Showing papers on "Differential scanning calorimetry published in 2019"
TL;DR: A comprehensive review of the many applications of DSC in glass science with focus on glass transition, relaxation, polyamorphism, and crystallization phenomena is presented and recent advances in DSC characterization technology are emphasized.
Abstract: Differential scanning calorimetry (DSC) is a powerful tool to address some of the most challenging issues in glass science and technology, such as the nonequilibrium nature of the glassy state and ...
207 citations
TL;DR: In this paper, a light-driven and electro-driven polyethylene glycol (PEG)/two-dimensional MXene composite with enhanced thermal conductivity and electrical conductivity as form-stable phase change material (FSPCM) is first obtained via the simple vacuum impregnation by employing MXene as the supporting skeleton as well as thermally conductive and electrically conductive filler and PEG as the phase change working substance.
Abstract: Novel light-driven and electro-driven polyethylene glycol (PEG)/two-dimensional MXene composite (PEG@MXene) with enhanced thermal conductivity and electrical conductivity as form-stable phase change material (FSPCM) is first obtained via the simple vacuum impregnation by employing MXene as the supporting skeleton as well as thermally conductive and electrically conductive filler and PEG as the phase change working substance. Fourier transform infrared spectroscopy (FT-IR) indicates that no chemical reaction occurred between PEG and MXene during adsorption process, but X-ray diffraction (XRD) results show the crystalline regions of PEG was decreased by the incorporation of MXene. The differential scanning calorimetry (DSC), polarizing microscope (POM), as well as XRD results demonstrate that the MXene nanosheets act as heterogeneous crystal nuclei and promote the crystallization of PEG. The melting and freezing latent heats of PEG@MXene are as high as 131.2 and 129.5 J/g, respectively, the relative enthalpy efficiency is 80.3%, and the thermal conductivity and electrical conductivity are 2.052 W/mK and 10.41 S/m, respectively. The obtained PEG@MXene has excellent light-to-thermal conversion, electro-to-thermal conversion and thermal energy storage performance. All these results demonstrate that the obtained PEG@MXene will have a great potential application for thermal energy storage.
145 citations
TL;DR: In this article, high-hydrophilic inorganic material graphene oxide (GO) was successfully prepared and incorporated into a cross-linked polyvinyl alcohol (PVA) matrix, which was used for the dehydration of ethanol by pervaporation (PV), monitoring their performance in terms of total permeate flux, partial components fluxes, as well as their separation factor.
144 citations
TL;DR: Biodegradable starch-pectin‑titanium oxide nanoparticles (TiO2 - NPs) blend edible films developed by casting filmogenic solution of sweet potato starch and lemon waste pectin incorporated with TiO2 nanoparticles revealed that with UV prevention capacity, the developed films can be used as food grade UV screening biodesgradable packaging material.
132 citations
TL;DR: In this article, the heat capacities of polyethylene glycol (PEG) samples with the molar mass varying from 1000 to 20,000 for the first time in the temperature range from (1.9 to 400) K using a combination method of physical property measurement system and differential scanning calorimeter (DSC).
128 citations
TL;DR: In this paper, five deep eutectic solvents (DESs) were successfully prepared using ethylene glycol (EG) as hydrogen bond donor (HBD) with N,N-diethylethanolammonium chloride (DAC), benzyltriphenylphosphonium chloride(BTPC), choline chloride (ChCl), MTPB and tetra-n-butylammonium bromide (TBAB) as salts.
126 citations
TL;DR: In this paper, the carboxymethyl cellulose and polyvinyl alcohol (CMC/PVA) based hybrid polymer (HPe) system with different ratio of composition have been prepared via solution casting.
Abstract: The carboxymethyl cellulose and polyvinyl alcohol (CMC/PVA) based hybrid polymer (HPe) system with different ratio of composition have been prepared via solution casting. The features of interaction between CMC and PVA were investigated using X-ray diffraction (XRD), and infrared (IR) spectroscopy to disclose the reduction of crystallinity of the HPe system. Morphological properties observed by Scanning electron microscopy (SEM) confirmed the homogeneity of the HPe system. Differential scanning calorimetry (DSC) result explains the miscibility of the HPe system which was confirmed by means of variations in the glass transition temperature (Tg). Two degradation mechanisms were revealed by thermogravimetric analysis (TGA) in the HPe system attributed to the decarboxylation in CMC and degradation of bond scission in PVA backbone. The blend of 80:20 compositions of CMC/PVA HPe system was found to be the optimum ratio with an increase in conductivity of CMC/PVA by one magnitude order from 10−7 to 10−6 S/cm with the lowest in crystallinity.
122 citations
TL;DR: In this paper, a shape-stabilized phase change material (PCM) prepared by impregnating eutectic salt hydrate (Na2SO4·10H2O-Na2CO3·10 H2O with 1:1 in mass ratio) into expanded vermiculite (EV) is carried out.
