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1.
Pentaerythritol diphosphonate melamine-urea-formaldehyde resin salt, a novel cheap macromolecular intumescent flame retardants
(IFR), was synthesized, and its structure was a caged bicyclic macromolecule containing phosphorus characterized by IR. Epoxy
resins (EP) were modified with IFR to get the flame retardant EP, whose flammability and burning behavior were characterized
by UL 94 and limiting oxygen index (LOI). 25 mass% of IFR were doped into EP to get 27.2 of LOI and UL 94 V-0.
The thermal properties of epoxy resins containing IFR were investigated with thermogravimetry (TG) and differential thermogravimetry
(DTG). Activation energy for the decomposition of samples was obtained using Kissinger equation. The resultant data show that
for EP containing IFR, compared with EP, IFR decreased mass loss, thermal stability and R
max, increased the char yield. The activation energy for the decomposition of EP is 230.4 kJ mol−1 while it becomes 193.8 kJ mol−1 for EP containing IFR, decreased by 36.6 kJ mol−1, which shows that IFR can catalyze decomposition and carbonization of EP. 相似文献
2.
Sigrid Lüftl Bruno Balluch Walter Smetana Sabine Seidler 《Journal of Thermal Analysis and Calorimetry》2011,103(1):157-162
The binder decomposition and burnout process of a commercial low temperature co-fired ceramic (LTCC) tape and an alumina tape
which is used as a sacrificial tape for the constrained sintering process of the LTCC-tape was investigated by thermogravimetry
(TG) and derivative thermogravimetry (DTG) up to 550 °C at different heating rates (from 1.5 to 10 K min−1) in air. TG revealed a multistage degradation behaviour of the binder system for both tapes, but the temperature range of
the different degradation stages varied. The activation energy of decomposition was determined by the Flynn–Wall isoconversional
method and the Coats–Redfern method. 相似文献
3.
The effect of ammonium sulfate (NH4)2SO4 on the flammability of 100% cotton woven fabric (plain 144 g m−2, the number of yarns 21 per 10 mm) has been of interest in this study. The laundered bone-dried, massed fabrics were impregnated
with suitable concentration of aqueous ammonium sulfate solutions by means of squeeze rolls, drying and conditioning. Afterwards
the specimen’s resistance to burning has been determined. The optimum add-on value of ammonium sulfate to impart flame-retardancy
to cotton fabric was in a range about 10.55–13.62 g anhydrous salt per 100 g fabric.
Thermogravimetry (TG/DTG) of the pure cotton and the treated one with the above-mentioned sulfate as well as for pure salt
were also accomplished and their TG curves were compared and commented to detect the combustion’s pathway of the supported
substrate. TG data confirm major mass loss in treated cotton. It occurred well below at a punctual duration of the thermal
degradation zone of the polymer. So fewer flammable volatiles and more char could be produced during combustion. The results
obtained are in compliance with gas dilution theory and also chemical action theory. 相似文献
4.
Adriana Fuliaş Titus Vlase Gabriela Vlase Nicolae Doca 《Journal of Thermal Analysis and Calorimetry》2010,99(3):987-992
The thermoanalytical curves (TA), i.e. TG, DTG and DTA for pure cephalexin and its mixtures with talc, magnesium stearate,
starch and microcrystalline cellulose, respectively, were drawn up in air and nitrogen at a heating rate of 10 °C min−1. The thermal degradation was discussed on the basis of EGA data obtained for a heating rate of 20 °C min−1. Until 250 °C, the TA curves are similar for all mixtures, up this some peculiarities depending on the additive appears.
These certify that between the pure cephalosporin and the excipients do not exists any interaction until 250 °C. A kinetic
analysis was performed using the TG/DTG data in air for the first step of cephalexin decomposition at four heating rates:
5, 7, 10 and 12 °C min−1. The data processing strategy was based on a differential method (Friedman), an integral method (Flynn–Wall–Ozawa) and a
nonparametric kinetic method (NPK). This last one allowed an intrinsic separation of the temperature, respective conversion
dependence on the reaction rate and less speculative discussions on the kinetic model. All there methods had furnished very
near values of the activation energy, this being an argument for a single thermooxidative degradation at the beginning (192–200 °C). 相似文献
5.
H. M. Ye N. Ren H. Li J. J. Zhang S. J. Sun L. Tian 《Journal of Thermal Analysis and Calorimetry》2010,101(1):205-211
The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single
crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process
of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double
equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH
≠, ΔG
≠, and ΔS
≠) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated. 相似文献
6.
Gabriel Lima Barros de Araujo Dalva Lucia Araujo de Faria Márcio Henrique Zaim Flávio Machado de Souza Carvalho Fabio Ramos Dias de Andrade Jivaldo do Rosario Matos 《Journal of Thermal Analysis and Calorimetry》2010,102(1):233-241
Tibolone polymorphic forms I (monoclinic) and II (triclinic) have been prepared by recrystallization from acetone and toluene,
respectively, and characterized by different techniques sensitive to changes in solid state, such as polarized light microscopy,
X-ray powder diffractometry, thermal analysis (TG/DTG/DSC), and vibrational spectroscopy (FTIR and Raman microscopy). The
nonisothermal decomposition kinetics of the obtained polymorphs were studied using thermogravimetry. The activation energies
were calculated through the Ozawa’s method for the first step of decomposition, the triclinic form showed a lower E
a (91 kJ mol−1) than the monoclinic one (95 kJ mol−1). Furthermore, Raman microscopy and DSC at low heating rates were used to identify and follow the thermal decomposition of
the triclinic form, showing the existence of three thermal events before the first mass loss. 相似文献
7.
