The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Liqun Zhang - One of the best experts on this subject based on the ideXlab platform.
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enhanced fatigue and durability properties of natural rubber composites reinforced with carbon nanotubes and graphene oxide
Materials, 2020Co-Authors: Hao Guo, Liqun Zhang, Istvan Zoltan Halasz, David Zoltan Pirityi, Tamas Barany, Long Zheng, Li Liu, Shipeng WenAbstract:Fibrous carbon nanotubes (CNTs) and lamellar graphene oxide (GO) exhibit significant advantages for improving the fatigue properties of rubber composites. In this work, the synergistic effect of CNTs and GO on the modification of the microstructure and fatigue properties of natural rubber (NR) was comprehensively investigated. Results showed that CNTs and GO were interspersed, and they formed a strong Filler Network in the NR matrix. Compared with those of CNT/NR and GO/NR composites, the CNT-GO/NR composites showed the smallest crack precursor sizes, the lowest crack growth rates, more branching and deflections, and the longest fatigue life.
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improved electromechanical properties of silicone dielectric elastomer composites by tuning molecular flexibility
Composites Science and Technology, 2018Co-Authors: Dan Yang, Shuo Huang, Mengnan Ruan, Shuxin Li, Yibo Wu, Liqun ZhangAbstract:Abstract Silicone rubber (SR) composites exhibited significantly improved electromechanical properties via tuning the molecular flexibility by adding plasticizer. To decrease the enhanced elastic modulus of SR composites filled with high-dielectric-constant BaTiO3 (BT) particles, silicone oil (SO) plasticizer was incorporated into the BT/SR composite to weaken the intermolecular interactions and break the structure of the Filler Network as result of swelling effect. The obviously decreased elastic modulus resulted in a high electromechanical sensitivity β and a relatively large actuated strain of 10.6% for 20 phr BT/SR composite filled with 50 phr SO at a low electric field of 25 kV/mm, approximately 380% increase compared to that of pure SR at the same electric field. The result indicates that tuning flexibility of composites is a good strategy to obtain high-performance dielectric elastomers.
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dispersion and Filler Network structure of fibrillar silicates in elastomers
Chinese Journal of Polymer Science, 2016Co-Authors: Haibin Sun, Liqun Zhang, Wang Qiao, Nanying Ning, Ming TianAbstract:The dispersion and Filler Network of fibrillar silicate (FS) in elastomers were studied. The results showed that a good dispersion of FS in matrix during mechanical blending in unvulcanized composites contributed to a strong FS Filler Network, different from that of traditional reinforcing Fillers. Meanwhile, the Filler re-aggregation during vulcanization caused by the overlapping and intertwining of FS further strengthened the Filler Network. The factors including Mooney viscosity and molecular polarity of elastomer, type and amount of silane coupling agents used for Filler modification, that may influence the Filler Network, were studied. Our study helps us to understand the mechanism for the formation of Filler Network of FS in elastomers and provides guidance for the preparation of high performance FS/elastomer composites.
