Derivative Thermal Analysis Research Articles

Thermal analysis, X-ray diffraction and infrared emission spectroscopy of the borate mineral meyerhofferite CaB3O3(OH)5·H2O

Meyerhofferite is a calcium hydrated borate mineral with formula Ca2(H3B3O7)2·4H2O and occurs as white complex acicular to crude crystals in sedimentary or lake-bed borate deposits. Simultaneous thermogravimetric analysis (TG) and derivative thermal analysis were performed. The TG curve shows a main decomposition at 195 °C followed by a second decomposition centered at about 436 °C. The total loss of mass is 28.1 % upon heating up to 1000 °C. The decomposition of meyerhofferite is also followed by the infrared emission spectra. A very sharp peak is observed at 3614 cm−1 in the 100 °C spectrum, which is attributed to the stretching vibration of OH units. This band shows a red shift with increasing temperature. The intensity of this band is lost by 250 °C. X-ray powder diffraction of the product of heating at 200 and 650 °C shows an amorphous phase, and at temperature up to 1000 °C is observed a partial reordering of the crystal structure, including calcium hexaboride, boron oxide, calcium peroxide, as well as unidentified phases.

Structure and properties of aluminium\u2013magnesium casting alloys after heat treatment

Since the forming of the microstructure depends on the specific of the casting method, which directly affects further mechanical and physical properties of the material, it is important to understand how to control the microstructure of the cast to understand changes that taking place during the crystallisation process. For estimating the metallurgical quality of the liquid metal before casting, the thermal-derivative analysis (TDA) is utilised. The TDA has been used for a long time, in both ferrous and non-ferrous industries casting. The Universal Metallurgical Simulator and Analyser (UMSA) platform is a rapid, sensitive and economical method of determining a full range of solidification features. The work focuses on the thermal analysis and heat treatment of aluminium alloys. The liquidus and solidus temperatures and dendrite coherency point (DCP) are then characterised. The research shows that the UMSA platform allows precise determination and calculation of thermal parameters. The influence of the heat treatment on structure and properties of aluminium castings has been determined as well. Heat treatment was carried out to increase the mechanical properties of aluminium alloys. Based on the findings above, the influence of microstructure on properties of the alloys is discussed.

Characterization of new natural cellulosic fiber from the Perotis indica plant

ABSTRACTThis investigation summarizes the characteristics of biofiber extracted from the Perotis indica plant. Cellulose content (68.4 wt%), density (785 kg m−3), crystallinity index (48.3%), tensile strength (317–1,608 MPa), and Young’s modulus (8.41–69.61 GPa) properties were identified in the P. indica fibers (PIFs), and thermal stability was studied using thermal gravimetric analysis and derivative thermogravimetric analysis, which revealed its cellulose degradation at a temperature of 339.1°C. Further, the properties of PIFs ensured that it can play an imperative role as new reinforcement as green composites in the manufacturing industries.

Chitosan Nanoparticles as a Drug Delivery System for 1,2,4-Triazole Derivatives: Release and Antimicrobial Activity

Chitosan (CS) 1,2,4-triazole derivatives including in the formulation tripolyphosphate (TPP) as crosslinking agent was prepared by a simple one step method using ultrasonic technique. The resultant nanoparticles were characterized by x-ray diffraction (XRD), Fourier transform infrared analysis (FT-IR), thermal gravimetric analysis (TGA), derivative thermal gravimetric analysis (D-TGA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results indicate that spherical nanoparticles with an average size of 21, 14.6, 23.95, 29.5 nm and their standard deviation (SD) were ±5, ±5.3, ±5.3, ±7.9 nm for CSTPP, CSTPPIII, CSTPPIV and CSTPPV, respectively were successfully prepared. The in vitro release and mechanism of 1,2,4-triazoles at different pH values was investigated. From values of R2 the mechanism of drug release is following zero order mechanism at pH 6.8; however in pH 2, CSTPPIII, CSTPPIV and CSTPPV are following Hixson-Crowell, zero order and Korsmeyer-Peppas equation, respectively .The antibacterial activity against the gram negative bacteria and gram positive bacteria was examined.

