Differential Scanning Calorimetric Analysis Research Articles

Effect of Humidity on the Thermal Properties of Aluminum Nanopowders with Different Surface Coatings

To investigate the effect of surface coating materials on the humidity stability of aluminum (Al) nanopowders, three kinds of core–shell structure Al nanopowders with an Al2O3 passivation coating, carbon coating, and plasticizer dioctyl sebacate (DOS) coating were prepared through laser-induction complex heating method. After one year’s storage at 95% relative humidity, their thermal properties were tested through differential scanning calorimeter (DSC) and thermal gravimeter (TG) analysis. The results show that the thermal properties of Al2O3-passivated Al nanopowders are entirely lost under high humidity because the Al2O3 passivation coating is very sensitive to moisture. The thermal properties of carbon-coated Al nanopowders are not well-protected under a high humidity due to the uneven thickness and structural defects of carbon coatings. However, the thermal enthalpy of DOS-coated Al nanopowders remains at 3.56 KJ/g under high humidity, which indicates that an organic DOS coating with a hydrophobic nature has an excellent protective effect on the thermal properties of the Al nanopowders. Given the good forming performance of organic DOS coatings and other components of propellants, DOS-coated Al nanopowders are a kind of energetic material with potential application value.

Effect of short- and medium-chain fatty acid mixture on polyhydroxyalkanoate production by Pseudomonas strains grown under different culture conditions.

Short- and medium-chain fatty acids (SMCFAs) derived from the acidogenic anaerobic mixed culture fermentation of acid whey obtained from a crude cheese production line and their synthetic mixture that simulates a real SMCFA-rich stream were evaluated for polyhydroxyalkanoate (PHA) production. Three individual Pseudomonas sp. strains showed different capabilities of growing and producing PHAs in the presence of a synthetic mixture of SMCFAs. Pseudomonas sp. GL06 exhibited the highest SMCFA tolerance and produced PHAs with the highest productivity (2.7 mg/L h). Based on these observations, this strain was selected for further investigations on PHA production in a fed-batch bioreactor with a SMCFA-rich stream extracted from the effluent. The results showed that PHA productivity reached up to 4.5 mg/L h at 24 h of fermentation together with the ammonium exhaustion in the growth medium. Moreover, the PHA monomeric composition varied with the bacterial strain and the type of the growth medium used. Furthermore, a differential scanning calorimetric and thermogravimetric analysis showed that a short- and medium-chain-length PHA copolymer made of 3-hydroxybutyric, -hexanoic, -octanoic, -decanoic, and -dodecanoic has promising properties. The ability of Pseudomonas sp. to produce tailored PHA copolymers together with the range of possible applications opens new perspectives in the development of PHA bioproduction as a part of an integrated valorization process of SMCFAs derived from waste streams.

Thermal Analysis of the Mechanism and Kinetics Parameters of the Metastable Phases Precipitation in the Al-Mg-Si Alloy

In this experimental study, the mechanism and kinetic parameters of the metastable phases precipitation in the Al-Mg-Si alloy were determined thermally by differential scanning calorimetric (DSC) analysis. All samples were treated up to 550 °C at heating rates of 5, 10, 20 and 30 °C/min. The apparent activation energy (56.74 kJ/mol) and the Avrami exponent (0.99), were determined by DSC from the non-isothermal method, using the Ozawa, Boswell and Kissinger methods while those obtained by isothermal method using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model were 51.04 kJ/mol and 1.18. The activation energies values indicate that the formation of the metastable phases was mainly controlled by the migration of Mg and Si. The values of n, are characteristics of a growth of plate after saturation of nucleation. The frequency factor (ko) calculated by the isothermal method is found to be 8.36×107 s-1.

Characterization, Properties and Antimicrobial Activity of Radiation Induced Phosphorus-Containing PVA Hydrogels

