Melting Enthalpy Research Articles

Nanoscale Stabilization Mechanism of Sodium Sulfate Decahydrate at Polyelectrolyte Interfaces.

Sodium sulfate decahydrate (SSD) is a low-cost phase-change material (PCM) for thermal energy storage applications that offers substantial melting enthalpy and a suitable temperature range for near-ambient applications. However, SSD's consistent phase separation with decreased melting enthalpy over repeated thermal cycles limits its application as a PCM. Sulfonated polyelectrolytes, such as dextran sulfate sodium (DSS), have shown great effectiveness in preventing phase separation in SSD. However, there is limited understanding of the stabilization mechanism of SSD by DSS at the atomic length and time scales. In this work, we investigate SSD stabilization via DSS using neutron scattering and molecular dynamics (MD) simulations. Neutron scattering and pair distribution function analysis revealed the structural evolution of the PCM samples below and above the phase change temperatures. MD simulations revealed that water from the hydrate structure migrates from the hydrate crystal to the SSD-DSS interfacial region upon melting. The water is stabilized at this interface by aggregation around the hydrophilic sulfonic acid groups attached to the backbone of the polyelectrolyte. This architecture retains water near the dehydrated sodium sulfate, preventing phase separation and, consequently, stabilizing SSD rehydration. This work provides atomistic insight into selecting and designing stable and high-performance PCMs for heating and cooling applications in building technologies.

Development of size and shape dependent model for various thermodynamic properties of nanomaterials

The models developed in this work are used to study various thermodynamic properties of nanomaterials. A better agreement between theory and experiment indicates the validity of the proposed model. Since the model is simple and easy to use, we extend the theory to understand, how the thermodynamic properties of different nanomaterials depend on size and shape. The results were compared with previous theoretical work and experimental data. We have concluded that the model predicts a better agreement with previous theoretical work and experimental studies. Current research produces thermodynamic models for the Debye frequency, melting entropy, melting enthalpy, and Einstein temperature. To the best of our knowledge, such models are not yet available in the literature that works well.

Production and assessment of UV-cured resin coated stearyl alcohol/expanded graphite as novel shape-stable composite phase change material for thermal energy storage

Expanded graphite-phase change materials (PCM) structures are reinforced to polymers with various methods to fabricate advanced thermal energy storage materials. However, these methods still suffer from processing time and product efficiency challenges. In this study, the UV-curing method was used to produce shape-stable EG-PCM-reinforced resin composites with fast curing and low process temperature of the resin. The composite material, comprising UV-curable resin (30 %), stearyl alcohol (65 %), and Expanded graphite (5 %), was synthesized. This synthesis aimed to address the limitations of traditional PCMs, such as low thermal conductivity and leakage. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the materials' phase change behavior and thermal stability. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted to elucidate the microstructure and crystallinity of composite materials. The composites, exhibiting near-perfect impermeability with leakage as minimal as 0.89 %, not only enable the attainment of cooler environments by 2–3 °C under hot air conditions but also demonstrate exceptional thermal stability up to 207 °C, as evidenced by TGA results. Additionally, they offer a remarkable melting enthalpy value of 153.1 J/g. These composites, with their shape-retention ability during phase transitions and high thermal energy storage capacity, are a versatile and efficient option for sustainable energy management. This research contributes to the development of innovative materials for renewable energy integration and reducing carbon emissions.

A polyurethane solid–solid phase change material for flexible use in thermal management

Phase change materials (PCMs) have received great attention in thermal management of electronic devices due to their high energy storage density and no need for additional energy supply. Yet the leakage problem after phase change limits their application greatly. In this paper, the block copolymerization was used to prepare a novel solid–solid phase change material (SSPCM) with a melting enthalpy of 90.26 J/g, starting pyrolysis at a temperature of more than 300 °C, and its physicochemical and thermal properties remained basically unchanged after 100 heating/cooling cycles. Notably, this SSPCM has excellent shape stability and can be pressed into phase change film with flexibility, thermally induced self-healing capability and recyclability. Finally, we innovatively combined this SSPCM, copper foam (CF), and polyimide tape (PI) to obtain a composite phase change material (CPCM) with both high thermal conductivity (1.1994 W/m·K) and high electrical insulating properties. Thermal management experiment shows that this CPCM has good thermal management performance and can significantly reduce the temperature rise rate of the simulated CPU. The SSPCM prepared in this study shows great potential for application in thermal management of portable electronic devices and flexible wearable electronic devices.

