Abstract:The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (GnP) on the thermal conductivity (k) of PE-GnP composites is investigated. Measurements reveal a large increase of 1100% in k of the aligned PE-GnP composite using 10 wt% GnPs relative to unoriented pure PE. The rate of increase of k with applied strain for the pure PE-GnP composite with 10 wt% GnP is found to be almost a factor of two higher than the pure PE sample, pointing to the beneficial effect of GnP alignment… Show more
“…The λ value of the Py-PGMA-GNPs/epoxy composite with 4 phr Py-PGMA-GNPs was increased to 1.91 W/mK, about 20 times graphite content (80-200 phr) to obtain the comparable λ value. Garg et al [149] fabricated the GNP/PE composites with ultrahigh λ value via the simultaneous alignment of PE lamellae and GNPs. The λ value of the aligned GNPs/PE composite with 10 wt% aligned GNPs was significantly enhanced to 5.90 W/mK, increased by 1100% compared to that of unoriented original PE matrix.…”
With the fast-developing miniaturization and integration of microelectronics packaging materials, ultrahigh-voltage electrical devices, light-emitting diodes (LEDs), and in areas which require good heat dissipation and low thermal expansion, the investigations on the polymeric composites with highly thermal conductivities and excellent thermal stabilities are urgently required, which would be beneficial to transferring the heat to the outside of the products, finally to effectively avoid substantial overheating and prolong their working life. Our article reviews recent progress in the classification, measurement methods, model and equations, mechanisms, commonly used thermally conductive fillers, and the correlative fabrication methods for the thermally conductive polymeric composites, aiming to understand and grasp how to enhance the λ value effectively. And future perspectives, focusing scientific problems and technical difficulties of the present thermally conductive polymeric composites are also described and evaluated.
“…The λ value of the Py-PGMA-GNPs/epoxy composite with 4 phr Py-PGMA-GNPs was increased to 1.91 W/mK, about 20 times graphite content (80-200 phr) to obtain the comparable λ value. Garg et al [149] fabricated the GNP/PE composites with ultrahigh λ value via the simultaneous alignment of PE lamellae and GNPs. The λ value of the aligned GNPs/PE composite with 10 wt% aligned GNPs was significantly enhanced to 5.90 W/mK, increased by 1100% compared to that of unoriented original PE matrix.…”
With the fast-developing miniaturization and integration of microelectronics packaging materials, ultrahigh-voltage electrical devices, light-emitting diodes (LEDs), and in areas which require good heat dissipation and low thermal expansion, the investigations on the polymeric composites with highly thermal conductivities and excellent thermal stabilities are urgently required, which would be beneficial to transferring the heat to the outside of the products, finally to effectively avoid substantial overheating and prolong their working life. Our article reviews recent progress in the classification, measurement methods, model and equations, mechanisms, commonly used thermally conductive fillers, and the correlative fabrication methods for the thermally conductive polymeric composites, aiming to understand and grasp how to enhance the λ value effectively. And future perspectives, focusing scientific problems and technical difficulties of the present thermally conductive polymeric composites are also described and evaluated.
“…Additionally, dispersed fillers can cause an unstable TC during solid–liquid phase transitions . To make full use of the geometric and dimensional properties of sheet‐like fillers, they are generally assembled and oriented into an aligned structure by pressure‐induced compression, vacuum‐assisted self‐assembly/alignment, solution casting, mechanical strain, electric‐field‐assisted orientation, or ice‐templated assembly to obtain a structurally anisotropic framework. The individual fillers act as building blocks of the framework, which serves as the thermally conductive matrix in a composite.…”
mentioning
confidence: 99%
“…The individual fillers act as building blocks of the framework, which serves as the thermally conductive matrix in a composite. Thermally conductive polymer‐based composites using an aligned GNP framework have been developed for thermal interface materials (TIMs) . The reported Κ comp at near room temperature can reach approximately 17 W m −1 K −1 .…”
Efficient thermal energy harvesting using phase‐change materials (PCMs) has great potential for cost‐effective thermal management and energy storage applications. However, the low thermal conductivity of PCMs (KPCM) is a long‐standing bottleneck for high‐power‐density energy harvesting. Although PCM‐based nanocomposites with an enhanced thermal conductivity can address this issue, achieving a higher K (>10 W m−1 K−1) at filler loadings below 50 wt% remains challenging. A strategy for synthesizing highly thermally conductive phase‐change composites (PCCs) by compression‐induced construction of large aligned graphite sheets inside PCCs is demonstrated. The millimeter‐sized graphite sheet consists of lateral van‐der‐Waals‐bonded and oriented graphite nanoplatelets at the micro/nanoscale, which together with a thin PCM layer between the sheets synergistically enhance KPCM in the range of 4.4–35.0 W m−1 K−1 at graphite loadings below 40.0 wt%. The resulting PCCs also demonstrate homogeneity, no leakage, and superior phase change behavior, which can be easily engineered into devices for efficient thermal energy harvesting by coordinating the sheet orientation with the thermal transport direction. This method offers a promising route to high‐power‐density and low‐cost applications of PCMs in large‐scale thermal energy storage, thermal management of electronics, etc.
“…Table 3 2007 [120] 2007 [120] 2014 [122] 2016 [121] 2016 [123] carbon [131]. Saeidijavash et al [25] reported an increase of 60% in κ c of the aligned PE-GNP composite using 10 wt.% GNP relative to oriented pure PE using mechanical strain. Table 5 summarizes the enhancement of κ in PE and PP using graphenebased materials.…”
Section: Simulation Of Thermal Conductivity In Polymer Compositesmentioning
confidence: 99%
“…Therefore, using filler with high κ f combined with the simultaneous alignment of PE chains and the embedded filler, κ c can be significantly enhanced. For instance, κ c of PE composite containing 10 wt.% graphene nanoplatelets has reached 5.9 W/m·K after stretching the composite, indicating the great potential to fabricate polyolefin composites with high κ c [ 25 ]. Figure 2.…”
The low thermal conductivity of polymers is a barrier to their use in applications requiring high thermal conductivity such as electronic packaging, heat exchangers, and thermal management devices. Polyolefins represent about 55 percent of global thermoplastic production, and therefore improving their thermal conductivity is essential for many applications. This review analyzes the advances in enhancing the thermal conductivity of polyolefin composites. First, the mechanisms of thermal transport in polyolefin composites and the key parameters that govern conductive heat transfer through the interface between the matrix and the filler are discussed. Then the advantage with different thermally conductive fillers are reviewed and analyzed. Finally, the key challenges and future directions for developing thermally enhanced polyolefin composites are outlined.
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