Form-stable Composite Phase Change Materials Research Articles

Preparation and characterization of eicosane-paraffin/expanded graphite/polyurethane as form-stable composite phase change materials with wide phase change temperature range

Phase change materials (PCMs) with wide phase change temperature range, high latent heat, good thermal conductivity, and shape stability are essential for applications such as solar energy conservation and thermal management of electronic devices. Form-stable composite PCMs (FSCPCMs) with a broad phase change temperature range of 18–65 °C were successfully developed by using a mixture of eicosane and paraffin mixture along with cross-linking polyurethane as PCM, expanded graphite as thermally conductive filler and supporting material. The prepared FSCPCMs demonstrated excellent thermal stability and thermal conductivity with a latent heat up to 142.5 J/g. In conclusion, the synthesized FSCPCMs exhibit promising potential for practical applications in thermal energy storage.

Epoxy resin/ aluminium hydroxide/expanded graphite synergistic effects on advancing flame retardancy, mechanical structure and thermal management of octadecanoic acid and octadecanol-based eutectic phase change materials

In the present research, a novel approach wherein a flame-retardant composite phase change material (PCMs) is devised by incorporating eutectic PCMs, epoxy resin (ER), aluminium hydroxide (ATH), and expanded graphite (EG). This innovative formulation capitalizes on the synergistic interaction between ER and ATH, alongside the porous structure of EG, resulting in a triple-layer encapsulation of the eutectic PCMs. The outcome of this formulation is marked by remarkable thermal stability, even under extreme conditions such as exposure to temperatures as high as 800 °C. Notably, one of the representative samples, denoted as S5, showcases impressive attributes with a thermal conductivity of 1.335 W∙m-1K−1 and a substantial phase change latent heat of 150.4 J∙g−1. It was observed an increase in latent heat up to 181.3 J∙g−1 after 100 heating–cooling cycles of composite PCMs. This indicates the good thermal reliability of the form-stable composite PCMs synthesized. Moreover, the composite PCMs exhibit outstanding mechanical properties, especially S5 which showed a 14.69 % and 400.12 % increase in compression strength and compression modulus compared with pure eutectic PCM (S0), respectively. Besides, the ternary composition of ER, ATH, and EG enhances the flame retardancy of the composite PCMs, yielding a substantial reduction of 67.33 % in peak heat release rate and 50.38 % in total heat release. This collaborative effect also establishes a robust defense mechanism against the rapid propagation of flames, as exemplified by the attainment of a V-0 rating in the UL-94 test. As a result, the flame-retardant ER/ATH/EG ternary-based form-stable composite PCM presents itself as a promising candidate for ensuring both safety and efficiency in thermal management applications.

Development and investigation of salt based composite phase change material containing diatomite as skeleton substance by cold sintering technology for medium and high temperature thermal energy storage

This work concerns the development of a nitrate salt based form-stable composite phase change material by cold sintering technology with the employment of diatomite as skeleton substance. Such fabrication strategy has never before been reported in the literature and we demonstrate for the first time the feasibility of salt-diatomite composite production through a cold sintering process by means of sodium hydroxide solution as sintering additive. The microstructural characteristics and development mechanism, chemical and physical compatibility, mechanical strength, phase change behaviour, thermal and shape stability of the composite are investigated to reveal the structure formation and densification mechanism of salt and diatomite. The results show that the composite could be sintered at a temperature of 180 °C, far lower than that required in the traditional hot sintering approach. Due to the congruent solubility of the salt and diatomite in aqueous alkali, a rigid and dense structure induced by a so-called dissolution-precipitation process could be generated in the composite, which provides solution to accommodate the salt, endowing the composite with splendid capacity to maintain the structure stability and restrain the liquid leakage over the phase change process. An excellent chemical and physical compatibility has been achieved between the salt and other components, and over 60 wt% salt could be encapsulated in the composite by which a melting temperature around 278 °C and an energy storage density over 650 kJ/kg at a temperature range of 50–600 °C are attained. The results also reveal that the composite exhibits preeminent mechanical strength and excellent thermal cycling performance. For a given cycling temperature range of 50–500 °C, a stable macroscopic shape with a compressive strength over 210 MPa could be achieved in the composite even after 100 times of thermal cycles.

