Thermogravimetric Analysis Mass Spectrometry Research Articles

Grafting from versus Grafting to Approaches for the Functionalization of Graphene Nanoplatelets with Poly(methyl methacrylate)

Graphene nanoplatelets (GNP) were exfoliated using a nondestructive chemical reduction method and subsequently decorated with polymers using two different approaches: grafting from and grafting to. Poly(methyl methacrylate) (PMMA) with varying molecular weights was covalently attached to the GNP layers using both methods. The grafting ratios were higher (44.6% to 126.5%) for the grafting from approach compared to the grafting to approach (12.6% to 20.3%). The products were characterized using thermogravimetric analysis–mass spectrometry (TGA-MS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The grafting from products showed an increase in the grafting ratio and dispersibility in acetone with increasing monomer supply; on the other hand, due to steric effects, the grafting to products showed lower absolute grafting ratios and a decreasing trend with increasing polymer molecular weight. The exc...

Catalytic Combustion of Heavy Oil in the Presence of Manganese-Based Submicroparticles in a Quartz Porous Medium

We synthesized manganese oxide(II) submicroparticles stabilized with oleic acid and used them as oil-dispersible catalyst precursor promoting a heavy oil oxidation process. Size, morphological properties, as well as composition of the catalyst were studied in depth by X-ray phase diffraction analysis, thermogravimetric–mass spectrometry analysis, scanning electron microscopy, energy dispersive X-ray analysis, and nitrogen adsorption measurements. We applied nonisothermal kinetic analysis coupled with an isoconversional approach to study the influence of catalyst on the combustion process and showed that Mn-based submicroparticles accelerate predominantly the high-temperature oxidation process.

Flame retardancy and thermal degradation of halogen-free flame-retardant biobased polyurethane composites based on ammonium polyphosphate and aluminium hypophosphite

In this work, based on castor oil (CO), flame retardant polyurethane sealants (FRPUS) with ammonium polyphosphate (APP) and aluminum hypophosphite (AHP) were prepared. The synergistic flame retardant effects between APP and AHP on flame retardancy, thermal stability, and flame retardant mechanisms of FRPUS were investigated. It was found that when the mass ratio of APP and AHP was 5:1, the limiting oxygen index (LOI) value of FRPUS increased to 35.1%, In addition, at this ratio, the parameters from cone calorimeter testing (CCT) were reduced; these parameters include peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR) and total smoke production (TSP). The thermal decomposition behavior of the FRPUS was investigated by thermogravimetric analysis (TGA). The results showed that AHP improved the thermal stability of the PUS/APP system and increased char residue at high temperatures. Moreover, the residual carbon was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM), gas phase pyrolysis products were investigated by thermogravimetric analysis/infrared spectrometry (TG-IR) and thermogravimetric analysis/mass spectrometry (TG-MS). It was observed that the flame retardant mechanisms of the APP/AHP system was the combination of gas and condensed phase flame retardant mechanisms.

Binary amide-containing tung-oil-based Ca/Zn stabilizers: effects on thermal stability and plasticization performance of poly(vinyl chloride) and mechanism of thermal stabilization

N-(2-amino ethyl) tung maleamic acid (AETMA) and N-(2-amino phenyl) tung maleamic acid (APTMA) were prepared from the ammonolysis of ethidene diamine (ED) and p-phenylenediamine (PPD) respectively with tung-maleic anhydride (TMA). Then LAETMA-Ca, LAPTMA-Ca, LABTMA-Zn and LAPTMA-Zn were separately synthesized through a one-step method and characterized by Fourier transform infrared spectrometry (FTIR), 1H nuclear magnetic resonance (NMR) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). LAETMA-Ca/LAETMA-Zn and LAPTMA-Ca/LAPTMA-Zn were both used as thermal stabilizers of polyvinyl chloride (PVC) and investigated using Congo red test, thermal aging test, ultraviolet-visible spectrometry, thermogravimetric analysis (TGA), TGA-FTIR, and TGA–mass spectrometry (MS). Their stabilizing efficiencies were compared with other common stabilizers. Dynamic mechanical of the PVC compounds were also studied. The LAPTMA-Ca/LAPTMA-Zn exhibits excellent long-term stability and better plasticization performance for PVC than other stabilizers, and thus can partly replace di(2-ethylhexyl) terephthalate in the processing of PVC. The mechanism underlying the stabilizing action of LAPTMA-Ca/LAPTMA-Zn is suggested.