Synergistic effect of nitrocellulose coating on structural and reactivity stabilization of ammonium nitrate oxidizer

The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate (AN) particles utilizing a microencapsulation technique, which involves solvent/non-solvent in which nitrocellulose (NC) has been employed as a coating agent. The SEM micrographs revealed distinct features of both pure AN and NC, contrasting with the irregular granular surface topography of the coated AN particles, demonstrating the adherence of NC on the AN surface. Structural analysis via infrared spectroscopy (IR) demonstrated a successful association of AN and NC, with slight shifts observed in IR bands indicating interfacial interactions. Powder X-ray Diffraction (PXRD) analysis further elucidated the structural changes induced by the coating process, revealing that the NC coating altered the crystallization pattern of its pure form. Thermal analysis demonstrates distinct profiles for pure and coated AN, for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6 °C, and 36%, respectively. Furthermore, the presence of NC coating alters the intermolecular forces within the composite system, leading to a reduction in melting enthalpy of coated AN by ∼39% compared to pure AN. The thermal decomposition analysis shows a two-step thermolysis process for coated AN, with a significant increase in the released heat by about 78% accompanied by an increase in the activation barrier of NC and AN thermolysis, demonstrating a stabilized reactivity of the AN-NC particles. These findings highlight the synergistic effect of NC coating on AN particles, which contributed to a structural and reactive stabilization of both AN and NC, proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.

Preparation and characterization of phase change erythritol/expanded graphite@Ag composite materials for thermal energy storage

In this paper, the composite PCMs of Erythritol (ET)/Expanded Graphite (EG)@Ag were prepared by vacuum impregnation method with EG@Ag as matrix and the ET as the phase change material (PCM). The chemical compatibility, thermodynamic properties and thermal stability of composite phase change materials (CPCMs) were systematically examined. The results illustrated that the CPCMs possessed good chemical compatibility with only physical interaction between ET and EG@Ag. The supercooling of ET/EG@Ag-8 wt% reduced by 42.13 °C, which also remain high melting and solidification enthalpy of −258.09 J/g and 187.63 J/g, respectively. The thermal conductivity of ET/EG@Ag-8 wt% reached to 2.87 W/(m·K), which resulted in an enhancement of 463 % in the thermal conductivity of ET. Thermal stability results show that all CPCMs of ET/EG@Ag present good thermal stability below 200 °C. This offers new prospects for the use of ET in the field of medium temperature phase transitions.

Synergistic enhancement of photothermal energy storage capacity of polyethylene glycol by polydopamine and nano-copper particles

Phase change materials (PCMs) are a crucial focus of research in the field of photothermal energy storage. However, due to their inherently low photothermal conversion efficiency, traditional PCMs absorb solar energy scarcely. The photothermal conversion ability of PCMs are usually enhanced by incorporating photothermal conversion nanoparticles. Polydopamine (PDA) is widely used in various fields due to its excellent photothermal conversion and adhesion performance. We dispersed PDA into PEG containing CuNPs to test the effect of PDA on thermal properties of cPCMs. Our team has conducted experiments to test the thermal characteristics and photothermal conversion ability of cPCMs. Results demonstrated that the addition of PDA mitigated the enthalpy loss caused by integrating CuNPs. The enthalpy of melting of cPCMs with addition of polydopamine is greater than that without polydopamine for the composites with different mass fractions. The addition of PDA in cPCMs enhanced their photothermal conversion capacity, resulting in higher temperatures being achieved within the same exposure time compared to samples without PDA. Therefore, the cPCMs with dispersed polydopamine can store higher energy. Meanwhile, PDA also improved the overall thermal conductivity of the material. Our work provided a new method to utilize the photothermal properties of polydopamine. Meanwhile, it can reduce the cost of photothermal energy storage PCMs and further improve the potential of PCM energy storage.

