Filler Particle Size Research Articles

<strong>Centrifugation effect on size distribution of organic dental filler made from glutinous rice flour</strong>

ABSTRACTIntroduction: Organic fillers made from the green-synthesis process can be utilized in dental treatment due to their non-toxic characteristic of the oral environment. Dental fillers must be smaller to improve their mechanical, physical, and biological properties. Material processing and centrifugation contribute to the size of processed materials. This study evaluates the effect of different centrifugation speeds on the size and distribution of glutinous rice flour as organic dental filler. Methods: This experimental study uses glutinous rice flour suspended in water and then centrifuged at different speeds of 3000 and 6000 rpm compared to untreated glutinous rice flour as control. The particle size was examined using Scanning Electron Microscope (SEM) and Dynamic Light Scattering (DLS). Next, Fourier Transform Infra Spectroscopy (FTIR) and X-ray Diffraction (XRD) were performed to evaluate whether there were structure and crystallinity changes. Finally, the cytocompatibility of fillers was examined by a cell viability test. Results: Centrifugation of glutinous rice flour at 3000 rpm resulted in smaller average size particles, evenly distributed, and higher crystallinity than other groups. There were no changes in functional groups, as shown by FTIR spectra. However, the processed samples were more amorphous compared to the control. Importantly, the processed samples appeared to be non-toxic, with a range of cell viability of 82.75-86.67% after 24 h incubation. Conclusion: Centrifugation speed of 3000 rpm has decreased in size, and a more homogenous particle size of organic filler made from glutinous rice flour. Importantly, it improved the cytocompatibility of particles compared to untreated control. Altogether, we proposed this organic material as a new potential material in the dental application that can be further investigated. Keywords: centrifugation speed; size distribution; organic dental filler; glutinous rice flour

The preparation and evaluation mechanism of mesoporous spherical silica/porous carbon-filled polypropylene composites obtained from coal gasification fine slag.

Coal gasification fine slag is a by-product of the entrained-flow gasifier, which has caused some environmental pollution. Through acid dissolution and calcination at different temperatures, mesoporous spherical silica/porous carbon composite filler was prepared using coal gasification fine slag. The particle size and specific surface area of the composite filler decreased with the decrease of unburned carbon content. The analysis of X-ray photoelectron spectroscopy (XPS) indicated the decrease of oxygen-containing functional groups and the increase of C-C groups with the decrease of the content of carbon. The effects of mesoporous spherical silica/porous carbon with different carbon content on the comprehensive properties of filled polypropylene (PP) were studied. The tensile strength and interface interaction increased at first and then decreased with the decrease of carbon content, due to the synergistic effect of mesoporous spherical silica and rough amorphous carbon. The scanning electron microscope showed that the composite filler with the carbon content of 14.47 wt.% at the calcination temperature of 450°C had the best compatibility with the matrix. Thermodynamic analysis of the PP composites indicated that thermal insulation properties and thermal stability improved with the incorporation of the composite filler. Differential scanning calorimetry (DSC) testing indicated the highest crystallinity of the matrix corresponding to the best comprehensive performances of the composites. XRD patterns revealed that the cooperation of fillers brought characteristic peaks and did not change the primary crystal structure of PP. Simultaneously, heavy calcium powders (CC) were used as comparative fillers, and the overall properties of the PP composites filled with the composite filler were better compared to those of the CC-filled PP composite. The results illustrated that mesoporous spherical silica/porous carbon particles can completely replace CC used in the PP composites, which can be used in auto bumpers, plastic pipes, display cases, and car air deflectors. The CGFS can be processed into a plastic filler for substituting heavy calcium powder particles, which can solve the environmental pollution caused by the accumulation of solid waste.