Effects of isothermal annealing on the oxidation behavior, mechanical and thermal properties of AlN ceramics

Abstract To evaluate the oxidation behavior of AlN ceramics prepared using a pressureless sintering method, aluminum nitride bulk samples were annealed at temperatures ranging from 900 °C to 1300 °C for 1–5 h under an air atmosphere. The phase composition, microstructure and weight change of the oxidized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis-mass spectrometry (TGA-MS), respectively. The results showed that certain of the gaseous oxidation products of AlN ceramics were nitrogen oxides (NO x ). The oxidation reaction started at approximately 800 °C to 900 °C. The thermal conductivity and flexural strength of AlN ceramics were enhanced slightly after the heat treatment in the 900–1100 °C temperature range. The entire surface of the AlN block was covered with a thin, compact alumina layer after oxidizing at 1100 °C for 3 h, which may enhance the metal adhesion to the AlN surface in a metallization process. At 1200 °C and higher, the AlN ceramics oxide layer became rough, porous, and cracked, leading to a sharp drop in the flexural strength and thermal conductivity of the AlN ceramics.

Investigating aging effects for porous silicon energetic materials

When infused with an oxidizer, on-chip porous silicon (PS) shows tremendous potential as an energetic material. However, applications such as fuzing and propulsion require long-term material stability. The present work utilizes accelerated lifetime testing for PS samples with sodium perchlorate (NaClO4) oxidizer. Devices were exposed to elevated temperatures for various time intervals, then subjected to an electrical pulse through an integrated bridgewire to test for ignition. The pass/fail data from ignition testing was then analyzed to determine the mean and median failure point at each temperature using an Arrhenius aging model and a lognormal probability density function (PDF). Samples were heated over a temperature range of 185–300 °C for up to 46 h with median failure times ranging from 0.4–20 h. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to evaluate chemical changes of PS/NaClO4 during aging. Comparison of DSC traces for aged samples showed differences for heating above and below 250 °C, suggesting two different aging mechanisms. FTIR results suggest that for low temperature aging (below ∼250 °C) the hydrogen termination layer of the porous silicon was still intact, but backbond oxidation did occur. Above ∼250 °C the hydrogen termination layer was no longer evident in FTIR and considerable oxidation occurred, suggesting reaction or dissociation of the hydrogen layer. This corresponds with an exothermic peak shown during DSC at 300 °C. Thermogravimetric analysis/mass spectroscopy (TGA/MS) was also performed, and confirmed hydrogen gas release beginning at ∼280 °C. A DSC peak at ∼400 °C is evident for fresh samples, but is greatly reduced or not evident for all aged samples. We attribute this peak to backbond oxidation, which is shown to occur in FTIR for all aged samples. Variable heating rate DSC experiments were also performed to determine activation energy of fresh and aged samples. Activation energy was calculated using the Kissinger Method for the first two exothermic peaks in DSC experiments. For the first peak, corresponding to hydrogen desorption (∼300 °C), activation energy for fresh and aged samples was 132.1 kJ/mol and 132.7 kJ/mol, respectively. The activation energy of the second exothermic peak, corresponding to backbond oxidation, for fresh and aged samples was 183.8 kJ/mol and 159.6 kJ/mol, respectively. Device failure during accelerated aging tests was also used to predict the mean lifetime of porous silicon/sodium perchlorate at room temperature (25 oC) as 100 years with a 90% confidence interval of 31 to 328 years.

Study of pyrolytic mechanisms of seaweed based on different components (soluble polysaccharides, proteins, and ash)

The pyrolysis mechanisms of the main components of seaweed (soluble polysaccharides, proteins, and ash) were investigated in this study using characterization analysis and thermogravimetric analysis–mass spectrometry. XPS analysis indicated that most of the metal ions existed in the ash, while substituents of Na and K ions were found in polysaccharides. Oxygen-containing functional groups in Enteromorpha were found to exist mainly in the following forms: -OH/C-O in polysaccharides, COO- in proteins, and inorganic oxygen in the ash. Pyrolysis thermogravimetric (TG) curves of the components of Enteromorpha indicated that the thermogravimetric analysis ranges of polysaccharides and proteins were 175–310 °C and 300–350 °C, respectively. During the pyrolysis process, due to the effects of metal ions, the maximum thermal weight loss rate was found to increase, while the pyrolysis temperature also increased. CO2 was generated from the decarboxylation of uronic acids and the decomposition of inorganic carbonates in proteins and polysaccharides.

