Improvement In Thermal Stability Research Articles

Flexible and thermoresponsive AEMR-pNIPAM/Cs0.33WO3 composite hydrogel film with NIR shielding potential for smart windows and smart curtains

Thermoresponsive flexible smart windows and smart curtains having high near-infrared (NIR) shielding and tuned visible light transmittance are essential for improving the energy efficiency of the buildings. The lower critical solution temperature (LCST) of the cross-linked poly(N-isopropylacrylamide) (pNIPAM) hydrogel film was precisely modified to a desired LCST value at 27.4 °C through the free radical copolymerization with 10 wt% of acrylated epoxidized methyl ricinoleate (AEMR). Cs0.33WO3 as NIR shielding nanoparticles (particle size < 200 nm) were synthesized via high energy ball milling method with AEMR as a surfactant for high NIR shielding efficiency and dispersion—the composite flexible hydrogel films with different wt% (0.3, 0.5,0.7, and 0.9 wt%) of Cs0.33WO3 nanoparticles were fabricated to analyze the NIR shielding efficiency and thermal insulation performance. The copolymeric hydrogel film with 0.7 wt% of Cs0.33WO3 nanoparticles (0.7-CWO) demonstrates a significant reduction in the NIR transmittance (15.0 % to 2.3 %) and variation in visible light transmittance from 73.6 % to 15.7 % while undergoing temperature-induced phase transition. The smart window fabricated with composite hydrogel film exhibits good integral luminous transmittance (Tlum, 380–780 nm, 68.7 %, below LCST) and justifiable solar modulation ability (ΔTsol, 300–2500 nm, 53.6 %). A model house was designed to monitor the indoor temperature difference, and a noticeable variation of 7 °C was observed in the house with and without 0.7-CWO film. Further, the developed composite material showed improvement in flexibility, water resistance, and thermal stability, confirming its usage for energy-saving smart windows or smart curtains.

Investigation of the Effects of Phenolic Extracts Obtained from Agro-Industrial Food Wastes on Gelatin Modification.

In this study, modified bovine gelatin was produced using the alkaline technique with four different oxidized agro-industrial food waste (pomegranate peel (PP), grape pomace and seed (GP), black tea (BT), and green tea (GT)) phenolic extracts (AFWEs) at three different concentrations (1, 3, and 5% based on dry gelatin). The effect of waste type and concentration on the textural, rheological, emulsifying, foaming, swelling, and color properties of gelatin, as well as its total phenolic content and antioxidant activity, was investigated. Significant improvement in gel strength, thermal stability, and gelation rate of gelatin was achieved by modification with oxidized agro-industrial waste extracts. Compared to the control sample, 46.24% higher bloom strength in the GT5 sample, 5.29 and 6.01 °C higher gelling and melting temperatures in the PP5 sample, respectively, and 85.70% lower tmodel value in the GT3 sample were observed. Additionally, the total phenolic content, antioxidant activity, foam, and emulsion properties of the modified gels increased significantly. This study revealed that gelatins with improved technological and functional properties can be produced by using oxidized phenolic extracts obtained from agricultural industrial food wastes as cross-linking agents in the modification of gelatin.

An insight into the co-doping effect of d-d transitions of transition metal ions and hypersensitivity of rare-earth ions in multicomponent glass-system

A multicomponent glass system with composition (70B2O3-22.5Bi2O3-5SeO2-2CuO-0.5Sm2O3) was synthesized via the conventional melt-quench technique. X-ray diffraction analysis confirmed the amorphous nature of this glass. The co-doping of transition and rare-earth metal ions results in the gradual decrease in glass transition temperature and improvement in thermal stability as observed from differential scanning calorimetry. The addition of CuO has increased non-bridging oxygens in multicomponent glass system. The increase in non-bridging oxygens results in a decrease in the optical band gap energy of the glass. Various results reveal that the hypersensitive nature of rare-earth ions has been suppressed by the d-d transition. A decrease in the energy band gap upon co-doping of transition and rare earth ions, suggests its applications in the fields of optoelectronics.

Comparative Analysis of Crosslinking Methods and Their Impact on the Physicochemical Properties of SA/PVA Hydrogels.

