Thermal Stability Research Articles

Significantly improving the thermal stability of alginate lyase AlyC3 from Psychromonas sp. C-3 by computational redesign

Alginate lyase is a key enzyme in the bioproduction of alginate oligosaccharides. The alginate lyase AlyC3, derived from Psychromonas sp. C-3, can hydrolyze homopolymerized mannuronic acid into oligosaccharides (primarily composed of mannuronate trimer), which possess physiological properties such as bacteriostatic and antioxidant activities and show a better application prospect. However, the poor thermal stability hinders its potential application in industrial production. In this study, AlyC3 mutants A35P, L95F, N138Y and M162I were obtained through the protein repair one-stop shop (PROSS) design combined with protein data bank in Europe (proteins, interfaces, structures and assemblies) (PDBePISA) analysis of the dimer interface. The results demonstrated that the thermodynamic and kinetic stability of these single-point mutants were significantly improved compared to the wild-type (WT), with the melting temperature increased by 4.33, 9.35, 9.74 and 11.24 °C, respectively, while the half-life (t1/2) was 1.66, 1.02, 1.02 and 1.53 times higher than that of WT, respectively. Based on this, the beneficial mutations were further combined to obtain a combinatorial mutant, A35P-L95F–N138Y-M162I, which exhibited the superior thermal stability. Notably, the combinatorial mutant's melting and optimal temperature increased by 17.05 and 10 °C, respectively; moreover, the mutant enzyme's t1/2 and enzyme activity were 8.21 times and 123.93% higher than those of the WT, respectively. Structural analyses indicated that increased hydrophobic interactions and polar bonding between the mutated and nearby residues, with improved rigidity in the flexible loop, might account for the significantly improved thermal stability of the reengineered AlyC3, which makes it a robust candidate for alginate oligosaccharide production.

Investigating the chemical stability and thermal functionality of DMPT promoted TiO2 nanoparticles on unsaturated polyester resin

The incessant emergence of failures in mining roofs, along with escalating demands for high and sustainable roof support products such as resin anchor bolt capsules (resin), necessitates strengthening these elements. This study explores the transformative influence of Titanium oxide nanoparticles (TiO2) and its concentration on the chemical properties, stability, and thermal performance of polyester resin (UPE) nanocomposites. The investigation was carried out using Fourier-transform infrared (FTIR), Raman spectroscopy, and X-ray diffraction (XRD). Rheological behavior was assessed with a Brookfield viscometer, while thermal stability was examined via thermogravimetric analysis (TGA, DTG, and DTA). From the results obtained, the addition of nanoparticle TiO2 yielded a little significant change in the shift of the FTIR wavelength. However, substantial Raman peak disappearance from the peaks of the UPE neat compared to composites. The shift in Raman is associated with an increase in crystallinity due to TiO2 content. X-ray diffraction confirms the seamless presence of anatase TiO2 nanoparticles in the polyester resin matrix. The resin curing kinetics exhibit a 50-second reduction in the time to reach the exothermic peak when the nanomaterial content reaches 3% in TiO2. An increase in nanomaterial content leads to a shorter time to peak at a higher exothermic temperature, indicating improved resin cure rates. This study substantiates enhanced chemical and thermal stabilities with increasing nanomaterial content, affirming the positive impact of nanomaterial infusion on resin resilience and stability.

Polyvinyl alcohol-based multifunctional hydrogel film: a novel strategy for food preservation packaging

Food spoilage leads to the annual huge wastage of food. There is a pressing need for safe, multifunctional food preservation packaging to curb this wastage and prevent contamination. In this study, we present a novel, cross-linked P-GL hydrogel film with a smooth surface microstructure, derived from polyvinyl alcohol (PVA), gallic acid (GA), and lysozyme (L). This hydrogel film serves as an exceptional packaging material for food preservation, displaying an ability to completely block UV light and efficiently impede the penetration of water vapor and O2. Remarkably, the P-GL hydrogel film exhibits a fracture strength of approximately 37.9 MPa, demonstrating superior water solubility, thermal stability, and mechanical properties. Also, this P-GL hydrogel film can effectively eliminate E. coli and S. aureus. The P-GL hydrogel film has proven to be successful in mitigating the spoilage of blueberries through coating and covering treatments, outperforming commercial plastic wrap. As a result, the shelf life of blueberries can be extended to 20 days. Our work provides innovative insights that could potentially drive the use of safe and multifunctional hydrogel films in the food preservation packaging industry.

