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The polyacrylonitrile multifilament yarn underwent a multistep heat treatment process including stabilization times ranging from 5 to 75 min following impregnation with a 30% ethylenediamine (EDA) aqueous solution. A series of measurements were employed to determine the structure and properties of thermally stabilized PAN samples. These included fiber thickness, fiber density, flame testing, tensile testing, X-ray diffraction, thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and infrared spectroscopy. The results from XRD and IR spectroscopy indicated that the rate of aromatization reactions increased with longer stabilization times. A detailed examination of the XRD curves obtained through curve-fitting procedures suggested a rapid transformation of the original structure into a disordered amorphous phase containing pre-graphitic domains, evidenced by a gradual reduction in the degree of apparent crystallinity of the original PAN sample. The integration of EDA before the thermal stabilization stage significantly reduced the cyclization time of nitrile groups in the PAN polymer structure, thereby accelerating the stabilization reactions. This chemical pretreatment also improved the thermal stability of the samples by promoting oxidative cross-linking of the PAN polymer chains. After a 75 min multistep stabilization, the carbon yield at 1000 °C was 70.5%. Conversion index values, calculated using IR, XRD, and DSC methods, were 98.3%, 94.8%, and 89.5% respectively for the 75 min sample. These findings highlight the importance of EDA in accelerating the formation of an aromatic structure, which is critical for withstanding the high temperatures of subsequent carbonization stages. [ABSTRACT FROM AUTHOR]

The efficiency of carbon sequestration in abandoned soils depends on the stability of accumulated organic matter. The resistance of soil organic matter (SOM) of postagrogenic dark gray forest soils (Luvic Phaeozems (Aric, Cutanic, Densic)) in the subtaiga deciduous forest to microbial decomposition was estimated by soil respiratory activity. The thermal stability of SOM was determined by thermogravimetry and differential scanning calorimetry methods. Based on the increase of SOM thermal stability according to the rising temperature, four pools were separated in the SOM: thermally labile (thermal oxidation occurs at temperatures from 200 to 380°С), stable (380–460°С), overstable (460–520°С), and persistent (520–600°С). The thermally labile pool predominated in the SOM (58% on average) in the soil layer 0–30 cm. As soil depth increased, total portion of thermally stable pools (380–600°C) in the SOM increased and accounted for 63% on average at the depth of 70–100 cm. The temperature, at which thermal oxidation of half of the organic matter is reached (T50), was the indicator of SOM thermal stability. In the soil layer 0–30 cm T50 equaled to 362 ± 4°С, and in the soil layer 30–100 cm to 408 ± 4°С, and this reflected the increase with depth of the portion of thermally stable pools in the SOM. It was found that respiratory activity of abandoned soils decreased, as thermal stability, estimated by the ratio of the resistant pool to the labile pool, increased in SOM. [ABSTRACT FROM AUTHOR]

Plasma polymerized (PP) methyl acrylate (MA) and vinyl acetate (VA) composite thin films were deposited onto glass substrate varying MA and VA monomer concentrations. Thickness of the composite polymers is observed to vary on the MA and VA monomer ratios, where MA is found more reactive. The FESEM images of the composite polymers show better surface morphology compared to those of the homopolymers. Appearance of broad absorption bands in the FTIR spectra of polymer indicates the structural changes compared to monomer during polymerization. Thermogravimetric analysis and differential scanning calorimetry indicate that composite films are thermally more stable (up to 617 K) compared to homopolymer thin films (563 K). The current density versus voltage (J–V) characteristics of PP(MA-VA) composite films (sandwiched between aluminum electrodes) with different MA and VA ratios showed that the J values of the composite films gradually increase with elevating VA monomer and also with temperature (298–373 K). On the other hand, this value increases with decreasing the thickness of the composite films, which complies with the other studies. The conduction of the thickness-dependent composite films showed Ohmic in nature in the lower voltage region (< 10 V) while the space charge-limited conduction is found to be dominated in the higher voltage region (> 10 V) operating over the entire range of temperature. The activation energy at room temperature was found to be ~ 0.019 eV in the Ohmic region and 0.260 eV in the non-Ohmic region. [ABSTRACT FROM AUTHOR]

The work was aimed to study the influence of multi-walled carbon nanotubes (MWCNT) on the thermostructural properties of aluminum matrix in a wide temperature range from 30 to 600 °C. To achieve this aim, a nanomaterial with a composition of Al + 1.5% MWCNT was elaborated by sintering and rolling from aluminum and MWCNT powders. This material has to combine the ductility and lightness of aluminum with the toughness and thermal properties of MWCNT, and it can replace classical metal materials. The mechanical and structural properties of Al + 1.5% MWCNT material were studied using different techniques: differential scanning calorimetry, X-ray diffraction, thermogravimetry, Raman spectroscopy, and dilatometry. The reaction between an Al matrix and nanotubes leads to the formation of the carbides and some carbon dissolution in the matrix's crystal network. These reactions also lead to a refinement of the matrix grain and a more homogeneous distribution of the residual MWCNT. These phenomena significantly influence the structure of the matrix as well as the mass and dilatometric stability of the material. Reduction of the dilatometric coefficients of the composite material was observed in the entire temperature range of 30–600 °C, especially a significant reduction was measured for temperatures higher than 200 °C. The results obtained by differential calorimetry showed a noticeable decrease in the calorific capacity of the nanocomposite compared to that of the pure material, especially for temperatures higher than 200 °C. The essential role of anisotropy in determining the thermal expansion characteristics of the nanocomposite was revealed. [ABSTRACT FROM AUTHOR]

The effect of the action of temperature on the structure and phase composition of an Fe3C/Fe7C3/P-phase/Cam composite obtained by mechanosynthesis of Fe–75 at % C has been studied by the methods of X‑ray diffraction, Mössbauer spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. It is shown that the structural and phase changes at heating have a multistage character. In the temperature range 315–400°C crystallization of the paramagnetic P-phase with generation of Fe3C and/or Fe7C3 occur. In the course of heating to higher temperatures, complete decomposition of carbide Fe7C3 (in the range 450–550°C) and partial decomposition of Fe3C (at 600°C and above) are observed. After cooling from 800–1000°C the mechanocomposite consists of α-Fe, cementite Fe3C, and graphite. The phase transformations are accompanied by the processes of composite oxidation with the formation of Fe3O4 oxide and its subsequent reduction. The P-phase is a disorded amorphous carbide Fe1 – xCx, which is characterized by magnetic ordering at the temperature of liquid nitrogen. [ABSTRACT FROM AUTHOR]