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effect of silane coupling agent on the structure and mechanical properties of nano dispersed clay filled styrene butadiene rubber
Polymer Composites, 2016Co-Authors: Shaojian He, Xiaoze Du, Liqun Zhang, Lin ChenAbstract:In rubber nanocomposites containing inorganic clay, the reinforcement effect has always been relatively insignificant due to the poor interfacial interaction between the rubber matrix and clay Fillers. In this work, the silane coupling agent bis[3-(triethoxysilyl)propyl]tetrasulfide (Si-69) was employed through mechanically blending with styrene butadiene rubber (SBR)/clay (100/30) nanocompound that was prepared by combined latex compounding and spray-drying technique, to serve as the molecular bridge between SBR matrix and clay Filler and strengthen the interfacial interaction. TEM and XRD characterization indicated that Si-69 significantly improved the dispersion of the silicate layers in the SBR matrix. The RPA analysis and the mechanical property study of the SBR/clay nanocomposites revealed that the Filler Network interaction was weakened while the Filler-rubber interaction was strengthened upon the addition of Si-69. POLYM. COMPOS., 37:890-896, 2016. (c) 2014 Society of Plastics Engineers
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preparation and performance of silica sbr masterbatches with high silica loading by latex compounding method
Composites Part B-engineering, 2016Co-Authors: Yan Gui, Liqun Zhang, Junchi Zheng, Dongli HanAbstract:Abstract With the help of a new coupling agent Si747, silica water slurry and styrene–butadiene rubber (SBR) latex were successfully co-coagulated by the latex compounding method, even silica/SBR masterbatches with silica loading as high as 200 phr could be prepared by such method. Compared to the traditional dry blending method, the latex compounding method had lower energy consumption during mixing and better silica dispersion in rubber matrix. Meanwhile, the effect of the amount of silica in the SBR latex on the properties of silica/SBR composites was investigated, and the results showed that the larger the amount of silica in the rubber matrix, the stronger the Filler Network. The performance of these composites was good and the dispersion of silica was relatively homogeneous. Furthermore, the masterbatches with high silica loading were mixed with emulsion polymerized styrene–butadiene rubber (ESBR) or solution polymerized styrene–butadiene rubber (SSBR). The silica dispersed better in ESBR than in SSBR.
Ke Wang - One of the best experts on this subject based on the ideXlab platform.
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largely enhanced thermal conductivity of hdpe boron nitride carbon nanotubes ternary composites via Filler Network Network synergy and orientation
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Junjin Che, Mengfan Jing, Dingyao Liu, Ke WangAbstract:Abstract In recent years, hybrid Fillers with different dimension are frequently used to improve the thermal conductivity of polymer/Filler composites. While the combined effect of hybrid Filler and orientation on the thermal conductivity of polymer/Filler composites has rarely reported. In this work, high density polyethylene (HDPE)/boron nitride (BN)/carbon nanotubes (CNT) ternary composites were prepared by melt blending then hot rolled to obtain oriented sheets. The thermal conductivity and internal structure of the obtained sheets were investigated and compared with those obtained by hot-pressed sheets with random distributed structure. Two representative systems were used, the one is that BN content is low and forms the isolated dispersions (using HDPE/5BN/CNT composites with 5 wt% of BN as example), the other one is that BN content is high and forms Network structure (using HDPE/25BN/CNT composites with 25 wt% of BN as example). For hot-pressed samples, no synergy between BN and CNT was found for HDPE/5BN/CNT system with BN dispersed in isolation in HDPE matrix, while an obvious increase of thermal conductivity was seen for HDPE/25BN/CNT system with BN Network formation in HDPE matrix, and a 300% increase of thermal conductivity could be achieved as 3 wt% of CNT was added, compared with that of net HDPE. For hot-rolled samples, an increase of thermal conductivity was observed for both HDPE/5BN/CNT and HDPE/25BN/CNT ternary composites by adding CNT into the composites, suggesting the importance of Filler orientation in the enhancement of thermal conductivity in polymer/Filler composites with hybrid Filler. The combined effect of hybrid Filler and orientation could result in a further increase of thermal conductivity and 600% increase of thermal conductivity could be achieved. Finally, based on the analysis of internal structure of prepared samples as obtained by SEM observation, rheology and XRD measurements, a possible mechanism for the enhancement of thermal conductivity via hybrid and orientation was proposed. Our work is important and could shed light for the preparation of polymer composites with super thermal conductivity.