Investigation of the structure of protein-polymer conjugates in solution reveals the impact of protein deuteration and the size of the polymer on its thermal stability.

The conjugation of proteins with polymers offers immense biotechnological potential by creating novel macromolecules. This article presents experimental findings on the structural properties of maltose-binding protein (MBP) conjugated with linear biodegradable polyphosphoester polymers with different molecular weights. We studied isotopic effects on both proteins and polymers. Circular dichroism and fluorescence spectroscopy and small-angle neutron scattering reveal that the conjugation process destabilizes the protein, affecting the secondary more than the tertiary structure, even at room temperature, and that the presence of two domains in the MBP may contribute to its observed instability. Notably, unfolding temperatures differ between native MBP and the conjugates. In particular, this study sheds light on the complex interplay of factors such as the deuteration influencing protein stability and conformational changes in the conjugation processes. The perdeuteration influences the hydrogen bond network and hydrophobic interactions in the case of the MBP protein. The perdeuteration of the protein influences the hydrogen bond network and hydrophobic interactions. This is evident in the decreased thermal stability of deuterated MBP protein, in the conjugate, especially with high-molecular-mass polymers.

Effect of phosphorus-doping on ternesite: Structure, thermal stability and hydration

The successful synthesis of the solid solution Ca5(Si1-x/2O4)2S1-x/2PxO4 (C5S2S̅Px, x = 0.05, 0.10, 0.15, 0.20) was confirmed through analysis of X-ray diffraction and energy dispersive spectrometer data. Rietveld refinement revealed that the purity of ternesite can reach up to 99.42 % at a doping concentration of 5 %. Furthermore, changes in X-ray diffraction peaks and morphology suggest a shift in the preferred growth direction of crystallites as a result of the introduction of impurity element. The incorporation of P elements in C5S2S̅Px not only effectively reduces weight loss under high-temperature conditions but also elevates the temperature at which decomposition occurs. Isothermal calorimetry data indicates that C5S2S̅Px-CSA samples display higher cumulative heat release compared to C5S2S̅–CSA. Furthermore, the presence of C5S2S̅P0.20 accelerates the hydration kinetics of CSA cement by hindering ettringite formation. Moreover, varying levels of phosphorus doping in C5S2S̅Px have resulted in enhanced compressive strength at various ages of CSA cement maturation.

Adsorption studies of tetracycline hydrochloride and diclofenac sodium on NH2-MIL-53(Al/Zr) sodium alginate gel spheres

Metal-organic frameworks are emerging inorganic-organic hybrid materials that can be self-assembled from metal ions and organic ligands via coordination bonds. These materials possess large specific surface area, tunable pore structure, abundant active center, diversity of functional groups as well as high mechanical and thermal stability which promote their applications in adsorption and catalysis studies. In this study, NH2-MIL-53(Al/Zr) was prepared and embedded into sodium alginate gel spheres (NH2-MIL-53(Al/Zr)-SA) and its adsorption properties towards TC and DCF in solution were investigated. According to XRD and FTIR analysis, the structure of the raw material was not changed after making the gel spheres. The maximum adsorption towards TC (pH =3) and DCF (pH =5) reached 98.5 mg·g−1 and 192 mg·g−1, respectively. The process was consistent with Langmuir and Freundlich, suggesting that there was both monolayer and multilayer adsorption which infers the presence of physical adsorption (intra-particle diffusion) and non-homogeneous chemical adsorption. The thermodynamic parameters showed that the adsorption process was a spontaneous entropy increasing reaction. The regeneration rate of spent NH2-MIL-53(Al/Zr)-SA could still reach 99.1 % after three cycles, indicating good regeneration performance. This study can provide a basis for the application of NH2-MIL-53(Al/Zr)-SA in wastewater treatment.