Parametric study of filler size and properties for a liquid-metal thermal energy storage

Liquid metals are promising heat transfer fluids since they remain liquid in a wide temperature range and can transfer heat efficiently due to their high thermal conductivity. A first-of-its-kind lab-scale thermal energy storage system with filler material and with lead-bismuth as heat transfer fluid is currently tested at the Karlsruhe Institute of Technology, while a 100-kWh storage system is under construction. This numerical study aims to analyse the influence of the filler parameters on the system’s efficiency when the fluid used is a liquid metal. The filler should store part of the thermal energy, be efficiently discharged during the cyclic process and buffer the degradation of the thermocline during standby. For each of these purposes different particle diameters and values of some thermophysical properties of the filler, such as thermal conductivity, specific heat capacity and density, may be advantageous. Their influence on the thermocline extension is numerically investigated using a one-dimensional concentric dispersion model. The results of the parameter study show that for an efficient discharge process in a liquid metal dual-media storage, a small filler particle size is beneficial (d< 10 mm for the reference case chosen in this work). In contrast, the standby phase is favoured by larger diameters, here an order of 10–20 mm. Furthermore, a high thermal conductivity of the filler material improves the discharge performance, due to the enhanced heat transfer, but leads to an accelerated growth of the thermocline during standby. For this case, the optimum value is 5–10 W/mK. Moreover, using a filler material with a high volumetric heat capacity leads to the best overall performance. A full factorial analysis shows that the filler diameter has the strongest effect on the discharge behaviour, while, during standby, the volumetric heat capacity has the largest influence.

The influence of inorganic fillers on the light transmission through resin-matrix composites during the light-curing procedure: an integrative review.

The objective of this study was to perform an integrative review on the effect the inorganic fillers on the light transmission through the resin-matrix composites during the light-curing procedure. A bibliographic review was performed on PubMed using the following search terms: "fillers" OR "particle" AND "light curing" OR "polymerization" AND "light transmission" OR "light absorption" OR "light irradiance" OR "light attenuation" OR "light diffusion" AND "resin composite." The search involvedarticles published in English language in the last 10years. Selected studies reported a decrease in biaxial strength and hardness in traditional resin-matrix composites in function ofthe depth of polymerization. However, there were no significant differences in biaxial strength and hardness recorded along the polymerization depth of Bulk-Fill™ composites. Strength and hardness were enhanced by increasing the size and content of inorganic fillers although some studies revealed a progressive decrease in the degree of conversion on increasing silica particle size. The translucency of glass-ceramic spherical fillers promoted light diffusion mainly in critical situations such as in the case of deep proximal regions of resin-matrix composites. The amount of light transmitted through the resin-matrixcomposites is influenced by the size, content, microstructure, and shape of the inorganic filler particles. The decrease of the degree of conversion affects negatively the physical and mechanical properties of the resin-matrix composites. The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization. As a consequence, the clinical performance of resin-matrix composites can be compromised leading to variable physical properties and degradation. The polymerization mode of resin-matrix composites can be improved according to the type of inorganic fillers in their chemical composition.

Ternary metal oxide filled PEO-based polymer electrolyte for solid-state lithium metal battery: The role of filler particle size

Composite polymer electrolytes with fillers exhibit appealing properties, such as high ionic conductivity, good flexibility, and low cost. However, poor compatibility and electrochemical instability, especially at high current rates, are the disadvantages of these electrolytes. In this study, we report the influence of particle size of Li2O. SiO2. TiO2. P2O5 (LSTP) on polyethylene oxide (PEO)-matrix towards the fabrication of Li-metal batteries with a LiFePO4 cathode. Compared to micron-sized particles, the high surface area of the nanoparticles in the polymer matrix is beneficial for improved electrochemical stability at 0.1 mA cm−2. Furthermore, the nanosized particulates facilitate faster ionic conductivity (1.09 × 10−3 S cm−1 at 80 °C) and excellent stability at higher voltage >4.5 V. Our results clearly indicate the role of filler morphology in enhancing the ionic conductivity and stability. Finally, the full cell made of metallic Li anode and LiFePO4 cathode displays a capacity of 110 mAh g−1 (after 100 cycles under 1C at 60 °C) with a reasonable cycle life using such a nanocomposite solid polymer electrolyte.