A novel cement mortar comprising natural zeolite/dodecyl alcohol shape stable composite phase change material for energy effective buildings

Investigations into Phase Change Materials (PCMs) for heat storage in facilities have gained significance, contributing to indoor temperature regulation, decreased energy usage, and improved building efficiency, thereby supporting sustainability initiatives. However, the issue of PCM leakage during the heating phase has constrained its thermal energy storage (TES) prospective at large scaled-practices. Addressing this concern, the present study emphases on elimination of the leakage problem of dodecyl alcohol (DA) as a PCM with appropriate melting temperature for building TES request by its impregnating into the natural zeolite (NZ) as a low cost host matrix. In the second stage of the work, using the developed shape stable-NZ/DA (SS-NZ/DA) composite PCM in cement mortar instead of sand, novel cementitious mortars with enhanced thermal properties were created by incorporating different weight percentages (25 %, 50 %, 75 %, and 100 %) compared to the mortar comprising NZ. Experimental works were carried out to analyze the shape-stability, TES features, cycling TES stability and thermal endurance of the SS-NZ/DA composite as well the physical properties, mechanical strength, and solar temperature regulation performance of the SS-NZ/DA included mortars. The SS-NZ/DA demonstrated the melting enthalpy of 107.5 J/g at 19.47 °C and a freezing enthalpy of 106.1 J/g at 19.86 °C. The performance test results obtained under real weather conditions indicated that the integration of SS-NZ/DA into mortar presented maximum drop of 10 % and 9.26 % in peak indoor temperature at the SS-CPCM slab surface and the center of SS-CPCM slab-cabin, respectively, accompanied by an approximate 3-hour time delay. Mortars with SS-NZ/DA composite PCM exhibited a decreased dry unit weight (1189 kg/m3) and thermal conductivity (0.394 W/mK) while experiencing a moderate strength loss (4.5 MPa). These favorable physico-mechanical properties, TES characteristics and thermal management capability make the novel cementitious mortar containing composite PCM as an energy-efficient material for creating thermo-regulative building components. In this study, the natural, economical, and environmentally friendly nature of the NZ material used for PCM impregnation, its ability to contain a high percentage of PCM (up to 45 %) without any leakage issues, is the most fundamental and important characteristic of the composite used. The most unique feature of this composite mortar is the ability to achieve sufficient mechanical and thermal properties in cementitious mortars produced using this composite material without any leakage problems.

Enhancing sustainability with waste hemp-shive and phase change material: Novel gypsum-based composites with advanced thermal energy storage properties

This study addresses the rising demand for sustainable construction by introducing composite materials from natural and renewable resources: gypsum, hemp, and phase change materials (PCMs). These materials cater to the growing preference for eco-friendly building solutions. Incorporating hemp enhances sustainability while integrating PCMs into the porous hemp structure ensures adequate thermal energy storage and release without leakage. Firstly, the agricultural waste hemp shives and lauryl alcohol (LA) PCM were mixed to create shape-stabilized hemp/PCM composites. The highest PCM ratio was determined in shape-stabilized composites exhibiting non-leakage properties, which was 45 wt %. These composites were then incorporated into gypsum materials at loadings of 7.5 %, 15 %, 22.5 %, and 35 wt % to produce the final composites. Morphological, thermal, and chemical characteristics of shape-stabilized composites were examined using SEM, TGA, and DSC, while the solar thermoregulation tests assessed the gypsum matrix composites. The phase change temperature of PCM was determined as 20.24 °C with a melting enthalpy value of 224.4 J/g. The hemp/PCM shape-stabilized composites demonstrated an impressive melting enthalpy value of 100.2 J/g, with only a slight reduction to 99.5 J/g after 750 test cycles. When the ambient temperature exceeded 50 °C, the central temperature of the cabins containing PCM composites was found to be at least 4 °C cooler than those containing only gypsum. Conversely, when the ambient temperature dropped to around 20 °C, it was observed that the central temperature of the cabins with PCM composites was approximately 2 °C warmer than those with only gypsum. This study introduces a novel approach to creating environmentally friendly gypsum/hemp/PCM composites for thermal energy storage systems.