This work investigates the swelling and physical properties of additively manufactured (AM) acrylate and traditionally manufactured (TM) O-rings when exposed to gasoline and organic mixtures. Fuel chemical compositions were determined using gas chromatography/mass spectrometry. Polymer properties were found using differential scanning calorimetry, thermal gravimetric analysis, and tensile testing. Exposure to gasoline for 24 h caused the AM and TM O-ring to lose from 54 to 80% of their unexposed failure strength. AM O-ring failure strength varied more (~ 20%) than TM O-rings (~ 7%). AM O-rings swelled from 46 to 110% with greater swelling in E10 than in E85 or ethanol-free gasolines. Volume changes ranged from −5 to 175% for commercial polymers. Aromatic compounds increased O-ring swelling. For ternary mixtures with 30% toluene, decane, and ethanol, increasing the ethanol up to mass 35% increased the swelling from 30 to 100 vol.%, after which the swelling remained level. Subsequent fuel evaporation from the polymers returned most of them to their original size and tensile strength, suggesting that the 24-h exposure caused no permanent damage. One AM O-ring exposed to 30% toluene/70% ethanol showed visible structural changes accompanied by a tensile strength less than half that of those with no visible changes. [ABSTRACT FROM AUTHOR]

Fused filament fabrication (FFF) represents a straightforward additive manufacturing technique applied in the medical sector for personalized patient treatment. However, frequently processed biopolymers lack sufficient thermal stability to be used as auxiliary devices such as surgical guides. The aim of this study was to evaluate the dimensional accuracy of experimental biocopolyester blends with improved thermal characteristics after printing, annealing and sterilization. A total of 160 square specimens and 40 surgical guides for oral implant placement were printed. One subgroup of each material (n = 10) underwent thermal annealing before both subgroups were subjected to steam sterilization (134 °C; 5 min). Specimens were digitized and the deviation from the original file was calculated. The thermal behavior was analyzed using differential scanning calorimetry and thermogravimetric analysis. A one-way ANOVA and t-tests were applied for statistical analyses (p < 0.05). All biocopolyester blends showed warpage during steam sterilization. However, the material modification with mineral fillers (21–32 wt%) and nucleating agents in combination with thermal annealing showed a significantly reduced warpage of printed square specimens. Geometry of the printing object seemed to affect dimensional accuracy, as printed surgical guides showed less distortion between the groups. In summary, biocopolyesters did benefit from fillers and annealing to improve their dimensional stability. [ABSTRACT FROM AUTHOR]

Aluminum particles are of significant interest in enhancing the energy release performance of explosives. One of the major impediments to their use is that Al2O3 shell significantly decreases overall performance. To address this issue, we investigate creating aluminum particles with a glycidyl azide polymer (GAP) coating to improve their reactivity while retaining their energy content. We found that the aluminum particles were coated with a GAP layer of thickness around 8.5 nm. The coated aluminum particles were compared to non-coated powder by the corresponding reactivity parameters obtained from simultaneous differential scanning calorimetry, thermal gravimetric analysis, coupled with mass spectral and infrared spectral analyses. Besides, the comparison on the energy content was also conducted based on P–t tests and a laser-induced air shock from energetic materials (LASEM) technique. It was found that GAP shifted the oxidation onset of aluminum particles to a lower temperature by ~ 10 °C. Besides, the oxidation activation energy of aluminum particles was also reduced by ~ 15 kJ mol−1. In return, aluminum particles reduced the activation energy of the second stage decomposition of the GAP by 276 kJ mol−1. And due to the synergistic effect between aluminum and GAP, the decomposition products of GAP were prone to be oxycarbide species rather than carbonitride species. In addition, the P–t test showed the peak pressure and pressurization rate of GAP coated aluminum particles were separately 1.4 times and 1.9 times as large as those of non-coated aluminum particles. Furthermore, the LASEM experiment suggested the shock wave velocity of the GAP coated aluminum particles was larger than that of non-coated aluminum particles, and the largest velocity difference for them could be 0.6 km s−1. This study suggests after coating by GAP, the aluminum particles possess enhanced reaction performance, which shows potential application value in the fields of aluminized explosives and other energetic fields. [ABSTRACT FROM AUTHOR]

Industrial processing of enzymes requires higher heating that affects the thermal stability of the enzyme and increases the production cost. In this study, xylanase–phytase (XP) fusion protein was generated via co-expression in a single vector with a cold-shock promoter, leading to improved activity at optimal pH, temperature and the thermal behaviour of the protein. Xylanase–phytase (XP) fusion and phytase proteins were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The XP fusion was thermally stable up to 124 °C, higher than phytase which was steady up to 113.5 °C. XP fusion exhibits higher stability at its thermal transition midpoint (Tm) 108 °C, higher than the Tm value of phytase which is 90 °C. Industrially efficient and environment-friendly proteins with low production cost and higher stability can be generated by 'fusion protein' technology. [ABSTRACT FROM AUTHOR]

In this study, a novel hybrid multilayered electrospun nanocomposite membrane (MENM) was developed for activated wound dressing applications. An established electrospinning process was employed to fabricate a tri-layer nanocomposite membrane where the lower layer was composed of chitosan (CS)/polyvinyl alcohol (PVA) and fibrin (having regeneration of tissues and bleeding resistance properties), both of which are directly in contact with the burn wound (BW) skin, and a middle layer of PVA/sodium alginate (SA) (having antibacterial properties). The top layer consisted of gelatin (super hydrophilic properties). The MENM morphology was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) which confirmed the presence of the elemental and chemical structures of MENM. The MENM was identified by Fourier transform infrared spectroscopy (FTIR) with a maximum drug release which was ascended within 10-h duration. X-ray diffraction (XRD) showed long-term absorbency due to the presence of more amorphous and less crystallinity percentages in the MENM. The nanocomposites' thermal stability was also observed via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The developed MENM has shown excellent antibacterial activity with a zone of inhibition of 18.7 ± 0.9 mm, 18.9 ± 0.9 mm, 20.0 ± 1 mm and 19.3 ± 0.9 mm, respectively, against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. The high water absorbant properties of MENM indicate that the produced membranes could absorb the maximum exudate from wounded skin within the shortest time and assist in healing the wound quickly. The produced MENMs could be potential wound dressing materials in the future. [ABSTRACT FROM AUTHOR]

