Differential Thermal Gravimetric Analysis Research Articles

Preparation, characterization, and thermal stability of double-composition shell microencapsulated phase change material by interfacial polymerization

Polyurea/polyurethane double-composition shell microcapsules with n-octadecane as the main core material were prepared by interfacial polymerization. The outer polyurea shell was formed by the polymerization of toluene-2,4-diisocyanate (TDI) and diethylene triamine (DETA), and the inner polyurethane shell was formed by the polymerization of TDI and polypropylene glycol 2000 (PPG2000). The phase change property, chemical structure, surface morphology, and thermal stability of microcapsules were investigated by differential scanning calorimetry (DSC), FTIR, SEM, TEM, and thermal gravimetric analysis. The results show that the melting temperature and melting enthalpies of double-composition shell microcapsules were 28.6 °C and 143 J g−1, respectively, and only one exothermic peak for n-octadecane and three peaks for microcapsules were observed in the DSC cooling curve. The prepared microcapsules with the average diameter 3 ~ 5 μm had a smooth and compact surface. The thermal stabilities and compactness of the microcapsules with double-composition shells were greatly improved compared to those of the microcapsules with single-composition shells.

Rapid Biological Synthesis of Silver Nanoparticles from Ocimum sanctum and Their Characterization

With development of nanotechnology, the biological synthesis process deals with the synthesis, characterization, and manipulation of materials and further development at nanoscale which is the most cost-effective and eco-friendly and rapid synthesis process as compared to physical and chemical process. In this research silver nanoparticles (AgNPs) were synthesized from silver nitrate (AgNO3) aqueous solution through eco-friendly plant leaf broth of Ocimum sanctum as reactant as well as capping agent and stabilizer. The formation of AgNPs was monitored by ultraviolet-visible spectrometer (UV-vis) and Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) and scanning electronic microscopy (SEM) have been used to characterize the morphology of prepared AgNPs. The peaks in XRD pattern are in good agreement with that of face-centered-cubic (FCC) form of metallic silver. Thermal gravimetric analysis/differential thermal analysis (TGA/DTA) results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The average grain size of silver nanoparticles is found to be 29 nm. The FTIR results indicated that the leaf broths containing the carboxyl, hydroxyl, and amine groups are mainly involved in fabrication of silver AgNPs and proteins, which have amine groups responsible for stabilizing AgNPs in the solution.

The investigation of the crystalline phases development in Macor® glass-ceramic

The commercially available, machinable, fluormica glass-ceramic, Macor®, was remelted to produce a glass. This glass was then characterized by differential scanning calorimetry (DSC), combined differential thermal analysis/thermal gravimetric analysis (DTA/TGA), X-ray powder diffraction (XRD) and 19F magic angle spinning −nuclear magnetic resonance (MAS-NMR). The Macor® glass was shown to crystallize to chondrodite (Mg5F2(SiO4)2), followed by the conversion of chondrodite to norbergite (Mg3SiO4F2) and the conversion of norbegite to a potassium fluorphlogopite phase (KMg3AlSi3O10F2). The glass exhibited an optimum nucleation temperature just above its glass transition temperature, which is indicative of a nucleation route involving amorphous phase separation. The 19F MAS-NMR spectra showed the fluorine environments being present as F-Mg(3) in the original glass, the chondrodite, norbergite and fluorphlogopite phases, indicating that the fluorine structure is conserved throughout the crystallization process. The activation energies for crystallization were found to be 215, 431 and 251kJmol−1 for chondrodite, norbergite and fluorphlogopite, respectively.

Development and Characterization of a Bayberry Tannin-based Adhesive for Particleboard

A renewable bio-based thermosetting adhesive named tannin-furanic-formaldehyde (TFF) resin was synthesized using natural raw materials from crops and forest, such as furfuryl alcohol and bayberry tannin. The thermal properties of the adhesives were studied using differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and thermal gravimetric analysis (TGA). The structure of the TFF resin was characterized by electrospray ionization mass spectrometry (ESI-MS) and Fourier transform infrared (FTIR) spectroscopy. The results indicated that TFF resin was easily prepared. Moreover, it showed an excellent modulus of elasticity (MOE) and thermal resistance. Moreover, the cross-linking reaction of bayberry tannin, furfuryl alcohol, and formaldehyde under acid condition was established.