Structural, Mechanical and Flammability Characterization of Crosslinked Talc Composites with Different Particle Sizes

The influence of filler particle size on selected physicochemical and functional properties of polymer composites was analyzed. The following test was carried out for the system: the bisphenol A glycerolate (1 glycerol/phenol) di-methacrylate (BPA.DM) was subjected to UV-polymerization in bulk with N-vinyl-2-pyrrolidone (NVP) as a polymer matrix and talc with particle sizes ranging from ≤8 to 710 µm as a non-toxic and cheap mineral filler. An effective method of preparing cross-linked polymeric composites with talc was developed. The obtained samples were subjected to structural analysis and the thermal, mechanical and flammability properties were assessed. It has been empirically confirmed that the talc particles are incorporated into the composite structure. However, with increasing particle size, the composite heterogeneity increases. In the case of the developed method of sample production, homogeneous systems were obtained for particles in the ≤8–250 µm range. The surface roughness of the samples correlates directly with the size of talc particles. The value of Young’s modulus during the axial stretching of samples decreases with the increasing size of talc particles. For the composites containing ≤15 and ≤35 µm talc particles, the highest values were obtained under bending conditions. There was no equivocal effect of particle size on the composites’ swelling in water. The addition of talc reduces the flame height and intensity slightly. The biggest difference was obtained for the composites containing relatively large talc particles. It was proved that the selected properties of polymer composites can be controlled depending on the size of the talc particles.

Thermal conductive polymer composite with similar PTC effect through latent foaming

At present, heat dissipation and heat insulation in power battery packs are two very important aspects in thermal management of electric vehicles. Heat dissipation is needed when the battery is working normally, but heat insulation is needed when the battery is thermal runaway. Now one surrounding material cannot meet these two opposite requirements at the same time. In this work, foaming agent as an initiator was used to prepare a thermal conductive polymer composite. Its thermal conductivity decreases sharply when the temperature rises to 160–180 °C, which shows a similar Positive Temperature Coefficient (PTC) effect. The main factors that affect its thermal conductivity, including foaming agent content, filler type, filler particle size and recombination are also discussed. By controlling the ratio of recombination, the change rate of thermal conductive PTC composite with latent foam structure can increase from only 4 times of formulation with only BN filler to 11 times of formulation with 80%Al2O3/20%BN below 190 °C. The infrared thermal imaging test further confirms that the prepared samples have good thermal conductivity at normal temperature, and the thermal conductivity decreases rapidly with the increase of temperature, confirming the effect of latent foam structure.

On the interfacial lithium dynamics in Li7La3Zr2O12:poly(ethylene oxide) (LiTFSI) composite polymer-ceramic solid electrolytes under strong polymer phase confinement

A better molecular-level understanding of Li+ diffusion through ceramic/polymer interfaces is key to design high-performance composite solid-state electrolytes for all-solid-state batteries. By considering as a case study a composite electrolyte constituted by Li+ conductive Ga3+ doped-Li7La3Zr2O12 (LLZO) garnet fillers embedded within a poly(ethylene oxide) and lithium bis(trifluoromethanesulfonyl) imide polymer matrix (PEO(LiTFSI)), we investigate Li+ interfacial dynamics at conditions of high polymer confinement, with large filler particles in a fully amorphous polymer phase. Such confinement scenario is aimed to capture the conditions near the percolation threshold, at which conductivity enhancement is often reported. Using molecular dynamics simulations combined with the generalized shadow hybrid Monte Carlo method and umbrella sampling calculations, we explain why the hopping towards the polymer phase of the Li+ sitting on the LLZO surface is thermodynamically hindered, while hopping of Li+ from the polymer to the LLZO is kinetically slowed-down by rigidified polymer near the interface. In addition, we demonstrate how the overlap of LLZO-bound polymer chains at high confinement leads to a decrease of Li+ diffusivity within the interstitial space. We put forward that these insights are relevant to interpret the variation of ionic conductivity as a function of volume fraction and filler particle sizes also below the glass transition temperature of the polymer, at the typical operating conditions of lithium ion batteries.

