Abstract
AbstractThe thermal properties of bio-based phase change material (PCM) microcapsules and their separate components, core and shell, were investigated considering the influence of used thermal enhancer. As a core, bio-based PCM, capric acid (CA), was used. Biodegradable material, such as polylactic acid (PLA), was used as a shell. To improve the thermal conductivity of PLA/CA microcapsules, the multiwall carbon nanotubes (MWCNTs) were used as a thermal enhancer. Composites of PCM with different concentrations of MWCNT as well as composites of PLA with these carbon compounds were prepared and investigated to assess how MWCNT influences the thermal conductivity of the core and the shell. The heat storage and release capacity, as well as the phase change temperatures of CA/MWCNT composites and manufactured PCM microcapsules, were determined using differential scanning calorimetry. To evaluate the thermal conductivity of prepared composites and to compare it with the conductivity of pure materials (without MWCNT), their thermal resistance was measured using the guarded-hotplate test method. To obtain the supplementary information and to assess the dynamic behavior of used PCM during the temperature changes, another technique, such as monitoring of a cold/hot plate with an IR camera, was used. The results of these measurements showed that introduced MWCNT increases the thermal conductivity of PCM used for the core and the conductivity of films prepared from PLA. Consequently, with reference to the results obtained, it could be stated that the introduction of MWCNT into PLA/CA microcapsules improved the thermal properties of these microcapsules. However, it was determined that too large concentration of MWCNT reduces an enthalpy of melting and crystallization of tested PCM and PCM microcapsules. Therefore, during the investigation, an optimal concentration of MWCNT additives has been determined.
Highlights
One of the main purposes of wearing clothes is the comfort of the body
This study aimed to investigate the possibility to improve the thermal conductivity of produced microcapsules, using multiwall carbon nanotube (MWCNT) as a thermal enhancer
The presence of MWCNT reduces the peak of melting temperature by about 1°C and the peak of crystallization temperature is even less
Summary
One of the main purposes of wearing clothes is the comfort of the body. Comfort can be classified into four major classes such as thermal or thermophysiological comfort, sensorial comfort, physiological comfort, and garment fit [1]. Thermal energy storage is the main concept of making thermoregulated fabrics. Thermal energy can be stored as sensible heat, latent heat, or thermochemical energy. The latent heat storage method is mostly used for thermoregulated fabric as in latent heat storage method high storage density is possible to achieve under nearly isothermal conditions [1,3]. Phase change materials (PCMs) represent an interesting potential energy carrier due to their high latent heat and capacity for energy transfer [4,5,6]. Organic PCMs can be divided into main parts, such as pure alkanes, paraffins, fatty acids and their derivatives, and polyols [7]. Organic PCMs are a well-suited candidate for energy storage owing to their especially high latent heat.
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