Role of microstructure in the exploitation of self-healing potential in form-stable composite phase change materials based on immiscible alloys

Metallic Phase Change Materials (PCMs), based on solid-liquid transitions, represents one of the most promising technologies for efficient Thermal Energy Storage (TES), due to their superior thermal conductivity and energy storability per unit volume, but suffer of limited solutions for their handling at the molten state. The use of Miscibility Gap Alloys (MGAs) allows to manage PCM volume expansion and keep it confined when molten, preventing interaction with the environment. A relevant example is provided by the Al-Sn system, where Al covers the role of the high-temperature stable and highly thermal-conductive passive matrix and Sn the active PCM. The alloy can thus be considered a Composite PCM (C-PCM). The response fastness of these systems depends on their thermal diffusivity, subjected to abrupt variations under the presence of discontinuities and damages. In this sense, the authors investigated the possibility to employ molten Sn mobility in a potentially damaged C-PCM for self-healing purposes, aimed to restore, at least partially, the material continuity and thus its thermal diffusivity. Exudation heat treatments above the melting temperature of Sn were performed on sets of Al-40%wt. Sn metallic composites, produced either with powder metallurgy or liquid metal routes, in order to quantify and assess the mobility of the Sn under simulated operating conditions. Exudation tests assess Simple Mixed powders and liquid metal routes sample as the ones with the highest healing potential. Al dissolution and re-deposition was established by EDS analyses as one of the principal Sn mobility mechanisms. Laser Flash Analysis tests, as well as microstructural investigations, were performed on the samples before and after both healing-focused and simulated service heat treatments to evaluate the changes of thermal diffusivity. Healing-focused treatment at 250°C for 1 hour generally displayed a moderate thermal diffusivity recovery and simulated service by shorter cycles between 170°C and 270°C slightly reduce it. The beneficial role of healing focused heat treatments at 250°C for 1 hour suggests that the presence of fully molten Sn phase during service for relatively long time could be beneficial for functional healing. The requirements of suitable Al-Sn microstructures for self-healing purposes, granting at the same time the C-PCM functionalities, i.e., thermal energy storage and form-stability, were set.

Research on modified expanded graphite/eutectic salt composite phase change material in cold chain transportation

Attention to the use of phase change materials (PCMs) in cold chain transportation has increased in recent years. In this work, a form-stable composite phase change material (CPCM) prepared by a novel eutectic salt (Na2SO4·10H2O-MgSO4·7H2OH2O) PCM composite with modified expanded graphite (MEG) was investigated. The hydrophilicity of expanded graphite (EG) and its compatibility with the eutectic salts were improved by coating SiO2. The results showed that microstructure of the EG was maintained after modification, and adsorption of the PCM by the MEG was 55.23 wt% higher than that of the EG. The CPCM with 20 wt% MEG exhibit a high enthalpy of 180.8 J/g, the phase transition temperature of −5.6 °C and a high thermal conductivity of 5.183 W/(m·K). The thermal conductivity of CPCM was 8 times as large as that of the PCM. Moreover, the thermal performance of the CPCM was small change after 200 thermal cycling, exhibiting good thermal cyclic reliability. Besides, a potential application test of the form-stable CPCM was performed through a low temperature insulation box. It showed that form-stable CPCM can control sudden temperature fluctuation and maintain stable temperature for longer time inside the insulation box.

