 92.0% by adding 66 wt% of fBNNS. Further, it could recover 99.3% of the thermal conductivity even after 6 healing cycles. The self-healing thermally conductive composites exhibited excellent wettability and good adhesion to different wafers and substrates, demonstrating excellent performance as thermal interface materials for high-power electronic devices.
RESUMO
The thermally conductive structural film adhesive not only carries large loads but also exhibits excellent heat-transfer performance, which has huge application prospects. Herein, a novel epoxy (Ep) thermally conductive structural film adhesive was prepared using polyphenoxy (PHO) as the toughening agent and film former, boron nitride (BN) nanosheets as the thermally conductive filler, and polyester fabric as the carrier. When the amount of PHO in the epoxy matrix was 30 phr and the content of nano-BN was 30 wt.% (Ep/PHO30/nBN30), the adhesive resin system showed good film-forming properties, thermal stability, and thermal conductivity. The glass transition temperature of Ep/PHO30/nBN30 was 215 °C, and the thermal conductivity was 209.5% higher than that of the pure epoxy resin. The Ep/PHO30/nBN30 film adhesive possessed excellent adhesion and peeling properties, and the double-lap shear strength at room temperature reached 36.69 MPa, which was 21.3% higher than that of pure epoxy resin. The double-lap shear strength reached 15.41 MPa at 150 °C, demonstrating excellent high temperature resistance. In addition, the Ep/PHO30/nBN30 film adhesive exhibited excellent heat-aging resistance, humidity, and medium resistance, and the shear strength retention rate after exposure to the complicated environment reached more than 90%. The structural film adhesive prepared showed excellent fatigue resistance in the dynamic load fatigue test, the double-lap shear strength still reached 35.55 MPa after 1,000,000 fatigue cycles, and the strength retention rate was 96.9%, showing excellent durability and fatigue resistance.