The physical properties of the organic–inorganic hybrid crystals having the formula [NH3(CH2)3NH3]ZnX4 (X = Cl, Br) were investigated. The phase transition temperatures (TC; 268K for Cl and 272K for Br) of the two crystals bearing different halogen atoms in their skeletons were determined through differential scanning calorimetry. The thermodynamic properties of the two crystals were investigated through thermogravimetric analysis. The structural dynamics, particularly the role of the [NH3(CH2)3NH3] cation, were probed through 1H and 13C magic-angle spinning nuclear magnetic resonance spectroscopy as a function of temperature. The 1H and 13C NMR chemical shifts did not show any changes near TC. In addition, the 1H spin–lattice relaxation time (T1ρ) varied with temperature, whereas the 13C T1ρ values remained nearly constant at different temperatures. The T1ρ values of the atoms in [NH3(CH2)3NH3]ZnCl4 were higher than those in [NH3(CH2)3NH3]ZnBr4. The observed differences in the structural dynamics obtained from the chemical shifts and T1ρ values of the two compounds can be attributed to the differences in the bond lengths and halogen atoms. These findings can provide important insights or potential applications of these crystals. [ABSTRACT FROM AUTHOR]

Highly energetic nitramines such as cyclotetramethylene-tetranitramine (HMX) experience high combustion enthalpy, as well as large volume of gaseous products. Despite the fact that HMX can expose high thermal stability, it exposes low sensitivity to different catalysts. HMX-based propellants will combust at low burning rate. Ferric oxide particles with hydrous surface can offer high catalyzing ability via release of active .OH radicals; active .OH species would attack heterocyclic ring with hydrogen atom abstraction. Highly crystalline, monodispersed Fe2O3 nanoparticles (NPs) of 3.39 nm average particle sizes were developed using hydrothermal processing. Fe2O3NPs were integrated into HMX via co-precipitation technique. The impact of Fe2O3NPs (1 wt%) on HMX thermolysis was investigated using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Fe2O3NPs demonstrated advanced catalytic performance. HMX main exothermic decomposition peak was decreased by 13.0 °C with an increase in decomposition enthalpy by 72.2%. Fe2O3NPs could alter HMX thermolysis from C–N cleavage to hydrogen atom abstraction through the released active surface .OH radical. Additionally released NO2 could be adsorbed on nanocatalyst surface offering high decomposition enthalpy. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is composited into electrolyte material, e.g., LaCePr-oxide-La0.6Sr0.4Co0.2Fe0.8O3-δ (LCP-LSCF), to improve its electrochemical performance and enhance its mechanical strength for a low-temperature solid oxide fuel cell. The influence of different PVDF contents on the performance of the as-prepared samples was studied in this work. X-ray diffraction results indicate that there is no impurity phase in the composite. Thermogravimetric analysis and differential scanning calorimetry were employed to investigate the composite's stability at operating temperature. The I–V and I–P characteristics indicate that the microstructures of the nanocomposites that can be controlled by PVDF which plays an important role in its electrochemical performance. The cell with 3 wt% PVDF that was heat treated at 210 °C achieved the highest power density of 687 mW cm−2 at 550 °C, which was 196 mW cm−2 higher than that without any heat treatment. The pores are formed by PVDF, and the heat treatment enlarged the triple-phase boundary (TPB), which was the main reason for improved performance. [ABSTRACT FROM AUTHOR]

Organic inner salt structures are ideal backbones for heat-resistant energetic materials and systematic studies towards the thermal properties of energetic organic inner salt structures are crucial to their applications. Herein, we report a comparative thermal research of two energetic organic inner salts with different tetraazapentalene backbones. Detailed thermal decomposition behaviors and kinetics were investigated through differential scanning calorimetry and thermogravimetric analysis (DSC-TG) methods, showing that the thermal stability of the inner salts is higher than most of the traditional heat-resistant energetic materials. Further studies towards the thermal decomposition mechanism were carried out through condensed-phase thermolysis/Fourier-transform infrared (in-situ FTIR) spectroscopy and the combination of differential scanning calorimetry-thermogravimetry-mass spectrometry-Fourier-transform infrared spectroscopy (DSC-TG-MS-FTIR) techniques. The experiment and calculation results prove that the arrangement of the inner salt backbones has great influence on the thermal decompositions of the corresponding energetic materials. The weak N4-N5 bond in "y-" pattern tetraazapentalene backbone lead to early decomposition process and the "z-" pattern tetraazapentalene backbone exhibits more concentrated decomposition behaviors. [ABSTRACT FROM AUTHOR]

Hot stage microscopy (HSM) is a thermal analysis technique that combines the best properties of thermal analysis and microscopy. HSM is rapidly gaining interest in pharmaceuticals as well as in other fields as a regular characterization technique. In pharmaceuticals HSM is used to support differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) observations and to detect small changes in the sample that may be missed by DSC and TGA during a thermal experiment. Study of various physical and chemical properties such sample morphology, crystalline nature, polymorphism, desolvation, miscibility, melting, solid state transitions and incompatibility between various pharmaceutical compounds can be carried out using HSM. HSM is also widely used to screen cocrystals, excipients and polymers for solid dispersions. With the advancements in research methodologies, it is now possible to use HSM in conjunction with other characterization techniques such as Fourier transform infrared spectroscopy (FTIR), DSC, Raman spectroscopy, scanning electron microscopy (SEM) which may have additional benefits over traditional characterization techniques for rapid and comprehensive solid state characterization. [ABSTRACT FROM AUTHOR]

Herein, we report, for the first time, the facile synthesis of VO2(paramontroseite) by doping of Ge4+ ions into VO2 via simple hydrothermal route. The synthesized materials were characterized by different techniques in terms of their structural, morphological, and thermal properties using X-ray diffraction, transmission electron microscopy, and thermogravimetric analysis and differential scanning calorimetry, respectively. It was observed that the formation of a tunnel by the octahedral arrangement of VO6 in VO2(P) allows intercalations of ions from ionic electrolytes, making it useful for electrochemical applications. The detailed cyclic voltammetric studies, at different scan rates, and electrochemical impedance spectroscopic results showed that the VO2(P) is a potential material for electrochemical applications. [ABSTRACT FROM AUTHOR]