Carbonated balsa-based shape-stable phase change materials with photothermal conversion and application in greenhouse

Greenhouse enables to promote plant yield through creating optimal environment. Efficient solar energy conversion and storage is a promising strategy to address energy shortage issue of greenhouse in winter. This paper prepares form-stable composite phase change materials (PCMs) to store solar energy efficiently. Lightweight and porous balsa wood subjected to high-temperature carbonization is designed to simultaneously solve the liquid leakage, enhance the thermal conductivity, and improve the photothermal conversion and thermal energy storage of PCM. OP44E and SEBS are utilized as PCM and thickener, followed by vacuum impregnation into the carbonized balsa wood (CW). Results indicate that carbon content of CW increases with the augment of carbonization temperature. Shaping effects of CW and SEBS endow composite PCMs to have highest adsorption rate of 92.7 wt% with enthalpy over 190 J/g. Composite PCMs reveal reliable thermal properties and thermal stability below 100 °C. Composite PCMs have photothermal conversion larger than 88 % under a xenon lamp radiation. Temperature of PCMs on the shallow layer is higher owing to its photothermal conversion capacity. Greenhouse test indicates that CW/OP44E/SEBS greenhouse gains higher PCM temperature of 71.5 °C at 70 min, compared to 40.3 °C in empty and OP44E/SEBS cases. CW/OP44E/SEBS greenhouse maintaining indoor temperature over 20 °C lasts 15.3 min longer than empty and OP44E/SEBS greenhouses. In addition, form-stable composite PCMs featured with excellent thermal stability and photothermal conversion are capable of maintaining stable indoor temperature of greenhouse, indicating potential in the field of agricultural building temperature regulation.

Experimental and analytical studies on latent heat of hydrated salt/modified EG-based form-stable composite PCMs for energy storage application

Expanded graphite (EG) is often used to encase phase change materials (PCMs) and improve their thermal performance. However, EG's effectiveness when used with disodium hydrogen phosphate dodecahydrate (DHPD) as a hydrated salt is diminished, due to its hydrophobic property. This study proposes modifying the hydrophobic surface of EG with highly hydrophilic nanoparticles, such as SiO2 and TiO2, to address this shortcoming and boost its hydrophilicity. Herein, the nanoparticles were synthesized by the sol-gel technique and mixed with EG to construct a modified EG (MEG). The microstructure, morphology, and adsorption ability of MEG were analyzed. Additionally, the thermal properties, as well as the thermal stability of form-stable composite PCMs, were investigated. The results revealed that by varying the mass ratio of SiO2@TiO2 in MEG, the supercooling degree of the form-stable composite PCMs decreased by 77.36%–78.49%. With 9% SiO2@TiO2 in MEG, the water contact angle of MEG was optimal, and the form-stable composite PCMs prepared (DSMEG3) exhibited a phase change temperature and latent heat of 32.88 °C and 142.13 J/g, respectively. This experimental latent heat was slightly lower than the calculated latent heat by 0.12 J/g. Meanwhile, the supercooling degree decreased to 3.01 °C, and the thermal conductivity increased to 1.23 W/(m ∙ K), which was 1.73 times than that of DHPD. Moreover, DSMEG3 also showed good shape stability, preventing leakage. Therefore, the form-stable composite PCMs, as prepared, are a great potential candidate for the energy storage applications.

CH3COONa·3H2O/flaky modified vermiculite composite phase change materials enhanced phase change behavior and thermal storage through curing lotus root starch modification