Hydrogels, versatile materials used in various applications such as medicine, possess properties crucial for their specific applications, significantly influenced by their preparation methods. This study synthesized 18 different types of hydrogels using sodium alginate (SA) and two molecular weights of polyvinyl alcohol (PVA). Crosslinking agents such as aqueous solutions of calcium (Ca2+) and copper (Cu2+) ions and solutions of these ions in boric acid were utilized. The hydrogels were subjected to compression strength tests and drying kinetics analysis. Additionally, six hydrogel variants containing larger PVA particles underwent Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) post-drying. Some samples were lyophilized, and their surface morphology was examined using scanning electron microscopy (SEM). The results indicate that the choice of crosslinking method significantly impacts the physicochemical properties of the hydrogels. Crosslinking in solutions with higher concentrations of crosslinking ions enhanced mechanical properties and thermal stability. Conversely, using copper ions instead of calcium resulted in slower drying kinetics and reduced thermal stability. Notably, employing boric acid as a crosslinking agent for hydrogels containing heavier PVA molecules led to considerable improvements in mechanical properties and thermal stability.

Improved Thermal Stability of Al-Si Alloy Coated Steel Sheet with Cr Thin Film Deposition

We investigated the effect of Cr thin film deposition on the thermal stability and corrosion resistance of hot-dip aluminized steel. A high-quality Cr thin film was deposited on the surface of the Al-9 wt. % Si-coated steel sheets by physical vapor deposition. When the Al-Si coated steel sheets were exposed to a high temperature of 500℃, Fe from the steel substrate diffused into the Al-Si coating layer resulting in discoloration. However, the highly heat-resistant Cr thin film deposited on the Al-Si coating prevented diffusion and surface exposure of Fe, improving the heat and corrosion resistances of the Al-Si alloy coated steel sheet.

The effect of gamma rays and stearic acid on calcium carbonate and its impact on the properties of epoxy-based composites

Abstract The purpose of this research is to produce composites of epoxy resin and calcium carbonate (EP/CaCO3) and investigate how treating the CaCO3 filler with stearic acid and gamma radiation affects the properties of the epoxy composites, enhancing their suitability for a range of applications. The CaCO3 powder was subjected to stearic acid treatment and later exposed to γ-radiation at various doses namely (10, 20 and 30 kGy), Different weight percentages of untreated and treated CaCO3 powder were added to epoxy resin (EP) to create EP/CaCO3 composites loaded with varying amounts of CaCO3 filler (5 %, 10 %, 20 %, 30 %, and 40 %). The influence of both stearic acid treatment and different doses of gamma radiation on CaCO3 was investigated. The composites were subjected to characterization of various properties including mechanical (splitting tensile strength, impact strength), thermal (TGA and dimensional thermal analysis) as well as morphological SEM examination. The analysis’ findings demonstrated that the stearic acid monolayer functions as a coupling agent in the EP matrix and can coat CaCO3 particles efficiently. The modification of CaCO3 by stearic acid and exposure to 30 kGy of gamma radiation shows a notable improvement in thermal stability and mechanical qualities for the epoxy composites loaded with various CaCO3 concentrations.

Solubilization and stabilization of lipoic acid trisulfide by creation of various β-cyclodextrin clathrates.

Lipoic acid trisulfide, a sulfane sulfur-containing trisulfide of α-lipoic acid, holds promise in pharmaceuticals, yet knowledge gaps persist regarding its synthesis, properties, and stability. Here, we synthesized the lipoic acid trisulfide with a purity exceeding 99% from α-lipoic acid on a gram scale and obtained novel β-cyclodextrin clathrates (84%-95% yield). Differential scanning calorimetry confirmed the inclusion of lipoic acid trisulfide in β-cyclodextrins. The resulting β-cyclodextrin clathrates exhibited significant improvements in water solubility and thermal stability. This pioneering study demonstrated a novel approach to the practical preparation of trisulfide and its β-cyclodextrin clathrates as active ingredients, paving the way for clinical development.

Improved Thermal Stability of a Novel Acidophilic Phytase.