Function modification of polyvinyl alcohol (PVA) having phosphorus-containing heterocyclic compounds is believed to have thermal and biological applications in the area of polymers. The synthesis of phosphorus-containing PVA (P-PVA) was performed using γ-radiation. The chemical structure of the composite polymer is confirmed by spectroscopic techniques of FT-IR, 1H, 13C, and 31P-NMR. Photosensitive properties of polymers were investigated by ultraviolet spectroscopy. Thermal studies are assigned using the Differential Scanning Calorimeter (DSC) and thermogravimetric analysis (TGA). Data display that P-PVA has more thermal stability than PVA. The surface morphology of the prepared hydrogels was performed using scanning electron microscopy (SEM). Quantitative elemental analysis of the P-PVA hydrogel was done through energy-dispersive X-ray spectroscopy (EDX). Antimicrobial activity of the prepared hydrogels using different fungi such as Aspergillus fumigatus, Geotrichum candidum, Candida albicans, and Syncephal-astrum racemosum, in addition to bacteria such as Staphylococcus aureus, Bacillis subtilis (as gram-positive bacteria), Pseudomonas aeruginosa, and Escherichia coli (as gram-negative bacteria), was studied. The phosphorus-contained PVA hydrogels were found to have antimicrobial activity against various fungi and bacteria compared to pure PVA hydrogels.

Evaluation of Physiochemical Properties, Thermal Behavior and Phytopharmaceutical Potential of Citrus aurantium’s Essential Oil

The study investigates the therapeutic potential of the Citrus aurantium var. amara essential oil extracted from the blossoms of the bitter orange plant by examining its chemical composition, thermal stability, and potency against infectious disease-causing pathogens. Initially, the volatile components of the essential oil were evaluated by obtaining a chromatographic fingerprint using HPTLC and FTIR spectrum identification. Furthermore, a thermal profile of the essential oil was obtained using the thermogravimetric-differential thermal analysis and differential scanning calorimetric analysis. A predetermined set of antibiotic-resistant microorganisms were used to examine the antibacterial activity of the essential oil. Lastly, its anti-inflammatory activity was assessed using the albumin denaturation assay. The research concluded that the Citrus aurantium var. Amara essential oil exhibits potential therapeutic characteristics which can be further explored through in vivo studies.

Synthesis, characterization, theoretical study, and anticancer application of a new asymmetric ligand, N‐trans‐cinnamylidene‐1,2‐phenylenediamine, and its complexes

In this work, a new asymmetric ligand, N‐trans‐cinnamylidene‐1,2‐phenylenediamine via the condensation reaction of 1,2‐phenylenediamine and trans‐cinnamaldehyde, and its complexes have been successfully synthesized. The ligand and its complexes were characterized by spectroscopic techniques including FT‐IR, 1H NMR, 13C NMR, ESI‐mass, UV‐vis, and physicochemical methods, such as molar conductivity, elemental analysis, and melting point. Based on the identification results, the general formula of MLX2 (X = Cl−, Br−, and M = Zn2+, Hg2+, Cd2+) was proposed for the complexes. Differential scanning calorimetric analysis was also used to investigate the thermal properties of the as‐synthesized compounds. Further, theoretical studies were performed on the ligand and its complexes. Molecular electrostatic potential surface analysis was done to distinguish the electrophilic and nucleophilic sites of the products. Nonlinear optical properties of the ligand and complexes were calculated and then compared with the standard nonlinear optical material. The frontier molecular orbitals were theoretically determined and the energy gap, global electrophilicity index, electronic chemical potential, ionization potential, absolute electronegativity, electron affinity, absolute hardness, and softness were calculated. Finally, thermodynamic properties of the compounds were evaluated. Moreover, the assessment of cytotoxicity effects of all compounds against HCT116 cancer cells was performed by the MTT assay. In vitro studies showed that HgLCl2 could considerably reduce cell viability and increase induction apoptosis and cell cycle arrest.

Enhanced thermal and tensile behaviour of MWCNT reinforced palm oil polyol based shape memory polyurethane

Shape memory polyurethane (SMPU) has received tremendous interest because of its low cost, low density, as well as easy processing. However, its inferior mechanical properties compared to shape memory alloys have constrained its application in a broad range of engineering areas. Nanofillers are commonly added to polymers to overcome the problem associated with low mechanical characteristics. This study aims to examine the effect of various loadings of multiwalled carbon nanotubes (MWCNT) on the thermal stability, soft segment crystallinity, tensile and shape memory behaviour of palm oil polyol based SMPU nanocomposites. The SMPU nanocomposites were synthesised using a two-step polymerisation process. Microphase-separated SMPU nanocomposites obtained as the differential scanning calorimetric analysis showed two melting transitions, which belonged to the soft and hard phase domains. Furthermore, it was found that MWCNT had acted as a nucleating agent, which promoted the crystallisation process of SMPU nanocomposites. The thermal stability and tensile properties of SMPU/MWCNT nanocomposites were enhanced significantly as the MWCNT was added to the SMPU matrix. A considerable enhancement in the shape fixity (SF) value was revealed for PU-30 and PU-40 samples with the addition of MWCNT. The shape recovery (SR) time of SMPU was faster for samples reinforced with MWCNT, whereas SF increased while SR decreased upon increasing the shape memory cycle. The SMPU nanocomposites produced demonstrated enhanced thermal and tensile properties, which has the potential as smart material in many industrial applications.