With the establishment of the basic policy of environmentally-friendly and resource-saving society, the energy storage technology using phase change materials (PCMs) as the medium has developed unprecedentedly. Hydrated salt PCMs plays a vital role due to its large latent heat density, wide range of phase transition temperature, and high thermal conductivity. However, the problems of low enthalpy, poor thermal stability and phase separation are critical drawbacks of composite phase change materials (CPCMs), which limited the extensive use in fields of energy storage. In this work, the flaky vermiculite (MEVM) was fabricated by the acid treatment and alkali leaching, and the cured lotus root starch (CLRS) was embedded and used to enhance the water holding capability of hydrated salts. A series of sodium acetate trihydrate (SAT)-CLRS/MEVM was prepared, and the form-stable composite phase change materials (SAT fs-CPCMs) were obtained. Results showed that the encapsulation capacity of SAT fs-CPCM with 2 wt% CLRS was 71.3 %, and the thermal enthalpy reached 180.1 J/g, which was 43.7 % higher than that of SAT/MEVM. The contact angle of the sample with H2O was 22.24°, which represented hydrophilicity. SAT fs-CPCM also had good thermal stability and thermal reliability. After 200 thermal cycles, the enthalpy loss of the SAT fs-CPCM was only 5.2 %, and the 200th enthalpy value was 173.72 J/g. In addition, Calculations indicated that there were hydrogen bonds and van der Waals weak interaction between SAT and CLRS. This work provides a new perspective for the improvement of the thermal properties of hydrated salt and offers a promising approach for the applications of PCMs in cost-effective energy storage.

Recent advances in phase change materials for thermal energy storage.

Efficient storage of thermal energy can be greatly enhanced by the use of phase change materials (PCMs). The selection or development of a useful PCM requires careful consideration of many physical and chemical properties. In this review of our recent studies of PCMs, we show that linking the molecular structures of organic molecules to their physical properties can be used to focus attention on the most useful PCMs, including eutectic mixtures. Two of the major limitations concerning broader use of phase change materials are low thermal conductivity, especially for organic phase change materials, and suitable containment. We have addressed both issues in our recent investigations of novel form-stable composite PCMs with a freeze-cast matrix. The use of thorough experimental investigations, including cycling of materials hundreds or thousands of times through the melt-freeze processes, promotes our goals of advancing the use of PCMs for increased energy efficiency and sustainability.

Form-Stable Composite Phase Change Materials Based on Porous Copper-Graphene Heterostructures for Solar Thermal Energy Conversion and Storage.

Solar-thermal energy conversion and storage technology has attracted great interest in the past few decades. Phase change materials (PCMs), by storing and releasing solar energy, are able to effectively address the imbalance between energy supply and demand, but they still have the disadvantage of low thermal conductivity and leakage problems. In this work, new form-stable solar thermal storage materials by impregnating paraffin PCMs within porous copper-graphene (G-Cu) heterostructures were designed, which integrated high thermal conductivity, high solar energy absorption, and anti-leakage properties. In this new structure, graphene can directly absorb and store solar energy in the paraffin PCMs by means of phase change heat transfer. The porous structure provided good heat conduction, and the large surface area increased the loading capacity of solar thermal storage materials. The small pores and superhydrophobic surfaces of the modified porous G-Cu heterostructures effectively hindered the leakage issues during the phase change process. The experimental results exhibited that the thermal conductivity of the prepared form-stable PCM composites was up to 2.99 W/(m·K), and no leakage took place in the solar-thermal charging process. At last, we demonstrated that the PCM composites as an energy source were easily integrated with a thermoelectric chip to generate electric energy by absorbing and converting solar energy.

Myristic acid-tetradecanol-capric acid ternary eutectic/SiO2/MIL-100(Fe) as phase change humidity control material for indoor temperature and humidity control

Building materials with the dual function of temperature and humidity regulation can improve people's living comfort and reduce energy consumption. In this work, a simple and convenient strategy for building a comfortable indoor temperature and humidity environment was proposed. The phase change humidity control material (PCHCM) was prepared by the mixing of form-stable composite phase change material (CPCM) as temperature-control component and hygroscopic MIL-100(Fe) as humidity-control component. In PCHCM, the CPCM was obtained by molten recombination of myristic acid, tetradecanol, and capric acid (MA-TD-CA) as phase change material and hydrophilic fumed silica (SiO2) as porous carrier, and MIL-100(Fe) was synthesized by low-temperature solution method. Thermal analysis indicated that, under the optimized mass ratio of 28.8%MA-61.2%TD-10%CA, the CPCM containing 30 % SiO2 could effectively prevent the leakage of ternary eutectic, with a suitable phase change temperature and enthalpy (21.74 °C, 96.70 J·g−1). The thermal and wet performance evaluation confirmed that the PCHCMs containing 40–50 % CPCM had human body comfortable phase change temperature (26.96–27.26 °C) and high saturation adsorption capacity (0.179–0.205 g/g) at 60 % RH as well as outstanding thermal and wet cycle reliability, indicating the novel MA-TD-CA/SiO2/MIL-100(Fe) PCHCM has broad application potential in room temperature and humidity control and building energy conservation.