Immobilization of Xylanase on ZnO nanoparticles obtained by green synthesis from Eupatorium cannabinum L. and its application in enrichment of fruit juices

Juice production is one of the main components of the nutritional food industry. Therefore, improving fruit juice quality and preventing the formation of negative by-products is important for human health. The role of environmentally friendly, safe and economically more affordable green nanocarriers in improving the quality of fruit juice is increasing day by day. For this purpose, zinc oxide nanoparticles (ZnONPs) were prepared from the aqueous extract of the Eupatorium cannabinum L. using the green synthesis method. After immobilization, structural and morphological characterizations of the prepared ZnONPs and xylanase (Xyl)@ZnONPs were carried out, which confirmed that both the synthesis of ZnONPs and the immobilization of Xyl enzyme on ZnONPs were successfully carried out. The biochemical parameters of Xyl@ZnONPs such as optimum pH and temperature, kinetic parameters, thermal stability, reusability, and storage stability were investigated and compared with free Xyl. After immobilization, the optimum pH of free Xyl shifted from 5.0 to an alkaline pH of 8.0, while no change in the optimum temperature (70 °C) was observed for both enzymes. While the activation energy of free Xyl was 5.56 kJ/mol, it was found to be 7.27 kJ/mol for Xyl@ZnONPs. Xyl@ZnONPs outperformed free Xyl due to its long-term storage stability and reusability. Moreover, Xyl@ZnONPs retained 50 % of its activity after 5 reuses and 87 % of its activity after 4 weeks of storage at room temperature. In addition, a decrease in Km value and an increase in Vmax value were observed after immobilization, which means the increased catalytic activity of the Xyl@ZnONPs. As a result of re-using Xyl@ZnONPs in orange juice for 6 cycles, clarification yield of 66.43 % was obtained under optimized conditions. Overall, this study prepared a suitable, environmentally friendly, and robust carrier support for Xyl immobilization and developed a biocatalyst that will provide high performance in the industrial field.

Flexible silver nanoparticle@aramid nanofiber SERS substrates fabricated by radio frequency magnetron sputtering for rapid detection of toxic substances

Aramid nanofibers (ANFs) have gained great interest as promising polymer substrates for various applications because of their exceptional mechanical properties, high aspect ratio, large specific surface area and excellent chemical and thermal stability. However, the use of ANFs as nano-sized functional substrates for surface-enhanced Raman scattering (SERS) sensing applications has been scarcely reported. In this research, ANF membranes fabricated by vacuum-filtration are served as SERS matrix materials. The silver nanoparticle-coated ANF (AgNP@ANF) membranes are fabricated by a facile, cost-effective, environmental-friendly, and scalable magnetron sputtering technique. Different sputtering times from 15 to 120s have been studied for AgNP@ANF substrates in terms of their SERS performance. The optimal AgNP-90@ANF SERS substrate exhibits good detection sensitivity of 10-10M for malachite green (MG), high enhancement factor of 7.7×108 and prominent signal reproducibility (RSD=5.87%), as well as impressive storage stability. Furthermore, the AgNP@ANF SERS substrates also demonstrated excellent detection capability for methylene blue and crystal violet, with sensitivities of 10-10 and 10-9M, respectively. Besides, the flexible AgNP@ANF SERS substrate can also be used to rapidly detect pesticide residues on uneven surfaces through a facile paste-and-read treatment. The simple-to-manufacture, inexpensive, scalable, and sensitive AgNPs@ANF sensors are very promising for commercial SERS applications in the future.

