Experimental Study On Thermal Conductivity Of Peek Fiber Modified By Silver Nanowires At Dynamic Temperature

In recent years,with the rapid development of flexible electronic devices continue to develop in the direction of more miniaturization and integration,the problem of heat dissipation of electronic devices is particularly important,and the temperature is too high to cause unstable operation of electronic devices,reduce the reliability of flexible electronic devices.Effectively solving the heat dissipation problem of electronic devices is of great significance to improve the overall performance of flexible electronic devices.The heat transfer of electronic devices by using high thermal conductivity materials can effectively improve the heat dissipation performance of electronic devices.In this paper,the silver nanowires were coated on the surface modified polyether ether ketone fiber matrix by dip-coating method.The thermal diffusion coefficient of silver nanowires polyether ether ketone fiber composite at the temperature of 10 K?290 K was measured by transient electrothermal technique,and then the thermal conductivity coefficient of the composite was obtained.The thermal conductivity of the composite at room temperature is 1.39 Wm^-1K^-1,which is 4.56 times higher than that of the unmodified polyether ether ketone.The silver nanowires adhere to the surface of the polyether ether ketone fiber uniformly and form a thermal conductivity network by lapping each other without obvious agglomeration,which effectively improves the thermal conductivity of the composite.The thermal diffusivity of the composites gradually increases during the temperature decrease from 290 K to 10 K.The thermal diffusivity of the composites is4.26×10^-7 m²/s at 290 K and 1.35×10^-6 m²/s at 10 K.The thermal diffusion coefficient is increased by a factor of 2.17.This is because with the decrease of temperature,the mean free path of phonon changes and the phonon scattering decreases,so the thermal diffusivity of the composites is significantly improved.The thermal conductivity of the composite decreases as the temperature decreases from 290 K to 10 K.The thermal conductivity of the composite is 1.39Wm^-1K^-1 at 290 K and 0.25 Wm^-1K^-1 at 10 K.Due to the change of the temperature,the volume specific heat of the composite will have a certain impact and decreases from 290 K to 10 K.The contribution of volume specific heat to thermal conductivity is greater than that of thermal diffusion coefficient,which leads to the decrease of thermal conductivity with the decrease of temperature.When the temperature decreases from 290 K to 10 K,the resistivity decreases with the decrease of temperature,and tends to be flat at lower temperature.The number of excited phonons decreases with the decrease of the temperature,the electron scattering by phonons decreases and the resistivity decreases gradually.At low temperature,the resistivity tends to be stableThe effect of structural defects on the thermal conductivity of composite was investigated by defining the thermal resistance coefficient,after fitting the resistance temperature coefficient at different temperatures,the residual resistance temperature coefficient of the composite is 7.96×10⁵ s/m²,and the ideal thermal conductivity of the composite is 2.42 Wm^-1K^-1.According to the residual resistance temperature coefficient,the lattice size of the composite is 0.86 nm.