scholarly journals Li-Nafion Membrane Plasticised with Ethylene Carbonate/Sulfolane: Influence of Mixing Temperature on the Physicochemical Properties

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1150
Author(s):  
Aigul S. Istomina ◽  
Tatyana V. Yaroslavtseva ◽  
Olga G. Reznitskikh ◽  
Ruslan R. Kayumov ◽  
Lyubov V. Shmygleva ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Ethylene Carbonate ◽  
Membrane Integrity ◽  
Amorphous Structure ◽  
Nafion Membrane ◽  
Polymer Gel ◽  
Scanning Calorimetry ◽  
Practical Applications ◽  
Heating And Cooling ◽  
Solvent Uptake

The use of dipolar aprotic solvents to swell lithiated Nafion ionomer membranes simultaneously serving as electrolyte and separator is of great interest for lithium battery applications. This work attempts to gain an insight into the physicochemical nature of a Li-Nafion ionomer material whose phase-separated nanostructure has been enhanced with a binary plasticiser comprising non-volatile high-boiling ethylene carbonate (EC) and sulfolane (SL). Gravimetric studies evaluating the influence both of mixing temperature (25 to 80 °C) and plasticiser composition (EC/SL ratio) on the solvent uptake of Li-Nafion revealed a hysteresis between heating and cooling modes. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) revealed that the saturation of a Nafion membrane with such a plasticiser led to a re-organisation of its amorphous structure, with crystalline regions remaining practically unchanged. Regardless of mixing temperature, the preservation of crystallites upon swelling is critical due to ionomer crosslinking provided by crystalline regions, which ensures membrane integrity even at very high solvent uptake (≈200% at a mixing temperature of 80 °C). The physicochemical properties of a swollen membrane have much in common with those of a chemically crosslinked polymer gel. The conductivity of ≈10−4 S cm−1 demonstrated by Li-Nafion membranes saturated with EC/SL at room temperature is promising for various practical applications.

scholarly journals Analysis of the Crystallization Kinetics and Thermal Stability of the Amorphous Mg72Zn24Ca4 Alloy

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3583
Author(s):  
Bartosz Opitek ◽  
Janusz Lelito ◽  
Michał Szucki ◽  
Grzegorz Piwowarski ◽  
Łukasz Gondek ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Amorphous Structure ◽  
Avrami Equation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Human Body Temperature ◽  
End Times

The aim of this study was to analyze the crystallization of the Mg72Zn24Ca4 metallic glass alloy. The crystallization process of metallic glass Mg72Zn24Ca4 was investigated by means of the differential scanning calorimetry. The glass-forming ability and crystallization are both strongly dependent on the heating rate. The crystallization kinetics, during the isothermal annealing, were modelled by the Johnson–Mehl–Avrami equation. Avrami exponents were from 2.7 to 3.51, which indicates diffusion-controlled grain growth. Local exponents of the Johnson–Mehl–Avrami equation were also calculated. In addition, the Mg phase—being the isothermal crystallization product—was found, and the diagram of the time–temperature phase transformation was developed. This diagram enables the reading of the start and end times of the crystallization process, occurring in amorphous ribbons of the Mg72Zn24Ca4 alloy on the isothermal annealing temperature. The research showed high stability of the amorphous structure of Mg72Zn24Ca4 alloy at human body temperature.

scholarly journals pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shafiq Ishak ◽  
Soumen Mandal ◽  
Han-Seung Lee ◽  
Jitendra Kumar Singh
Keyword(s):  
Electron Microscopy ◽  
Phase Change ◽  
Lauric Acid ◽  
Photoelectron Spectroscopy ◽  
Phase Change Materials ◽  
Precursor Solution ◽  
Thermal Reliability ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling

AbstractLauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

Graphene Nanoplates Filled Nylon 6,6 Nanocomposites, Morphological, Thermal, Mechanical and Solvent Uptake Study