Site-directed mutagenesis reveals the interplay between stability, structure, and enzymatic activity in RidA from Capra hircus.

Reactive intermediate deaminase A (RidA) is a highly conserved enzyme that catalyzes the hydrolysis of 2-imino acids to the corresponding 2-keto acids and ammonia. RidA thus prevents the accumulation of such potentially harmful compounds in the cell, as exemplified by its role in the degradation of 2-aminoacrylate, formed during the metabolism of cysteine and serine, catalyzing the conversion of its stable 2-iminopyruvate tautomer into pyruvate. Capra hircus (goat) RidA (ChRidA) was the first mammalian RidA to be isolated and described. It has the typical homotrimeric fold of the Rid superfamily, characterized by remarkably high thermal stability, with three active sites located at the interface between adjacent subunits. ChRidA exhibits a broad substrate specificity with a preference for 2-iminopyruvate and other 2-imino acids derived from amino acids with non-polar non-bulky side chains. Here we report a biophysical and biochemical characterization of eight ChRidA variants obtained by site-directed mutagenesis to gain insight into the role of specific residues in protein stability and catalytic activity. Each mutant was produced in Escherichia coli cells, purified and characterized in terms of quaternary structure, thermal stability and substrate specificity. The results are rationalized in the context of the high-resolution structures obtained by x-ray crystallography.

Indium-free nonmetal and Nb co-doped anatase TiO2 transparent conductive oxide materials for photovoltaic applications: From first-principles calculations to macroscopic simulation

Various researchers have attempted to design indium-free transparent conductive materials. This study first employed density functional theory combined with the Hubbard U parameter to predict the photoelectric properties of nonmetal (B, C, N, F, P, and S) and Nb co-doped anatase TiO2. The results indicate that Ti0.875Nb0.125O1.96875N0.03125, Ti0.9375Nb0.0625O1.96875F0.03125, Ti0.875Nb0.125O1.96875P0.03125 and Ti0.9375Nb0.0625O1.96875S0.03125 possess characteristics of n-type semiconductors with high transmittance, exceptional thermal stability and wide bandgap. Notably, Ti0.9375Nb0.0625O1.96875S0.03125 exhibits optimal electronic conductivity due to its lower effective mass and higher electron concentration. Then, we used the SCAPS-1D solar cell simulation software to simulate the macroscopic characteristics of the MASnI3-based perovskite solar cell with Ti0.9375Nb0.0625O1.96875S0.03125 transparent conductive oxide layer based on the microscopic properties computed at the density functional theory level. A maximum efficiency of 27.17 % is obtained by regulating the thickness, electron affinity, and defect density of Ti0.9375Nb0.0625O1.96875S0.03125 layer and the thickness of MASnI3 absorber layer. The findings highlight the tremendous potential of Ti0.9375Nb0.0625O1.96875S0.03125 as an indium-free transparent conductive oxide candidate material for photovoltaic applications.

Soft-Hard segments regulated framework of Nitrogen-Doped reduced graphene oxide aerogel for efficient adsorption of pollutants

Graphene aerogel (GA) is recognized for its high porosity, rendering it a promising candidate for water treatment applications. However, its reuse potential is hampered due to inherent limitations. To address this, the present study introduces a nitrogen-doped graphene aerogel (NGA) developed by integrating polydopamine soft segments and polyaniline hard segments into the GA matrix. This approach promotes the formation of a cohesive and durable 3D network by bridging reduced graphene oxide (rGO) nanosheets, with the hard segments of polyaniline interposed among rGO layers to mitigate significant restacking, thereby enhancing surface area and adsorption sites. NGA demonstrates remarkable properties including strength (67 kPa), reversible compressibility under 64 % strain, low density (12.26 mg/cm3), and thermal stability (Tdecomposition = 679.6 °C in air), which collectively enhance its adsorption capacity and recyclability. This study further examines the influence of various factors such as pH, adsorbates (dyes and organic solvents), initial concentration, and cycle times on the aerogel’s adsorption efficacy. Additionally, simulation outcomes reveal that NGA’s adsorption kinetics and thermodynamics align more closely with the endothermic pseudo-first-order kinetic model, indicative of predominant physical adsorption mechanisms. Given its superior adsorption capabilities for pollutants, NGA holds significant promise for application in water treatment.