Form-Stable Composite Phase Change Material Based Cooling of Small Brushless DC Motor Windings

Form-Stable Composite Phase Change Material Based Cooling of Small Brushless DC Motor Windings

Numerical investigation of form-stable composite phase change material for battery passive cooling

Phase change material (PCM) has gathered much attention in battery thermal management for electric vehicles, in which form-stable PCM is a promising method to reduce the leakage of energy storage material. In this paper, a composite PCM that has form-stable property is used for passive cooling of electric car battery. Three cooling configurations are set up in the gap between two batteries, and their performance is analysed by a numerical model. The results show that integrating composite PCM with forced air convection can maximally prevent battery from heat accumulation at 5C and reduce the core temperature by 15.9 K, while filling the gap with composite PCM can reduce the temperature by 15.7 K. With the discharge rate decreased, forced air convection plays more significant role than PCM in slowing down the rise in battery temperature. The maximum battery temperature reduces when the ratio of PCM thickness to battery width increases from 0 to 0.1, but the maximum temperature is limited to a certain level with thicker PCM. The addition of 4.6 wt% graphite to the composite PCM greatly improved the heat absorption capacity of PCM, and the forced air with 20 m·s-1 velocity has better cooling behaviour than PCM.

ZIF-67@MXene structure synergistically improve heat storage and photothermal conversion of phase change material

How to design and construct the MOF-based composite phase change materials (PCMs) with simultaneously enhanced heat storage and photothermal conversion to meet the performance requirement of solar energy utilization still remains a challenge. Herein, the polyethylene glycol was selected as PCM, the ZIF-67@MXene acted as supporting structure, a series of polyethylene glycol/ZIF-67@MXene form-stable composite PCMs (PZM fs-CPCMs) with improved latent heat and photothermal conversion were designed and prepared. All the PZM fs-CPCMs showed obvious heat storage and release characteristics, and their latent heat reached ∼106.01 J/g. Furtherly, the latent heat loss of PZM40 was only 1 % after 100 phase change cycles, indicating outstanding thermal reliability, which was closely related to the structure and morphology of the PZM fs-CPCMs. More importantly, during irradiation, the maximum surface temperature of PZM fs-CPCMs regularly increased (42.5–45.2 °C) with increasing ZIF-67@MXene content, while during cooling, it regularly decreased (27.4–23.2 °C). Based on the surface temperature distribution results, the photothermal conversion ability and heat transfer rate of PZM fs-CPCMs were effectively improved, which was mainly attributed to the remarkable light absorption and conversion ability and high thermal conductivity of MXene. Meanwhile, the PZM fs-CPCMs showed good chemical compatibility, crystallinity characteristic and thermal stability, which was conducive to the solar energy utilization.

Development and properties of n-octadecane / kaolinite composites as form-stabilized phase change materials for energy storage