Phytase increases the availability of phosphate and trace elements by hydrolyzing the phosphomonoester bond in phytate present in animal feed. It is also an important enzyme from an environmental perspective because it not only promotes the growth of livestocks but also prevents phosphorus contamination released into the environment. Here we present a novel phytase derived from Turicimonas muris, TmPhy, which has distinctive structure and properties compared to other previously known phytases. TmPhy gene expressed in the Pichia system was confirmed to be 41 kDa in size and was used in purified form to evaluate optimal conditions for maximum activity. TmPhy has a dual optimum pH at pH3 and pH6.8 and exhibited the highest activity at 70°C. However, the heat tolerance of the wildtype was not satisfactory for feed application. Therefore, random mutation, disulfide bond introduction, and N-terminal mutation were performed to improve the thermostability of the TmPhy. Random mutation resulted in TmPhyM with about 45% improvement in stability at 60°C. Through further improvements, a total of three mutants were screened and their heat tolerance was evaluated. As a result, we obtained TmPhyMD1 with 46.5% residual activity, TmPhyMD2 with 74.1%, and TmPhyMD3 with 66.8% at 80°C heat treatment without significant loss of or with increased activity.

Development of soy protein isolate-based orally disintegrating film: Improvement of disintegration speed, mechanical properties, and thermal stability by β-Cyclodextrin

The effect of β-Cyclodextrin (β-CD) at different concentrations (0–20% w/w) on the function and properties of soy protein isolate (SPI)-based orally disintegrating films (ODF) was studied. The results of moisture content and contact angle indicate that the inclusion of β-CD enhances the moisture content and surface hydrophilicity of ODF. The thickness ODF samples is between 0.031 and 0.041 mm. Due to the addition of β-CD, ODF disintegration rates increased by 47.86%–64.62%. Scanning electron microscope, and mechanical analysis show that ODF with a β-CD concentration of 10% w/w has the best performance, presenting the smoothest surface, maximum tensile strength (TS) and elongation at break (EB). FTIR spectrum results show that there are physical entanglements and hydrogen bonding interactions between SPI and β-CD, and appropriate concentrations of β-CD (5% w/w and 10% w/w) can transform random coils into β-sheets. Once the concentration exceeding 10% w/w, β-CD will crystallize and precipitate on the ODF surface, which weakens the mechanical properties of the ODF and the strength of the SPI network structure. Thermogravimetric test results show that β-CD improves ODF thermal stability. This research offers a significant theoretical foundation for the advancement of ODF that are protein-based and not hydrolyzed.

Enhancing the Tribological Properties of Low-Density Polyethylene Using Hard Carbon Microfillers.

The application of low-density polyethylene (LDPE) has been confined to packaging applications due to its inadequate mechanical and tribological characteristics. We propose enhancing LDPE by integrating hard carbon spheres (CSs) to improve its strength, frictional characteristics, and wear resistance. LDPE/CS composites were created by blending LDPE with varying CS amounts (0.5-8 wt.%). Analysis using scanning electron microscopy and Raman spectroscopy confirmed CS presence in the LDPE matrix, with X-ray diffraction showing no microstructural changes post-blending. Thermal characterization exhibited notable improvements in thermal stability (~4%) and crystallinity (~7%). Mechanical properties such as hardness and Young's modulus were improved by up to 4% and 24%, respectively. Tribological studies on different composite samples with varying surface roughness under various load and speed conditions revealed the critical role of surface roughness in reducing friction by decreasing real contact area and adhesive interactions between asperities. Increased load and speed amplified shear stress on asperities, possibly leading to deformation and failure. Notably, integrating CSs into LDPE, starting at 1 wt.%, effectively reduced friction and wear. The composite with the highest loading (8 wt.%) displayed the most significant tribological enhancement, achieving a remarkable 75% friction reduction and a substantial 78% wear reduction.

Impact of hydrogenation on the stability and mechanical properties of amorphous boron nitride

Interconnect materials with ultralow dielectric constant, and good thermal and mechanical properties are crucial for the further miniaturization of electronic devices. Recently, it has been demonstrated that ultrathin amorphous boron nitride (aBN) films have a very low dielectric constant, high density (above 2.1 g cm−3), high thermal stability, and mechanical properties. The excellent properties of aBN derive from the nature and degree of disorder, which can be controlled at fabrication, allowing tuning of the physical properties for desired applications. Here, we report an improvement in the stability and mechanical properties of aBN upon hydrogen doping. With the introduction of a Gaussian approximation potential for atomistic simulations, we investigate the changing morphology of aBN with varying H doping concentrations. We found that for 8 at% of H doping, the concentration of sp 3-hybridized atoms reaches to a maximum which leads to an improvement of thermal stability and mechanical properties by 20%. These results will be a guideline for experimentalists and process engineers to tune the growth conditions of aBN films for numerous applications.