Coupling effect of waste automotive engine oil in the preparation of wood reinforced LDPE plastic composites for panels

We demonstrated the formulation of wood plastic composite (WPC) materials with flexural strength of 13.69 ± 0.09 MPa for applications in outdoor fencing using municipal waste precursors like low density polyethylene (LDPE) plastics (54.0 wt. %), sawn wood dust with particle size between 64 and 500 μm derived from variable hardwood species (36.0 wt. %) and used automotive engine oil (10 wt. %). The WPC panels were prepared by pre-compounding, extruding at a screw auger torque of 79.8 Nm and pressing through a rectangular mould of dimension 132 mm × 37 mm × 5 mm at temperature 150 °C. The efficacy of black waste oil, as a coupling agent, was demonstrated by the absence of voids and pull-outs on microscopic examination using scanning electron microscopy. No hazardous substances were exhaled during thermo-gravimetric mass spectrometry analysis. The percentage crystallinity of the LDPE in the as-prepared material determined by differential scanning calorimetry was 11.3%.

Comparative Study between Acoustic Emission Analysis and Immersion Bubble-Metric Technique, TGA and TD-GC/MS in View of the Characterization of Granular Activated Carbons Used in Rum Production

Microscopic and acoustic emission analysis and sound patterns recognition techniques were applied for the characterization of granular activated carbon (GAC). A new and improved methodology has been developed to characterize the exhaustion degree of GAC used in rum production: (1) based on the acoustic emission analysis of the sound produced by water flooded on GAC; and (2) based on the microscopic analysis of bubbles formed by immersion into glycerol. Acoustic measurements are made in a specific set-up, bubble detection and analysis is performed using dedicated software developed in MATLAB® for circular shape pattern detection based on the Hough transform. Both have been correlated with data of GAC characteristics based on thermogravimetric analysis (TGA) and Thermal Desorption-Gas Chromatography Mass Spectrometry (TD-GC/MS). Eight samples of GAC used in the rum production, obtained at different depths within the fixed-bed filter, have been evaluated. Good correlations are found between the immersion “bubble-metric” technique and the acoustic measurement data from the original signal processed by Band-Pass (BP) filtering at 1.3 kHz and weight loss amounts of adsorbed compounds on the GAC. The found relationship gives the possibility to determine the exhaustion degree of GAC applying these methods and to evaluate high-porosity materials.

Benchmarking of manganese oxide materials with CO oxidation as catalysts for low temperature selective oxidation

CO oxidation behavior of different manganese oxide materials was studied as a model probe reaction to benchmark catalytic activities that could be useful for other aerobic oxidations. K-OMS-2, which showed intermediate activity [Ea=3.0 and 6.3kcal/mol for K-OMS-2 (made in solvent free procedure or SF) and K-OMS-2 (made via hydrothermal route or REF) respectively], were chosen for metal dopant studies using microwave assisted hydrothermal synthesis. These were further characterized using X-ray diffraction (XRD), N2 sorption, Raman spectroscopy, scanning electron microscopy (SEM), and carbon monoxide temperature programmed reduction (CO-TPR). Additional characterization was carried out for Ni-K-OMS-2 materials using atomic absorption spectroscopy (AAS) and thermogravimetric analysis-mass spectroscopy (TGA-MS). Doping K-OMS-2 with Ni resulted in a large increase in oxygen mobility and re-adsorption, and the moderate activation energy for CO oxidation (13.kcal/mol) by Ni-K-OMS-2(SF) suggests that Ni-doped materials are good candidates for low temperature selective oxidation.

Silica-Supported Phosphonic Acids as Thermally and Oxidatively Stable Organic Acid Sites

Organic–inorganic materials consisting of organophosphonic-acid-supported-on-silica materials C3/SiO2 and C4/SiO2 are described, where C3 is propane-1,2,3-triphosphonic acid and C4 is butane-1,2,3,4-tetraphosphonic acid. Solid-state structures of both of these phosphonic acids are analyzed using single-crystal X-ray diffraction, and these data reveal extensive intermolecular hydrogen bonding and no intramolecular hydrogen bonds. Thermogravimetric analysis/mass spectroscopy (TGA/MS) data show a lack of combustion for these materials in air at temperatures below 400 °C, and only release of water corresponding to reversible organophosphonic acid condensation below 150 °C. A comparative series of silica-supported materials were synthesized, consisting of organophosphonic acid CX8, which represents a calixarene macrocycle that is decorated with a high density of organophosphonic-acid substituents on both the lower and upper rim, as well as polyvinylphosphoric acid (PVPA). Material CX8/SiO2 possesses a signific...