Conceptual approach to thermal analysis and its main applications/Aproximación conceptual al análisis térmico y sus principales aplicaciones

This work shows to the reader a general description about the techniques of classic thermal analysis as known as Differential Scanning Calorimetry (DSC), Differential Thermal Analysis (DTA) and Thermal Gravimetric Analysis. These techniques are very used in science and material technologies (metals, metals alloys, ceramics, glass, polymer, plastic and composites) with the purpose of characterizing precursors, following and control of process, adjustment of operation conditions, thermal treatment and verifying of quality parameters.

Synthesis and characterization of new coordination polymer with l-proline amino acid ligand; new precursor for preparation of pure phase lead(II) oxide nanoparticles via thermal decomposition

A new two-dimensional lead(II) coordination polymer, [Pb(Pro)2] n (1); Pro = l-proline amino acid, has been synthesized and characterized by IR and X-ray diffraction. Structural determination of compound 1 reveals the Pb(II) ion is four-coordinated, bonded to two nitrogen atoms and two oxygen atoms from the l-proline ligand. PbO nanoparticles were synthesized by calcination of compound 1 at 500, 550 and 600 °C under air atmosphere. The PbO nanostructure was characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The thermal stability of compound 1 was studied by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). Increase in calcination temperature decreased particles size and also led to layer-shape nanostructures morphology.

Influence of different bonding and fluxing agents on the sintering behavior and dielectric properties of steatite ceramic materials

Abstract The focus of the study was on providing insights into interconnections between sintering and development of the crystalline microstructure, and consequently variations in dielectric behavior of four steatites fabricated from a low-cost raw material, i.e. talc. The changes, induced by the alternations of the binders (bentonite, kaolin clay) and fluxing agents (BaCO 3 , feldspar), were monitored in the temperature range 1000° to 1250 °C in which complete densification and re-crystallization of the investigated structures were accomplished. The critical points in the synthesis of steatite materials were assessed by instrumental analyses. Crystallinity changes and mineral phase transition during sintering were monitored by X-ray diffraction technique. Microstructural visualization of the samples and the spatial arrangements of individual chemical elements were achieved via scanning electron microscopy accompanied with EDS mapping. The thermal stability was observed on the green mixtures using differential thermal and thermo gravimetric analyses. Electrical measurements recorded variations of the dielectric constant (e r ) and loss tangent (tan δ) as a function of the sintering temperature. The investigation highlighted critical design points, as well as the optimal combinations of the raw materials for production of the steatite ceramics for advanced electrical engineering applications.

Dual-curable PVB based adhesive formulations for cord/rubber composites: The influence of reactive diluents

In this study, the effects of reactive diluent type on the adhesion strength of cord/rubber surfaces were investigated. For this purpose, a urethane acrylate oligomer was synthesized by the reaction of 2,4-toluene diisocyanate (TDI), 2-hydroxyethyl methacrylate (HEMA) and polyvinyl butyral (PVB) in the presence of di-n-butyltin dilaurate (T12) as catalyst. The structure of the oligomer was characterized by nuclear magnetic resonance (NMR) spectroscopy. Then the oligomer was included in adhesive formulations together with trimethylolpropane trimethacrylate (TMPTMA) and tricyclodecane dimethanol diacrylate (TCDDA) as reactive diluents and thermal and photo initiator respectively. Polyester/polyamide cord fabrics were dipped into the adhesive solution and cured by UV-light. Then coated fabrics were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Contact angle measurement was employed to investigate the wettability properties of the coated fabrics. Thermal curing between the coated fabric and rubber was performed under heat and pressure. The adhesion strength between the cord/rubber surfaces was determined by T-peel test. The highest adhesion strength of 100.4N/cm with the lowest contact angle value of 70.2° were obtained in the sample containing TCDDA as reactive diluent, due to a higher functionality resulting in a greater crosslinking density.

Cellulose/Paraffin Composite Fibers for Thermal Energy Storage and Temperature Regulation

Cellulose is a good bio-based material for rich resources and recyclability. Paraffin is widely used in the field of energy storage and temperature regulation due to its excellent heat storage properties and mature preparation technology. In this paper, the cellulose fibers with energy storage and temperature regulation were prepared by wet spinning process using paraffin as phase change material. Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA) were utilized to characterize the morphology structure, crystalline properties, phase transition properties and heat resistance of fibers and so on. The results showed that the fiber surface without holes and paraffin was uniformly distributed in the cellulose matrix, and paraffin was not easily overflow during the process of phase change. Paraffin and cellulose substrate had good compatibility due to the interaction of hydrogen bonding, and 30% of paraffin did not cause a significant impact on the degree of crystallinity and thermal stability of cellulose fibers. Enthalpy of the resultant functional fibers could reach 27.44 J/g, and the thermal decomposition temperature was over 300 °C. The fibers possessed the phase change ability and certain mechanical properties. Furthermore, it was found that the fibers still had good resistance to washing under extreme conditions.

Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials.

In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin—a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

Studies on gum Dammar based composite ion exchanger and their characterization

Gum Dammar and zirconium (IV) Iodooxalate [Gd-cl-poly (AAm)-Zr (IV) Iodooxalate] composite ion exchanger was prepared by incorporating inorganic precipitates of zirconium (IV) iodooxalate into polymeric mixture under vacuum conditions. The polymeric mixture (hydrogel) was prepared using gum Dammar (Gd), acrylamide (AAm) as monomer, N,N′-methylene-bis-acrylamide as crosslinker and potassium persulphate as initiator. The reaction conditions for synthesis of hydrogel such as time (60 min), temperature (65 °C), pressure (550 mmHg), solvent (5 ml), concentration of monomer (9.72 × 10−3 mol L−1) and cross-linker (1.40 × 10−4 mol L−1), ratio of zirconium oxychloride (0.1 M), potassium iodate (0.1 M) and oxalic acid (0.1 M) in ratio 1:1:1 were optimized to obtain the maximum ion exchange capacity (1.78 meq g−1). The morphology and structure of ion-exchanger were studied using Fourier transform infrared spectroscopy, scanning electron microscopy and Energy dispersive spectroscopy, X-ray diffraction data, Thermo gravimetric analysis, differential thermal analysis and differential thermo gravimetric analysis. The maximum ion exchange capacity, obtained after the optimized reaction conditions was 1.78 meq g−1. Polymeric-inorganic hybrid material enables the integration of useful organic and inorganic characteristics within a molecular scale composite.

Effect of gamma irradiation on structural, molecular, thermal and rheological properties of sunflower protein isolate

Protein isolates were prepared from sunflower meal using alkaline extraction technique and were irradiated at different doses (0, 10, 20, 30, 40 and 50 kGy). Sunflower protein isolates were evaluated for structural, molecular, thermal and rheological properties. Secondary structure of proteins was disrupted with decrease in α-helix content and concomitant increase in β-sheet content. The change in fluorescence spectra was observed indicating the alteration in tertiary structure of protein molecules mainly due to the conformational changes especially aggregation and crosslinking of protein molecules. Increase in thermal stability of protein after irradiation was found as determined by differential scanning calorimetry and thermal gravimetric analysis. Molecular weight of protein was increased in a dose dependent manner due to protein-protein crosslinking. Development of cracks on the surface of protein particle after irradiation was observed by scanning electron microscopy. Storage (G′) and loss modulus (G″) of protein dispersion was increased after gamma irradiation.

Synthesis and Characterization of Poly(glycidyl nitrate-block-caprolactone-block-glycidyl nitrate) (PGN-PCL-PGN) Tri-Block Copolymer as a Novel Energetic Binder

An energetic binder was synthesized through ring opening copolymerization of glycidyl nitrate (GLYN) with polycaprolactone (PCL) as a macroinitiator to form tri-block copolymer PGN-PCL-PGN. Effect of monomer concentration, catalyst, reaction time and solvent was investigated in polymerization. Resulting tri-block copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The DSC result shows that glass transition temperature of tri-block copolymer (Tg=−56.2 °C) is lower than PGN (Tg=−35 °C). In optimal condition, the Mw of this polymer was obtained 2900 g/mol.

Preparation and Characterisation of Linear Low-Density Polyethylene / Thermoplastic Starch Blends Filled with Banana Fibre

In this study, the influence of banana fibre (BF) loading using sodium hydroxide (NaOH) pre-treated and succinic anhydride-treated (SA) BF on the mechanical properties of linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) matrix is investigated. LLDPE/TPS/BF composites were developed under different BF conditions, with and without chemical modifications with the BF content ranging from 5% to 30% based on the total composite. The tensile strength showed an increase with an increase of fibre content up to 10%, thereby decreasing gradually beyond this level. NaOH pre-treated and SA treated BF added with LLDPE/TPS composite displays a higher tensile strength as compared to untreated BF in LLDPE/TPS composites. Thermal behaviour of the BF incorporated in LLDPE/TPS composite was characterised using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). This showed that SA treated BF exhibits better thermal stability, compared to other composites. This is because of the improvement in interfacial adhesion existing between both the fibre and matrix. In addition, a morphology study confirmed that pre-treated and treated BF had excellent interfacial adhesion with LLDPE/TPS matrix, leading to better mechanical properties of resultant composites.