2019 ◽  
Vol 41 (3) ◽  
pp. 388-388
Author(s):  
Khalid Saeed Khalid Saeed ◽  
Tariq Shah and Ahmad Hassan Tariq Shah and Ahmad Hassan
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Neutral Red ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Nucleation Effect ◽  
Morphological Studies ◽  
Solvent Uptake ◽  
Nylon 6,6 ◽  
Dsc Analyses ◽  
Graphene Nanoplates

Effect of graphene nanoplates (GNPs) on the properties of Nylon 6,6 (Nyl 6,6) is investigated in present study. The morphological studies presented that the GNPs were dispersed inside the Nyl 6,6 matrix. The thermo gravimetric analysis (TGA) illustrated that the thermal degradation of nanocomposites samples were started at the range of 350-393 oC, which was appreciably higher than neat Nyl 6,6 (360 oC). The differential scanning calorimetry (DSC) analyses revealed that the crystallization temperature (Tc) of GNPs/Nyl 6,6 increased as increased the addition of GNPs, which might be due to the nucleation effect of GNPs. The mechanical properties of Nyl 6,6 was enhanced by incorporation of GNPs upto the addition of an optimal quantity of filler (5%wt GNPs) into the polymer matrix. The stress yield and Young’s modulus of 5%wt GNPs/Nyl 6,6 was 96.79 and 1.54, N/nm2, respectively. Both Nyl 6,6 and nanocomposites samples were also used for the adsorption of Neutral red chloride (NRC) dye, which significantly remove the dye from the aqueous solution. The neat nylon 6,6 and GNPs (5 and 10 wt%)/Nyl 6,6 adsorbed about 88.49, 93.15, and 93.60% within 2 h, respectively.

scholarly journals Simultaneous Enhancement of Strength and Toughness of PLA Induced by Miscibility Variation with PVA

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1178 ◽  
Author(s):  
Yanping Liu ◽  
Hanghang Wei ◽  
Zhen Wang ◽  
Qian Li ◽  
Nan Tian
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Fracture Strain ◽  
Electrospun Fiber ◽  
Structural Evolution ◽  
Amorphous Structure ◽  
Poly Lactic Acid ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
Strength And Toughness

The mechanical properties of poly (lactic acid) (PLA) nanofibers with 0%, 5%, 10%, and 20% (w/w) poly (vinyl alcohol) (PVA) were investigated at the macro- and microscale. The macro-mechanical properties for the fiber membrane revealed that both the modulus and fracture strain could be improved by 100% and 70%, respectively, with a PVA content of 5%. The variation in modulus and fracture strain versus the diameter of a single electrospun fiber presented two opposite trends, while simultaneous enhancement was observed when the content of PVA was 5% and 10%. With a diameter of 1 μm, the strength and toughness of the L95V5 and L90V10 fibers were enhanced to over 3 and 2 times that of pure PLA, respectively. The structural evolution of electrospun nanofiber was analyzed by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Although PLA and PVA were still miscible in the concentration range used, the latter could crystallize independently after electrospinning. According to the crystallization behavior of the nanofibers, a double network formed by PLA and PVA—one microcrystal/ordered structure and one amorphous structure—is proposed to contribute to the simultaneous enhancement of strength and toughness, which provides a promising method for preparing biodegradable material with high performance.

scholarly journals A STUDY OF PARAMETERS RELATED TO ANALYSIS OF TRANSITION TEMPERATURES AND ENTHALPIES OF POLYPROPYLENE BY DIFFERENTIAL SCANNING CALORIMETRY (DSC)

2002 ◽  
Vol 10 (11) ◽  
pp. 73-78
Author(s):  
Carlos R. Wolf ◽  
Emir Grave
Keyword(s):  
Differential Scanning Calorimetry ◽  
Material Characterization ◽  
Transition Temperatures ◽  
Nitrogen Flow ◽  
Thermoplastic Polymer ◽  
Scanning Calorimetry ◽  
Know How ◽  
Heating And Cooling ◽  
Polypropylene Material ◽  
Dsc Method