Development and analysis of the physical and electrochemical characteristics of a nano titanium (IV) tungstomolybdate supported on polyethersulfone composite cation exchange membrane

In this study, a series of novel composite membranes were synthesized utilizing polyethersulfone (PES), sulfonated polyethersulfone (SPES) as base polymer and titanium tungstomolybdate (TWM) as an inorganic ion exchange resin. The membranes were fabricated through the solution casting technique. The composite membranes exhibited enhanced thermal and chemical stability, as well as improved oxidative stability. All the composite membranes demonstrated higher hydrophilicity, with the SPES-TWM composite membranes displaying the lowest contact angle of 65°. The composite membranes also displayed favorable water uptake (up to 26% for SPES-TWM) and lower methanol uptake (maximum 12% for SPES-TWM) and better mechanical stability (maximum of 40 MPa for SPES-TWM). The SPES-TWM composite membranes exhibited the maximum ion exchange capacity of 1.32 meq.g−1. The transport number of 0.95 was obtained for SPES-TWM, which is comparable to the Nafion-117 membrane. The proton conductivity of both membranes increased as the temperature increased. The maximum proton conductivity of 6.3 mScm−1 was observed for SPES-TWM at 60 °C.

EXPERIMENTAL AND THEORETICAL INTERPRETATIONS OF STRUCTURAL, OPTICAL, MECHANICAL AND THERMAL PROPERTIES OF 2 AMINOPYRIDINIUM PHTHALATE SINGLE CRYSTALS

Nonlinear optical good quality single crystals of 2-aminopyridinium phthalate single crystals are synthesized by solution growth technique. Structural parameters are elucidated by Single Crystal X-ray diffraction method which reveals that the material crystallizes in non-centrosymmetric crystalline framework. Vibrational assignments are interpreted by Fourier Transform Infrared spectral analysis. The thermal, mechanical and laser stability are explored by TG/DTA, microhardness and Laser Damage threshold analysis. The material has good emission nature in the violet emission region. The linear optical properties are elucidated with the help of UV-visible spectral analysis. The intermolecular charge transfer interactions are analyzed by HOMO-LUMO and MESP maps by using Gaussian ’09 software program. The second harmonic generation efficiency of the synthesized material are predicted by Kurtz Perry powder technique.

Field demonstration of a 10 MW CO2 capture pilot plant in extended operation using KoSol absorbents for treating off-gas in a coal fired power plant

Efficient CO2 absorbents are crucial for reducing energy use in CO2 capture absorption process. This study evaluates the performance of amine-based CO2 absorbents, KoSol-5 and KoSol-6, developed by the Korea Electric Power Corporation. In a 10 MW pilot plant, KoSol-6 was found to capture more than 90% of the daily CO2 emissions, amounting to over 180 tons per day, from the exhaust gasses of a coal-fired power plant. Its regeneration energy (Qregen) was 2.42 GJ/ton CO2 in the standard absorption process, which is 39.2% less than the monoethanolamine (MEA) system. Implementing advanced techniques like intercooling, lean vapor compression, and thermal vapor recompression further optimized this process. Among these, the thermal vapor recompression mode turned out to be the most efficient and stable. In addition, KoSol-6 showcased excellent thermal and chemical stability, with a consistent Qregen of 2.34 GJ/ton CO2 over a 10,000-hour test. The study provides insights into the potential of KoSol-5 and KoSol-6 for large-scale applications and further developments in CO2 capture technology.