Polymer hybrid films were prepared by solution casting technique, using polyvinyl alcohol–polyethylene glycol (PVA–PEG) blend host matrix as the organic component and Ag2S (in-situ formed) as the inorganic component. Differential scanning calorimetry (DSC) studies revealed the increased flexibility of polymer hybrid films, when compared to pure PVA–PEG blend film. Thermal stability of the hybrid film PPS3 (with AgNO3:Na2S ratio equal to 3.0 ml: 1.5 ml) which has uniformly distributed Ag2S nanostructures is more, when compared to other hybrid films, as revealed by thermogravimetric analysis (TGA). Polymer hybrid film PPS1 (with AgNO3:Na2S ratio equal to 1.0 ml: 0.5 ml) which has uniformly distributed Ag2S microstructures shows increased values of tensile strength and percentage elongation at break. The presence of Ag2S nanoparticles in PPS3 film has increased the overall toughness of the corresponding hybrid film. The highest bulk conductivity equal to 1.43 × 10–5 Sm−1 is observed for PPS4 film (with 4.0 ml: 2 ml ratio of precursors), which has a comparatively lower degree of crystallinity and porous structure. Impedance spectroscopy studies reveal that Ag2S filler, in its micro and nano forms, can substantially improve the AC conductivity and dielectric properties of PVA–PEG polymer blend (loaded with Ag2S). [ABSTRACT FROM AUTHOR]

In this work, we present a new strategy to engineer novel self-healing ionomers, namely, zwitterionic polymers, and a comprehensive analysis of their mechanical, viscoelastic, and scratch-healing properties. This new method enables reproducible damage of the polymer surfaces, calculation of the scratch volume through tactile profile scans, and quantification of the self-healing efficiency. Based on the results of the scratch tests and complementary rheology, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and hardness tests, new trends, and structure–property relationships can be identified. Polymers: Materials that pull themselves together A novel soft material that can heal itself has been engineered by researchers in Germany. Polymeric molecules are formed by long chains of atoms. Some polymers can reform when broken, giving them the intrinsic ability to repair scratches or tears. These self-healing properties are useful for applications in long-lasting biomedical implants, for example. Martin D. Hager and colleagues from the Friedrich Schiller University Jena synthesized and characterized a novel type of self-healing materials using a so-called zwitterionic polymer, a polymer which includes both positive and negative charges in the side-chains. Using a simple new method to create their material, the team investigated its hardness, its viscoelastic properties and quantified how efficiently it healed scratches of different sizes. This novel approach to scratch-healing tests, which utilizes the scratch volume, is both reproducible and quantifiable and could be extended to other materials. New self-healing zwitterionic polymer networks are prepared and the healing efficiency is quantified by 3D plotting, as well as volume calculation of the damaged surface after tactile profile scans. The results are complemented by comprehensive investigations of the mechanical, viscoelastic, and thermal properties in order to identify structure-property relationships. [ABSTRACT FROM AUTHOR]

A series of polyazomethines (PAM-01, PAM-02, PAM-03) containing various amounts of tetraphenylthiophene-oxazole (TPTP-o) moieties were produced by the polycondensation of a diamine precursor (TPTP-o) with equimolar proportions of two aromatic dialdehydes [isophthalaldehyde (1,3 IPA) and terephthalaldehyde (1,4 TPA)]. The TPTP-o precursor was successfully synthesized in three steps. The synthesized TPTP-o and the polymers (PAM-01, PAM-02, PAM-03) were characterized by ultraviolet–visible (UV–Vis) spectroscopy, FT-IR spectroscopy, x-ray diffraction (XRD), 1H-NMR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. The effects of the TPTP-o units in the PAM on the insertion with azo linkages were studied with respect to conductivity and thermal stability. The room-temperature DC electrical conductivity of the PAM films was found to range from 9.59 × 10−7 S/cm to 9.73 × 10−7 S/cm. UV absorption at 342 nm confirmed the formation of azo (–C=N–) linkages in the polymer, which is helpful for electron conductivity throughout the polymer network. All three PAMs had a glass transition temperature (Tg) between 260°C and 267°C, and T10% thermal degradation values of thermally stable polyazomethines were in the range of 517–530°C. All three PAMs showed moderate solubility in organic solvents and inherent viscosity of between 0.31 dL/g and 0.35 dL/g. The XRD study indicated that all three PAMs were amorphous in nature, with a broad peak in the vicinity of 20°. [ABSTRACT FROM AUTHOR]

Cerium-doped K2Pb(SO4)2 was synthesized by a coprecipitation method. K2Pb(SO4)2 is a semitransparent colourless or white material that occurs as a rare fumarolic sublimate. Only the crystal structure of palmierite has been reported to date. The present work concentrates on its vibrational and physical properties, including optical, thermal, and dielectric studies. The crystalline nature and lattice distortion were confirmed by x-ray diffraction analysis. Fourier-transform infrared (FTIR) spectroscopy revealed the functional groups present in the material. Morphological and elemental composition analyses were carried out by scanning electron microscope/energy-dispersive spectroscopy (SEM/EDAX). Thermogravimetric-differential scanning calorimetry (TG-DSC) analysis was carried out for improved understanding of the thermal characteristics of undoped and Ce-doped K2Pb(SO4)2. The optical characteristics were analyzed by photoluminescence (PL) spectrophotometry. The presence of cerium ions was confirmed by the emission peak at 314 nm, which may be due to 5d-4f transitions of Ce3+ ions. The dielectric constant and loss were measured as functions of frequency. The results indicate that cerium doping has a significant influence on the dielectric properties of K2Pb(SO4)2. [ABSTRACT FROM AUTHOR]

In this study, we use simultaneous differential scanning calorimetry and thermogravimetric analysis to analyze the solid-state reaction characteristics of Al/Fe2O3 nanothermites before n-Al melts. Different experimental setups for thermal analysis are compared, and the heat-release characteristics are studied on Al/Fe2O3 nanothermites in the form of powder and pellet, respectively. It is found that protection provided by mere argon flow is far from enough for thermal analysis of Al/Fe2O3 nanothermites. The experimental setup must be free of oxygen; otherwise, the determined exothermic peak is mostly the oxidation of n-Al by the residue oxygen molecules in the furnace body, due to the high reactivity and moderate accessibility of free oxygen molecules. Under proper experimental setup, it is found that besides the redox reaction between n-Al and n-Fe2O3, intermetallic reaction also occurs to form Fe4Al13. Moreover, the intermetallic reaction is more noticeable for nanothermite pellet than for nanothermite powder, and the eutectic reaction of Fe4Al13 and n-Al leads to melting peaks below 655 °C. The results indicate that instrument configuration and sample status affect the testing results to a large extent, and one should be prudent to derive reaction characteristics of nanothermites. [ABSTRACT FROM AUTHOR]