Hélio Salvio Neto Jivaldo do Rosário Matos 《Journal of Thermal Analysis and Calorimetry》2011,103(1):393-399
In this work, TG/DTG and DSC techniques were used to the determination of thermal behavior of prednicarbate alone and associated
with glyceryl stearate excipient (1:1 physical mixture). TG/DTG curves obtained for the binary mixture showed a reduction
of approximately 37 °C to the thermal stability of drug (
T\textdm/\textdt = 0 \textDTG\textMax T_{{{\text{d}}m/{\text{d}}t = 0\,{\text{DTG}}}}^{\text{Max}} ). The disappearance of stretching band at 1280 cm−1 (νas C–O, carbonate group) and the presence of streching band with less intensity at 1750 cm−1 (νs C–O, ester group) in IR spectrum obtained to the binary mixture submitted at 220 °C, when compared with IR spectrum of drug
submitted to the same temperature, confirmed the chemical interaction between these substances due to heating. Kinetics parameters
of decomposition reaction of prednicarbate were obtained using isothermal (Arrhenius equation) and non-isothermal (Ozawa)
methods. The reduction of approximately 45% of activation energy value (E
a) to the first step of thermal decomposition reaction of drug in the 1:1 (mass/mass) physical mixture was observed by both
kinetics methods. 相似文献
8.
Piotr Szynkaruk Marek Wesolowski Malgorzata Samson-Rosa 《Journal of Thermal Analysis and Calorimetry》2010,102(2):505-512
Thermal decomposition of magnesium salts of organic acids used in medicine (Mg acetate, Mg valproate, Mg lactate, Mg citrate,
Mg hydrogen aspartate, Zn hydrogen aspartate) was analyzed by thermoanalytical, calorimetrical, and computational methods.
Thermoanalytical studies were performed with aid of a derivatograph. 50-, 100-, and 200-mg samples were heated in a static
air atmosphere at a heating rate of 3, 5, 10, and 15 °C min−1 up to the final temperature of 700–900 °C. By differential thermal analysis (DTA), thermogravimetry (TG), and derivative
thermogravimetry (DTG) methods, it has been established that thermal decomposition of the salts under study occurs via two
stages. The first stage (dehydratation) was distinctly marked on the thermoanalytical curves. Calorimetrical studies were
carried out by using of a heat-flux Mettler Toledo differential scanning calorimetry (DSC) system. Ten milligram samples of
compounds under study were heated in the temperature range from 20 to 400 °C at a heating rate of 10 and 20 °C min−1 under an air stream. The studies showed that the values of transitions heats and enthalpies of dehydration for investigated
salts varied with the increasing of heating rate. For chemometric evaluation of thermoanalytical results, the principal component
analysis (PCA) was applied. This method revealed that points on PC1 versus PC2 diagrams corresponding to the compounds of
similar chemical constitution are localized in the similar ranges of the first two PC’s values. This proves that thermal decomposition
reflects similarity in the structure of magnesium salts of organic acids. 相似文献
9.
Ju-Lan Zeng Sai-Bo Yu Bo Tong Li-Xian Sun Zhi-Cheng Tan Zhong Cao Dao-Wu Yang Jing-Nan Zhang 《Journal of Thermal Analysis and Calorimetry》2011,103(3):1087-1093
An N-tert-butyloxycarbonylated organic synthesis intermediate, (S)-tert-butyl 1-phenylethylcarbamate, was prepared and investigated by means of differential scanning calorimetry (DSC) and thermogravimetry
(TG). The molar heat capacities of (S)-tert-butyl 1-phenylethylcarbamate were precisely determined by means of adiabatic calorimetry over the temperature range of 80-380 K.
There was a solid–liquid phase transition exhibited during the heating process with the melting point of 359.53 K. The molar
enthalpy and entropy of this transition were determined to be 29.73 kJ mol−1 and 82.68 J K−1 mol−1 based on the experimental C
p–T curve, respectively. The thermodynamic functions, [HT0 - H298.150 H_{T}^{0} - H_{298.15}^{0} ] and [ST0 - S298.150 S_{T}^{0} - S_{298.15}^{0} ], were calculated from the heat capacity data in the temperature range of 80–380 K with an interval of 5 K. TG experiment
showed that the pyrolysis of the compound was started at the temperature of 385 K and terminated at 510 K within one step. 相似文献
10.