Hydroxyapatite–lignin hybrid systems as improved poly(vinyl chloride) fillers: From preparation to application

In this study, new, functional hydroxyapatite–lignin hybrid systems were designed and characterized. The efficacy of the mechanical method utilized to obtain these systems was confirmed by Fourier transform infrared spectroscopy. The hybrid materials were also noted for their good electrokinetic stability and thermal stability.The introduction of 2.5 to 10 wt% hydroxyapatite–lignin systems into an unplasticized PVC blend using a two-step kneading and pressing method resulted in composites with relatively homogeneous distribution, as confirmed by SEM observations. The processing properties of the filler-containing blends were investigated using plastographometric analysis and MFR tests. The introduction of a lignin-predominant hybrid system into the PVC matrix results in a significant improvement of thermal stability, softening temperature, and tensile strength, while maintaining sufficient impact strength for numerous applications. Hybrid materials containing higher amounts of added lignin are promising materials with bacteriostatic properties. This can be utilized to stabilize and prevent the deposition of microorganisms, as well as the formation of biofilms, on material surfaces, thereby limiting the spread of pathogens. New eco-composites based on PVC and a hybrid filler containing lignin show promise in producing components with surfaces resistant to bacterial colonization. Hence, these materials could be used in medical and hospital equipment.

Surface modification of spherical silica micro‐powder using silane coupling agents and their application in epoxy resin‐based composite materials

AbstractIn recent years, the packaging industry has utilized electronic packaging materials with epoxy resin (EP) and high‐performance fillers, exhibiting superior mechanical properties and thermal conductivity. Spherical silica micro‐powder (SSP) is a critical thermal conductive filler but faces challenges due to its inorganic nature. Surface modification is essential to improve SSP's compatibility and dispersion in organic matrices for effective use in EP‐based composites. In this paper, the effects of the following four modification methods on SSP/EP composites were studied: (1) the processes include co‐modification with dimethyldimethoxysilane (DMDMS) and trimethylethoxysilane (MTES), (2) modification with NaOH, (3) co‐modification with DMDMS and MTES in an alkaline environment after NaOH modification, and (4) co‐modification with methyltrimethoxysilane (MTMS) and propyltrimethoxysilane (PTMOS). Through comprehensive characterization and evaluation, it is evident that modification schemes 1, 3, and 4 significantly enhance SSP's hydrophobicity, dispersibility, and compatibility with EP. This led to the improvement of thermal conductivity and stability of the composite, and modification scheme 4 showed the highest enhancement, with a 42.6% increase in thermal conductivity. Moreover, the mechanical properties of modified composite materials, such as bending strength, impact resistance, and tensile strength, surpass those of unmodified SSP/EP composite materials. The study provides valuable insights for reducing manufacturing costs and enhancing productivity in the electronic packaging sector.

Effect of gamma irradiation and electrospinning applications on the physicochemical, antioxidant, and molecular properties of anthocyanin colorant obtained from black carrot pomace

This research article describes the approach of the electrospinning technique for the development of nanofibers from anthocyanin powder and the possibility of using biodegradable polymers, such as gelatin. The irradiation technique was also examined to improve the technological properties of the AP, which was prepared from black carrot pomace. In the present study, the monomeric anthocyanin content of the anthocyanin powder was reduced from 254.6 to 167.9 mg/g after irradiation treatment. The nano-encapsulated anthocyanin powder with wall material showed stronger color properties compared to those of the irradiated samples. FTIR results revealed that changes in OH stretching and galacturonic acid peaks were observed in anthocyanin powder samples at wave numbers of 3500–3200 cm−1 and 800–1000 cm−1, respectively. The electrospinning technique showed a significant improvement in the thermal stability of the AP compared to that with irradiation. Based on this evidence thus far, it can be concluded that irradiation and electrospinning are promising techniques to develop a natural red colorant from industrial food waste for food, food supplement, and pharmaceutical applications. Industrial relevanceNatural colorants are attracting growing attention as a result of consumer demand. For this reason, the black carrot pomace can be considered an important source of natural colorants from industrial food waste resulting from juice extraction. However, the use of BCP to produce red colorants for various products (eg., food and food supplements) is not an easy task. In this regard, both electrospinning and irradiation are beneficial and effective technologies to produce a red colorant from industrial food waste sources, and improve its technological properties that provide opportunities for clean labeling.

