373 research outputs found
Enhancing the thermal conductivity and shape stability of phase-change composites using diatomite and graphene nanoplates for thermal energy storage
No full textThe 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
Production and characterization of chitosan-fungal extract films
No full textA fungal extract obtained from an edible species (Tricholoma terreum) was used to produce chitosan-based films. Fungal extracts were analyzed using HPLC and chitosan-based films were characterized with FT-IR, SEM, DSC and TGA analysis. High phenolic content was found in the fungal extracts using HPLC. FT-IR results showed that fungal extracts were successfully added into the chitosan films. The addition of fungal extract increased elasticity, hydrophobicity and antioxidant and antimicrobial activity of the chitosan films. Additionally, antiquorum sensing and antimicrobial activities of chitosan-fungal extract films were found to be much higher than gentamicin (a commonly used antibiotic). However, incorporation of extracts into chitosan films decreased transparency and thermal stability. All these results suggested that chitosan-fungal extract films might be beneficially used to improve food packaging technology.ASUBTAM, Aksaray UniversityThe major portion of this study was carried-out as a master thesis of the first author. The experimental studies were self-supported without any internal/external financing at the corresponding author's laboratory in ASUBTAM, Aksaray University. The analyses were supported by Professor Jalel Labidi at the University of the Basque Country
Potential use of kraft and organosolv lignins as a natural additive for healthcare products
No full textWOS: 000440243600050The growing interest in substituting synthetic products coming from non-renewable sources with products from biomass has focused attention on the lignin biopolymer. Its high availability, low price and properties make the development of new and valuable uses for lignin interesting, thus improving the economic and environmental aspects of the biomass conversion. To achieve this objective, the potential use of industrial kraft and organosolv lignins as antioxidants, antimicrobials and sunscreen products has been evaluated. The results of a detailed antibacterial and antifungal study demonstrated the high potential of kraft lignins against a variety of foodborne and human pathogenic microorganisms. Moreover, both organosolv and kraft lignins presented an effective protection factor (SPF values from 10-20), demonstrating their effectiveness as natural additives for the sun lotion market. In addition, lignin samples presented high antioxidant capacity compared to butylated hydroxytoluene (BHT), one common commercial antioxidant industrially used. Therefore, the development of innovative applications of lignins as a commodity for the chemical, pharmaceutical or cosmetic industries could expand their possible uses in the market giving new added values to lignin.University of the Basque Country [PIF 13/050]; Basque Government [IT1008-16]The authors are grateful for the financial support received from the University of the Basque Country (doctoral grant of Ms Gordobil Grant No. PIF 13/050) and to the Basque Government (scholarship of young researchers training and project IT1008-16)
Kraft Lignin Modification and Application as Aqueous Binder for Carbon Anode in Lithium Battery
No full textAlthough lithium batteries contribute to a green energy economy, most of the materials used in their production are fossil-based. A way to diminish the carbon footprint is by utilizing sustainable and biobased products like lignin, which is highly abundant in nature and vastly produced industrially as a low-value side product in the paper and pulp industry. In the current work, chemically modified Kraft lignins (KL) with different chemical functionalities such as carboxymethyl and sulfomethyl were applied as binder materials for preparing active carbon-based electrodes for lithium metal lab-scale battery cells. The optimization of the lignin binders through functionalization allowed for a significantly enhanced aqueous processability and performance of anodic electrodes composed of hard carbon as the electroactive material and carbon black as the conducting additive. Battery performances were comparable with the state-of-the-art biopolymer binders carboxymethylcellulose (CMC) reaching specific capacity values of 170 mA h g–1. The functionalization shows an alternative approach to the valorization of lignin in high-tech applications
Antifungal cellulose by capsaicin surface grafting
