Highly thermally conductive UHMWPE/graphite composites with segregated structures

Feng

J of Applied Polymer Sci

et al. 2020

A scalable strategy to fabricate thermally conductive but electrically insulating polymer composites was urgently required in various applications including heat exchangers and electronic packages. In this work, multilayered ultrahigh molecular weight polyethylene (UHMWPE)/natural graphite (NG)/boron nitride (BN) composites were prepared by hot compressing the UHMWPE/NG layers and UHMWPE/BN layers alternately. Taking advantage of the internal properties of NG and BN fillers, the UHMWPE/NG layers played a decisive role in enhancing thermal conductivity (TC), while the UHMWPE/BN layers effectively blocked the electrically conductive pathways without affecting the thermal conductive pathways. The in-plane TC, electrical insulation, and heat spreading ability of multilayered UHMWPE/NG/BN composites increased with the increasing layer numbers. At the total fillers loading of 40 wt%, the in-plane TC of multilayered UHMWPE/NG/BN composites with nine layers was markedly improved to 6.319 Wm −1 K −1 , outperforming UHMWPE/BN (4.735 Wm −1 K −1) and pure UHMWPE (0.305 Wm −1 K −1) by 33.45% and 1971.80%, respectively. Meanwhile, the UHMWPE/NG/BN composites still maintained an excellent electrically insulating property (volume resis-tance~5.40×10 14 Ω cm; breakdown voltage~1.52 kV/mm). Moreover, the multilayered UHMWPE/NG/BN composites also exhibited surpassing heat dissipation capability and mechanical properties. Our results provided an effective method to fabricate highly thermal conductive and electrical insulating composites. K E Y W O R D S applications, composites, thermal properties, molding 1 | INTRODUCTION Owing to the rapidly escalation of power densities and integration in electronic components, heat dissipation has become a critical issue to protect electronics from overheating. Polymer-based composites are widely used in many fields for their excellent processability, lightweight, low cost, and outstanding chemical stability. 1-3

Section: Characterizationmentioning

confidence: 99%

Multilayered ultrahigh molecular weight polyethylene/natural graphite/boron nitride composites with enhanced thermal conductivity and electrical insulation by hot compression

Feng

J of Applied Polymer Sci

et al. 2020

Advances in Polymer Technology

“…In order to allow the thermally conductive particles to be well distributed in the UHMWPE matrix, scholars are currently mixing them: (1) by dispersing the ller and UHMWPE particles in an organic solvent, then volatilizing the organic solvent to dry; (2) by stirring the ller with UHMWPE pellets at high speed in a high speed mixer for a period of time [16]; (3) by mixing the ller and UHMWPE pellets at a certain temperature [17]. For the rst type of dispersion, the organic solvents commonly used by research scholars are acetone [18], ethanol [19][20][21][22], 1,2 dicholorobenzene [23], etc. Whether dispersed in a solvent or stirred in a high-mixer, the composite has a segregated structure with a good thermal path, since compression molding is a static ow eld.…”

Section: Introductionmentioning

confidence: 99%

Thermal Performances of UHMWPE/BN Composites Obtained from Different Blending Methods

Guo

Cao

Cheng

et al. 2019

UHMWPE/BN composites were prepared by solvent mixing (SM) in this work, then were characterized by scanning electron microscope (SEM), Raman mapping, differential scanning calorimeter (DSC), thermogravimetric analysis (TG), and thermal conductivity meter to study the morphology, filler distribution, segregated structure, and thermal stability as well as thermal conductivity. Compared to the traditional melt mixing (MM), SM followed by molding contributes to the construction of segregated structures in UHMWPE composite. This segregated structure can greatly improve the thermal conductivity of the composites. The segregated structure of composites prepared by MM is destroyed by shearing. Moreover, the thermal stability of composites by SM is improved with the increment of BN content, which is better than that of samples by MM, probably resulting from the barrier function of the segregated structure.

“…Polymer materials with enhanced thermal conductivity (TC) have become some of the most popular thermal management materials due to their advantages of good processability, low weight, high electrical resistivity, high voltage breakdown strength and most importantly, low cost. However, bulk polymers generally exhibit very low TC in the 3,4 range of 0.1-0.5 W/mK, necessitating the development of highly thermally conductive polymer-based materials to meet increasing [5][6][7][8] demands, which is highly challenging. Typically, introducing highly heat-conductive fillers, such as carbon-9- 13 14, 15 16,17 based materials, ceramic fillers, and metallic fillers, into polymers to increase the TC of polymer composites has been the conventional approach both in scientific research and industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Effect of PLA Crystallization on the Thermal Conductivity and Breakdown Strength of PLA/BN Composites

Bai¹,

Zheng²,

Bao³

et al. 2018

ES Mater.Manuf.

Polylactide (PLA), whose crystallinity could be easily tuned, was selected to examine the effect of polymer crystallization on thermal conductivity (TC) of the polymer composites. Compression-molded PLA/boron nitride (BN) were heat-treated at 120 °C to fabricate highly crystalline samples. It demonstrated crystallization of the PLA significantly affects TC of the PLA/BN composites. With increased BN content, the improvement of the TC of PLA/BN composites via crystallization is more obvious. TCs of the crystalline PLA/BN composites with 5 wt% and 40 wt% BN are increased by 23 % and 47 % in the in-plane direction and are increased by 21 % and 54 % in the through-plane direction compared to those of amorphous PLA/BN, while TC of pure PLA is increased by 17 % via crystallization. When BN content is 40 wt%, the in-plane and through-plane TCs of the crystalline PLA/BN are 4.7 W/mK and 0.8 W/mK, respectively. Both the amorphous and crystallized PLA/BN exhibit high breakdown strengths.