Insight into the formation of conjugated ladder structure of polyacrylonitrile by X-ray photoelectron spectroscopy

Understanding the formation of conjugated ladder structure of polyacrylonitrile (PAN) is of great significance to optimize the conditions of thermal stabilisation. Here, X-ray photoelectron spectroscopy (XPS) is applied to observe the structural evolution in order to find the optimal conditions for thermal stabilisation. And a new method of analysing the transition temperature of conjugated ladder structure (TCLS) is introduced. Thermogravimetric (TG) and differential scanning calorimeter (DSC) analysis confirm the necessity of air atmosphere to the formation of stable structure, and XPS analysis reveals the complete formation of conjugated ladder structure between 200 and 300 °C. In this range, a method of analysing TCLS is established by the considerable increase of conjugated ladder carbon content and asymmetric tail in C1s spectrum. Besides, the optimal conditions for thermal stabilisation are determined, which are a heating rate of 5 °C/min, a temperature of 250 °C (the TCLS), and a retention time of 60 min, respectively.

Characteristics of thermal storage heat pipe charged with graphene nanoplatelets enhanced organic phase change material

The challenge on the thermal management of highly integrated electronic devices and avionics equipment has grown continuously. To meet fully passive and highly reliable requirements, a novel thermal storage heat pipe (TSHP) charged with phase change material (PCM) is designed. Paraffin RT70HC and graphene nanoplatelet (GNP) are used as energy storage material and heat transfer enhancer, respectively. The microstructure, chemical and thermophysical properties of RT70HC/GNP composite are systematically characterized through Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Differential Scanning Calorimeter (DSC) and thermal conductivity analyzer. A visualization experimental investigation is conducted to study the effects of nano-enhanced phase change material (NEPCM) on the thermal performance of TSHP at different heat fluxes. Results show that the thermal conductivity of PCM is improved maximally 21.6% by adding GNP, whereas the latent heat of fusion decreased 10.5%. It is also observed that the TSHP with NEPCM has better thermal management performances, which effectively lowers the temperature rising speed of the chipset, and extends the sustainable time to reach the chip permitted highest temperature of 85 °C. Finally, the saturation pressure of NEPCM during the melting process is measured and discussed.

Development of antibacterial textiles by cyclodextrin inclusion complexes of volatile thyme active agents

AbstractThe study aims to develop wash‐resistant antibacterial cotton fabrics without using synthetic chemicals. Therefore, natural active agents of thyme, thymol and carvacrol were selected. The inclusion complexes were formed with β‐cyclodextrin using kneading method which is a simple and reproducible method for the encapsulation with high production yield. Differential scanning calorimeter analysis showed that 1:1 and 1:2 β‐CD: Guest Molecule (M:M) for thymol and carvacrol from different ratios studied has the highest complexation degree as 50% and 100%, respectively. It is also revealed that the volatile agents are retained and showed better thermal stability as a result of complexation. Carvacrol inclusion complexes were found relatively more stable (Zeta potential: −28.2 mV) than thymol complexes with smaller particle sizes (204.9 nm). Chemical structures of the inclusion complexes were revealed with Fourier transform‐infrared spectroscopy and nuclear magnetic resonance analyses. The optimum formulations for each active agent were applied to cotton fabrics as per the impregnation method and the capsule treated fabrics were washed 1, 10 and 20 times. The images exhibited the presence of inclusion complexes on the fabrics after 20 washing cycles. Although the antibacterial efficacy of fabrics decreased with increasing washing, the fabrics showed the antibacterial effect after 20 washes against Klebsiella pneumoniae and Staphylococcus aureus. This study showed that the developed products can be an alternative to the other products in the market as the long‐lasting fragrant natural antibacterial.