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largely improved thermal conductivity of hdpe expanded graphite carbon nanotubes ternary composites via Filler Network Network synergy
Composites Part A-applied Science and Manufacturing, 2017Co-Authors: Junjin Che, Yunjie Lin, Ke WangAbstract:Abstract Utilizing the synergistic effect of various Fillers is an efficient strategy to enhance the thermal conductivity of polymer composites, in which the key is to modulate their dispersion and Network formation in polymer matrix. In this work, expanded graphite (EG) was individually added into high density polyethylene (HDPE) to fabricate first the binary composites through melt blending. The electrical conductivity of the prepared composites was measured to determine the percolation threshold for HDPE/EG composites. Then HDPE/EG composites with three compositions, representing below percolation, just percolation and above percolation, respectively, were chosen as matrix and melt mixed with carbon nanotubes (CNTs) to make HDPE/EG/CNTs ternary composites. It was found that adding CNTs results in a linear increase of thermal conductivity for HDPE/EG composites with composition below percolation, along the line by adding the same amount of EG. While a jump of thermal conductivity was observed by adding CNTs for HDPE/EG composites with composition just and above percolation. The electrical conductivity and rheology property were measured and SEM experiment was carried out to explore the Filler dispersion and their Network formation in HDPE matrix. All the results suggested a possible location CNTs in EG Filler Network for HDPE/EG composites with composition just and above percolation. Thus the formation of CNTs Network within EG Network is attributed to the main reason for the largely enhanced thermal property. This work endows a new enlightenment to fabricate the composites with a great thermal conductivity.
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the role of clay Network on macromolecular chain mobility and relaxation in isotactic polypropylene organoclay nanocomposites
Polymer, 2006Co-Authors: Ke Wang, Hong Yang, Qin Zhang, Si Liang, Jinni Deng, Qiang Fu, Xia Dong, Dujin WangAbstract:Abstract It is well known that a so-called “three-dimensional Filler Network structure” will be constructed in the polymer/layered silicate nanocomposites when the content of layered clay reaches a threshold value, at which the silicate sheets are incapable of freely rotating, due to physical jamming and connecting of the nanodispersed layered silicate. In this article, the effect of such clay Network on the mobility and relaxation of macromolecular chains in isotactic polypropylene(iPP)/organoclay nanocomposites was investigated in detail with a combination of DMTA, DSC, TGA, TEM, rheometry and melt flow index measurements. The main aim is to establish a relationship between the mesoscopic Filler Network structure and the macroscopic properties of the polymer nanocomposites, particularly to explore the role of the clay Network on the mobility and relaxation of macromolecular chains. It was found that the nanodispersed clay tactoids and layers play less important or dominant roles on the mobility of iPP chains depending on the formation of percolating Filler Network. The turning point of macroscopic properties appeared at 1 wt% organoclay content. Before this point, the effect of organoclay can be negligible, and the increase of chain mobility was ascribed to the decrease of molecular weight of polymer chains, as commonly occurs during dynamic melt processing; after this point, however, a reduced mobility of chains and a retarded chain relaxation were observed and attributed to the formation of a mesoscopic Filler Network. The essential features of such a mesoscopic organoclay Network were estimated and discussed on the basis of stress relaxation and structural reversion measurements. A schematic model was proposed to describe the different relaxation and motion behaviors of macromolecular chains in the unfilled polymer and the filled hybrids with partial and percolated organoclay Networks, respectively.
Qiang Zheng - One of the best experts on this subject based on the ideXlab platform.
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Rigid nanoparticles promote the softening of rubber phase in filled vulcanizates
Polymer, 2019Co-Authors: Yihu Song, Ruiquan Yang, Xinyan Shi, Qiang ZhengAbstract:Abstract Enhanced mechanical softening accompanying nanoparticles reinforcement of rubber is an important source of energy dissipation and heat buildup of industrially engineered elastomers. Its mechanism previously assigned to damages in the Filler Network, rubber-Filler interface and rubber phase remains controversial in more than 70 years. Through investigating the typical Payne effect of styrene-butadiene rubber gum and its vulcanizates as well as silica filled compounds and vulcanizates and the Mullins effect of unfilled and filled vulcanizates, we herein evidence that the Filler-promoted softening of the rubber phase softens the filled elastomer nanocomposites. Especially we show that the Mullins effect is relevantly involved in the disentanglement/re-entanglement of dangling chains superposed on the entropically elastic Network of the rubber phase. This paper clarifies that the mechanism of nonlinear mechanical softening for filled rubber compounds and vulcanizates should be rooted in macromolecular chains in the entanglement Network (gum and filled compounds) or long dangling chain in non-ideally crosslinked Network (vulcanized gum and filled vulcanizates), rather than damages involved in the “Filler Network” or Filler-rubber interface. This suggests that adjusting the nonideally crosslinked Network structure of viscoelastic rubber matrix should be able to optimize the use performance of the rubber nanocomposite products.