Characteristics of using layered double hydroxides to reduce the VOCs from bituminous materials

Various types of molecules in the volatile organic compounds (VOCs) from bituminous materials were detected and analyzed by means of thermogravimetric-mass spectrometry (TG-MS) analysis. The effect of layered double hydroxides (LDHs) additives as VOCs inhibitor was also studied. The ion histogram of volatile components from bituminous binder was obtained through TG-MS analysis. Analysis results show that the environmental temperature has significant influence only on the volatile characteristics of smaller molecules in the pure bituminous binder. The effect of environmental temperature has been found marginal for the volatile speed of bigger molecules and LDHs modified bitumen binder.The obtained results regarding the pure bitumen and LDHs-modified bitumen demonstrate that LDHs modifiers have the potential to reduce VOC emissions. The reduction effect on different molecules or components varies. For smaller molecules, this effect on volatile speed is significant. LDHs affect the volatile speed of more carcinogenic volatile components to reduce more significantly for dichloroethane and naphthalene, compared with normal octane. The study findings indicate that a LDH percentage of 4% is an optimum for achieving the best emission reduction effect of VOCs for the selected binder, which is 40–60% percent reduction in VOCs.

In English

Gelatin-based films with silica-to-gelatin weight ratio 1:5 or 8:5, containing either hydrophilic or hydrophilic-hydrophobic silica, have been prepared and studied by means of thermogravimetric analysis and temperature-programmed desorption mass spectrometry. It has been shown that silica presence has no effect on the mechanism of thermal decomposition of gelatin; however, it affects the kinetics of gelatin thermolysis both in vacuum and in air, including an increase in the activation energy of the volatile products formation at hydrophilic silica content about 17 wt. %. Hydrophobization of silica surface as well as an increase in hydrophilic silica concentration in the film from 17 to 62 wt. % decreases the activation energy of the volatile products formation during gelatin thermolysis. This effect is explained by reduced binding of gelatin with silica owing to either substitution of some surface silanol groups upon partial hydrophobization of silica, or their involving into interparticle rather than in silica-gelatin interactions at higher silica content.

Physicochemical Characterization of Functional Lignin-Silica Hybrid Fillers for Potential Application in Abrasive Tools.

Functional lignin–SiO2 hybrid fillers were prepared for potential application in binders for phenolic resins, and their chemical structure was characterized. The properties of these fillers and of composites obtained from them with phenolic resin were compared with those of systems with lignin or silica alone. The chemical structure of the materials was investigated by Fourier transform infrared spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance spectroscopy (13C CP MAS NMR). The thermal stability of the new functional fillers was examined by thermogravimetric analysis–mass spectrometry (TG-MS). Thermo-mechanical properties of the lignin–silica hybrids and resin systems were investigated by dynamic mechanical thermal analysis (DMTA). The DMTA results showed that abrasive composites with lignin–SiO2 fillers have better thermo-mechanical properties than systems with silica alone. Thus, fillers based on lignin might provide new, promising properties for the abrasive industry, combining the good properties of lignin as a plasticizer and of silica as a filler improving mechanical properties.

Hydrogen measurement during steam oxidation using coupled thermogravimetric analysis and quadrupole mass spectrometry

An analytical technique is presented with the goal of measuring reaction kinetics during steam oxidation reactions for three cases in which obtaining kinetics information often requires a prohibitive amount of time and cost. The technique presented relies on coupling thermogravimetric analysis (TGA) with a quantitative hydrogen measurement technique using quadrupole mass spectrometry (QMS). The first case considered is in differentiating between the kinetics of steam oxidation reactions and those for simultaneously reacting gaseous impurities such as nitrogen or oxygen. The second case allows one to independently measure the kinetics of oxide and hydride formation for systems in which both of these reactions are known to take place during steam oxidation. The third case deals with measuring the kinetics of formation for competing volatile and non-volatile oxides during certain steam oxidation reactions. In order to meet the requirements of the coupled technique, a methodology is presented which attempts to provide quantitative measurement of hydrogen generation using QMS in the presence of an interfering fragmentation species, namely water vapor. This is achieved such that all calibrations and corrections are performed during the TGA baseline and steam oxidation programs, making system operation virtually identical to standard TGA. Benchmarking results showed a relative error in hydrogen measurement of 5.7–8.4% following the application of a correction factor. Finally, suggestions are made for possible improvements to the presented technique so that it may be better applied to the three cases presented.

