Effect of halloysite nanotubes on shape stabilities of polyethylene glycol-based composite phase change materials
Introduction
Phase change materials (PCMs) have been widely used as thermal heat storage in several applications such as conservation and transport of temperature-sensitive materials, buildings, and solar power plants [1]. PCMs are temperature-responsive substances, which absorb and release a large amount of latent heat energy during a temperature-driven phase change [2]. In food packaging, temperature is one of the most important factors affecting the qualities of perishable food, frozen food, and beverages during storage and distribution [3], [4]. Gas and water are also important factors determining the quality of food during storage. The introduction of PCMs into a polymer matrix is a feasible approach to control the gas or water vapor permeability corresponding to the desired temperature changes under the external atmosphere of packaging.
Many types of PCMs including salt hydrates, paraffin, fatty acids, and their mixtures have been widely used in packaging materials. Among various PCMs, polyethylene glycol (PEG) has attracted significant interest owing to its good characteristics, including various phase change temperatures depending on the molecular weight, congruent melting, non-toxicity, small or no volume changes during solid–liquid phase changes, and high thermal and chemical stabilities after a long-term service. In addition, PEG can be directly incorporated into porous materials [5]. Moreover, it has a melting temperature in the range of 3.2–68.7 °C and very high phase change enthalpy depending on its molecular weight [6]. However, the direct utilization of PEG for thermal storage is limited owing to its low thermal conductivity and leakages during the solid–liquid phase change process [7], [8]. There are three general methods to generate shape-stabilized PEG composites: (1) encapsulation of PEG in shell materials [9], (2) preparation of polymer/PEG composites [10], [11], and (3) impregnation of PEG into inorganic materials with porous and layered structures, such as expanded graphite [12], diatomite [5], and silica [13]. The first and second methods have some disadvantages such as a low thermal conductivity, incongruent melting and freezing, latent heat capacities, complex manufacturing processing, and high cost [12], [14]. On the contrary, the third method is simple and cost-effective. In addition, a shape-stabilized PCM composite with no leakage, high thermal conductivity, and latent heat capacity can be obtained through this method [14], [15], [16].
Halloysite nanotube (HNT) is a two-layer aluminosilicate clay with an Al:Si ratio of 1:1 and stoichiometry of Al2Si2O5(OH)4·nH2O. It is chemically similar to kaolin, different mainly in crystal morphology [15], [17], [18]. HNT has a hollow nanotubular structure and large surface area, promising for a low-cost adsorbent. The simple exfoliation (because of the absence of stacked platy sheets) of HNT makes it a promising material for preparing polymer composites [15], [17], [19], [20]. Mei et al. successfully prepared form-stable stearic acid/HNT and capric acid/HNT composites via the solvent-solution method for thermal energy storage [15], [16]. However, this method is not environmentally friendly and is a discontinuous process, which limits its use for industrial applications. Cavallaro et al. investigated the effect of HNT on the thermal stabilities of PEG/HNT composites obtained by the casting technique [21]. However, no study has been reported on utilization of HNT as an adsorbent to prepare shape-stabilized PEG via the melt-extrusion technique.
In this study, we developed shaped-stabilized PEG/HNT composites to minimize the PEG migration and leakage and endow functionalities such as temperature-dependent permeability. We applied melt-extrusion using a twin-screw extruder to obtain PEG-impregnated HNT. This technique is not only environment-friendly (solventless), but also it consists of a continuous process providing convenience, high production rate, and homogeneous mixing for shape-stabilized PCM composites. The chemical and morphological structures, thermal properties, thermal stabilities, and shape-stabilities of PEG/HNT composites were investigated as a function of the HNT content.
Section snippets
Materials
PEG 35000 (average Mn: 35,000) was purchased from Sigma-Aldrich Korea Ltd. (Yongin, Korea) and used as received. HNT was purchased from Sigma-Aldrich Korea Ltd. (Yongin, Korea) and dried at 100 °C for 24 h before use.
Preparation of PEG/HNT composites
The PEG/HNT composites were prepared using a laboratory‐scale twin‐screw extruder (BA‐19, BauTech Co., Uijeongbu, Korea) with a length/diameter (L/D) ratio of 40:19 for homogeneous mixing and dispersion. Six samples with different composition ratios (%) of 100:0, 90:10, 80:20,
Chemical structures of PEG and PEG/HNT composites
We studied the impregnation of PEG into the HNT matrix using FT-IR spectroscopy. The FT-IR spectra of HNT, PEG, and PEG/HNT are presented in Fig. 2. HNT exhibited several strong bands, at: 3694, 3621, and 1648 cm−1 corresponding to Al–OH stretching bands and deformation vibration of absorbed water, 1118, 1006, and 908 cm−1 assigned to a stretching mode of apical Si–O, stretching vibration of Si–O–Si, and bending band of Al–OH, and 459 cm−1 indicating a deformation vibration of Al–O–Si,
Conclusions
Shape-stabilized PEG/HNT composites with PEG as the PCM were successfully prepared using a melt-extrusion process. According to the BET, TEM, and DSC analyses, the shape-stability of PEG was significantly enhanced by the introduction of HNT. Moreover, PEG was homogeneously mixed and effectively confined in the porous structure of HNT, which prevented the leakage of melted PEG during the solid-to-liquid phase change. Among the various PEG/HNT composites, the composites with the HNT contents of
Declarations of interest
None.