An investigation of novel biodegradable flexible copolyester derived from bio-based isosorbide: Synthesis and characterization of poly(butylene-co-isosorbide sebacate)

A series of fully bio-based poly(butylene-co-isosorbide sebacate) (PBISe) copolyesters are synthesized from sebacic acid (Se), 1,4-butanediol (BDO), and isosorbide (IS) via a two-step melt polycondensation method. The synthesized PBISe copolyesters are characterized using various techniques, including 1H NMR spectroscopy; GPC; FT-IR spectroscopy; HR-XRD; DSC; TGA; transparency, tensile, and tear strength testing; and rheological property analysis. The Mw and Mn values of the PBISe copolyesters are 126,000–148,000 and 50,000–63,500, respectively. The introduction of the rigid, bulky, and asymmetric IS unit disrupts the regularity and mobility of the polymer chain, resulting in a nearly linear reduction of the melting temperature, enthalpy, and crystallinity, from 66 to 42 °C, 81 to 37 J/g, and 41.4 to 19.0%, respectively, with an increase in the IS content from 0 to 30 mol% relative to the total diol concentration. The reduction of crystallinity without the formation of new crystal planes with the poly(butylene sebacate (PBSe) copolyester containing 30 mol% IS resulted in improved transparency (73.8% transmittance at 600 nm). Additionally, the PBISe copolyesters exhibit Tonset and Tmax in excess of 405 °C and 425 °C, respectively, as well as shear-thinning and viscous melt-flow behaviors, making them suitable for melt processing. The tensile strength and elongation at break of the hot-pressed films of the IS-added PBISe copolyesters with ≤16% content are 31.6–36.3 MPa and 639.2–809.9%, respectively. The developed PBISe copolyesters have great potential as bio-based, biodegradable, and flexible materials for packaging and coating applications with low processing temperatures.

Experimental investigation on the performance of binary carbon-based nano-enhanced inorganic phase change materials for thermal energy storage applications

Phase change materials (PCMs) are considered potential resources for Thermal energy storage (TES) applications. However, the PCMs are limited because of their lower thermal conductivity, resulting in a significant decrease in heat transport and energy storage capability. The foremost objective of the present research is to formulate a novel salt hydrate PCM filled with binary carbon-based nanoparticles (graphene and multi-walled carbon nanotubes) at various weight concentrations and examine the thermophysical properties. A two-step approach is used to formulate binary nanomaterials dispersed salt hydrate PCM. The formulated binary nanocomposite's thermo-physical properties like morphological behaviour, thermal stability, chemical stability, melting enthalpy, optical performance, rate of heat transfer and thermal reliability were characterized. The binary nanoparticle-enhanced nanocomposites can form a decent thermal network, resulting in a remarkable enhancement in thermal conductivity by 160 % (1.2 W/mK) compared to pure salt hydrate. Moreover, a remarkable improvement in optical absorptance and a reduction in optical transmittance by 82.55 % for 0.7 wt% graphene and 0.07 wt% MWCNT enhanced salt hydrate PCM (SAHGrM-0.07) than pure salt hydrate PCM. In addition, the formulated nanocomposites possess excellent heat storage capability, chemical and thermal stability after 300-thermal cycling. The binary carbon-based nanoparticle-enhanced salt hydrate nanocomposites offered acceptable thermal and chemical stability, thermal reliability, and heat transmission characteristics, by this means reflecting its appropriateness for medium-temperature solar TES applications.