The ball milling route has been used to produce the LaSrMnFeO (LSMFO) nanocrystalline sample from oxide precursors. The sample was characterized using x-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDAX), differential scanning calorimetry (DSC) and thermogravimetric (TGA) measurements. The x-ray diffraction confirms the phase purity of sample and shows that the sample crystallizes in the rhombohedral perovskite structure with a R-3c space group. The scanning electron micrograph shows the presence of well-faceted crystallites of LSMFO. The EDAX spectrum demonstrates the molar ratio of different elements of nanocrystalline LSMFO. Furthermore, the crystallite size using the Debye-Scherrer formula and William-Hall analysis has been found as 24 nm and 29 nm, respectively. Our results support the idea that a good quality nanocrystalline LSMFO sample can be obtained using the ball milling route. We also discuss the DSC and TGA curves and analyse the results in terms of phase transition, calcination temperature and activation barrier energies. [ABSTRACT FROM AUTHOR]

Powder mixtures of low-density polyethylene and aluminum with the 20-80% weight ratio of the species are subjected to plastic deformation at pressures of 1 and 4 GPa in high-pressure devices of the Bridgman anvil type. Mass changes in the deformed mixtures in the temperature range from 30 to 800◦C are studied by the method of thermal gravimetry. A mass loss associated with polymer decomposition occurs in the temperature range from 30 to 450◦C, which is always smaller than the polymer content in the mixtures. A possible reason is the formation of thermally stable products due to aluminum interaction with polymer decomposition products. In the temperature range from 450 to 800◦C, the mass of the specimens increases, which is caused by aluminum oxidation and nitridation. The mass change depends on the deformation magnitude and pressure. To separate the oxidation and nitridation processes, the thermogravimetric measurements are performed in air, nitrogen and argon. The thermal effects of aluminum interaction both with the polymer decomposition products and with oxygen and nitrogen are analyzed by the method of differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

In the present study, epoxidized polybutadiene rubber (EBR) was synthesized from commercial-grade cis-polybutadiene rubber (BR) and was characterized by NMR, FTIR, differential scanning calorimetry, thermogravimetric analysis and surface energy by contact angle measurement. To circumvent the drawback of the existing compatibilizers, the EBR was successfully used as an alternate compatibilizer for a silica-based 'green-tire' composite. The significant rise of surface energy was observed after epoxidation of BR, which represents the enhancement of the polar character of the rubber chains and eventually leads to improved compatibility between silica fillers and rubber chains. Out of various epoxidation levels, EBR with 30 mol% epoxidation showed the best compatibilizing effect. The optimum loading of EBR was found to be 12% with respect to total silica content. Apart from using EBR alone as a compatibilizer, combination of EBR with commercial silane-coupling agents, namely, bis(triethoxy-silylpropyl) tetrasulphide (TESPT) and 3-aminopropyltrimethoxy silane, was also investigated. The physico-mechanical and dynamic properties of the compounds with a combination of TESPT:EBR (40:60-60:40) were comparable with those of the compound prepared using TESPT compatibilizer. The results observed with EBR-compatibilized samples revealed that EBR has a potential to be an effective compatibilizer which eventually could minimize the drawbacks associated while using commercial silane as a compatibilizer at the industrial scale. [ABSTRACT FROM AUTHOR]

In an attempt to develop an alternate to lead-based X-ray shielding material, we describe the X-ray attenuation property of nanocomposites containing GdO as nanofiller and silicone resin as matrix, prepared by a simple solution-casting technique. GdO nanoparticles of size 30 and 56 nm are used at concentrations of 25 and 2.5 wt%. The nanoparticles and the nanocomposites are characterized using X-ray diffraction (XRD) studies, small angle X-ray spectroscopy (SAXS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The X-ray attenuation property of nanocomposites, studied using an industrial X-ray unit, shows that nanocomposites containing nanoparticles of size 56 nm (G2) exhibit better attenuation than nanocomposites containing nanoparticles of size 30 nm (G1), which is attributed to the greater interfacial interaction between the G2 nanofillers and silicone matrix. In the case of nanocomposites containing G1 nanoparticles, the interfacial interaction between the nanofiller and the matrix is so weak that it results in pulling out of nanofillers, causing voids in the matrix, which act as X-ray transparent region, thereby reducing the overall X-ray attenuation property of G1 nanocomposites. This is further corroborated from the AFM images of the nanocomposites. The weight loss and heat flow curves of pure silicone matrix and the nanocomposites containing GdO nanoparticles of size 30 and 56 nm show the degradation of silicone resin, due to chain scission, between 403 and 622 °C. The same onset temperature (403 °C) of degradation of matrix with and without nanoparticles shows that the addition of nanofillers to the matrix does not deteriorate the thermal stability of the matrix. This confirms the thermal stability of nanocomposites. Therefore, our study shows that nanocomposites containing G2 nanoparticles are potential candidates for the development of X-ray opaque fabric material. [ABSTRACT FROM AUTHOR]

Development of (K,Na)NbO-based ceramics has attracted much attention in recent decades. In this work, KNaNbAlO ceramic was prepared using conventional solid-state processing. A deliquescence phenomenon was observed when the specimen was exposed to moist atmosphere. The reaction mechanism and cause of deliquescence were investigated using x-ray diffraction analysis, scanning electron microscopy, energy-dispersive spectrometry, electron microprobe analysis, inductively coupled plasma mass spectrometry, and thermogravimetric/differential scanning calorimetric analysis. The results revealed interactions mainly amongst the raw materials KCO, NaCO, and NbO as well as KCO, NaCO, and AlO, which can influence the sintering behavior of the mixture. (K,Na)NbO and (K,Na)AlO were present in the sintered KNaNbAlO ceramic, with the latter leading to deliquescence. During the sintering process, AlO reacts with alkali oxides (NaO and KO), which are the decomposition products of carbonates, to form (K,Na)AlO. In addition, AlO is more likely to react with KO compared with NaO. [ABSTRACT FROM AUTHOR]

Cycloaliphatic epoxy resin was modified by phenyl methyl silicone resin to investigate the influence of silicone content on the performance and reliability of epoxy packaged light-emitting diode. The silicone modification of epoxy encapsulants was characterized by transform infrared (FT-IR) spectrophotometer. Rotational rheometer was used to study rheology behavior. Differential scanning calorimetry, thermogravimetric analyses, dynamic mechanical analysis, thermomechanical analyzer were introduced to measure the thermal and mechanical properties. Ultraviolet visible spectrophotometer was utilized to study heat and ultraviolet resistance. In reliability test, scanning acoustic microscope and scanning electron microscope were applied to observe interfacial delamination. Water sorption process was monitored using gravimetric measurement. FT-IR study shows a chemical bonding between hydroxyl group of silicone resin and epoxy resin. With the incorporation of silicone resin, favorable properties were obtained such as higher thermal decomposition temperature, lower equilibrium water sorption, and better heat and UV resistance. Among these systems, 10% silicone modified epoxy resin exhibits the best performance in reliability test. [ABSTRACT FROM AUTHOR]