No full textCellulose is one of the most abundant materials in nature. Besides its biological function, cellulose can be extracted from the cell wall and used in several industrial applications. Thus, it can be used in papers, pharmaceuticals, food, cosmetics and innovative materials such as nanocomposites, packaging, coatings and dispersion technology. With the aim of extending cellulose applications and producing so-called “smart” materials, new functionality can be introduced by physical or chemical modifications. Taking into account that capsaicin, the active component of chili peppers, is an excellent antifungal agent, a potential new material could be obtained by chemical reaction between this active compound and cellulose. In this work, capsaicin grafting onto cellulose using polycarboxylic acid as linking agent is proposed. The reaction occurrence was corroborated by Fourier transform infrared spectroscopy and UV–Vis spectrophotometry in reflectance mode. Modified cellulose with <2 wt% of capsaicin shows a strong change in antifungal activity with respect to the unmodified one. This activity was evaluated by the fungal growth inhibition test with two different fungi, Trametes versicolor and Gloeophyllum trabeum. Modified cellulose samples showed a high percentage of fungal growth inhibition, demonstrating the success of the cellulose modification and high antifungal power of the grafting molecule.Fil: Martini, Raquel Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Serrano, Luis. Universidad del País Vasco; EspañaFil: Barbosa, Silvia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Labidi, Jalel. Universidad del País Vasco; Españ
Synthesis of symmetric bis-α-ketoamides from renewable starting materials and comparative study of their nucleating efficiency in PLLA
No full textAn efficient and smart synthesis of bis-α-ketoamides has been disclosed. The desired products have been obtained through a Passerini multicomponent reaction using biobased aldehydes, acetic acid and bis-isocyanides (prepared from the corresponding biobased diamides), followed by a deprotection/oxidation step. The effect of the synthesized compounds on the crystallization behavior of poly(L-lactide) (PLLA) has been investigated by differential scanning calorimetry (DSC) in non-isothermal conditions. Among all the synthesized compounds, only a few are able to meaningfully enhance the nucleation of PLLA, as confirmed by a shift of the polymer crystallization peak temperature towards higher values. With the research of active polymer nucleating agents being mostly empirical, the combinatorial synthetic approach proposed herein, coupled with the possibility of a small scale mixing procedure, can potentially represent a useful strategy for the discovery of new efficient biobased polymer additives
Enhancing the thermal transfer properties of phase change material for thermal energy storage by impregnating hybrid nanoparticles within copper foams
No full textA phase-change material (PCM) is recommended for thermal energy storage. However, conventional PCMs suffer from poor thermal conductivity. To solve this problem, this study presented different compositions to improve PCM thermal conductivity. The effects of the average specific surface of metal foams and the weight percentage of metal foams and hybrid nanoparticles on the phase-change materials' thermal characteristics were investigated. The findings demonstrate that thermal performance of the PCM composite is noticeably better than that of pure PCM and increasing the weight content of foam metal and hybrid nanoparticles leads to an increase in thermal conductivity of 37.7% for the same type of copper. The results also reveal that thermal conductivity performance increases as the amount of metal foam and hybrid nanoparticles increases. The average specific surface value of 1600 m2/m3 shows better thermal properties compared with other average specific surface values. Moreover, the heat capacity is affected by the increase in the content of metal foam. Many drawbacks have been found in using foam metal in PCM preparation, mainly the fixed shapes of metal foams compared with the formability nature of the PCM, which effects the shapes of the PCM composites and thus limits its use in applications with limited size. This novel approach to improving PCM's thermal behaviour may be applied to the creation of thermal energy storage devices with predetermined characteristics
Synthesis of symmetric bis-α-ketoamides from renewable starting materials and comparative study of their nucleating efficiency in PLA
No full textSynthesis of polyols of different lignocellulosic residues to obtain greener products.
No full text216 p.Diferentes residuos lignocelulósicos, fueron convertidos en polioles usando alcoholes poli hídricos como disolventes. Mediante un diseño experimental se determinaron las condiciones óptimas de los polioles. Los distintos polioles fueron caracterizados y usados para sustituir parcialmente el fenol en las formulaciones de resinas fenólicas. Por último, las resinas fueran caracterizadas y evaluadas como adhesivo para tableros de madera.Los resultados obtenidos demuestran que los polioles pueden sustituir parte del fenol en las formulaciones de resinas resoles. Los adhesivos fenólicos presentaron buenas propiedades mecánicas
Synthesis of polyols of different lignocellulosic residues to obtain greener products.
No full text216 p.Diferentes residuos lignocelulósicos, fueron convertidos en polioles usando alcoholes poli hídricos como disolventes. Mediante un diseño experimental se determinaron las condiciones óptimas de los polioles. Los distintos polioles fueron caracterizados y usados para sustituir parcialmente el fenol en las formulaciones de resinas fenólicas. Por último, las resinas fueran caracterizadas y evaluadas como adhesivo para tableros de madera.Los resultados obtenidos demuestran que los polioles pueden sustituir parte del fenol en las formulaciones de resinas resoles. Los adhesivos fenólicos presentaron buenas propiedades mecánicas
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