Thermal and photo/electro-thermal conversion characteristics of high energy storage density expanded graphite/polyethylene glycol shaped composite phase change materials

Compared with other energy storage materials, phase change materials (PCMs) are drawing widespread attention because of their high enthalpy and low temperature change. However, its low thermal conductivity, low photo/electro-thermal conversion characteristics, phase separation and easy leakage are still urgent problems. In this work, expanded graphite/polyethylene glycol (EG/PEG) composites were prepared based on physical adsorption method, the relationship between the mass percentage of EG and the microstructure, phase transition properties (phase change enthalpy, supercooling degree) and energy conversion properties was studied. The composite PCM exhibits exceptional thermal conductivity (2.48 W·m−1·K−1, 7 folds greater than that of PEG) and outstanding melting enthalpy (161.4 J/g). The thermal conductivity of the EG/PEG composites is almost constant versus temperature over measured temperature range (26 ℃∼60 ℃). The energy conversion capacities (photo/electro-thermal conversion) increase as the expanded graphite mass fraction increases. The prepared composite PCM obviously overcomes the shortcomings of the pure polyethylene glycol, and highlights enormous application in the domains of multi-physical energy conversion and premium quality power absorption.

Synthesis and characterization of long carbon chain polyamide 1012 modified polyamide 6 via melt copolymerization

Polyamide6 is a vital high-performance commercial engineering thermoplastics polymer, but it exhibits low toughness and high hydrophilicity. To improve its disadvantages, the facile melt co-polycondensation method was proposed to synthesis a novel polyamides 6-1012 copolymers (PA6-1012) with different PA1012 salt loading. Experimental results show that the melting temperature (Tm), crystallization temperature(Tc), melting enthalpy(ΔHm), and crystallinity(Xc) decreased with the increase of PA1012 loading in the copolyamides. The size and number of the copolymers’ spherical crystals decrease by the additions of 1012 units, but its crystalline structure and thermal stabilities does not be affected. The hydrophilicity decreases with increasing PA1012 content from 0 to 28 wt% and the highest contact angle value at the PA1012 loading of 28 wt% is 96°, which can be considered as a surface hydrophobic material. Low temperature (−5 °C)mechanical test results reveal that loss in tensile strength is exchanged for a considerable increase in the strain at break. The impact strength of the PA6-1012 copolyamides is notably enhanced by increasing the PA1012 loading in different test temperatures due to the increase of molecular chain flexibility, indicating that the copolyamindes exhibit enough toughness to suitably apply in low temperature environment.

Changes in the structure and enzyme binding of starches during in vitro enzymatic hydrolysis using mammalian mucosal enzyme mixtures

Starches are hydrolyzed into monosaccharides by mucosal α-glucosidases in the human small intestine. However, there are few studies assessing the direct digestion of starch by these enzymes. The objective of this study was to investigate the changes in the structure and enzyme binding of starches during in vitro hydrolysis by mammalian mucosal enzymes. Waxy maize (WMS), normal maize (NMS), high-amylose maize (HAMS), waxy potato (WPS), and normal potato (NPS) starches were examined. The order of the digestion rate was different compared with other studies using a mixture of pancreatic α-amylase and amyloglucosidase. NPS was digested more than other starches. WPS was more digestible than WMS. Hydrolyzed starch from NPS, NMS, WPS, WMS, and HAMS after 24 h was 66.4, 64.2, 61.7, 58.7, and 46.2 %, respectively. Notably, a significant change in the morphology, reduced crystallinity, and a decrease in the melting enthalpy of the three starches (NPS, NMS, and WPS) after 24 h of hydrolysis were confirmed by microscopy, X-ray diffraction, and differential scanning calorimetry, respectively. The bound enzyme fraction of NPS, NMS, and WPS increased as hydrolysis progressed. In contrast, HAMS was most resistant to hydrolysis by mucosal α-glucosidases in terms of digestibility, changes in morphology, crystallinity, and thermal properties.