A cost effective method for conversion of a vertical tube thermogravimetric analysis system into a magnetic balance capable of measuring Curie Temperatures is presented. Reference and preliminary experimental data generated using this system is analyzed via a general-purpose wavelet based Curie point edge detection technique allowing for enhanced speed, ease and repeatability of magnetic balance data analysis. The Curie temperatures for a number of Heusler compounds are reported. [ABSTRACT FROM AUTHOR]

Industrial applications of microfibrillated cellulose (MFC) and nanofibrillated cellulose (NFC) have been in use for some time; however, there is a need to improve the production steps and at the same time to obtain better quality products. NFC and MFC were generated from $$\hbox {NaBH}_{4}$$ -modified kraft pulp, produced from a red gum tree plant ( Eucalyptus camaldulensis). The generated NFC and MFC were characterized by high-performance liquid chromatography, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and $$^{13}\hbox {C}$$ -nuclear magnetic resonance (NMR). Morphological and viscoelastic properties were investigated by scanning electron microscopy and rheometry, respectively. The storage moduli of biofilms produced from NFC and MFC were investigated by dynamic mechanical thermal analysis (DMTA). Both exhibited mostly identical FTIR spectra. When the spectra were compared with those of $$\hbox {NaBH}_{4}$$ -modified kraft pulp, minor shifts were observed due to crystallinity. In NMR spectra, disordered cellulose structures were observed for both NFC and MFC, and these findings were also confirmed by differential scanning calorimetry. Rheology studies revealed that the lowest viscosity was observed with MFC. TGA results showed that NFC degraded earlier compared with $$\hbox {NaBH}_{4}$$ -modified kraft pulp. DMTA exhibited that NFC films had about six times higher storage modulus compared with MFC. [ABSTRACT FROM AUTHOR]

Low-temperature (<500°C) stages in the synthesis of gamma-lithium monoaluminate through heat treatment of a mechanically activated mixture of aluminum hydroxide and lithium carbonate have been studied by thermogravimetry and differential scanning calorimetry in combination with mass spectrometry. The results demonstrate that heating the mixture to above 80-100°C is accompanied by the release of not only water (resulting from the decomposition of X-ray amorphous aluminum hydroxide) but also carbon dioxide. The carbon dioxide originates from the reaction of the lithium carbonate with the products of X-ray amorphous aluminum hydroxide thermolysis. [ABSTRACT FROM AUTHOR]

Phase transformations of model compositions of cordierite ceramic based on silicon dioxide synthesized by the micellar technology are studied by means of thermogravimetry, differential scanning analysis, and diffractometry. The formation temperature bounds of the cordierite phase in the samples are determined. [ABSTRACT FROM AUTHOR]

A bulk combinatorial approach for synthesizing alloy libraries using laser engineered net shaping (LENS™; i.e., 3D printing) was utilized to rapidly assess material systems for magnetic applications. The LENS™ system feeds powders in different ratios into a melt pool created by a laser to synthesize samples with bulk (millimeters) dimensions. By analyzing these libraries with autosampler differential scanning calorimeter/thermal gravimetric analysis and vibrating sample magnetometry, we are able to rapidly characterize the thermodynamic and magnetic properties of the libraries. The Fe-Co binary alloy was used as a model system and the results were compared with data in the literature. [ABSTRACT FROM AUTHOR]

The characteristic details of the carbothermal synthesis of TiB powders from the stoichiometric mixture TiO-HBO-C at temperatures lower 1700 K are investigated using thermal analysis (ТG-thermogravimetry and DSC-differential scanning calorimetry), as well as X-ray diffraction and scanning electron microscopy. In the temperature interval 300 K → 1673 K → 1273 K and at a heating rate of 10 K/min, the reaction in the powder mixture begins at approximately 1300 K and ends at 1470 K during cooling. After 3 h of isothermal synthesis at 1473 K, the TiB yield is more than 90%. The resulting products are hexagonal plate-like crystals 5-10 μm across with thickness of 3 to 4 μm. Kinetic analysis showed that in the temperature range of 1330 to 1673 K the TiB synthesis reaction is of the first-order, and the calculated activation energy of the process is 315 ± 24 kJ/mol. [ABSTRACT FROM AUTHOR]

In this article, a new type of epoxy resin, diglycidyl ether of 9,9-bis [4-(2-hydroxyethoxy) phenyl] fluorine (DGEBEF) was successfully synthesized and characterized by H-NMR, FTIR, and FDMS analyses. The kinetics of DGEBEF cured with 4,4′-diamino diphenyl sulfone (DDS) was investigated by nonisothermal differential scanning calorimetry and thermal stability of the cured resin was characterized by thermogravimetric analysis. The DGEBEF/DDS system exhibits excellent processability, mechanical strength, and toughness, high thermal stability and low water absorption. Glass transition temperature ( T) of the cured epoxy was 170 °C determined by DMA. The ratio of the storage modulus of the cured resin at glassy state to that at rubbery state was as large as about 400, indicating its potential applications as shape memory material. The excellent shape memory properties were confirmed by fold-deploy shape memory and tensile-shrinkage tests. The shape fixed ratio was 99 %. and the shape recovery ratio was nearly 100 % after 30-s recovery at 185 °C in the fold-deploy shape memory test. In the tensile-shrinkage test, the recovery stress is 2.5 MPa at the strain of 25 % and temperature of 185 °C, and both the shape fixed and shape recovery ratios maintained at about 99 % after six test cycles. [ABSTRACT FROM AUTHOR]

Thermokinetic data on the oxidation of ASD-4 powder modified by impregnation with VO gel were obtained by thermogravimetry and differential scanning calorimetry under heating in air to 1250°C at a rate of 10 deg/min. The phase formation process directly during oxidation of the modified ASD-4 was studied by powder x-ray diffraction method using a synchrotron radiation source. A mechanism for the effect of VO on the oxidation of ASD-4 is proposed on the basis of literature data and analysis of the results of the studies performed. [ABSTRACT FROM AUTHOR]

Using thermogravimetry, differential scanning calorimetry, X-ray diffraction, mass spectrometry, and Fourier transform IR spectroscopy, we have determined the composition of VO(acac) thermal decomposition products and gained insight into the bond breaking sequence in this compound. A two-step annealing procedure has been proposed to ensure control over VO(acac) to VO conversion processes without changing the oxidation state of vanadium in the preparation of VO films by a sol-gel process. [ABSTRACT FROM AUTHOR]