Acknowledgment
This study was supported by the National Research Foundation of Korea (NRF), grant funded by the Korea government (MSIP) [grant number 2017R1A2B4011234].
References (50)
- et al.
Review on thermal energy storage with phase change: materials, heat transfer analysis and applications
Appl. Therm. Eng.
(2003) - et al.
Review on phase change materials (PCMs) for cold thermal energy storage applications
Appl. Energy
(2012) - et al.
Development of polystyrene-based films with temperature buffering capacity for smart food packaging
J. Food Eng.
(2015) - et al.
Polyethylene glycol (PEG)/diatomite composite as a novel form-stable phase change material for thermal energy storage
Sol. Energy Mater. Sol. Cells
(2011) - et al.
A poly (ethylene glycol)-based smart phase change material
Sol. Energy Mater. Sol. Cells
(2008) - et al.
Preparation and performance of form-stable polyethylene glycol/silicon dioxide composites as solid–liquid phase change materials
Appl. Energy
(2009) - et al.
Preparation and performance of porous phase change polyethylene glycol/polyurethane membrane
Energy Convers. Manage.
(2010) - et al.
Thermal and electrical conductivity enhancement of graphite nanoplatelets on form-stable polyethylene glycol/polymethyl methacrylate composite phase change materials
Energy
(2012) - et al.
Shape-stabilized phase change materials based on polyethylene glycol/porous carbon composite: the influence of the pore structure of the carbon materials
Sol. Energy Mater. Sol. Cells
(2012) - et al.
Preparation and characterization of PEG/SiO2 composites as shape-stabilized phase change materials for thermal energy storage
Sol. Energy Mater. Sol. Cells
(2013)
Structure and thermal properties of octadecane/expanded graphite composites as shape-stabilized phase change materials
Int. J. Heat Mass Transf.
Preparation of capric acid/halloysite nanotube composite as form-stable phase change material for thermal energy storage
Sol. Energy Mater. Sol. Cells
Thermal stability and flame retardant effects of halloysite nanotubes on poly (propylene)
Eur. Polym. J.
Chain orientation in poly (glycolic acid)/halloysite nanotube hybrid electrospun fibers
Polymer
Aggregation behavior of chemically attached poly (ethylene glycol) to single-walled carbon nanotubes (SWNTs) ropes
Mater. Sci. Eng., C
Thermal performance evaluation of Bio-based shape stabilized PCM with boron nitride for energy saving
Int. J. Heat Mass Transf.
Pore structure characterization of cement pastes blended with high-volume fly-ash
Cem. Concr. Res.
Study of Pd (II) adsorption over titanate nanotubes of different diameters
J. Colloid Interface Sci.
Form-stable phase change materials for thermal energy storage
Renew. Sustain. Energy Rev.
Thermal energy storage performance of paraffin-based composite phase change materials filled with hexagonal boron nitride nanosheets
Energy Convers. Manage.
Structure and thermal properties of octadecane/expanded graphite composites as shape-stabilized phase change materials
Int. J. Heat Mass Transfer
Capric–myristic acid/expanded perlite composite as form-stable phase change material for latent heat thermal energy storage
Renew. Energy
Characterization of halloysite-water nanofluid for heat transfer applications
Appl. Clay Sci.
Preparation and thermal energy properties of paraffin/halloysite nanotube composite as form-stable phase change material
Sol. Energy
Mechanical behaviour and essential work of fracture of halloysite nanotubes filled polyamide 6 nanocomposites
Compos. Sci. Technol.
Cited by (46)
Polyethylene glycol/polypyrrole aerogel shape-stabilized phase change material for solar-thermal energy storage and thermoelectric power generation
2024, Solar Energy Materials and Solar CellsRecent advances and perspectives in solar photothermal conversion and storage systems: A review
2024, Advances in Colloid and Interface SciencePreparation and applicability of polylactic acid/polyethylene glycol/nanoclay composite films for smart steam release in microwave packaging
2023, Food Packaging and Shelf LifePhase change materials in food: Phase change temperature, environmental friendliness, and systematization
2023, Trends in Food Science and Technology