Analysis of Crystallisation Process of Cast Magnesium Alloys Based on Thermal Derivative Analysis / Analiza Procesu Krystalizacji Odlewniczych Stopów Magnezu W Oparciu O Analizę Termicznoderywacyjną

The paper presents the results of the crystallisation process of cast magnesium alloys based on the thermal-derivation analysis. The effects of aluminium content and cooling rate on the characteristic parameters of the evaluation of magnesium dendrites during solidification at different cooling rates were investigated by thermal-derivative analysis (TDA). Dendrite coherency point (DCP) is defined with a new approach based on the second derivative cooling curve. Solidification behaviour was evaluated via one thermocouple thermal analysis method. Microstructural evaluations were characterised by light microscope, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. This research revealed that utilisation of d2T/dt2 versus the time curve methodology allows for analysis of the dendrite coherency point.

Methodology of Comparative Validation of Selected Foundry Simulation Codes

Abstract The validation of each simulation code used in foundry domain requires individual approach due to its specificity. This validation can by elaborated on the basis of experimental results or in particular cases by comparison the simulation results from different codes. The article concerns the influence of grey cast iron density curve and different forms of solid fraction curve Fs=f(T) on the formation of shrinkage discontinuities. Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups. The numerical tests were realized using NovaFlow&Solid (NF&S), ProCast and Vulcan codes. In this work, the coupled influence of both curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been revealed. The final evaluation of the simulation systems usefulness should be based on validation experiment, preceded by comparing the simulation results of available systems which are proposed in given technology.

Optimization of lead (ii) ions adsorption on to chemically activated carbon from sugarcane bagasse

The adsorption of Lead (II) ion on to chemically activated carbon has been studied and optimized in a batch reactor system. The zinc chloride impregnated sugarcane bagasse was thermal activated in a fixed bed reactor in the presence of argon gas. The surface morphology, surface functional group and thermal stability were determined. The SEM micrograph revealed porous structures which enhance the sorption capacity of the developed activated carbon. The derivative thermal analysis (DTA) and thermogravimetric analysis (TGA) profile of the activated carbon were employed in the proximate analysis. The BET surface area shows a high microporous surface area and micropore volume of 840.38 m2/g and 0.30 cc/g respectively which aids sorption efficiency. The adsorption of lead ion was optimized using 2k factorial experimental design where pH, mass of absorbent, temperature and time was studied in a batch reactor. pH has the highest positive impact on the adsorption of Pb 2+ while considering single effect as studied using atomic absorption spectrophotometer. After estimating the main effects, the interacting factors affecting the removal of Pb 2+ were determined by performing the analysis of variance (ANOVA) with R-Square of 99.97%. This study has demonstrated that Zinc chloride activated carbon has high affinity for lead ion sorption. Keywords: Sugarcane Bagasse, Activated Carbon, Characterization, Adsorption and Optimization.

Thermal analysis and microstructural characterization of Mg-Al-Zn system alloys

The influence of Zn amount and solidification rate on the characteristic temperature of the evaluation of magnesium dendrites during solidification at different cooling rates (0.6-2.5°C) were examined by thermal derivative analysis (TDA). The dendrite coherency point (DCP) is presented with a novel approach based on second derivative cooling curve. Solidification behavior was examined via one thermocouple thermal analysis method. Microstructural assessments were described by optical light microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. These studies showed that utilization of d2T/dt2 vs. the time curve methodology provides for analysis of the dendrite coherency point

Liquidus Surface of the ZrO2–Y2O3–Eu2O3 Phase Diagram

The derivative thermal analysis in air up to 3000 °C, X-ray diffraction, petrography, and electron microscopy are employed to examine phase equilibria on the liquidus surface of the ZrO2–Y2O3–Eu2O3 phase diagram. It is established that the liquidus surface of the system is formed by four primary solidification fields of the phases: solid solutions based on hexagonal (N) and cubic (C) crystalline modifications of Y2O3, cubic ZrO2 modification with fluorite (F) structure, and high-temperature cubic modification (X) of Eu2O3. Two four-phase invariant incongruent equilibria are found in the ternary system.