Performance Enhancement of Flexible and Self-Powered PVDF-ZnO Based Tactile Sensors

Flexible, self-powered, and intelligent tactile sensors are essential for accurate sensing in prosthetic devices. This paper explores piezoelectric polyvinylidene difluoride - zinc oxide (PVDF-ZnO) nanocomposite layer-based sandwich assembly as tactile sensor. ZnO nanoparticle addition as filler can overcome the challenges associated with PVDF-based tactile sensors. The effect of filler particle size on the enhancement of sensing performance of PVDF-ZnO-based tactile sensors is investigated. Structural, morphological, piezoelectric and thermal studies were performed on the PVDF-ZnO composite layers using SEM, EDS, DC-EFM and Raman Spectroscopy. A comparative investigation of the potential developed across the sensor samples with different filler particle sizes was performed for touch and bending actions. The obtained results showed a remarkable improvement in performance due to particle size reduction of the ZnO fillers. The nanocomposite sensor with less filler particle size generated more voltage on the same applied force. The experimental analysis demonstrates that the filler size reduction can improve the piezo-voltage response up to 123 mV/N for dynamic touch events. The self-powered sensor also has excellent potential in detecting finger bending action with a response of 29 mv/&#x00B0;. The results demonstrate the promising application of the polymer nanocomposite-based sensor in the prosthetic application.

Impacts of filler loading and particle size on the transition to linear-nonlinear dichotomy in the rheological responses of particle-filled polymer solutions

In this study, the nonlinear behavior of carbon black-filled polybutadiene solutions under large-amplitude oscillatory shear is investigated. The results show that in the nonlinear regime, the third harmonic intensity, as measured by the ratio of the third to the first harmonics I3/I1, decreases significantly above a critical concentration ϕc of the polymer in the matrix, which results in the amplitude stress deviating strongly from the linear dependence of strain, while the time dependence of stress remains sinusoidal. Increasing the filler particle size significantly decreases the critical ϕc. However, increasing the filler loading basically has no effect on the transition to linear-nonlinear dichotomy. This transition happens when the mesh size ξ of the entangled polymer network in the matrix becomes smaller than the primary filler particle size. Above ϕc, the topological hindrance of the entangled polymer chains apparently considerably slows down the recovery speed of the broken filler network in the material. Hence, the quasisinusoidal response in the system that has a strain-dependent modulus is probably due to the restoration of the broken filler network requiring longer than the time scale of a typical dynamic perturbation.

Experimental characterisation and modelling of the strain rate dependent mechanical response of a filled thermo-reversible supramolecular polyurethane

• A sugar-filled healable polyurethane composite was fabricated, characterized and modelled. Composites consisting of a polymer binder filled with various particles are widely used in industrial applications, and key to their engineering design is the ability to produce mechanical models of these materials. One limitation of many composites is the use of cross-linked elastomers as matrix materials, which reduces re-usability and recyclability. In this research, a recently developed reusable and low temperature processable supramolecular polyurethane was mixed with sugar particles to produce a model composite material with different particle sizes or volume fractions, which were subsequently characterised and modelled. Large strain mechanical properties of the material were analysed in compression at strain rates up to approximately 1800 s −1 , supported by measurements of the small strain viscoelastic response at different temperatures and frequencies. A model was developed that combined the known viscoelastic response of the supramolecular polyurethane with filler reinforcement and strain activated damage equations calibrated against quasi-static experiments. The model provided a good prediction of the high strain rate behaviour, for which the effect of adiabatic heating in the sample was also considered. The model parameters were related back to the filler particle size and volume fraction. Finally, a preliminary study of geometry and strength recovery was performed.