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understanding the reinforcement and dissipation of natural rubber compounds filled with hybrid Filler composed of carbon black and silica
Chinese Journal of Polymer Science, 2017Co-Authors: Yihu Song, Lingbin Zeng, Qiang ZhengAbstract:The performance of reinforced rubber compounds depends on the Filler composition while the reinforcement and dissipation mechanisms still remain unclear. Herein linear and nonlinear dynamic rheological responses of carbon black/silica hybrid Filler filling nature rubber compounds are investigated. The rheological contributions of dynamically retarded bulk phase and Filler Network are revealed to be crucial at high and low frequencies, respectively, and the bulk phase is shown to be of vital importance for the occurrence of nonlinear Payne effect at mediate frequencies. A framework for simultaneously solving reinforcement and dissipation varying with Filler composition and content is suggested, providing a new perspective in understanding the filling effect for manufacturing high-performance rubber materials.
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revealing the three dimensional Filler structure in a rubber matrix based on fluorescein modified layered double hydroxides
RSC Advances, 2017Co-Authors: Weiyang Lv, Jianliang Xiao, Miao Du, Yihu Song, Qiang ZhengAbstract:To gain insight into nonlinear viscoelastic behavior, e.g. the Payne effect, and in situ visualize the Filler structure in a rubber matrix under strain, a methodology was developed to detect and track structural evolution based on fluorescent labeling. As a model system, layered double hydroxides (LDHs) with different lateral sizes (nanosheets and microsheets) were labeled with fluorescein (FLU) and then uniformly introduced into the rubber matrix through solution blending. The strain-induced deformation and destruction of the three-dimensional LDH Filler structure were directly observed for the first time through laser scanning confocal microscopy (LSCM). The contributions of the breakdown of the Filler Network, strain softening of the glassy layer and macromolecular disentanglement to the Payne effect were qualitatively determined and analyzed in detail based on the structural information probed via LSCM together with transmission electron microscopy, rheometry and modulated differential scanning calorimetry. The primary mechanism for the Payne effect in this system was then proposed and the macromolecular disentanglement in the rubber matrix played a key role. Furthermore, the enhanced Payne effect with increasing LDH content was ascribed to the strain amplification effect induced by the Filler Network for the LDH nanosheet filled system and the chain sliding on orientated LDHs for microsheet filled compounds, respectively.
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the role of Filler Network in nonlinear viscoelastic behavior of vapor grown carbon nanofiber filled polystyrene a strain dependent rheological behavior and electrical conductivity study
Polymer Engineering and Science, 2012Co-Authors: Yihu Song, Qiang Zheng, Li Zhao, Hongmei Yang, Yeqiang TanAbstract:Influence of Filler Network on Payne effect and modulus recovery for vapor grown carbon nanofiber (VGCF)/polystyrene (PS) composites with VGCF content above electrical percolation threshold was studied by using simultaneous measurements of viscoelasticity and electrical conductivity. The strain softening seems to be closely related to breakdown of Filler Network. Recovery tests of modulus and electrical conductivity by means of time sweep indicate that the reformation of deformed VGCF Network structure could not be completed in several hours. Compared with recovery behavior of carbon black (CB) and silica (SiO2) Network, the reformation of VGCF Network appears more difficult. Moreover, solidification of composites exerts some effect on modulus recovery. The Filler Network disrupted by small strain can be perfectly recovered by matrix solidification while the initial Filler structure collapsing at large strain is only partially restored. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
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on time temperature concentration superposition principle for dynamic rheology of carbon black filled polymers
Journal of Rheology, 2009Co-Authors: Yihu Song, Qiang ZhengAbstract:Time-temperature-concentration superposition principle is disclosed to linear dynamic rheology of carbon black (CB) filled high-density polyethylene (HDPE) with a wide range of CB volume fraction. The time-concentration superposition (TCS) principle is also validated in CB filled ethylene-tetrafluoroethylene (ETFE) alternating copolymer at 260 °C. The frequency-dependent viscoelastic functions can be superposed onto universal master curves with the reference of the unfilled HDPE and ETFE. The Filler Network and strain amplification concepts are used for accounting for the TCS principle.