Selected Aspects of Nitrogen Refinement of Silumin 226

Abstract The work presents the results of the investigations of the effect of the nitrogen (N2) refining time „τraf” and the gas output on the course of the crystallization process, the microstructure and the gassing degree of silumin 226 used for pressure casting. The refinement of the examined silumin was performed with the use of a device with a rotating head. The crystallization process was examined by way of thermal analysis and derivative analysis TDA. The performed examinations showed that the prolongation of the N2 refining time causes a significant rise of the temperature of the crystallization end of the silumin, „tL”, as well as a decrease of its gassing degree, „Z”. An increase of the nitrogen output initially causes an increase of the temperature „tL” and a drop of the gassing degree „Z”, which reach their maximal values with the output of 20 dm3/min. Further increase of the output causes a decrease of the value „tL” and an increase of „Z”. The examined technological factors of the refining process did not cause any significant changes in the microstructure of silumin 226.

FT-IR spectroscopic and thermal study of M(1,6-hexanedithiol)Ni(CN)4⋅2(1,4-dioxane) clathrate (M=Mn, Co, Ni and Cd)

Abstract In this study, clathrate of Cyclohexanethiol-tetracyanonickel-dioxane, given by the formula M(Cyclohexanethiol) 2 Ni(CN) 4 ·(l,4-dioxane) (M = Mn, Co, Ni and Cd), is obtained for the first time through chemical methods. The FTIR spectroscopic data in the region of (4000–400) cm −1 was recorded and the IR frequencies were given and explained in detail. The thermal behavior of these clathrates was also investigated by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and derivative thermal gravimetric analysis (DTG). The spectral and thermal analysis results of the newly synthesized clathrate of Cyclohexanethiol–tetracyanonickel–dioxane suggest that these clathrates are new examples of the Hofmann-type clathrates. In our study, the Hofmann-type clathrates formed by bounding electrons of sulfur-donor atoms of the thiol group of Cyclohexanethiol ligand molecule to transition metal atoms consist of the corrugated |M–Ni(CN) 4 | ∞ polymeric layers which are held in parallel through the van der Walls interactions (–M–Cyclohexanethiol⋯Cyclohexanethiol–M–).

Vibrational Spectroscopic Investigation on Some M(Benzonitrile)2Ni(CN)4 Complexes (M = Ni, Zn, Cd, and Hg)

The first synthesis of benzonitrile tetracyanonickelate complexes, represented by the general formula M(benzonitrile)2Ni(CN)4 (M = Ni, Zn, Cd, and Hg), is reported. Fourier transform infrared spectroscopy and Raman spectroscopic data in the region of 4,000–400 cm − 1 are presented, and the vibrational frequencies are assigned and explained in detail. The thermal behavior of these complexes was also investigated by thermogravimetric analysis, differential thermal analysis, and derivative thermal gravimetric analysis. The spectral and thermal analysis results of the newly synthesized complexes suggest that these complexes are new examples of Hofmann-type complexes. The spectral data obtained show that the complexes consist of |M–Ni(CN)4|∞ polymeric layers with the ligand (benzonitrile) molecules bound to metal through the N-donor atom of the cyanide group.

Solidification Process, Microstructure, Density and Hardness of the Mg-Al Alloys with Zn, Cu, Ni and AlTiB Additions

The paper presents the results of the investigations of the solidification process of magnesium alloys containing 5 and 10 wt.% Al, the additions of Zn, Cu, Ni, and of an AlTiB master alloy. The plotted DTA (derivative thermal analysis) curves were used for the determination of solidification parameters Tliq, Teut and Tsol. Knowledge of these parameters is very important in determination of alloy pouring temperature and maximum casting operating temperature. On samples taken from the area of temperature measurements, the chemical composition and microstructure were determined. The density and hardness HB were measured as well. Applying the method of multiple regression analysis at the significance level α = 0.1, the intensity and direction of the effect of alloying elements on the solidification parameters, density and hardness HB of castings were evaluated.

