Thermal conductivity of sorghum and sorghum–thermoplastic composite panels

Published Date
February 2013, Vol.45:455–460, doi:10.1016/j.indcrop.2013.01.011

Author 

• Chusheng Qi ^a,b
• Vikram Yadama ^b,,
• Kangquan Guo ^a
• Michael P. Wolcott ^b

• aCollege of Mechanical and Electronic Engineering, Northwest A&F University, Yanlgling 712100, China
• bComposite Materials and Engineering Center, Washington State University, Pullman 99163, WA, USA

Received 5 October 2012. Revised 25 December 2012. Accepted 4 January 2013. Available online 30 January 2013. 

Abstract

Thermal conductivity of a material is a key parameter to simulate heat transfer during manufacturing of a composite under heat and pressure. This study investigated the thermal conductivity of composite panels hot-pressed with varying proportions of sweet sorghum and high-density polyethylene (HDPE). Thermal conductivity of the composites was tested under steady-state conditions. The effects of temperature (12.5–62.5 °C), density (0.7–1.0 g/cm³) and HDPE (0–40%) content on thermal conductivity of the composite products were investigated. Thermal conductivity increases in a linear manner with temperature and density, and in a nonlinear manner with HDPE content. An empirical equation for describing the thermal conductivity of sweet sorghum and HDPE composite panels was fitted, and has a good agreement with testing data. Compared with other empirical equations for predicting the thermal conductivity of wood, the experimental values in this study consistently had lower values, indicting a significant difference in thermal conductivity of composites manufactured with agro-based natural fibers compared to wood fibers. Additionally, predicted thermal conductivity values are limited by those estimated by the parallel and series models for two phase composites.

Graphical abstract

Highlights

► Sweet sorghum–HDPE composites were fabricated and evaluated for thermal conductivity. ► Thermal conductivity of the tested composites linearly increases with temperature and density. ► Thermal conductivity of the tested composites nonlinearly increases with HDPE content. ► Empirical equation predicting thermal conductivity is presented and compared.

Keywords

• Thermal conductivity
• Natural fiber composites
• Sorghum
• High-density polyethylene
• Hot pressing

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  Corresponding author at: Washington State University, Composite Materials and Engineering Center, Pullman, WA, 99164-1806, USA. Tel.: +1 509 335 6261.

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