Abstract
An optimized thermal conductivity model of spherical particle-filled polymer composites considering the influence of interface layer was established based on the classic series and parallel models. ANSYS software was used to simulate the thermal transfer process. Meanwhile, linear low-density polyethylene/alumina (LLDPE/Al2O3) composites with different volume fractions and Al2O3 particle sizes were prepared with the continuous mixer, and the effects of Al2O3 particle size and volume fraction on the thermal conductivity of the composites were discussed. Finally, the test result of the thermal conductivity was analyzed and compared with ANSYS simulations and the model prediction. The results proved that the thermal conductivity model considering the influence of the interface layer could predict the thermal conductivity of LLDPE/Al2O3 composites more precisely.
Highlights
The establishment of the mathematical model on thermal conductivity for polymer composites is of great significance in analyzing the influencing factors of heat transfer performance, revealing the heat transfer mechanism, predicting the thermal conductivity of polymer composites and further optimizing the formulation design and products
The thermal conductivity of the composites showed sharp improvement when the volume fraction of Al2 O3 increased from 27.6% to 32.5%
The phenomenon could be analyzed from Figure 6: The distance among Al2 O3 particles became closer and the Al2 O3 particles were still individually wrapped by LLDPE matrix when the volume fraction of Al2 O3 increased from 9.8% to 27.6%
Summary
Conductive composites have been widely applied in the fields of lighting, solar energy, electronic, medical and health [1,2]. More and more mathematical models for predicting the thermal conductivity of polymer composites have been established based on the shape, size and content of thermally conductive fillers. Some scholars use numerical simulation methods to study the thermal transfer process and simplify the whole composites to the unit body [23–25]. These models generally assume that the two-phase interface is infinitely thin, and the effect of the interface phase on the thermal conductivity of the polymer composites could be neglected during model establishment or numerical simulation [13–15,20–25]. A new effective thermal conductivity model of spherical particle-filled composites is established based on the classic series and parallel models. A series of LLDPE/Al2 O3 composites were prepared with different Al2 O3 volume fractions and particle diameters to verify the precision of the established thermal conductivity model
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