Cheese whey mother liquor as dairy waste with potential value for polyhydroxyalkanoate production by extremophilic Paracoccus homiensis

The production of scl-polyhydroxyalkanoates homopolymers and heteropolymers by Paracoccus homiensis was investigated using cheese whey mother liquor (CWML) and cheese whey (CW). Our results showed that the analyzed strain was able to convert waste streams of dairy processing into biopolymers, reaching a maximum of 3.3 ± 0.31 g/L of cell dry mass (CDM) with 1.1 g/L of P(3HB-co-3 HV) copolymer (29.0% of CDM) at 72 h. CWML was the preferred substrate to achieve a high level of PHAs. Moreover, our data suggested that PHA content in the analyzed bacterial cells was stimulated by nitrogen deficiency when CWML was used. Whereas nutrients limitation did not enhance the PHA concentration in the cultivations supplmented with CW. We proved that the monomeric composition of extracted PHAs depended on the type of substrate, its concentration supplied and the culture media composition. Detailed characterization of the extracted PHAs biofilms using a differential scanning calorimetric, thermogravimetric and water contact angle analysis proved that they have useful material properties suitable for various applications. PHA production on dairy waste by Paracoccus species has not been reported so far. Taking into account the positive aspects of employing extremophiles in industrial biotechnology, Paracoccus homiensis is a very interesting halophilic bacterium for PHA production using cheese manufacturing wastes. Valorizing cheese whey mother liquor as the PHA production feedstock would be an excellent dairy processing waste management strategy.

In vitro antibacterial effect of forsterite nanopowder: synthesis and characterization

The aims of this study were the preparation, characterization, and in vitro antibacterial activity evaluation of forsterite (FS, Mg2SiO4) nanopowder obtained by two major methods, namely sol-gel (FSsg) and co-precipitation (FSpp). The main aim was to determine the influence of preparation methodologies on physical properties and in vitro antibacterial activity of obtained forsterite nanopowder. To assess the best working temperature for the preparation of FSsg and FSpp, the synthesis and thermal treatment conditions were optimized on the basis of thermal gravimetric (TG) and differential scanning calorimetric (DSC) analysis performed on the dried gel and dried co-precipitated solid, respectively. The FSsg and FSpp powders were characterized by X-ray powder diffraction (XRD), indicating a high purity for both FSsg and FSpp powders. The morphology of FSsg and FSpp nanopowders was explored by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). In vitro antibacterial activity was investigated using a targeted pathogen, namely Staphylococcus aureus (S. aureus) ATCC 6538 P as tested strain by broth dilution technique and inoculations on nutrient agar to highlight the bactericidal inhibitory effect. FSsg nanopowder has no inhibitory capacity, while FSpp produced inhibition, the effect being bactericidal at a concentration of 10 mg/mL. The superior bactericidal activity of FSpp against FSsg is due to variation in the own surface properties, such as specific surface area (SSA) and nano-regime particle size. The FSpp nanoparticles, NPs, obtained by co-precipitation method are reported for the first time as a novel bactericidal nanomaterial against S. aureus.

Curable benzoxazine/siloxane hybrid networks from renewable phenolics and glycerol

Siloxane bearing benzoxazines from renewable phenolics such as vanillin and coumarin were prepared and reacted with glycerol by silyl ether exchange reactions to yield processable, soft, and curable bio-hybrid gels. Moreover, these benzoxazine-based gels were cured below 200 °C favored by the catalytic effect of hydroxyl groups present on glycerol moieties to yield bio-hybrid polybenzoxazines. All the synthesized intermediates, gels, and ultimate networks were characterized by 1H, 13C NMR, FTIR, and UV–Vis analyses. The curing behavior and thermal stabilities of the monomers, glycerol-based gels and related polybenzoxazines were investigated by differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). Moreover, the activation energies of polymerization of benzoxazine monomers were determined by DSC using the Kissinger and Ozawa methods.

Low‐temperature processable glass fiber reinforced aromatic diamine chain extended bismaleimide composites with improved mechanical properties

AbstractThe synthesis of 4,4′‐bismaleimido diphenylmethane (BMIM) and modified BMIM by its chain extension using commercially available aromatic diamines like 4,4′‐diamino diphenyl methane (DDM), 4,4′‐diaminodiphenyl sulphone (DDS), and 4,4′‐diamine diphenyl ether (DDE) was done. The synthesized materials have been characterized for structural aspects using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The structure of BMIM was confirmed due to the presence of specific bands at ~1400 and 1705 cm−1 responsible for CC and OCNCO groups, respectively. The reduction in the heat of fusion and enthalpy of curing for chain extended bismaleimides/modified BMIM shows the influence of the swivel group in diamine during curing. The curing window has broadened for BMIM_M and BMIM_E by ~40°C and narrowed for BMIM_S by ~100°C. The mechanical properties and the chemical resistance were studied for the composites made from the BMIM and modified BMIM based composites. Fiber‐enhanced modified bismaleimide resin has improved mechanical properties.