Synthesis and Hg2+ removal ability of renewable furfurylamine-derived bio-polythioureas

Petroleum-derived polythioureas (PTUs) are typical functional polymers that have been applied as essential materials in the optoelectric and environmental fields. The design and preparation of sustainable PTUs are the current focus in this field. In the present study, we first proposed that PTUs can be prepared from bisfuran diamines by solution polymerisation with CS2 without any catalyst. The diamine monomers were prepared from renewable furfurylamine, which enabled the final PTUs to be sustainable. The highest molecular weight of the resulting PTUs was 86.64 kg/mol, with a polydispersity of 1.32. The glass transition temperature (Tg) of PTU can be tuned by changing the spacer of monomers. All synthesised PTUs showed excellent thermal stability, and the char yield at 800 °C was > 40 %. Attractively, these PTUs are excellent Hg2+ ion capturers due to their thiourea structure.

Comparative study on the flame retardancy, pyrolysis behavior, and flame retardant pathways of black phosphorus in polyurethane and polypropylene

Black phosphorus nanosheets (BPns) have gained widespread attention in the field of flame retardancy due to their highly efficient flame-retardant properties achieved with a low addition rate (e.g., 0.4%). However, the pyrolysis pathways of BP in polymers have not yet been elucidated. This work systematically studies the flame retardancy and pyrolysis behavior of BP in oxygen-containing (polyurethane, PU) and oxygen-free (polypropylene, PP) polymers, distinguishing between the gas-phase and the condensed-phase flame retardant effect of BP. Through slow heating and staged heating methods, the condensed phase and gas phase pyrolysis products of BP in PU and PP at different temperatures are compared in detail. The distinct flame retardant pathways of BP in PU and PP are revealed. The results indicate that the oxidation of BP commences with its reaction with atmospheric oxygen, implying that the condensed-phase flame-retardant effect of BP primarily occurs at the polymer surface. In PP, BP mainly functions as a gas-phase flame retardant. In the condensed phase, BP generates phosphate derivatives that cover the substrate surface, providing solely a physical barrier effect. In PU, while BP demonstrates an outstanding gas-phase flame-retardant effect, it also accelerates the early dehydration carbonization of alcohols within the substrate, resulting in the formation of phosphate ester compounds (P–O–C structure) to bolster the thermal stability of residual carbon. Additionally, the side reactions of BP during catalytic carbonization will decrease the thermal stability of ester bonds in PU. This work lays a theoretical foundation for the development and application of BP-based flame retardant systems.

Phase change material microcapsules doped with phosphorus-based flame retardant filled titanium dioxide nanotubes for enhancing the energy storage and temperature regulation performance of buildings

Solar energy is not only a green alternative to fossil energy but also a candidate for future mainstream energy sources. To improve the efficiency and application range of solar energy, we investigated tris (1-chloro-2-propyl) phosphate (TCPP) modified titanium dioxide nanotubes (TNTs) doped phase change material microcapsules (p-t-MPCMs) to enhance the temperature regulation and flame retardancy of epoxy resin (EP) coatings. Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy determined the successful preparation of p-TNTs and p-t-MPCMs. Moreover, it was confirmed that the p-t-MPCMs had great thermal stability and reliability by the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The p-t-MPCMs increased residual mass by 12.2 % at 600 ℃ while correcting the initial melting temperature of MPCMs by 1.0 ℃. Based on the principle of oxygen consumption, the heat release rate (HRR) of EP coatings containing the p-t-MPCMs (p-t-MPCM/EP) was reduced from 665.92 kW/m2 to 443.78 kW/m2, resulting in a total heat release reduction (THR) of 17.73 % tested by a conical calorimeter. Then the results of the miniature chamber model demonstrated that p-t-MPCM/EP had outstanding temperature control ability. In summary, the p-t-MPCMs expressed great potential in regulating building temperature timely and improving the fire safety of EP coatings.