An efficient bonding-type Eu-containing copolymer as red phosphor applied in LED

Abstract A luminescent europium-containing copolymer, poly(MMA- UA -co-Eu (DBM)2 (TOPO)2)was synthesized The copolymer was characterized by FT-IR, UV–vis, gel permeation chromatograph (GPC), ICP, thermogravimetric analysis (TGA), derivative thermal gravimetric analysis (DTG) and differential scanning calorimetry (DSC). The Eu-copolymer phosphor exhibited high thermal stability, high glass transition, excellent photoluminescence properties (PL), appropriate CIE chromaticity coordinates for red and good quantum yield (18%) under near-UV light excitation. An intense red-emitting light-emitting diode (LED) was fabricated by combining poly[UA-MMA-co-Eu (DBM)2(TOPO)2] with a 395 nm-emitting InGaN chip. The results indicate that the Eu-copolymer phosphor may act as a red component for fabrication of white LEDs.

FTIR spectroscopic and thermal study of M(Cyclohexanethiol) 2Ni(CN) 4·(1,4-dioxane) clathrate (M = Mn, Co, Ni and Cd)

In this study, clathrate of Cyclohexanethiol-tetracyanonickel-dioxane, given by the formula M(Cyclohexanethiol) 2Ni(CN) 4·(l,4-dioxane) (M = Mn, Co, Ni and Cd), is obtained for the first time through chemical methods. The FTIR spectroscopic data in the region of (4000–400) cm −1 was recorded and the IR frequencies were given and explained in detail. The thermal behavior of these clathrates was also investigated by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and derivative thermal gravimetric analysis (DTG). The spectral and thermal analysis results of the newly synthesized clathrate of Cyclohexanethiol–tetracyanonickel–dioxane suggest that these clathrates are new examples of the Hofmann-type clathrates. In our study, the Hofmann-type clathrates formed by bounding electrons of sulfur-donor atoms of the thiol group of Cyclohexanethiol ligand molecule to transition metal atoms consist of the corrugated |M–Ni(CN) 4| ∞ polymeric layers which are held in parallel through the van der Walls interactions (–M–Cyclohexanethiol⋯Cyclohexanethiol–M–).

Mechanical and Thermal Properties of Polyamide 6 Nanocomposite Toughened with Epoxidised Natural Rubber-25

Polyamide (PA6) is an engineering plastic with wide range of applications and the development in the field of montmorillonite (MMT) filled polymer nanocomposites has resulted in the development of PA6/MMT nanocomposites. However, MMT filled PA6 nanocomposites are notch sensitive and brittle at low temperatures, which posed as a major setback for many of its applications. The main objective of this study is to enhance the toughness of PA6/MMT (100/4) nanocomposites with epoxidised natural rubber-25 (ENR25). The ENR-25 content in the composites ranged from 15 to 30 wt%. The PA6/ENR/MMT nanocomposites were extruded and injection molded into tensile and impact test samples. The addition of ENR25 into PA6/MMT nanocomposites improved the impact strength of the nanocomposites while tensile modulus and tensile strength decreased with increasing ENR25 content. The thermal properties of PA6/ENR/MMT nanocomposites were also investigated via thermal gravimetric analysis (TGA). Both T10% and derivative thermal analysis (DTA) determined the lower thermal stability of PA6/MMT nanocomposites after addition of ENR.

FT-IR spectroscopic study on some Hofmann-type clathrates: M( p-Benzoquinone)Ni(CN) 4·2G (M = Mn, Co, Ni or Hg; G = Aniline)

Some new Hofmann type aniline clathrates in the form of M( p-Benzoquinone)Ni(CN) 4·2G (M = Mn, Co, Ni or Hg, p-Benzoquinone = pBQ and G = Aniline = An) have been obtained for the first time in powder form and their FT-IR spectra have been reported in the range of (4000–400) cm −1. The thermal behavior of these clathrates has been also investigated by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and derivative thermal gravimetric analysis (DTG). The spectral and thermal analysis results of the new Hofmann type aniline clathrates suggest that the obtained clathrates are new examples of the Hofmann-type clathrates. The Hofmann-type clathrates consist of the corrugated |M–Ni(CN) 4| ∞ polymeric layers which are held in parallel through the chain of (-M-pBQ-M-pBQ-) in our new Hofmann type aniline clathrates formed by bounding electrons of oxygen atoms of the carbonyl groups of pBQ ligand to transition metal atoms.