A PMMA bone cement with improved antibacterial function and flexural strength

A novel non-leaching antibacterial bone cement has been developed and evaluated. An antibacterial furanone derivative was synthesized and covalently coated onto the surface of alumina filler particles, followed by mixing into a conventional poly(methyl methacrylate) bone cement. Flexural strength and bacterial viability were used to evaluate the modified cements. Effects of coated antibacterial moiety content, coated alumina filler particle size and loading were investigated. Results showed that almost all the modified cements showed higher flexural strength (up to 10%), flexural modulus (up to 18%), and antibacterial activity (up to 67% to S. aureus and up to 84% to E. coli), as compared to original poly(methyl methacrylate) cement. Increasing antibacterial moiety and filler loading significantly enhanced antibacterial activity. On the other hand, increasing coated filler particle size decreased antibacterial activity. Increasing antibacterial moiety content and particle size did not significantly affect flexural strength and modulus. Increasing filler loading did not significantly affect flexural modulus but reduced flexural strength. Antibacterial agent leaching tests showed that it seems no leachable antibacterial component from the modified experimental cement to the surrounding environment. Within the limitations of this study, the modified poly(methyl methacrylate) bone cement may potentially be developed into a clinically useful bone cement for reducing in-surgical and post-surgical infection.

Daytime passive radiative cooling materials based on disordered media: A review

Daytime passive radiative cooling (DPRC), a cooling method without extra energy consumption, has attracted more and more attentions in recent years. The strong reflection ability in the sunlight waveband (0.3–2.5 μm) and the intensive infrared radiative characteristic within the atmospheric window (8–13 μm), which called spectral selectivity, are the key point to realize DPRC. Spectral selectivity achieved by photonic crystals are difficult to promote on large scale because of complicated manufacturing process. With the rapid development of nanotechnology, materials with disordered media are playing an increasingly important role in functional devices. Combining disordered media with polymeric photonics will become an effective way to realize the large-scale preparation of DPRC materials. This review summarizes two kinds of disordered DPRC structures, paint and film with fillers, as well as porous polymers, including the influence of types, morphology, and particle size of fillers, as well as pore morphology, pore size distribution and preparation methods of porous polymers on the spectral performance and cooling effect of radiators. Also, we briefly introduce the biologically inspired microstructures for radiative cooling, in order to provide guidance for the practical application of DPRC materials.

Dielectric Properties and 3D-Printing Feasibility of UV-Curable Resin/Micron Ceramic Filler Composites

To prepare high-permittivity composite materials for dielectrically functional gradient materials (d-FGMs) by the stereolithographic 3D-printing technique, three ceramic powders (i.e., alumina, barium titanate, and strontium titanate) are selected as functional fillers for a UV-curable resin matrix. The viscosity and UV curing depth of the uncured slurry are tested for feasibility of 3D printing. Comprehensive electrical properties, including volume resistivity, permittivity, dielectric loss, and breakdown strength of the cured composites are measured. The effects of the filler types, morphologies, particle sizes, and volume fractions on the UV curing characteristics of the slurry and dielectric properties of cured composites are systematically analyzed. The experimental results show that spherical fillers with large particle sizes, smooth surfaces, and high permittivity are conducive for reducing the slurry viscosity, increasing curing depth and adjusting the composite’s permittivity over a wide range. We believe that the proposed strategy for material system establishment can improve the 3D printability of high-permittivity composites and promote other applications of the d-FGMs by the stereolithography technique.

Terahertz frequency domain sensing for fast porosity measurement of pharmaceutical tablets