Morphological and thermal properties of PLA/OMMT nanocomposites prepared via vane extruder

Polylactide/Organo-Montmorillonite (PLA/OMMT) Nanocomposites were prepared by melting extrusion using a novel vane extruder (VE), which can induce global elongational flow. In the study, the influence of different concentrations of the OMMT on the morphological and thermal properties were investigated. The morphology and structure of the nanocomposites were evaluated using Fourier Transform Infrared Spectroscopy (FTIR), the X-ray diffraction (XRD) and transmission electron microscopy (TEM) respectively, whereas the thermal behaviors and thermal stabilities were characterized using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) respectively. The results illustrate that PLA/OMMT nanocomposites displayed clear intercalation and/or exfoliation structures. Interestingly, increasing the clay content did not lead to the agglomeration of OMMT layers. Moreover, the presence of nanoclay decreased the enthalpy of crystallization of PLA/OMMT composites. Also, the melting temperatures of the nanocomposites were reduced by the addition of nanoclay.

Compatibility Issues Between Electrodes and Electrolytes in Solid-State Batteries

Solid-state batteries have recently attracted significant attention because of their advantages compared with conventional batteries employing liquid electrolytes. Remarkable success has been achieved in the discovery of ceramic alkali superionic conductors as electrolytes in solid-state batteries; however, obtaining a stable interface between these electrolytes and electrodes is difficult. Only limited studies on the compatibility between electrodes and solid electrolytes have been reported, partially because of the need for expensive instrumentation and special cell designs. Without simple yet powerful tools, these compatibility issues cannot be systematically investigated, thus hindering the generalization of design rules for the integration of solid-state battery components. In this work, we present a methodology that combines density functional theory (DFT) calculations and simple experimental techniques such as X-ray diffraction(XRD), simultaneous differential scanning calorimetry and thermal gravimetric analysis (SDT), and electrochemistry to efficiently screen the compatibility of numerous electrode/electrolyte pairs. Employing a Na solid-state system as an example, we demonstrate the efficiency of our method by finding the most stable system (NaCrO2|Na3PS4|Na-Sn) within a selected chemical space (more than 20 different combinations of electrodes and electrolytes). Important selection criteria for the cathode, electrolyte, and anode in solid-state batteries are also derived from this study. This work has two important implications for the future studies in the related fields: (1) the study of the stability window of the electrolyte and the reaction conditions and products of the reactions between electrode and electrolyte provide an essential guide for integrating all-solid-state battery components; and (2) this current method can significantly accelerate the expansion of the electrolyte/electrode compatibility database. Figure 1

Preparation, Characterization and Mechanical Properties of Bio-Based Polyurethane Adhesives from Isocyanate-Functionalized Cellulose Acetate and Castor Oil for Bonding Wood.

Nowadays, different types of natural carbohydrates such as sugars, starch, cellulose and their derivatives are widely used as renewable raw materials. Vegetable oils are also considered as promising raw materials to be used in the synthesis of high quality products in different applications, including in the adhesive field. According to this, several bio-based formulations with adhesion properties were synthesized first by inducing the functionalization of cellulose acetate with 1,6-hexamethylene diisocyanate and then mixing the resulting biopolymer with a variable amount of castor oil, from 20% to 70% (wt). These bio-based adhesives were mechanically characterized by means of small-amplitude oscillatory torsion measurements, at different temperatures, and standardized tests to evaluate tension loading (ASTM-D906) and peel strength (ASTM-D903). In addition, thermal properties and stability of the synthesized bio-polyurethane formulations were also analyzed through differential scanning calorimetry and thermal gravimetric analysis. As a result, the performance of these bio-polyurethane products as wood adhesives were compared and analyzed. Bio-polyurethane formulations exhibited a simple thermo-rheological behavior below a critical temperature of around 80–100 °C depending on the castor oil/cellulose acetate weight ratio. Formulation with medium castor oil/biopolymer weight ratio (50:50 % wt) showed the most suitable mechanical properties and adhesion performance for bonding wood.