Discoloration performance and mechanism research of a novel thermochromic energy storage material

The combination of phase change materials and thermochromic materials can realize the purpose of changing color while storing energy, so as to play the role of temperature regulation and color warning. In this paper, a thermochromic energy storage material (TESM) was prepared by using crystal violet lactone (CVL) and cresol red (CSR) as color former and color developer each other, taking octadecanol (OD) as the solvent and the energy storage material. The phase transition of OD induces ring-opened and ring-closed of lactone in both CVL and CSR, further leading to better discoloration. The influence of different proportions on the discoloration effect was studied. The thermal properties and functional groups of the samples were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and Fourier transform infrared spectrometer (FT-IR). The discoloration and re-coloration mechanism were explored. The results showed that the color of the prepared TESM can reversibly change between yellow-green (at room temperature) and red (at high temperature). The discoloration is attributed to the change of the intermolecular force between OD and CSR caused by the solid-liquid phase transformation of OD. When m(CVL): m(CSR): m(OD) = 3:1:500 (B3), the color difference of the prepared TESM is 38.81 NBS and the melting enthalpy is 219.8 J/g. Moreover, the prepared TESM shows good thermal stability and thermal cycling performance, and it has broad application prospects in the field of temperature alert and control.

Solar to thermal energy storage performance of composite phase change material supported by copper foam loaded with graphite and boron nitride

Phase Change Materials (PCM) have emerged as one of the potential candidates for solar Thermal Energy Storage (TES) because of their high energy density, low volume change, and easy availability in varying temperature ranges. However, PCM suffers from a few critical drawbacks such as leakage during phase transformation, low thermal conductivity, and poor photothermal energy conversion performance. In this study, shape-stable composite PCM loaded with varying percentages of Graphite (GR) and Boron Nitride (BN) were prepared. Copper foam of 96 PPI was used as 3-dimensional skeleton support to provide shape stability to the eutectic mixture of Lauric Acid (LA)-Myristic Acid (MA). Shape stable composite PCM CF/LA-MA/GR with 0 %, 5 %, 15 %, 25 %, and 35 % of GR and CF/LA-MA/BN with 0 %, 5 %, 15 %, 25 %, and 35 % of BN were prepared and characterized for thermal, physical, and photothermal energy conversion performance. A maximum loading percentage of 67 % of LA-MA in CF without leakage was obtained. The PCM composites show excellent thermal stability at elevated temperatures and suitable TES parameters for solar thermal storage applications. Among all the prepared samples, CF/LA-MA/GR35% shows a maximum rise of 76.1 % in heating rate and 81.2 % in photothermal energy conversion efficiency in comparison with CF/LA-MA/GR0%. In addition, CF/LA-MA/GR35% shows a maximum of 1.08 W/m-K of thermal conductivity at a melting enthalpy of 95.36 J/g. The shape-stable composite PCM shows a stable physical structure along with good surface morphology.

Thermal conductivity enhancement and shape stability of composite phase change materials using MIL-101(Cr)-NH2/expanded graphite/multi-walled carbon nanotubes

Low heat conductivity and leakage much restrict the effective use of phase changing materials (PCMs) in heat energy management. Here, an expanded graphite (EG)/ multi-walled carbon nanotube (MWCNT) / metal organic framework (MOF: MIL-101(Cr)-NH2) composite was developed to solve these issues. The porous MOF can avoid the loss of liquid paraffin wax (PW). The heat conductivity of composite PCMs (CPCMs) was improved using EG/MWCNT with a mass ratio of 4:1. The thermophysical properties, heat stability and chemical compatibility of CPCMs were comprehensively investigated. Results demonstrate the successful preparation of CPCMs without any chemical reaction. The MOF (35 %)/EG(4 %)/MWCNT(1 %)/PW(60 %) CPCM exhibits superior thermophysical properties and its melting enthalpy (74.59 J/g) is near the theoretical level after 500 heating/cooling cycles. It exhibits a 792 % increment in heat conductivity from pure PW.