A novel heterogeneous biocatalyst based on graphene oxide for synthesis of pyran derivatives

Graphene oxide modified with tryptophan (GO-Trp) has been introduced as a new heterogeneous acid-base biocatalyst for synthesis of some pyran derivatives. GO was prepared according to the Hummer’s method and tryptophan as a low-cost green amino acid is covalently bonded to the surface of GO without any organic or toxic reagents in a green way. The new catalyst was characterized by different spectroscopic methods such as Fourier transform infrared, X-ray diffraction (XRD), etc. …. The results of XRD patterns showed an increase in the distance between the GO plates in the presence of the modifying agent which specifies the presence of amino acid between the GO layers. XPS analysis also confirmed successful modification through the presence of C–N bonds in the structure of the catalyst. In addition, improvements in thermal stability and changes in the morphology of the samples were observed using thermogravimetric analysis and Field emission scanning electron microscopy analysis respectively. Evaluation of the catalyst performance in the synthesis of some benzo[b]pyran and pyrano[3,2-c] chromene derivatives showed presentable results. Seven benzo[b]pyran (4a–4g) and five pyrano[3,2-c] chromene (4h–4l) derivatives were synthesized. GO-Trp as a safe, natural and efficient catalyst, could be reused up to 5 runs for synthesis of pyran derivatives without any significant decrease in its potency. High purity of the products and desirable yields are other points that make the present work more attractive.

In silico Characterization of Natural Blending Agents in Conjunction with Polyhydroxybutyrate (PHB) to Solicit Biopolymer film with Improved Thermal Stability

Polyhydroxybutyrate (PHB) is known to exhibit limitations in terms of thermal stability. Its susceptibility to thermal degradation, particularly when exposed to high temperatures, can hinder its performance in various applications. This study addresses the thermal stability limitations of Polyhydroxybutyrate (PHB) by exploring strategies to enhance its performance through blending with biodegradable polymers. Focusing on the PHB-pectin blend, computational simulations unveil a remarkable 346.92 K increase in the glass transition temperature (Tg), surpassing pure PHB. This elevation indicates strong intermolecular interactions, potentially involving hydrogen bonding, leading to a more rigid and thermally stable polymer system. The heightened Tg has practical implications for critical applications, such as automotive components and electronic devices, where resistance to elevated temperatures is essential. Emphasizing environmental benefits, the study highlights the use of biodegradable and bio-based polymers as eco-friendly alternatives to traditional plastics, contributing to reduced plastic waste. Overall, this research underscores the potential of thermally stable polymers to both enhance material performance and address environmental concerns across diverse industries.

Improvement of Thermal Stability and Sensitivity of Furazan/Furoxan via Ring Closure Generation of Vicinal Amino-Nitro Structure.

Energetic compounds that display high thermal stability and insensitivity properties are essential for applications in mining, gas drilling, etc. In this work, a novel 4-nitro-5-aminoisoxazole energetic moiety oriented to enhance thermal stability and decrease the sensitivity of furazan/furoxan analogues was constructed. The generation of a vicinal amino-nitro structure can be effectively realized in one step by a green and mild ring-closing reaction of nitroacetonitrile potassium salt with chloroxime in aqueous solution. Seven new energetic compounds with good thermal stability (Td: 155.8∼270.3 °C) and low sensitivity (IS: >40 J, FS: 96∼192 N) were synthesized. The nitro-furazan and isoxazole combined product exhibits the advantages of both skeletons, with energetic properties (Dv = 8350 m s-1, P = 30.1 GPa) that may find value in insensitive energetic materials. This strategy promises to achieve a balance between energy levels and stability of furazan/furoxan analogues and offers a new way for the design and synthesis of highly thermally stable compounds that meet special applications.

