Breaking Through Bottlenecks for Thermally Conductive Polymer Composites:A Perspective for Intrinsic Thermal Conductivity,Interfacial Thermal Resistance and Theoretics

Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer composites.Aimed at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental optimization.Also,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.

Roadmap towards new generation liquid metal thermal interface materials

As electronic devices continue to evolve toward miniaturization and integration,traditional thermal interface materials(TIMs)are no longer able to meet the ever-tougher thermal management challenges.Owing to their high thermal conductivity and excellent conformability within a highly confined space,liquid metals have great potential for advanced thermal management in various cutting-edge devices and have become a key candidate for next-generation high-performance TIMs.In addition to already known materials,such as liquid metal alloy TIMs,particle-filled liquid metal TIMs,and liquid metal-filled TIMs,more TIMs are still being developed.This review presents a systematic classification of the liquid metal TIMs developed thus far,interprets the fundamental mechanisms underlying material innovation and in-situ heat transfer enhancement,and comparatively evaluates their respective advantages and shortcomings.Subsequently,a series of representative theoretical models for characterizing the thermal conductivities of composites are summarized,and the limits of the thermal conductivity of liquid metal TIMs are predicted to guide practical R&D efforts.To address the urgent need for higher-performance TIMs to overcome future thermal management challenges of electronic devices,a roadmap is outlined for the development of high-performance liquid metal TIMs,and a strategy for running these technologies is demonstrated.

Time fractional dual-phase-lag heat conduction equation

We build a fractional dual-phase-lag model and the corresponding bioheat transfer equation, which we use to interpret the experiment results for processed meat that have been explained by applying the hyperbolic conduction. Analytical solutions expressed by H-functions are obtained by using the Laplace and Fourier transforms method. The inverse fractional dual-phase-lag heat conduction problem for the simultaneous estimation of two relaxation times and orders of fractionality is solved by applying the nonlinear least-square method. The estimated model parameters are given. Finally, the measured and the calculated temperatures versus time are compared and discussed. Some numerical examples are also given and discussed.

Governing the Inclination Angle of Graphite Flakes in the Graphite Flake/Al Composites by Controlling the Al Particle Size via Flake Powder Metallurgy

The inclination angle of the flake particle has a significant impact on the in-plane thermal conductivity of composites.The graphite flake/Al composites(50 vol%)with different inclination angles were fabricated via flake powder metallurgy,and the results show that with increasing the size of Al particle from 25.6 to 50.7μm,the inclination angle of graphite flake decreases from 7.3°to 4.4°,while the in-plane thermal conductivity of composites increases from 473 to 555 Wm-1 K-1.Based on the rules of mixture,an effective model was established to qualify and quantify the relation between the inclination angle and the in-plane thermal conductivity of the corresponding composites.This model can also be applied to other flake particle-reinforced composites.