Thermophysical behavior in Y2O3 under high intensity fast neutron irradiation

In this work, differential scanning calorimetric (DSC) analyses were performed in an Ar inert medium in the temperature range of 100–750 K for the Y2O3 compound with the purity rate of 99.99%, the density in powder form is 0.069 g/cm3, the specific surface area is 100–150 m2/g, the particle size is in the range of 8–10 nm irradiated with fast neutrons with different intensities ([Formula: see text] MeV). Using mathematical approximation methods, the equations of dependence of the heat flux function on temperature and heat capacity after irradiation at different intensities for the Y2O3 compound over a wide temperature range were determined. It was found that in the temperature range of [Formula: see text] K, the value of the heat flux increases by 16.6%, up to 86 mW for the case of maximum radiation. At all radiation intensities, anomalies recorded with very small changes were observed in the spectra of the heat flux function related to the internal structural transitions.

Ginger Essential Oil as an Active Addition to Composite Chitosan Films: Development and Characterization.

The recent interest in food biopackaging is showing an increasing trend, especially in the development of antimicrobial coatings and films. The focus of this study is to assess the potential application of ginger (Zingiber officinale) essential oil (GEO) to polysaccharide films based on chitosan (CHf) and their utilization as an active edible packaging. The films were characterized by different instrumental techniques, and data indicated significant differences (p < 0.05) in the chemical composition of the samples. Forty-seven active compounds from ginger rhizomes were identified in the examined essential oil by gas chromatography mass spectrometer (GC-MS). Fourier transforms infrared spectra (FT-IR) confirmed an interaction between the hydroxyl groups of the phenolic compounds of the essential oil and the amine groups of the bioactive matrix, as shown by the peaks at wavenumbers 1639 cm−1 and 1558 cm−1. X-ray diffraction data suggested a lower crystallinity in the CHf due to the addition of GEO. Differential scanning calorimetric (DSC) analysis revealed that the CHf possessed high thermal stability, especially when different concentrations of GEO were added. The bioactive CHf showed distinct activity against both Gram-positive and Gram-negative bacteria, such as Staphylococcus aureus, Bacillus subtilis, Streptococcus sp., Escherichia coli, Salmonella sp., and Pseudomonas aeruginosa, thus improving the antimicrobial activity to these films. The results provide a comprehensive insight into the importance of films with incorporated EOs as novel types of active food packaging. Antimicrobial food packaging is one of the most promising kinds of active packaging, and acts to reduce, inhibit, or retard any microorganism growth that could contaminate packaged food items.

Coagulansin-A improves spatial memory in 5xFAD Tg mice by targeting Nrf-2/NF-κB and Bcl-2 pathway

The present study was designed to investigate the underlying molecular signaling of Coagulansin-A (Coag-A) as a therapeutic agent against Alzheimer’s disease (AD). Preliminarily, it exhibited a neuroprotective effect against H2O2-induced oxidative stress in HT-22 cells. The in vivo studies were performed by administering Coag-A (0.1, 1, and 10 mg/kg) intraperitoneally to 5xFAD transgenic (Tg) mouse model. Coag-A (10 mg/kg) significantly attenuated the cognitive decline compared to Tg mice group in the shallow water maze (SWM) and Y-maze test paradigms. The anti-aggregation potential of Coag-A was determined by performing Fourier transform-infrared (FT-IR) spectroscopy and differential scanning calorimeter (DSC) analysis in the prefrontal cortex (PFC) and hippocampal (HC) regions of mice brain. The FT-IR spectra demonstrated the inhibition of amyloid beta (Aβ) through a decrease in β-sheet aggregation, along with the inhibition of changes in the lipids, proteins, and phospholipids. The DSC analysis displayed a low-temperature exotherm associated with the reversible process of aggregation of soluble protein fractions prior to denaturation. Furthermore, Coag-A treatment displayed a regular density of granule cells in H&E stained sections, along with a reduced amyloid load and PAS-positive granules in all the regions of interest in mice brain. The real-time polymerase chain reaction (q-PCR), western blot and immunohistochemical (IHC) analysis demonstrated antioxidant, anti-inflammatory, and anti-apoptotic effect of Coag-A by enhancing the expression of nuclear factor erythroid-2-related factor (Nrf-2) and reducing nuclear factor kappa B (NF-κB) and Bax protein expression. In addition, Coag-A significantly increased the antioxidant enzymes and proteins level, along with a reduced pro-inflammatory cytokines production.