Mario Beiner - One of the best experts on this subject based on the ideXlab platform.
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common origin of Filler Network related contributions to reinforcement and dissipation in rubber composites
Polymers, 2021Co-Authors: Sriharish Malebennur Nagaraja, S Ilisch, Sven Henning, Mario BeinerAbstract:A comparative study focusing on the visco-elastic properties of two series of carbon black filled composites with natural rubber (NR) and its blends with butadiene rubber (NR-BR) as matrices is reported. Strain sweeps at different temperatures are performed. Filler Network-related contributions to reinforcement (ΔG') are quantified by the classical Kraus equation while a modified Kraus equation is used to quantify different contributions to dissipation (ΔGD″, ΔGF″). Results indicate that the Filler Network is visco-elastic in nature and that it is causing a major part of the composite dissipation at small and intermediate strain amplitudes. The temperature dependence of Filler Network-related reinforcement and dissipation contributions is found to depend significantly on the rubber matrix composition. We propose that this is due to differences in the chemical composition of the glassy rubber bridges connecting Filler particles since the Filler Network topology is seemingly not significantly influenced by the rubber matrix for a given Filler content. The underlying physical picture explains effects in both dissipation and reinforcement. It predicts that these glassy rubber bridges will soften sequentially at temperatures much higher than the bulk Tg of the corresponding rubber. This is hypothetically due to rubber-Filler interactions at interfaces resulting in an increased packing density in the glassy rubber related to the reduction of free volume. From a general perspective, this study provides deeper insights towards the molecular origin of reinforcement and dissipation in rubber composites.
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detection of surface immobilized components and their role in viscoelastic reinforcement of rubber silica nanocomposites
ACS Macro Letters, 2014Co-Authors: Anas Mujtaba, M Keller, S Ilisch, Hansjoachim Radusch, Mario Beiner, Thomas Thurnalbrecht, Kay SaalwachterAbstract:Immobilized polymer fractions have been claimed to be of pivotal importance for the large mechanical reinforcement observed in nanoparticle-filled elastomers but remained elusive in actual application-relevant materials. We here isolate the additive Filler Network contribution to the storage modulus of industrial styrene–butadiene rubber (SBR) nanocomposites filled with silica at different frequencies and temperatures and demonstrate that it is viscoelastic in nature. We further quantify the amount of immobilized polymer using solid-state NMR and establish a correlation with the mechanical reinforcement, identifying a direct, strongly nonlinear dependence on the immobilized polymer fraction. The observation of a temperature-independent Filler percolation threshold suggests that immobilized polymer fractions may not necessarily form contiguous layers around the Filler particles but could only reside in highly confined regions between closely packed Filler particles, where they dominate the bending modulus ...
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mechanical properties and cross link density of styrene butadiene model composites containing Fillers with bimodal particle size distribution
Macromolecules, 2012Co-Authors: A Mujtaba, M Keller, S Ilisch, Hansjoachim Radusch, Thomas Thurnalbrecht, Kay Saalwachter, Mario BeinerAbstract:Mechanical properties and cross-link density of model composites being solution styrene–butadiene rubbers filled with different amounts of nanosized silica particles or mixtures of nanosized silica particles and micrometer-sized borosilicate glass particles are studied. The cross-link density of the rubber matrix is measured based on a double-quantum NMR spectroscopy method. Shear data show that reinforcement and dissipation G″ in the rubber plateau range depend systematically on the total surface area of the Filler per unit composite. Different contributions to reinforcement due to hydrodynamic effects, “Filler Network”, glassy polymer layer, and “occluded rubber” are quantified based on a comparison of linear response measurements with strain sweeps performed at different temperatures. The results show a percolation threshold at silica volume fractions of about 0.15. The load-carrying capacity of the “Filler Network” decreases significantly with temperature. This may indicate the existence of a glassy p...