Chromium (Cr) doped strontium hexaferrites with nominal composition SrFeCrO (x = 0.0, 0.1, 0.2, 0.3) were prepared using co-precipitation method. Thermal analysis of the samples was carried out using thermogravimetric analysis and differential scanning calorimetry to study the thermal stability as well as the transitions within the samples with variation in temperature. Structural analysis of the samples was carried out using X-ray diffraction (XRD). XRD revealed that all the samples possess hexagonal structure with space group P63/mmc. AC electrical properties including dielectric constant ( έ), dielectric loss tangent (tan δ) and ac electrical conductivity ( σ) were studied as a function of frequency (1 kHz-3 MHz) at temperatures 100-700 °C. The dielectric losses tend to decrease with increasing Cr content. AC conductivity could be very well explained by Jonscher power law. These materials have applications in high frequency devices with reduced energy losses. [ABSTRACT FROM AUTHOR]

Using thermogravimetric analysis and differential scanning calorimetry in air and argon, we have studied the products of reactions between the BH anion and water glass (WG) sodium silicates. The reaction products have the form of spatially branched supramolecular structures. Supramolecular structures of various compositions have been synthesized at initial WG/( EtNH)BH reactant ratios of 70/30, 60/40, 50/50, and 40/60. In the range 20-600℃, we have studied the following processes in the WG/BH systems: removal of adsorbed water (50-200℃), condensation of silicates containing silanol groups (200-300℃), and oxidation of the BH anion in the silicate matrix (300-600℃). All three processes have been shown to depend on content. [ABSTRACT FROM AUTHOR]

The thermal stability of the LaFeCoSb skutterudite was examined by varying the aging conditions of temperature, time, and atmosphere (air and vacuum). Thermogravimetry, differential scanning calorimetry and x-ray diffraction analyses revealed that the LaFeCoSb was significantly oxidized at temperatures above 673 K in air. The Sb-based oxides were preferably formed when aged at high temperatures in air. The thickness of the oxide layers was found to increase with increasing aging temperature and time, while the activation energy for the oxidation of the Fe-Sb-based skutterudite was lower than that of the Co-Sb-based skutterudites. However, when the analysis was performed in a vacuum, the LaFeCoSb skutterudite was stable, and no oxide layers were observed after aging at 823 K for 100 h. These results suggest that a protective coating for the skutterudite materials or the encapsulated packaging of the skutterudite modules is required for high-temperature applications. [ABSTRACT FROM AUTHOR]

Polyvinylchloride (PVC) powders containing (or not) calcium carbonate were mechanochemically modified using a ball mill. Membranes prepared by phase inversion of the modified PVC were tested by scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry to compare the structure and properties before and after mechanochemical modification. The results showed that after mechanochemical modification, pure water flux of the phase inversion PVC membrane reached up to 378.6 L/(m h), significantly higher than that before modification [123.3 L/(m h)]; calcium carbonate enhanced the dechlorination effect of mechanochemical modification and further increased pure water flux of the membrane to 454.2 L/(m h). Mechanochemical modification increased the tensile strength of the PVC membrane by 4.1 % and decreased crystallinity of the PVC powder by about 34 %. [ABSTRACT FROM AUTHOR]

The influences of various factors on the formation of 2,3-dihydro-3,5-dihydroxy-6-methyl-4( H)-pyran-4-one (DDMP) were investigated in a solid-state Maillard reaction system. Thermogravimetric analysis (TG) and differential scanning calorimetry analysis (DSC) showed that the solid-state Maillard reaction mainly occurred at around 150 °C. The DDMP formation from reducing sugars (glucose or fructose) and several selected amino acids ( l-proline, l-alanine, l-asparagine, l-threonine, l-tyrosine and l-lysine) was compared. Proline was found to have special activity in DDMP formation when reacted with glucose because of its special catalytic action. The influences of reactant ratios, oxygen, reaction temperature and reaction time on DDMP formation from the reaction of proline with glucose were studied. Reactant molar ratios of glucose to proline played important impact on DDMP formation, and the formation of DDMP was improved when the ratio was higher than 1:1 and achieved the highest level at 2:1. Oxygen had no obvious effects on DDMP formation. The effects of reaction time and temperature were investigated together and revealed the information on the highest yield and minimum temperature for DDMP formation. Furthermore, the kinetics of DDMP formation was studied, and DDMP formation in the initial stage was shown to follow an apparent first-order reaction with an activation energy of 68.8 kJ/mol. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate the use of poly (ethylene oxide) (PEO) for in-situ modification of the inner surface of halloysite nanotubes (HNTs) with water molecules as the hydrogen bond forming medium, as well as the nano-confinement of PEO molecular chains within the nanotube. Before testing, the Soxhlet experiment of PEO/HNTs powder is applied in order to remove the physical adsorption of PEO molecules onto the outmost surface of HNTs. The crystal temperature of PEO changes sharply from 36.9 °C of neat PEO to −25 °C of PEO in the PEO/HNTs powder and the decomposed temperature of PEO in the PEO/HNTs powder is about 13.1 °C higher than that of neat PEO, which is mainly owing to the nano-confinement effect of PEO within the HNTs with a diameter of about 10 nm. From thermo-gravimetric (TG) analysis, about 7.71 % by weight of PEO has been chemically bonded to HNTs. The hydrogen bonds among PEO, HNTs, and water molecules are evidenced by FTIR and XPS performances. Meanwhile, the binding energy of Al2p in the innermost surface of HNTs shifts from 74.7 eV in the neat HNTs to 74.5 eV in the PEO/HNTs powder, while that of Si2p on the outmost surface of HNTs keeps almost constant, indicating that the hydrogen bonds only exists inner the nanotube and PEO molecular chains have been trapped in nano-scale within HNTs, which is in accordance with the DSC and TG observation. [ABSTRACT FROM AUTHOR]