Development of Atorvastatin Calcium Biloaded Capsules for Oral Administration of Hypercholesterolemia.

The goal of this study was to develop atorvastatin (ATN) calcium biloaded, i.e., immediate release (IR) and sustained release (SR) capsules that would promote the quick onset of action and a better dissolution profile on both the IR and SR aspects. The IR granules were prepared by the wet granulation method, and an aqueous solubility study proved that the IR granules released the ATN within 25 min compared to the pure drug due to the addition of PEG and super disintegrants such as croscarmellose (CC) and crospovidone (CP). The sustained release nanoparticles (SR-NPs) were synthesized using a solvent evaporation technique and an optimal combination of hydrophilic and hydrophobic polymers. The addition of a hydrophobic polymer to a hydrophilic polymer delays drug release, resulting in a sustained and controlled release lasting up to 12 hours. The drug release of ATN from SR nanoparticles followed the Higuchi and Korsmeyer–Peppas models and had first-order kinetics (r2 = ???). Fourier transform infrared spectrophotometry, powder X-ray diffraction, and differential scanning calorimetric analysis were used to test the prepared biloaded capsules, and the results showed that there was no significant interaction between the polymers, excipients, and drug. The SEM and DLS analysis clearly demonstrated that drug particles in a continuous layer were enclosed by polymers at the nanoscale. To summarise, integrating both layers into a single capsule resulted in a superior release profile and patient compliance. Finally, prepared biloaded capsules were discovered to exhibit both an IR and an SR profile.

Facile Synthesis of Catalyst Free Carbon Nanoparticles From the Soot of Natural Oils

The growth of carbon nanostructures from vegetable oils using a modified conventional approach is a simple and environmentally friendly technology with controllable features. The goal of this study is to develop a simple and environmentally friendly process for making carbon nanoparticles using commercially available, low-cost vegetable oils. The technique involves the controlled burning of “Mustard”, “Olive”, and “Linseed” oils using the traditional clay lamps and collecting the carbon soot on a ceramic plate. The prepared carbon nanoparticles were purified through sonication and subjected to characterization using powder X-ray diffraction, SEM, Fourier transformed infrared, Thermogravimetric and differential scanning calorimetric analyses. The average particle size of carbon nanoparticles as investigated by powder X-Ray Diffraction analyses was found to be 18, 24, and 57 nm for mustard, olive and linseed oils respectively. SEM analyses revealed the surface morphology of these carbon nanostructures as spherical particles. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) providing knowledge about the thermal stability of these carbon nanoparticles. The synthesized carbon nanoparticles were screened for antibacterial activities against different species (e.g., Pseudomonas aeruginosa, Streptococcus haemolyticus, Proteus refrigere and Staphylococcus aureus) and fruitful results have been obtained.

Physicochemical Characterization of Phase Change Materials for Industrial Waste Heat Recovery Applications

The recovery and storage of process heat in industrial applications are some of the key factors to improve the sustainability and reliability of high temperature applications. In this sense, one of the main drawbacks is focused on the selection of proper thermal energy storage (TES) materials. This paper performs a full characterization of four phase change storage materials (PCM), KOH, LiOH, NaNO3 and KNO3, which are proposed for storage applications between 270 and 500 °C, according to the results obtained through differential scanning calorimeter and thermogravimetric analysis. One of the main innovations includes the corrosive evaluation of these materials in a promising alumina forming alloy (OC4), close to their corresponding phase change temperature during 500 h. The physicochemical properties obtained confirm the optimal use of NaNO3 and KNO3 and recommend the use, with caution, of KOH, due to its higher corrosive potential. FeCr2O4, NiCr2O4 and FeAl2O4 were the main protective spinels formed in the alloy surface, however, the cross-section study in the alloy immersed in KOH, revealed a non-uniform behavior, presenting some cracks and spallation in the surface. On the other hand, the proposal of LiOH was disregarded since it presents a narrow operation temperature range between melting and solidification point.