115 citations
TL;DR: In this paper, Cyrene was employed for the first time as solvent for polyethersulfone (PES) and polyvinylidene fluoride (PVDF) membrane preparation via phase inversion.
112 citations
TL;DR: In this paper, an ultrasonic extraction technology was utilized to extract the different functional groups from coals and the extracted coal samples were further collected for tests of Fourier infrared (FTIR) spectrum, electron paramagnetic resonance (EPR) spectrum and thermogravimetric (TG) analysis.
98 citations
TL;DR: The modulated differential scanning calorimetry (MDSC) relies on the accurate detection of complex transitions and the possibility of distinguishing reversible events (dependent on the heat capacity) from non-reversible events ( dependent on kinetics).
Abstract: Phase transition issues in the field of foods and drugs have significantly influenced these industries and consequently attracted the attention of scientists and engineers. The study of thermodynamic parameters such as the glass transition temperature (Tg), melting temperature (Tm), crystallization temperature (Tc), enthalpy (H), and heat capacity (Cp) may provide important information that can be used in the development of new products and improvement of those already in the market. The techniques most commonly employed for characterizing phase transitions are thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC). Among these techniques, DSC is preferred because it allows the detection of transitions in a wide range of temperatures (-90 to 550 °C) and ease in the quantitative and qualitative analysis of the transitions. However, the standard DSC still presents some limitations that may reduce the accuracy and precision of measurements. The modulated differential scanning calorimetry (MDSC) has overcome some of these issues by employing sinusoidally modulated heating rates, which are used to determine the heat capacity. Another variant of the MDSC is the supercooling MDSC (SMDSC). SMDSC allows the detection of more complex thermal events such as solid-solid (Ts-s) transitions, liquid-liquid (Tl-l) transitions, and vitrification and devitrification temperatures (Tv and Tdv, respectively), which are typically found at the supercooling temperatures (Tco). The main advantage of MDSC relies on the accurate detection of complex transitions and the possibility of distinguishing reversible events (dependent on the heat capacity) from non-reversible events (dependent on kinetics).
TL;DR: In this article, a multi-arm hyperbranched polyethylenimine macromolecule was used to develop epoxy superadhesives for metal/polymer composite interfaces.
TL;DR: In this paper, the authors investigated the structure and hydrogen storage properties of a series of quaternary and quintary highentropy alloys related to the ternary system TiVNb with powder X-ray diffraction (PXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and manometric measurements in a Sieverts apparatus.
TL;DR: Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number and ionic conductivity at ambient temperature, by tailoring the structural/morphological characteristics ofThe polymer matrix.
Abstract: We report a thorough, multitechnique investigation of the structure and transport properties of a UV-cross-linked polymer electrolyte based on poly(ethylene oxide), tetra(ethylene glycol)dimethyl ether (G4), and lithium bis(trifluoromethane)sulfonimide. The properties of the cross-linked polymer electrolyte are compared to those of a non-cross-linked sample of same composition. The effect of UV-induced cross-linking on the physico/chemical characteristics is evaluated by X-ray diffraction, differential scanning calorimetry, shear rheology, 1H and 7Li magic angle spinning nuclear magnetic resonance (NMR) spectroscopy, 19F and 7Li pulsed field gradient stimulated echo NMR analyses, electrochemical impedance spectroscopy, and Fourier transform Raman spectroscopy. Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number (>0.5) and ionic conductivity (>0.1 mS cm?1) at ambient temperature, by tailoring the structural/morphological characteristics of the polymer matrix. Finally, the polymer electrolyte allows reversible operation with stable profile for hundreds of cycles upon galvanostatic test at ambient temperature of LiFePO4-based lithium-metal cells, which deliver full capacity at 0.05 or 0.1C current rate and keep high rate capabilities up to 1C. This enforces the role of UV-induced cross-linking in achieving excellent electrochemical characteristics, exploiting a practical, easy up-scalable process.
TL;DR: In this paper, a high-purity zeolite 4A was synthesized by the hydrothermal method using fly ash as the raw material, and the effects of sodium hydroxide (NaOH) or/and sodium carbonate (Na2CO3) on the activation of fly ash were studied.
TL;DR: In this paper, a novel flame retardant with phosphaphenanthrene group and tetrazole ring, 6-(((1H-tetrazol-5-yl)amino)(4-hydroxyphenyl)methyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide (ATZ), was synthesized and incorporated into epoxy matrix as co-curing agent to remarkably improve the flame retardancy of epoxy resin.
TL;DR: The observed phenomenon of liquefaction and re-solidification of biuret in the temperature range of 193-230 °C is explained by formation of a eutectic mixture with urea.