Effect of Azo Dyes on the Thermal Degradation of Post-consumer Polyester Fabrics

Thermogravimetric analysis(TGA) and pyrolysis gas chromatography mass spectrometry (Py-GC-MS) investigations were carried out on the thermal degradation of white and red post-consumer polyester fabrics. The results show that red PET fabrics which was dyed with C.I. Disperse red 167 for its typical azo structure exhibits larger activation energy compared with white PET. The addition of azo dyes displays an inhibiting effect on the deep pyrolysis and the formation of biphenyl and bis(2-hydroxybutyl) terephthalate produced by the free radical mechanism.

Does halloysite behave like an inert carrier for doxorubicin?

Thermogravimetric analysis-mass spectrometry revealed more details of the interaction between doxorubicin and halloysite surface.

Dehydrogenation properties of chromium-based ammine borohydrides: CrCl3·nNH3/3LiBH4 (n = 3, 4 and 5)

Three new chromium-based ammine borohydrides were synthesized by ball milling CrCl3·nNH3 (n = 3–5) and LiBH4 in a molar ratio of 1:3. Thermogravimetric analysis–mass spectrometry (TG–MS) measurements showed that the chromium-based ammine borohydrides release H2 in the temperature range of 100–170 °C, concurrent with the evolution of a small amount of NH3 evolution. The dehydrogenation purity increases with decreasing coordination number of ammonia, with the highest dehydrogenation purity (91.8 mol%) achieved for CrCl3·3NH3/3LiBH4. Further improvement on the dehydrogenation of CrCl3·3NH3/3LiBH4 is conducted by the addition of ZnCl2. The 0.5 mol ZnCl2 assisted sample is able to release 7.4 wt.% of hydrogen with a purity of 98.8 mol%.

Novel MII (M = Mn, Fe, Co, Ni) Coordination Assemblies Based on 2-(((1-(Pyridin-n-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl)thio)pyridine Ligands

Three novel 1D coordination polymers [M(L1)2(OH2)2(ClO4)2]n (M = Mn (1), Co (2)) and [Ni(L1)2(OH2)2(NO3)2]n (3), and two mononuclear complexes [Fe(L2)2(MeOH)2(ClO4)2] (4) and [Co(L2)2(OH2)2(ClO4)2] (5) were prepared from 2-(((1-(pyridin-n-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl)thio)pyridine ligands (n = 4 (L1), and 2 (L2)). The complexes 1–5 were characterised by single-crystal X-ray diffraction (XRD), powder XRD, thermogravimetric analysis, elemental analysis, infrared, and electrospray ionisation mass spectrometry analyses. The complexes 1–5 showed good purity and thermal stability. The structural outcome of 1–3 is driven by the double and open-bridging coordination mode preference of the spacer L1 which favours the formation of polymeric 18-member metallomacrocycles. Use of an isomeric L2 with different picolyl nitrogen orientation, which favours chelate formation, resulted in mononuclear complexes 4 and 5. This work demonstrates a simple but powerful spacer-directed strategy to define and construct coordination frameworks tuned by different metal characters and hybrid 1,2,3-triazoles.

Catalyzing aluminum particle reactivity with a fluorine oligomer surface coating for energy generating applications

Abstract Exothermic surface reaction between fluorine from a fluorine-containing polymer and the alumina (Al2O3) monolayer shell surrounding aluminum (Al) fuel particles promotes aluminum reactivity. This study investigates the reactivity of Al when coated with a liquid fluorinated oligomer, specifically perfluoropolyether (PFPE). Flame speeds, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and quadruple mass spectrometry (QMS) were performed for Al-PFPE blends with varying Al particle sizes (i.e., 80, 100, 120 and 5500 nm average diameter). The results show that the combustion performance of these blends is highly dependent on the Al2O3 exposed surface area that catalyzes the decomposition of PFPE. As Al particle diameter increases from 80 to 120 nm, the Al-PFPE blends exhibit an increase in flame speeds by 48% and a corresponding increase in surface exothermic reaction identified as a pre-ignition reaction (PIR) that promotes an increase in the calorific output of the main reaction. But, from 120 to 5500 nm Al-PFPE blends, flame speeds decrease by 93%. The higher activation energy and lower Al-Al2O3 particle surface area to volume ratio for micrometer-scale Al fails to significantly catalyze the PIR and results in reduced overall Al reactivity. These results introduce a new and simplified synthesis approach for catalyzing a PIR in Al that strategically promotes overall Al particle reactivity.