Macroencapsulated Al-Si phase change materials for high temperature latent thermal energy storage

This research investigated the encapsulation of Al-Si alloy phase change materials (PCMs) for efficient thermal storage at high temperature. Two strategies, the direct powder formation route and in situ powder alloying formation route, were employed successfully. In the direct powder formation route, Al-Si alloy powders were spheroidized into spheres and encapsulated within Al2O3 powder shells with the help of organic binder, which were finally sintered at high temperature, forming Al-Si@Al2O3 capsules with cavities. Isostatic pressing at 50 MPa and 200 MPa were applied to the Al-Si cores, in order to optimize the cavity size. In the in situ powder alloying formation route, Al and Si powders were used as raw materials, which could be in situ transferred to Al-Si alloy inside the capsule during the sintering formation process. With the powders as the raw materials, the final capsules obtained after sintering could provide a buffer cavity inside the capsules, which could accommodate the volumetric expansion of the PCMs during melting, thereby mitigating the potential leakage and rupture of the capsules. Investigations into the melting-solidification cycles revealed the remarkable durability of the Al-Si phase change capsules. Isostatic pressure treatment decreased internal ineffective cavities, improving the heat storage density of the capsules. The Al-12Si(Ar)-200 MPa capsule exhibited superior thermal storage performance, enduring up to 1300 cycles. The Al-12Si core had a melting enthalpy of 479 J/g, while the thermal storage density of the phase change capsule within the temperature range of 500 °C–700 °C reached 496 J/g. The results underscore the significant potential of macroencapsulated Al-Si PCM, positioning it as a promising candidate for high-temperature thermal storage applications.

Potential Wound Dressing with Antibacterial Effect from Cross‐Linked Polyvinyl Alcohol/Sodium Caseinate/CuO NP Electrospun Mat

AbstractIn this study, nanofibers were produced from Polyvinyl alcohol (PVA)/Sodium Caseinate (SoCAS)/Copper Oxide nanoparticle (CuO NP) mixtures by electrospinning method. Nano surfaces were cross‐linked by immersion in a Glutaraldehyde (GLA) bath. Electrospun mats are designed as modern wound dressings with antibacterial effects for exuding wounds. The cross‐linking process by dipping has thickened a bit of nanofiber diameter by creating a coating effect on fiber surface. The increase of acetal bonds and decrease of hydroxyl groups in structure by cross‐linking have improved thermal properties of nanofibers. The increase in melting enthalpy has also improved mechanical properties of mats. The mixture of semicrystalline PVA and SoCAS has increased breaking stress of nanostructure. Besides, the CuO NP additive improved the breaking strength and elongation behavior of mats. It was stated that cross‐linked nanofibers swelled without dissolving in distilled water and contained water‐repellent groups. The CuO NP supplementation delayed the growth of Escherichia coli (E. coli). However, it was observed that antibacterial effect against Staphylococcus aureus (S. aureus) was higher than against E. coli. It was reported that 5 % CuO NP‐doped nanofiber can be used as a wound dressing, owing to its high fibroblast cell viability at 24th and 48th hours and 99.48 % antibacterial activity against S. aureus.

Study on the potential of multi-performance enhanced phase change materials in battery thermal management

Lots of research has proved the effectiveness of flexible composite phase change material (CPCM) in thermal management of electronic products. However, the key properties of materials, e.g., flexibility, thermal conductivity and resistance are mutually restricted, further limiting its application in practical thermal management engineering. Unfortunately, the above performance has not been comprehensively considered in the existing research. In this work, a novel shape-stabilized flexible CPCM with considerable comprehensive performance was proposed. Styrene-b-ethylene-co-butylene-b-styrene (SEBS) was used as a flexible matrix to expand the flexible temperature range, and ALN was used to improving the thermal conductivity (0.786 W·m−1·K−1), strengthening the three-dimensional thermal conductivity skeleton of expanded graphite and improving the resistivity to 5.16 × 1010 Ω·m. Meanwhile, the CPCMs showed excellent performance in cycle stability, the melting enthalpy only decreased by 1.29 % after 500 cycles. The result of thermal management exhibited that the maximum temperature (Tmax) and maximum temperature difference (ΔTmax) of the battery at 6C discharge rate were 43.64 °C and 2.39 °C respectively with the help of CPCMs. More importantly, it was also obtained that the thermal conductivity played a major role in the battery temperature control in the long-term operation, the increase of the thermal conductivity reduced ΔTmax by 68.05 %. This work will further provide technical support for the practical engineering application of flexible CPCMs for electronic thermal management.