Thermal energy storage (TES) is one of the promising options applied for obtaining energy-saving possibilities. This goal can be attained by using phase change materials (PCMs) that allow storing/releasing latent heats without losses caused by temperature differences. However, in most cases these materials need to be encapsulated for various applications, especially to prevent contamination and/or loss of substance. In this work, incorporation of a kind of an organic PCM belonging to the paraffins was performed by one step impregnation method. For this purpose, n-octadecane (n-OD) having 191.7 kJ/kg latent heat of melting and 34.2 οC peak melting temperature was used. In here, Kaolinite clay (KC), which was modified with cetyltrimethylammonium bromide in order to enhance the incorporation amount of n-OD, was utilized as the support matrices and called as m-KC. The development of form-stable composite PCMs was carried out by applying different recipes with varying the amounts of n-OD impregnation. Among the obtained composite PCMs, m-KC/OD30 having m-KC/n-OD: 70/30 composition ratio, demonstrated the highest TES capacity without any leakage during the usage. Accordingly, TES capacity and latent heat of melting peak temperature of m-KC/OD30 were found as 81.8 kJ/kg and Tpm = 30.4 °C, respectively. Based on the appropriate phase transition temperatures and favorable latent heat of melting value, the obtained form-stable composite PCMs can be implemented for the regulation of ambient temperatures in the low-medium temperature application fields, thus a cleaner process can be implemented by realizing energy savings.

Form-stable phase change materials based on graphene-doped PVA aerogel achieving effective solar energy photothermal conversion and storage

Polyvinyl alcohol (PVA) aerogel is usually used to restrict the flow of liquid polyethylene glycol (PEG) for the preparation of composite phase change materials (PCM). Currently, the vacuum freeze-drying method is demonstrated to be the most valid way to prepare PVA aerogel. However, achieving a high thermal conductivity and optical thermal conversion efficiency in composite PCM remains challenging, due to the lack of effective thermal conductivity fillers and optical thermal conversion media within the reported PVA aerogel. Herein, we report a simple method to prepare PVA-reduced graphene oxide (rGO) aerogel by reductant reduction and vacuum freeze-drying methods. PVA-rGO aerogel is well suitable to accommodate PEG, and the consequent composite PCM (PEG/PVA-rGO) demonstrates an outstanding PEG loading rate of up to 96.9 wt%. In addition, due to the efficient light absorption and highly thermal conductivity of rGO, the photothermal conversion efficiency of PEG/PVA-rGO was increased to 88.2%, while also increasing its thermal conductivity to 0.348 W/(m·K). The melting enthalpy of PEG/PVA-rGO is measured to be as large as 155.5 J/g. Furthermore, the use of PEG/PVA-rGO for solar-thermal energy storage application is demonstrated. This work provides valuable guidance for preparing high-performance form-stable composite PCM and raises their potential for practical use in solar energy storage and energy-efficient buildings.

A novel form-stable phase change material based on elastomeric copolymer and carbon nanotubes with photo-thermal conversion performance

In this paper, the composite form-stable phase change materials (FSPCMs) with a photo-thermal conversion function for solar thermal energy storage were prepared using paraffin wax (PW) as a PCM, both styrene ethylene butylene styrene (SEBS) and olefin block copolymer (OBC) as supporting materials, and carbon nanotubes (CNT) as an efficient light-absorbing material. The PW/SEBS + OBC composite with 80 wt% PW can maintain a stable shape without leakage above the phase change temperature. The latent heat of the PW/SEBS + OBC/CNT composite with 8 % CNT is 136.2 J/g, and the entrapment efficiency is 71.2 %. The prepared composite FSPCMs have good flexibility, thermal reliability, and thermal stability. And the absorbance of PW/SEBS + OBC/CNT composite is higher than that of pure PW and PW/SEBS + OBC. Moreover, the photo-thermal conversion efficiency of PW/SEBS + OBC/CNT composite with 2 wt% CNT, 4 wt% CNT, 6 wt% CNT, and 8 wt% CNT is 72.9 %, 81.9 %, 82.3 %, and 83.2 %, respectively. The prepared composite FSPCMs have a promising application in the field of solar energy storage.