Abstract: The selective catalytic reduction technique for automotive applications depends on ammonia production from a urea–water solution via thermolysis and hydrolysis. In this process, undesired liquid and solid by-products are formed in the exhaust pipe. The formation and decomposition of these by-products have been studied by thermogravimetric analysis and differential scanning calorimetry. A new reaction scheme is proposed that emphasizes the role of thermodynamic equilibrium of the reactants in liquid and solid phases. Thermodynamic data for triuret have been refined. The observed phenomenon of liquefaction and re-solidification of biuret in the temperature range of 193–230 °C is explained by formation of a eutectic mixture with urea.
TL;DR: In this paper, a 2D-MMT/SA composite has been used in encapsulating stearic acid (SA) latex particles to enhance the thermal energy storage capacity and thermal conductivity.
TL;DR: While GF shows little effect on thermal resistance, heat treatment can remarkably improve thermal stability, in particular for PLA/GF composites, which leads to the outstanding mechanical performance of PLA/ GF composites.
TL;DR: In this article, a free standing and flexible solid polymer electrolyte (SPE) based on nonhazardous and environmental friendly material, carboxymethyl cellulose (CMC) was successfully produced in order to overcome environmental and pollution issues.
TL;DR: In this article, a facile approach was used to synthesize poly(benzoxazine-co-imide,co-siloxane) (oHPNI-oda-PDMS), a new main chain-type copolymer featuring benzoxazine, imide, and siloxane units as repeating units.
TL;DR: In this paper, the microstructure, chemical components and interactions that between two materials were characterized via Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR).
TL;DR: In this paper, a dynamic cross-linked SSPCMs (DC-PCMs) was facilely fabricated by bonding polyethylene glycol (PEG) to a polymeric skeleton through the thermally reversible Diels-Alder (DA) reaction for sustainable TES.
Abstract: Conventional solid–solid phase-change materials (SSPCMs) exhibit good thermal energy storage (TES) ability and shape stability, but they cannot be recycled and re-shaped once fabricated due to the chemical cross-links. Hence, endowing SSPCMs with recyclability and malleable properties is advantageous for numerous applications, and contributes to environmental protection. Herein, a novel class of dynamic cross-linked SSPCMs (DC-PCMs) was facilely fabricated by bonding polyethylene glycol (PEG) to a polymeric skeleton through the thermally reversible Diels–Alder (DA) reaction for sustainable TES. PEG segments function as energy-storage units, while the polymeric skeleton affords shape stability and robust mechanical properties. The crystalline structure of DC-PCMs was investigated by X-ray diffraction (XRD), polarized optical microscopy (POM) and differential scanning calorimetry (DSC). DSC characterization also confirms the reversible energy-capture and release ability of DC-PCMs. The results suggest that SSPCMs show typical solid–solid phase transitions within the temperature range from 40 °C to 70 °C and can achieve a high latent heat storage capacity of about 107.2 J g−1. Meanwhile, the thermally reversible DA reaction endows the DC-PCMs with good thermal recyclability and solid-state plasticity. After multiple thermal cycles, DC-PCMs can retain the original mechanical properties and TES ability. Moreover, the DC-PCMs are highly scalable for practical applications because of their uncomplicated and cost-effective fabrication.
TL;DR: In this paper, a series of facile flexible reversible thermochromic membranes containing micro/nano-encapsulated phase change materials were fabricated, which presented excellent therm-romic performance and striking latent heat storage property.
TL;DR: In this paper, a form-stable composite phase change materials (FS-CPCM) was prepared by the vacuum impregnation method by grafted lauric acid (LA) on the surface of graphene aerogel (GA) by an esterification reaction and reduction process to increase the thermal conductivity.
TL;DR: Citric acid-incorporated chitosan films manufactured by compression molding were found to show potential for food and pharmaceutical applications and a good compatibility among all the components of the mixture and enhancing the mechanical properties of the resulting films.
TL;DR: In this article, a mixture of polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) was used as filler material to increase the Young's modulus.
TL;DR: In this article, the in-situ TiB2 reinforcement particles were prepared by the exothermic reaction of K2TiF6 and KBF4 salts in melted aluminium copper alloy which improved the hardness, yield, and tensile strengths to the extent of ∼ 89 VHN, ∼ 236 MPa and ∼ 295 MPa, respectively.
TL;DR: In this paper, a silicone rubber (SR)/paraffin (Pa)@silicon dioxide (SiO2) composite form-stable phase change material (PCM) was developed by choosing Pa as PCM core microencapsulated in SiO2 shell based on TEOS and γ-aminopropyl triethoxysilane (APTES).
TL;DR: The preliminary safety evaluation and oral tolerability showed that the hydrogel suspension was biocompatible and well tolerable upto 4000 mg/kg of body weight without causing any hematological or histopathological changes in rabbits.