Solubility and thermodynamic parameters of apigenin in different neat solvents at different temperatures

In the current study, the solubility of a poorly water-soluble bioflavonoid apigenin in twelve different neat solvents including “water, methanol, ethanol, isopropanol (IPA), ethylene glycol (EG), propylene glycol (PG), 1-butanol, 2-butanol, ethyl acetate (EA), dimethyl sulfoxide (DMSO), polyethylene glycol-400 (PEG-400) and Transcutol®” was measured at temperatures “T=298.2K to 318.2K” and pressure “p=0.1MPa”. The experimental solubilities of apigenin were measured by a static equilibrium method using ultra performance liquid chromatography at 336nm. The measured solubilities of apigenin in mole fraction were correlated with “van't Hoff and Apelblat models”. Good correlation was observed with both models with root mean square deviation values of <3.0% in all solvents evaluated. The solid state characterization of apigenin was performed using differential scanning calorimetry and thermal gravimetric analysis. The solubilities of apigenin in mole fraction were obtained highest in PEG-400 (4.27×10−1) followed by DMSO (4.18×10−1), Transcutol (3.83×10−1), PG (1.50×10−2), EG (8.22×10−3), 1-butanol (9.18×10−4), 2-butanol (8.90×10−4), IPA (6.29×10−4), ethanol (4.86×10−4), EA (4.46×10−4), methanol (2.96×10−4) and water (3.08×10−6) at “T=318.2K” and similar trend was recorded at each temperature evaluated. The solute-solvent interaction was described based on the polarity and activity coefficient. Apparent standard thermodynamic parameters of apigenin in twelve different neat solvents were determined using “apparent thermodynamic analysis” and results showed an “endothermic and entropy-driven dissolution” of apigenin in each solvent evaluated. Based on these results, PEG-400, DMSO and Transcutol were selected as the best solvents and water and methanol were selected as the anti-solvents for apigenin.

Second-Order NLO Active Heterotrimetallic Schiff Base Metallopolymer

The new ionic heterotrimetallic unsymmetrically-substituted Schiff base complex [Ni{(η 5-Cp)Fe(η 5-C5H4)-C(=O)CH=C(4-HO-C6H4)NCH2CH2N=CH-(2-O-(η 6-C6H4)Ru(η 5-Cp*)}][PF6] (3; Cp = C5H5 and Cp* = C5(CH3)5) was prepared in 86% yield by a one-pot procedure by mixing equimolar amounts of 4-hydroxyphenyl functionalized ferrocenylenaminone 1, the organometallic aldehyde [(η 5-Cp*)Ru(η 6-2-HO-C6H4CHO)][PF6] (2) and nickel(II) acetate tetrahydrate in refluxing ethanol for 2 h. Its corresponding side-chain metallopolymer 4 was synthesized by reacting the organometallic-inorganic hybrid 3 with polyacrylic acid (DP = 25) in DMF at 110 °C for 48 h with an equimolar quantity of N,N′-dicyclohexylcarbodiimide and a catalytic amount of 4-dimethylaminopyridine. The new complex 3 was characterized by FT-IR and multidimensional NMR spectroscopy, elemental analysis and mass spectrometry. Single crystal X-ray diffraction analysis of 3 showed that the ferrocenyl and [(η 5-Cp*)Ru]+ units exhibit an anti-conformation and are almost coplanar with the unsymmetrical Schiff base complex fragment, while the 4-HO-C6H4 plane is almost perpendicular. The four-coordinate NiII metal ion adopts a square planar geometry, with two nitrogen and two oxygen donor atoms that are mutually trans. Size-Exclusion Chromatography established that metallopolymer 4 is formed of approximately three pendant ionic trimetallic units, while Differential Scanning Calorimetry and Thermal Gravimetric Analysis indicated that 3 and 4 are thermally stable with decomposition temperatures that exceed or border to 250 °C. Harmonic Light Scattering measurements at 1.91 µm incident wavelength showed that compounds 3 and 4 exhibit rather high second-order nonlinear responses, with hyperpolarizability β 1.91 values strongly increasing on passing from the monomeric unit 3 to its metallopolymeric counterpart 4.

Oxidation behavior of high-purity nonstoichiometric Ti2AlC powders in flowing air

Abstract