Flame-Retardant and Form-Stable Delignified Wood-Based Phase Change Composites with Superior Energy Storage Density and Reversible Thermochromic Properties for Visual Thermoregulation

The development of form-stable phase change materials (PCMs) with flame retardancy and the visual thermal storage process is crucial for their application in building energy conservation. Herein, an active phosphorus/ammonium-containing non-formaldehyde flame retardant (APA) was synthesized based on the natural compound phytic acid. Then, wood-based form-stable PCM composites (PTPCMs) with high energy storage density, excellent flame retardancy, and real-time and visual reversible thermochromic properties were successfully fabricated by impregnating the thermochromic compound into the APA-grafted delignified wood. The delignified wood well supports the solid–liquid PCMs and avoids their liquid leakage during phase transition due to the high surface tension and strong capillary effect. The differential scanning calorimetry (DSC) results showed that the PTPCMs possessed high thermal energy storage density (165.3–198.6 J/g) and reliable thermal stability. With the concentration of the flame-retardant APA increased, the peak heat release rate (pHRR) and total heat release (THR) of PTPCMs reduced noticeably, demonstrating the enhanced flame retardancy of PTPCMs. Moreover, PTPCM composites had good thermoregulation properties and the visualization of the phase transition process was made possible by the reversible thermochromic properties. In summary, the novel PTPCMs show tremendous application potential for efficient building energy conservation.

Phytic acid–decorated κ-carrageenan/melanin hybrid aerogels supported phase change composites with excellent photothermal conversion efficiency and flame retardancy

Organic phase change materials (PCMs) have been widely applied to thermal energy storage systems; however, poor solar–thermal conversion performance, high flammability, and liquid leakage issues considerably limit their practical application in efficient solar energy utilization. Herein, phytic acid–decorated melanin/κ-carrageenan aerogels (PMCAs) with excellent solar–thermal effect and satisfactory flame retardancy were developed using the cationic induction method. Then, form-stable PCM composites (PMPCMs) were fabricated by integrating molten n-octacosane into PMCAs through vacuum impregnation. The PMCAs effectively supported n-octacosane and avoided liquid leakage during the solar–thermal storage process owing to their strong surface tension and capillary force. The PMPCMs exhibited considerably high encapsulated efficiency (up to 97.73%), satisfactory thermal storage ability (246.7–257.7 J/g), and excellent thermal reliability. The introduction of natural melanin (natural photothermal conversion compound) and phytic acid (bio-based phosphorus-rich compound) significantly enhanced the solar–thermal conversion efficiency (from 61.7% to 89.4%) and flame retardancy of the PMPCMs. Thus, the synthesized form-stable composites possess tremendous potential for solar energy utilization.

A novel one-step ultraviolet curing fabrication of myristic acid-resin shape-stabilized composite phase change material for low temperature thermal energy storage

In this work we present for the first time a simply, fast and efficient process for the fabrication of form-stable composite phase change material (PCM) by ultraviolet (UV)-curing technique. Simply by UV-curing of the PCM with a desired UV curable carrier for several minutes, a neoteric UV-cured composite that suitable for low temperature thermal energy storage (TES) can be fabricated. The feasibility of such a novel technique is demonstrated by investigating a case of myristic acid (MA) dispersed into a UV curable resin containing polyurethane acrylate (PUA). The results show that a crosslinked structure is formed in the composite after UV-curing due to the occurrence of photochemical reaction, which offer sufficient paths to accommodate the PCM, endowing the composite with the great ability to maintain the structure stabilization and prevent the liquid leakage. A good physical and chemical compatibility has been achieved in the composite and 40 wt% of UV-curing resin grants the composite optimum formula at which a melting temperature of 52 °C and an energy storage density over 210.8 kJ/kg at temperature ranged 25–100 °C are obtained. The results also reveal that the material mechanical strength can be linked to the UV-curing duration. For a given V-curing time of 5–30 mins, the composite mechanical strength is measured over 25–34 MPa, almost over twice as high as that of high-density polyethylene (HDPE) and styrene ethylene butylene styrene (SEBS) based composites. Owing to the high shape strength and excellent thermal cycling performance, such UV-curable composites can be utilized for modular design of TES devices, and also be used to precisely and directionally produce TES devices through additive manufacturing. This work exploits a new perspective for the energy-saving and time-effective fabrication of shape stabilized composite PCMs for low temperature thermal energy storage.