Preparation and thermal performance study of a novel hydrated salt composite PCM for space heating

In order to effectively address the mismatch between thermal energy supply and demand in buildings, latent heat storage (LHS) based on phase change material (PCM) stands out as a key technology. While hydrated salt has emerged as a promising PCM, it encounters common issues such as substantial supercooling, phase separation, and low thermal conductivity, hindering its development. To mitigate these limitations, this study focused on modifying Ba(OH)2·8H2O by incorporating various nucleating agents and thickening agents to reduce supercooling, enhancing the composite PCM's thermal properties by introducing expanded graphite (EG) to elevate thermal conductivity. Subsequently, the thermal stability of the PCM was evaluated through accelerated thermal cycling tests, encompassing the assessment of critical thermal parameters, including supercooling degree, enthalpy, and thermal conductivity of the composite PCM. Experimental findings unveiled the effectiveness of incorporating 2 wt% BaCl2·2H2O and 1 wt% CMC to Ba(OH)2·8H2O, effectively diminishing the supercooling degree from 14 °C to 1.42 °C. Further integration of 3.5 wt% EG led to a substantial decrease in the supercooling degree to 0.24 °C. Simultaneously, the addition of EG resulted in an improvement in thermal conductivity, elevating it from 0.62 W/(m·K) to 1.03 W/(m·K), while the enthalpy decreased from 283.68 J/g to 252.81 J/g. Notably, the composite PCM exhibited notable thermal reliability with a latent heat drop of 15.9 % following 1000 accelerated cycles of testing. Moreover, the composite PCM demonstrated superior thermal storage density, measuring at 2.36 times that of traditional paraffin wax, yet with a thermal storage cost merely a quarter of paraffin wax, rendering it more favorable for extensive deployment in building energy systems.

Enhancing the Thermal Conductivity and Shape Stability of Phase-Change Composites Using Diatomite and Graphene Nanoplates for Thermal Energy Storage

The effects of mixing diatomite and graphene nanoplatelets (GNP) with xylitol were examined in this study. Form stability and thermal conductivity were also evaluated. According to the experimental results, the PCM composites exhibited a thermal conductivity of 0.403 W/mK. Melting and solidification points were determined by differential scanning calorimetry (DSC) to be 89.0°C and 36.5°C, respectively. To maximize the thermal characteristics of the PCM, the response surface methodology (RSM) was utilized to create prediction models for thermal conductivity based on the mass fractions of diatomite and GNP. These findings highlight the importance of understanding how the introduction of nanoparticles affects thermal properties. The prospective use of PCM in thermal energy storage is enhanced by its higher solidification enthalpy, noteworthy thermal stability, and insights into the impacts of diatomite and GNP.

Study on surface grafting of hydroxyapatite and its influence on the properties of urea-formaldehyde resin

Urea formaldehyde (UF) is the most widely used resin in the wood composite board industry. UF has formaldehyde emission, which is harmful to the environment and human health. In this paper, hydroxyapatite (HAP) was surface modified by silane coupling agent (HAP-KH). And hydroxyapatite/urea formaldehyde resin (HAP-UF) was prepared by adding different amounts of HAP-KH. The optimal amount of HAP-KH was determined by wet shear strength and formaldehyde release. The degradation performance and degradation kinetics of the resin were also studied. The results show that the addition of HAP-KH can improve the wet shear strength of plywood and reduce the release of formaldehyde. The optimal content of HAP-KH was 3%, and the formaldehyde emission of plywood reached the lowest level of 0.35 mg L−1, 52.32% lower than that of the control resin. The wet shear strength was 1.14 MPa, 14.4% higher than that of the control resin. HAP-KH had no significant effect on the thermal stability of UF resins. However, HAP-KH has a significant effect on the thermal degradation mechanism of UF resins. The most likely kinetics mechanism models for UF and HAP-UF are G(a) = [−ln(1−α)]2 and G(a) = [−ln(1−α)]3, respectively.