Study Of Thermal And Dielectric Conductivity Of Polyetherketoneketone Resin-based Composite Films

Due to the continuous development and rise of information technology,the power density of new generations of electronic components is increasing.With this increase in power density comes an increase in heat generation,which necessitates greater heat dissipation performance requirements for electronic and electrical equipment materials.However,the high power density of electronic components can also cause dielectric losses,resulting in reduced equipment performance and energy utilization.Polymer materials,which typically have poor thermal conductivity,often require modification through techniques such as grafting,filling,and other means to improve their overall performance and thermal conductivity for a variety of market environments and products.Among these techniques,particle filling has become a popular research topic due to its ease of processing,low cost,and flexible structure design.Polyetherketoneketone（PEKK）is a special engineering plastic with high strength,high temperature resistance,acid and alkali resistance,and radiation resistance,and it is widely used in aerospace,medical,electrical and electronic,and automotive fields.However,the high melting point of PEKK requires specialized processing methods such as melt extrusion,hot pressing,and flow extension,which are primarily suited for large-scale industrial equipment preparation.This method is not well-suited for the field of electronic appliances,where miniaturization is a key development trend,and the limitations of PEKK’s processing method constrain its potential for development.This paper introduces a new processing method for preparing Polyetherketoneketone films using the template spraying method,which is simpler and faster than traditional processing methods such as melting,hot pressing,molding,and blow molding.Additionally,functional particles such as hexagonal boron nitride（h-BN）,aluminum trioxide（Al₂O₃）,and carbon nanotubes（MWCNTs）were modified and compounded to create functional composite particles with excellent thermal conductivity and dielectric properties.These composite particles were then used to prepare Polyetherketoneketone composite films using the same template spraying method,demonstrating the wide applicability of this method.The main contributions of this work are as follows.1.To configure the Polyetherketoneketone dispersion and slurry,deionized water and ethanol were used as the base solvent,and various additives such as emulsifiers,dispersants,defoamers,and leveling agents were added.The viscosity rheological characteristics of the dispersion and slurry were studied using a rheometer to regulate the dispersion and film formation effect of Polyetherketoneketone slurry on the template.In this paper,we propose a simple and fast processing method for preparing Polyetherketoneketone films using the template spraying method.Compared to traditional processing methods such as melting,hot pressing,molding and blow molding,this method is more efficient.In addition,we modified and compounded hexagonal boron nitride（h-BN）,aluminum trioxide（Al₂O₃）,and carbon nanotubes（MWCNTs）particles to obtain functional composite particles with excellent thermal conductivity and dielectric properties.We then added these composite particles to the Polyetherketoneketone slurry to prepare composite films using the template spraying method.The BN-CNTs composite particles were obtained by covalently bonding hydroxylated hexagonal boron nitride（BN-OH）with acidified carbon nanotubes（MWCNTs-COOH）in N,N-dimethylacetamide.The composite particles were characterized using FTIR,XRD,and TEM tests,which confirmed the connection structure.After dispersion in a solution,the mixed slurry was obtained by adding polyether ketone co-blending.The crystalline behavior of the Polyetherketoneketone composite films was analyzed using XRD,DSC,and TG tests.The results showed that the filling of composite particles enhanced the crystallization ability and thermal stability of Polyetherketoneketone.At 5 wt.%particle filling content,the crystallinity of the composite film increased by 60%,providing more continuous thermal conductivity paths for phonons and enhancing thermal conductivity.The thermal conductivity of the composite film measured by a thermal conductivity meter was 0.128W/m.K,which increased by 66%compared to the pure sample.Furthermore,the filling of particles significantly reduced the dielectric constant and dielectric loss performance of the composite film.At 5 wt.%particle filling content,the dielectric constant of the composite film in the low-frequency region（<100 Hz）reduced by 69%,and the dielectric loss in the high-frequency region（200000 Hz）reduced by 95%.This reduction effect increased with the increase of composite particle filling content.2.Using the viscosity property of polydopamine,Al₂O₃-CNTs composite particles were obtained by using dopamine hydrochloride and self-polymerization reaction with trihydroxyaminomethane（Tris）,mixing Al₂O₃ particles in the reaction system to make polydopamine grow on the surface of Al₂O₃ particles,and then adding carbon nanotubes to make them adhere to the surface of the particles.The FTIR,XRD and TEM tests showed that the composite particles had been successfully prepared,and the poly（ether ketone）composite films were also prepared by the thin plate spraying method.The thermal and dielectric properties of the composite films were characterized by DSC,TG,thermal conductivity meter,and dielectric tests.When the particle content was 20 wt.%,the DSC crystallization enthalpy of the composite film increased from 15.3 J/g to 21.1 J/g by 37%,and the crystallization performance and thermal stability of the composite film also became stronger,and the measured thermal conductivity was 0.107 W/m.K by 38%compared with the pure sample.Similarly,the dielectric constant of the composite film at 20 wt.%particle content is only 2.78 in the low frequency region（<100 Hz）,a reduction of about 59%,and the dielectric loss is reduced by 89%at high frequencies（200000 Hz）.