Polypropylene is a thermoplastic polymer, widely employed by converter industries to produce different plastic objects. In order to control and optimize the final properties of the polypropylene material, the evaluation of transition temperatures and enthalpies by Differential Scanning Calorimetry (DSC) has a very important role. Therefore, it is fundamental to know how the analytical conditions influence the results. In this study heating and cooling rates, 10°C/min and 20°C/min, and two different rates of nitrogen flow, 20mL/min and 50mL/min were investigated. It was concluded that thermal properties are influenced by rates of heating and rates of nitrogen flow. The best precision was obtained with the low heating rate, 10°C/min, and high flow rate, 50mL/min. These conditions are being used with the DSC method for polyolefin quality control and material characterization.

scholarly journals Effects of Pectin on the Physicochemical Properties and Freeze-Thaw Stability of Waxy Rice Starch

Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2419
Author(s):  
Yuheng Zhai ◽  
Jiali Xing ◽  
Xiaohu Luo ◽  
Hao Zhang ◽  
Kai Yang ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Loss Modulus ◽  
Rice Starch ◽  
Scanning Calorimetry ◽  
Freeze Thaw ◽  
Textural Parameter ◽  
Waxy Rice ◽  
Pasting Temperature ◽  
Starch Paste ◽  
Waxy Rice Starch

In this study, the effects of the addition of pectin (PEC) on the physicochemical properties and freeze-thaw stability of waxy rice starch (WRS) were investigated. As PEC content increased, the pasting viscosity and pasting temperature of WRS significantly increased (p < 0.05), whereas its breakdown value and setback value decreased. Differential scanning calorimetry showed that the addition of PEC increased the gelatinization temperature of WRS, but decreased its gelatinization enthalpy. Rheological measurements indicated that the addition of PEC did not change the shear-thinning behavior of WRS–PEC blends, and the storage modulus and loss modulus were positively correlated with PEC content. Moreover, the textural parameter of WRS decreased with the increase in PEC content. Furthermore, the addition of PEC decreased the transmittance of starch paste, but enhanced the freeze-thaw stability of WRS to some extent. These results may contribute to the development of WRS-based food products.

scholarly journals Temperature-Dependent X-Ray Studies of Discotic Hexagonal Columnar Mesophases in Trinuclear Gold(I) Pyrazolate Complex

2021 ◽  
Vol 17 (3) ◽  
pp. 285-294
Author(s):  
Mohamad Azani Abd Khadir Jalani ◽  
Hendrik O. Lintang ◽  
Siew Ling Lee ◽  
Juan Matmin ◽  
Nur Fatiha Ghazalli ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
Gold Complex ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling ◽  
Depth Study ◽  
Columnar Mesophases ◽  
Hexagonal Columnar

Gold(I) pyrazolate complex ([Au3Pz3]C10TEG) has been widely studied due to its interesting liquid crystalline properties by exhibiting the discotic hexagonal columnar arrangement. Generally, the liquid crystalline properties of the gold complex were confirmed based on their differential scanning calorimetry thermogram and polarized optical microscopy (POM) images. However, there is still no in-depth study on the phase transition in liquid crystals of [Au3Pz3]C10TEG especially on its structural change at variable temperature. In this study, the resulting liquid crystalline properties of [Au3Pz3]C10TEG upon being heated and cooled was extensively demonstrated via variable-temperature POM (VT-POM) and small angle X-ray scattering (VT-SAXS). Based on the VT-POM images, it was indicated that [Au3Pz3]C10TEG displayed a fan-shaped texture for typical arrangements of discotic hexagonal columnar of liquid crystals. Moreover, VT-SAXS results was in good agreement with the VT-POM images as it showed that [Au3Pz3]C10TEG might consist of two types of stacking system, which are ordered and disordered hexagonal discotic arrangements. Likewise, VT-SAXS analysis also demonstrated that hexagonal columnar mesophase of [Au3Pz3]C10TEG could be recovered even after the heating and cooling for two cycles.