Junjin Che - One of the best experts on this subject based on the ideXlab platform.
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largely enhanced thermal conductivity of hdpe boron nitride carbon nanotubes ternary composites via Filler Network Network synergy and orientation
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Junjin Che, Mengfan Jing, Dingyao Liu, Ke WangAbstract:Abstract In recent years, hybrid Fillers with different dimension are frequently used to improve the thermal conductivity of polymer/Filler composites. While the combined effect of hybrid Filler and orientation on the thermal conductivity of polymer/Filler composites has rarely reported. In this work, high density polyethylene (HDPE)/boron nitride (BN)/carbon nanotubes (CNT) ternary composites were prepared by melt blending then hot rolled to obtain oriented sheets. The thermal conductivity and internal structure of the obtained sheets were investigated and compared with those obtained by hot-pressed sheets with random distributed structure. Two representative systems were used, the one is that BN content is low and forms the isolated dispersions (using HDPE/5BN/CNT composites with 5 wt% of BN as example), the other one is that BN content is high and forms Network structure (using HDPE/25BN/CNT composites with 25 wt% of BN as example). For hot-pressed samples, no synergy between BN and CNT was found for HDPE/5BN/CNT system with BN dispersed in isolation in HDPE matrix, while an obvious increase of thermal conductivity was seen for HDPE/25BN/CNT system with BN Network formation in HDPE matrix, and a 300% increase of thermal conductivity could be achieved as 3 wt% of CNT was added, compared with that of net HDPE. For hot-rolled samples, an increase of thermal conductivity was observed for both HDPE/5BN/CNT and HDPE/25BN/CNT ternary composites by adding CNT into the composites, suggesting the importance of Filler orientation in the enhancement of thermal conductivity in polymer/Filler composites with hybrid Filler. The combined effect of hybrid Filler and orientation could result in a further increase of thermal conductivity and 600% increase of thermal conductivity could be achieved. Finally, based on the analysis of internal structure of prepared samples as obtained by SEM observation, rheology and XRD measurements, a possible mechanism for the enhancement of thermal conductivity via hybrid and orientation was proposed. Our work is important and could shed light for the preparation of polymer composites with super thermal conductivity.
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largely improved thermal conductivity of hdpe expanded graphite carbon nanotubes ternary composites via Filler Network Network synergy
Composites Part A-applied Science and Manufacturing, 2017Co-Authors: Junjin Che, Yunjie Lin, Ke WangAbstract:Abstract Utilizing the synergistic effect of various Fillers is an efficient strategy to enhance the thermal conductivity of polymer composites, in which the key is to modulate their dispersion and Network formation in polymer matrix. In this work, expanded graphite (EG) was individually added into high density polyethylene (HDPE) to fabricate first the binary composites through melt blending. The electrical conductivity of the prepared composites was measured to determine the percolation threshold for HDPE/EG composites. Then HDPE/EG composites with three compositions, representing below percolation, just percolation and above percolation, respectively, were chosen as matrix and melt mixed with carbon nanotubes (CNTs) to make HDPE/EG/CNTs ternary composites. It was found that adding CNTs results in a linear increase of thermal conductivity for HDPE/EG composites with composition below percolation, along the line by adding the same amount of EG. While a jump of thermal conductivity was observed by adding CNTs for HDPE/EG composites with composition just and above percolation. The electrical conductivity and rheology property were measured and SEM experiment was carried out to explore the Filler dispersion and their Network formation in HDPE matrix. All the results suggested a possible location CNTs in EG Filler Network for HDPE/EG composites with composition just and above percolation. Thus the formation of CNTs Network within EG Network is attributed to the main reason for the largely enhanced thermal property. This work endows a new enlightenment to fabricate the composites with a great thermal conductivity.