Development of Curcumin Composite Gel Inhibitor for Preventing Spontaneous Combustion of Coal

ABSTRACT To improve their whole-stage inhibition effects on the spontaneous combustion of coal, curcumin (CCM) and chitosan (CTS) were grafted, and the natural nanomaterial montmorillonite (MMT) was used for intercalation to prepare the composite gel inhibitor CTS-CCM/MMT. Its macro effect and micro mechanism of inhibition were studied. SEM analysis revealed a significant increase in the surface folds and pores of CTS-CCM, suggesting enhanced mechanical properties and thermal stability. XRD and DSC experiments demonstrated a reduction in the diffraction angle 2θ from 21.148° to 20.011° for CTS-CCM/MMT, along with a 21.3% increase in glass transition temperature. This supports the effective improvement of thermal stability through intercalation treatment. Thermogravimetric analysis indicated a higher characteristic temperature point for the inhibitor composite. Infrared diffuse reflection experiments showed deactivation of oxidation activity for the hydroxyl and aliphatic groups through combined inhibition treatment. These findings collectively suggest that the gel exhibits heightened stability and flame retardancy, and can effectively inhibit the entire spontaneous combustion reaction of coal.

Epoxidized Olive Oil as a Sustainable Plasticizer to Polylactic Acid

The consumption of synthetic, non-biodegradable polymer plastics has drawn attention to growing environmental concerns, prompting the development of other materials, particularly bio-based materials. Biopolymer-based biocomposite materials are plasticized to improve their ductility. In this study, five distinct weight ratios of biopolymers (PA/EOO), 90 wt.%, 80 wt.%, 70 wt.%, 60 wt.%, and 50 wt.% were employed as plasticizers for poly-lactic acid (PA) in a fluid molding process. The mechanical, thermal stability, and morphological characteristics of the blends were each examined using a viscometer measurement (R.V.), tensile properties (TP), a scanning electron microscope (SEM), and a thermogravimetric analyzer (TGA). All composite materials (PA/EOO) mixtures show notable improvements in mechanical properties and excellent thermal stability when compared to pure PA. The maximum PA/EOO elongation at break was around 213 % when the PA/EOO mix was 80 wt %. Attractive morphological results from composite materials (PA/EOO) blends showed that EOO was compatible with PA and that the resulting composite material (PA/EOO) was thought to be an ecologically beneficial mixture because it contained vegetable oil.

4'-C-Acetamidomethyl-2'-O-methoxyethyl Nucleic Acid Modifications Improve Thermal Stability, Nuclease Resistance, Potency, and hAgo2 Binding of Small Interfering RNAs.

In this study, we designed the 4'-C-acetamidomethyl-2'-O-methoxyethyl (4'-C-ACM-2'-O-MOE) uridine and thymidine modifications, aiming to test them into small interfering RNAs. Thermal melting studies revealed that incorporating a single 4'-C-ACM-2'-O-MOE modification in the DNA duplex reduced thermal stability. In contrast, an increase in thermal stability was observed when the modification was introduced in DNA:RNA hybrid and in siRNAs. Thermal destabilization in DNA duplex was attributed to unfavorable entropy, which was mainly compensated by the enthalpy factor to some extent. A single 4'-C-ACM-2'-O-MOE thymidine modification at the penultimate position of the 3'-end of dT20 oligonucleotides in the presence of 3'-specific exonucleases, snake venom phosphodiesterase (SVPD), demonstrated significant stability as compared to monomer modifications including 2'-O-Me, 2'-O-MOE, and 2'-F. In gene silencing studies, we found that the 4'-C-ACM-2'-O-MOE uridine or thymidine modifications at the 3'-overhang in the passenger strand in combination with two 2'-F modifications exhibited superior RNAi activity. The results suggest that the dual modification is well tolerated at the 3'-end of the passenger strand, which reflects better siRNA stability and silencing activity. Interestingly, 4'-C-ACM-2'-O-MOE-modified siRNAs showed considerable gene silencing even after 96 h posttransfection; it showed that our modification could induce prolonged gene silencing due to improved metabolic stability. Molecular modeling studies revealed that the introduction of the 4'-C-ACM-2'-O-MOE modification at the 3'-end of the siRNA guide strand helps to anchor the strand within the PAZ domain of the hAgo2 protein. The overall results indicate that the 4'-C-ACM-2'-O-MOE uridine and thymidine modifications are promising modifications to improve the stability, potency, and hAgo2 binding of siRNAs.