Porosity is an important property of pharmaceutical tablets since it may affect tablet disintegration, dissolution, and bio-availability. It is, therefore, essential to establish non-destructive, fast, and compact techniques to assess porosity, in situ, during the manufacturing process. In this paper, the terahertz frequency-domain (THz-FD) technique was explored as a fast, non-destructive, and sensitive technique for porosity measurement of pharmaceutical tablets. We studied a sample set of 69 tablets with different design factors, such as particle size of the active pharmaceutical ingredient (API), Ibuprofen, particle size of the filler, Mannitol, API concentration, and compaction force. The signal transmitted through each tablet was measured across the frequency range 500–750 GHz using a vector network analyzer combined with a quasi-optical set-up consisting of four off-axis parabolic mirrors to guide and focus the beam. We first extracted the effective refractive index of each tablet from the measured complex transmission coefficients and then translated it to porosity, using an empirical linear relation between effective refractive index and tablet density. The results show that the THz-FD technique was highly sensitive to the variations of the design factors, showing that filler particle size and compaction force had a significant impact on the effective refractive index of the tablets and, consequently, porosity. Moreover, the fragmentation behaviour of particles was observed by THz porosity measurements and was verified with scanning electron microscopy of the cross-section of tablets. In conclusion, the THz-FD technique, based on electronic solutions, allows for fast, sensitive, and non-destructive porosity measurement that opens for compact instrument systems capable of in situ sensing in tablet manufacturing.

Mastering of Filled Rubber Strength beyond WLF: Competition of Temperature, Time, Crack Deflection and Bond Breaking.

Tensile strength is an important indicator for elastomer toughness. However, in filled materials, its dependency on temperature and time appears to be poorly understood. We present experimental tensile data of carbon-black-filled ethylene propylene diene rubber at different temperatures. Tensile strength vs. filler loading exhibited a temperature-dependent S-shape and could be rescaled to collapse onto a single master curve. A model based on the extension of the time–temperature superposition principle, crack deflection, and breakage of covalent bonds is proposed. It successfully predicted the behavior of tensile strength due to the change of the filler particle size and filler amount, temperature variation, and deformation speed typically found in the literature. Moreover, stress relaxation during temperature ramp-up was reproduced correctly. Altogether, the successful modeling suggests that the true toughness of rubber (e.g., chemical bonds) becomes important once enough crack-screening filler is present.

Improvement of the Electrical-Mechanical Performance of Epoxy/Graphite Composites Based on the Effects of Particle Size and Curing Conditions.

This study aims to improve the electrical-mechanical performance of traditional epoxy/graphite composites for engineering applications. The improvement in the properties of these composites depended on the incorporation of different sizes of graphite particles of the same type and controlling their curing process conditions. The thermal properties and microstructural changes were also characterized. A maximum in-plane electrical conductivity value of approximately 23 S/cm was reported for composites containing 80 wt.% G with a particle size of 150 µm. The effect of combining large and small G particles increased this value to approximately 32 S/cm by replacing the large particle size with 10 wt.% smaller particles (75 µm). A further increase in the electrical conductivity to approximately 50 S/cm was achieved due to the increase in curing temperature and time. Increasing the curing temperature or time also had a crucial role in improving the tensile strength of the composites and a tensile strength of ~19 MPa was reported using a system of multiple filler particle sizes processed at the highest curing temperature and time compared to ~9 MPa for epoxy/G150 at 80 wt.%. TGA analysis showed that the composites are thermally stable, and stability was improved by the addition of filler to the resin. A slight difference in the degraded weights and the glass transition temperatures between composites of different multiple filler particle sizes was also observed from the TGA and DSC results.

Properties and Degradability of Poly(Butylene Adipate-Co-Terephthalate)/Calcium Carbonate Films Modified by Polyethylene Glycol.

Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable polymer synthesized from petrochemical resources. PBAT has an exceptionally high elongation at break values which makes it one of the most promising substitutes for LDPE packaging films. However, the applicability of PBAT films is still limited by low strength and high production costs. In this work, we used polyethylene glycol 600 (PEG-600) as a coating agent to modify the surface of calcium carbonate and improve compatibility with the polymer matrix. A series of PBAT/CaCO3 composite films having different CaCO3 particle size and content of coating agent was prepared using extrusion blow molding. The effect of particle size of CaCO3 filler and the content of a coating agent on the mechanical and rheological properties of composite films have been studied. The biodegradation properties have been tested by burying the samples in soil or keeping them in artificial seawater for 90 days. It was shown that the addition of PEG-600 improves compatibility between the matrix and CaCO3 filler as polar –OH groups of PEG have a high affinity toward the polar surface of CaCO3. Moreover, the hydrophilicity of PEG-600 increased the diffusivity of water molecules and facilitated PBAT degradation. This work provides experimental data and theoretical guidance that support the development of high-performance PBAT/calcium carbonate films for the single use packaging industry.