Effect of Heat Treatment on the Properties of (Fe0.6Co0.4)71Si5Nb4B20 Bulk Metallic Glass

2021 ◽  
Vol 875 ◽  
pp. 70-75
Author(s):  
Syed Zameer Abbas ◽  
Rashid Ali ◽  
Syed Muttahir Shah ◽  
Owais Jan ◽  
Munim Awan
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Cast Alloy ◽  
Amorphous Structure ◽  
Indentation Hardness ◽  
Alloy Sample ◽  
Scanning Calorimetry ◽  
Heat Treated Sample ◽  
Heat Treated

Bulk metallic glasses (BMGs) are an important class of materials with unique set of properties. A bulk metallic glass with composition of (Fe0.6Co0.4)71Nb4Si5B20 was cast in the form of a 1 mm thick strip in a water cooled copper mold. The BMG produced was characterized for structure, thermal and mechanical properties. The X-ray diffraction performed on the as cast alloy has shown completely amorphous structure. The glass transition and crystallization peak temperatures obtained through differential scanning calorimetry scan were 542 °C and 588.4 °C, respectively. Some cast amorphous alloy sample was annealed below glass transition (450 °C for 30 mi93nutes) and others above glass transition (580 °C for 5 minutes) temperatures. Nano- indentation hardness of 13.3 GPa was obtained for as cast alloy while a hardness values of 12.8 and 15.84 GPa were measured for heat treated alloys at temperature of 450 °C and 580 °C, respectively. Increase in hardness was attributed to formation of crystals in an amorphous matrix whereas decrease in hardness was due to relaxation of quenching residual stresses. The maximum value of elastic modulus obtained through indentation was 255 GPa for 580 °C heat treated sample.

scholarly journals Production and Physicochemical Properties of Starch Isolated from Djulis (Chenopodium formosanum)

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 551 ◽  
Author(s):  
Wen-Chien Lu ◽  
Yung-Jia Chan ◽  
Fang-Yu Tseng ◽  
Po-Yuan Chiang ◽  
Po-Hsien Li
Keyword(s):  
Physicochemical Properties ◽  
Amylose Content ◽  
Starch Content ◽  
Isolation Procedure ◽  
Point Of View ◽  
Degree Of Crystallinity ◽  
Morphological Observation ◽  
Scanning Calorimetry ◽  
Transition Range ◽  
Ray Patterns

Djulis (Chenopodium formosanum Koidz.) is an annual fast-growing underutilized pseudo cereal with a high percentage of starch content. In this study, djulis starch was extracted from the flour of dried grains by three different isolation procedures: (1) hydrochloric acid (HCl) isolation procedure (HP); (2) deionized water isolation procedure (WP); and (3) sodium hydroxide (NaOH) isolation procedure (NP), followed by investigation of the physicochemical properties of the isolated djulis starch. The amylose content of HP, WP, and NP was 22.14%, 24.15%, and 22.43%, respectively. For scanning electron microscopy (SEM) morphological observation, djulis starch presented a polygonal shape with granule sizes of 0.56–1.96, 0.74–3.02, and 0.62–2.48 μm, respectively. Djulis starch showed the classification of typical A-type x-ray patterns, and the relative degree of crystallinity for HP, WP, and NP was 33.15%, 36.17%, and 37.42%, respectively. Differential scanning calorimetry (DSC) analysis was used to determine the transition temperatures, transition range, and enthalpies of the gelatinization of starches. HP and WP isolated starch exhibited the highest ΔH 9.24 and 8.51 J/g, respectively, whereas NP starch showed the lowest ΔH of 6.95 J/g. The pasting temperatures of HP, WP, and NP isolated starch, which were analyzed by using a Rapid Visco Analyzer (RVA), were 71.70 °C, 72.80 °C, and 69.53 °C, respectively. The dependence of swelling power for the three isolated starches on temperature was tested at 10 °C with intervals between 60 °C and 90 °C. In short, the NP isolation procedure with a stable reaction is compelling from a technological point of view.

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