Thermal analysis of Romanian ancient ceramics

The present work is focused on thermoanalyt- ical investigations as thermogravimetric analysis (TG) and derivative thermal analysis (DTG), applied for the char- acterization of some samples collected from archaeological sites (Brasov and Trofeum Traiani) located in different regions of Romania. New informations derived about ceramic technologies concerning raw materials and binding materials (mineralogical components) have been obtained. All these experimental results have been correlated with related techniques as X-ray diffraction (XRD), energy- dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma—atomic emission spectrometry (ICP- AES). By progressive heating in static air atmosphere and in the temperature range of 20-800 � C, all investigated materials exhibit three main successive processes, associ- ated with the dehydration and thermo-oxidative degrada- tions. The rate of the first thermooxidative process, temperatures corresponding to the maximum rate of the second thermooxidative process and shrinkage temperature were associated with the damage of the investigated materials due to environmental impact. Heating also affects the contact between the fine-sized clay matrix and mineral clast fragments, appearing in reaction rims, sometimes showing newly formed phases. The temperature at which ancient ceramics and pottery were fired varies over a wide range (600-800 � C) depending on the type of clay used, although firing temperatures not above 30-400 � C have also been suggested. Clay minerals, as the main material for production of ceramics and pottery, show some char- acteristic reactions (dehydroxylation, decomposition, transformation) in the course of firing (heating effects) and several thermoanalytical criteria can be used for recon- struction of former production conditions.

Erythrocyte membrane defects in hemolytic anemias found through derivative thermal analysis of electric impedance

Hereditary hemolytic anemias originate mainly from defects in hemoglobin and plasma membrane proteins. Here, we propose a new method, thermal analysis of impedance, sensitive to membrane defects. It detects three processes in erythrocyte membrane; fall in membrane capacity at 49.5 °C and activation of passive PO 4 2+ permeability at 37 °C and inorganic ions at 61.5 °C. The denaturation of spectrin is involved in the first process whilst the anion channel is involved in latter processes. Using this method three persons with xerocytosis were found whereby the fall in membrane capacity and spherization of erythrocytes were both postponed (53 °C) compared to control (49.5 °C). In contrast to control cells, strong activation of passive permeability for Cl − at 37 °C and sucrose at 61 °C were detected that were both eliminated by pre-inhibition of the anion channel with 4,4′-diisothiocyanato-stilbene-2,2′-disulfonic acid (DIDS). In addition, erythrocytes from 15 patients with various forms of anemia were studied in intact state and after refreshment. The results were compared with the data of clinical laboratory and osmotic fragility test. The final conclusion is that this method detects membrane defects with altered spectrin and anion channel syndrome (hereditary xerocytosis, spherocytosis, poikilocytosis and pyropoikilocytosis, elliptocytosis and stomatocytosis) and, after refreshment, helps differentiate them from the anemia with hemoglobinopathy.

Characterization and thermal degradation studies on polyaniline‐intercalated montmorillonite nanocomposites prepared by a solvent‐free mechanochemical route

AbstractPolyaniline (PANI)‐montmorillonite (MMT) nanocomposites were prepared by direct intercalation of aniline molecules into MMT galleries, followed by in situ polymerization within the nano‐interlamellar spaces under solvent‐free conditions. The basal spacing of aniline‐intercalated MMT increased gradually up to 1.5 nm with increasing amounts of aniline loaded. This result suggests that aniline molecules were adsorbed by MMT clay and that intercalated aniline likely located perpendicular to the silicate sheets. After polymerization, X‐ray diffraction and Fourier transform infrared analyses confirmed the successful synthesis of PANI chains between the MMT nano‐interlayers. The scanning electron microscopy images indicated that the surface morphologies of PANI–MMTs were strongly different depending on the PANI content. The electrical conductivities of PANI nanocomposite particles in pressed pellets ranged in the order of between 10−3 and 10−2 S/cm. UV–vis spectroscopy and doping level measurement were further used to discuss the conductivities of nanocomposites. The thermal stabilities of PANI–MMT nanocomposites were examined by using thermogravimetric‐differential thermal analysis and derivative thermogravimetric analysis, and both analyses consequently demonstrated the improved thermal stabilities of the PANI chains in the nanocomposites as compared to pure PANI. The thermal stabilities of resulting nanocomposites were strongly related to the PANI content, which increased as the PANI content decreased in the nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2705–2714, 2005