Particle morphology of mineral filler and its effects on the asphalt binder-filler interfacial interaction

This paper focused on the particle morphology of mineral filler and its effects on asphalt binder-filler interfacial interaction. The limestone, basalt, and granite fillers with various particle sizes were selected to prepare asphalt mastics. The relationship between morphological characteristics of mineral filler and asphalt binder-filler interfacial interaction was established. The results show that the angularity index and fractal dimension decrease while the form factor increase with the decreasing particle size. The granite filler particles demonstrated the higher morphological index values than the limestone and basalt ones. The K-B-G* value based on Palierne emulsion model exhibits the least susceptibility but strongest stability to filler particle size among the evaluation parameters studied. Form factor is the determining influential factor for asphalt binder-filler interfacial interaction, regardless of filler lithology. Furthermore, the packing characteristics of filler particles and the associated mastic morphologies could provide insight to possible relationship between particle morphology and interfacial behavior. All the results contribute to the selection of appropriate mineral filler to improve the asphalt binder-filler interfacial interaction and then the performance of asphalt mix system.

Progress on the polymer composite insulating materials with high thermal conductivity

<p indent="0mm">The continuing miniaturization and increasing power density of electrical and electronic equipment have created higher requirements for the heat dissipation capacity of packing and insulating materials. Long-term operation of electronic devices will cause local overheating of core components, which will significantly affect the reliability and service life of the components. Heat dissipation has even become a technical bottleneck in the development of electronic devices with high integration. Therefore, developing new composite materials which offer excellent thermal conductivity has attracted significant interest worldwide in recent years. To address these issues, researchers improve the thermal conductivity of polymer materials mainly through the following two aspects. One is to modify the polymer body so that the internal molecular and chain structure of the polymer has a high degree of crystallization or orientation, thereby improving its thermal conductivity, but this method is a cumbersome preparation process and is still in the laboratory research stage. Second, inorganic fillers with high thermal conductivity can be filled in the polymer preparation process to form a thermal conductivity channel, thus improving the thermal conductivity. The latter composite material has been widely used in electronic packaging, electric machine potting and other fields because of its low cost, simple processing and convenient industrial production. This paper reviews the research status and progress of the preparation and application of composites with high thermal conductivity in recent years. Firstly, the factors that affect the thermal conductivity of materials are mainly introduced from two aspects: (1) The crystallinity of polymer matrix, the interaction between molecular chains and the micro-scale ordered structure; (2) the particle size, doping amount and geometry of thermal conductivity filler. Researchers have found that the key to obtaining composites with high thermal conductivity is to increase the ordered structure of the polymer or make the thermal conductivity packing form the maximum density thermal conductivity path consistent with the heat transfer direction in the polymer system. In view of the above key factors, we summarize five preparation methods that significantly improve the thermal conductivity of composites: Functionalized packing surface treatment, random blending, electrostatic spinning, field control and three-dimensional skeleton construction. Among them, constructing the 3D skeleton is considered as the most promising method at present. A large number of papers reported the use of casting technology, 3D printing technology and other methods to prepare three-dimensional thermal conductivity networks. In the casting technology, the 3D thermal skeleton is firstly formed by the ice template method or salt template method, and then the polymer matrix such as epoxy resin and PDMS is poured into the 3D skeleton to obtain the composite material with high thermal conductivity. This method fundamentally improves the thermal conductivity of composites. Finally, in view of the current situation of polymer insulating materials with high thermal conductivity in industry applications, we provide an outlook on the future directions for the development of composite materials. It is hoped that material properties can be optimized from the microscopic point of view in the future to obtain polymer composites with higher thermal conductivity with less filler and lower cost.