To investigate liquid crystalline properties and structure relationships of chiral compounds based on menthol, a series of new chiral monomers derived from menthol derivatives, a mesogenic crosslinking agent, the corresponding side chain homopolymers with siloxane backbone, and cholesteric elastomers were synthesized. The structures and purity of these chiral compounds obtained in this study were characterized using FTIR, 1H NMR, and elemental analyses. The mesomorphism and thermal stabilities were investigated using differential scanning calorimetry, polarizing optical microscopy, thermogravimetric analysis, and X-ray diffraction. The selective reflection of light for the chiral monomers was studied with UV/visible/near IR. The effect of the crosslinking agent content on the phase transition temperatures of the elastomers was discussed. It was found that these chiral monomers seemed beneficial for the formation of the mesophases when a flexible spacer was inserted between the mesogenic core and the terminal menthyl groups. All obtained chiral monomers showed a cholesteric phase, chiral smectic C phase, and cubic blue phase. The crosslinking agent exhibited a smectic A (S A) phase and nematic phase. However, their corresponding homopolymers with siloxane chains tended to form a lower order S A phase. With an increase of the mesogenic rigidity, the melting temperatures, glass transition temperatures ( Tg), and isotropic temperatures ( Ti) of chiral monomers or homopolymers all increased. For the elastomers, general tendency was toward increased Tg and Ti with increasing the crosslinking agent content. [ABSTRACT FROM AUTHOR]

The effect of current density and sodium chloride concentration in solution on the phase composition and pore structure of the products of ac electrolysis of metallic Sn has been studied using X-ray diffraction, thermogravimetry, differential scanning calorimetry, electron microscopy, and low-temperature nitrogen adsorption measurements. The results demonstrate that the synthesis products consist of tin(II) and tin(IV) oxides and hydroxides, whose percentages depend on electrolysis conditions, and have a large specific surface area and mesoporous structure. The average particle size ranges from 10 to 30 nm. [ABSTRACT FROM AUTHOR]

Two sensitive, simple and rapid UV and second order derivative spectrophotometric methods were developed for the determination of nizatidine and ranitidine hydrochloride in pure form and pharmaceutical preparations. For the first method, UV spectrophotometic method, nizatidine was determined at 325 nm and ranitidine at 325.5 nm with detection limits of 0.07 and 0.04 μg/mL, respectively. For the second method, the distances between two extremum values (peak-to-peak amplitudes), 328/356.5 nm for nizatidine and 326/357 nm for ranitidine were measured in the second order derivative-spectra. The detection limits were found to be 0.02 μg/mL for nizatidine and 0.016 μg/mL for ranitidine, respectively. The thermal analysis of the two drugs was studied by Thermogravimetric Analysis-Differential Scanning Calorimetry (TGA-DSC) techniques. Enthalpy changes were obtained 121.9 and 124.15 J/g for nizatidine and ranitidine, respectively. The proposed method was successfully applied to the analysis of pharmaceutical preparations. The results were in good agreement with those obtained using the reference method; no significant difference were found in the accuracy and precision as revealed by the accepted values of t- and F-tests. [ABSTRACT FROM AUTHOR]

With polylactic acid (PLA) as shell and capsaicin as core substances, microcapsules were prepared based on solvent evaporation method. The orthogonal test was used to analyze the effects of the process conditions such as polyvinyl alcohol and PLA concentrations, stirring rate, and oil/water ratio on the particle size of the microencapsulated capsaicin (MC) agents. The chemical composition, morphology and size distribution of the microcapsules prepared by the most satisfactory conditions were analyzed by Fourier transform infrared spectroscopy, laser light scattering, and scanning electron microscopy. The MC agents had a mean diameter of 3-5 μm. The thermal properties of the MC agents were measured by differential scanning calorimetry and thermogravimetric analysis, it was demonstrated that the thermal stability of the MC agents was changed or even improved by the encapsulated PLA over the surface, when compared with similar parameters of the uncovered capsaicin. The in vitro release profile suggested that the microcapsules could be a suitable material for controlled release of capsaicin. [ABSTRACT FROM AUTHOR]

Silver (Ag) doped thermally stable TiO nanoparticles in the anatase phase have been synthesized by a low temperature hydrothermal method. The formation of anatase phase has been investigated by X-ray diffraction. Thermogravimetry and differential scanning calorimetry have been used for thermal studies. Scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy have been used for the morphology and composition studies. Surface areas were studied by the Brunauer-Emmett-Teller method. Dielectric properties were studied for dopant levels of 0.25, 0.5 and 1.0 wt% at 300 K in the frequency range of 42 Hz-5 MHz. The crystallite size, alternating current (AC) conductivity and dielectric properties of undoped TiO nanoparticles were greatly affected by doping with Ag. At high frequencies, the materials showed high AC Conductivity and low dielectric constant. [ABSTRACT FROM AUTHOR]

Degradation kinetics of sequential IPNs, based on novolac resin and poly (2-ethyl hexyl acrylate), are studied at linear heating rates of 2°C/min, 5°C/min, 10°C/min and 20°C/min by thermogravimetric analyser (TGA). Activation energy ( E and order ( n) of thermal decomposition reaction for IPNs and pure phenolic resin are evaluated from TGA curves using differential method of Freeman and Carroll. Decrease in T with an increase of acrylate content in IPNs are seen. Lower activation energy ( E), as calculated by applying Kissinger equation, for the concerned transition of IPNs, compared to that of pure phenolic resin is quite evident from DSC study. [ABSTRACT FROM AUTHOR]

The present study emphasizes the influence of non-covalent interactions on the mechanical and thermal properties of the scaffolds of chitosan/collagen origin. Malonic acid (MA), a bifuncitonal diacid was chosen to offer non-covalent cross-linking. Three dimensional scaffolds was prepared using chitosan at 1.0% (w/v) and MA at 0.2% (w/v), similarly collagen 0.5% (w/v) and MA 0.2% (w/v) and characterized. Results on FT-IR, TGA, DSC, SEM and mechanical properties (tensile strength, stiffness, Young's modulus, etc.) assessment demonstrated the existence of non-covalent interaction between MA and chitosan/collagen, which offered flexibility and high strength to the scaffolds suitable for tissue engineering research. Studies using NIH 3T3 fibroblast cells suggested biocompatibility nature of the scaffolds. Docking simulation study further supports the intermolecular hydrogen bonding interactions between MA and chitosan/collagen. [ABSTRACT FROM AUTHOR]

Difference in the kinetics of chemiluminescence (CL) and differential scanning calorimetry records for decomposition of originally solid benzoyl peroxide continuing as a melt reaction was outlined. While the main portion of heat measured by DSC is released in the spontaneous decomposition of benzoyl peroxide starting as a homolytic scission of peroxidic bonds, the CL light emission in oxygen comes presumably from the subsequent disproportionation reaction of polyphenyl peroxyl radicals and monitors the induced decomposition of peroxide. Thermogravimetry revealed that oxygen remains partially bound to the products of benzoyl peroxide decomposition. [ABSTRACT FROM AUTHOR]