K. E. Ozbas 《Journal of Thermal Analysis and Calorimetry》2008,93(2):641-649
In this study, the relationship between particle size and pyrolysis characteristics of Elbistan lignite was examined by using
the thermogravimetric (TG/DTG) and differential thermal analysis (DTA) techniques. Lignite samples were separated into different
size fractions. Experiments were conducted at non-isothermal conditions with a heating rate of 10°C min−1 under nitrogen atmosphere up to 900°C. Pyrolysis regions, maximum pyrolysis rates and characteristic peak temperatures were
determined from TG/DTG curves. Thermogravimetric data were analyzed by a reaction rate model assuming first-order kinetics.
Apparent activation energy (E) and Arrhenius constant (A
r) of pyrolysis reaction of each particle size fraction were evaluated by applying Arrhenius kinetic model. The apparent activation
energies in the essential pyrolysis region were calculated as 27.36 and 28.81 kJ mol−1 for the largest (−2360+2000 μm) and finest (−38 μm) particle sizes, respectively. 相似文献
11.
Fabiana S. Felix L. C. Cides da Silva L. Angnes J. R. Matos 《Journal of Thermal Analysis and Calorimetry》2009,95(3):877-880
The thermal decomposition of salbutamol (β2 — selective adrenoreceptor) was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry
(TG/DTG). It was observed that the commercial sample showed a different thermal profile than the standard sample caused by
the presence of excipients. These compounds increase the thermal stability of the drug. Moreover, higher activation energy
was calculated for the pharmaceutical sample, which was estimated by isothermal and non-isothermal methods for the first stage
of the thermal decomposition process. For isothermal experiments the average values were E
act=130 kJ mol−1 (for standard sample) and E
act=252 kJ mol−1 (for pharmaceutical sample) in a dynamic nitrogen atmosphere (50 mL min−1). For non-isothermal method, activation energy was obtained from the plot of log heating rates vs. 1/T in dynamic air atmosphere (50 mL min−1). The calculated values were E
act=134 kJ mol−1 (for standard sample) and E
act=139 kJ mol−1 (for pharmaceutical sample). 相似文献
12.
Özlem Özen Karakuş Gülbanu Koyundereli Çilgi Hasalettin Deligöz 《Journal of Thermal Analysis and Calorimetry》2011,105(1):341-347
In the present study, thermal decomposition of mono- and di-azocalix[4]arene derivatives (A1–A8 and B1–B8) was investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and derivative thermogravimetry
(DTG). The exclusion of methanol, hydrolysis of benzoyl ester and methyl ketone groups in lower rim, and decomposition of azo groups in upper rim have occurred during thermal analysis, consecutively. The thermal decomposition degrees amount of volatile pyrolysis products
were determined in air atmosphere using TG, DTA and DTG curves. In conclusion, the thermal analyses of azocalix[4]arenes demonstrated
that its stability depends on the substituted groups and their positions in the calix[4]arene structure. 相似文献
13.
P. R. Oliveira H. K. Stulzer L. S. Bernardi S. H. M. Borgmann S. G. Cardoso M. A. S. Silva 《Journal of Thermal Analysis and Calorimetry》2010,100(1):277-282
In the present work, the thermal decomposition of sibutramine hydrochloride monohydrate (SBT) (an appetite suppressant agent)
was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG). Solid-state
characterization was carried out by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), scanning electron
microscopy (SEM) and X-ray powder diffraction (XRPD). Isothermal and non-isothermal methods were employed to determine the
kinetic data of decomposition process. From isothermal experiments, activation energy (Ea) can be obtained from slope of ln t versus 1/T, and the value obtained was 96.06 and 101.43 kJ mol−1 in N2 and air atmospheres, respectively. For non-isothermal method Ea can be obtained from plot of logarithms of heating rates, as a function of inverse of temperature, resulting in a value
of 96.56 and 98.22 kJ mol−1 in N2 and air atmospheres, respectively. The compatibilities of several commonly used pharmaceutical excipients (microcrystalline
cellulose, magnesium stearate, colloidal silicon dioxide, lactose monohydrate) and empty hard-gelatin capsules with SBT were
evaluated using DSC. The 1:1 physical mixtures of these excipients with SBT showed physical interaction of the drug with magnesium
stearate. On the other hand, DRIFT results did not evidence any chemical modifications. 相似文献
14.
F. Sahnoune N. Saheb B. Khamel Z. Takkouk 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1067-1072
Thermal analysis techniques remain important tools amongst the large variety of methods used for analysis of the dehydroxylation
of kaolinite. In the present study, the kinetics of dehydroxylation of Algerian kaolinite, wet ball milled for 5 h followed
by attrition milling for 1 h, was investigated using differential thermal analysis (DTA) and thermogravimetry (TG). Experiments
were carried out between room temperature and 1350 °C at heating rates of 5, 10 and 20 °C min−1. The temperature of dehydroxylation was found to be around 509 °C. The activation energy and frequency parameter evaluated
through isothermal DTA treatment were 174.69 kJ mol−1 and 2.68 × 109 s−1, respectively. The activation energies evaluated through non-isothermal DTA and TG treatments were 177.32 and 177.75 kJ mol−1, respectively. Growth morphology parameters n and m were found to be almost equal to 1.5. 相似文献
15.
Alexandra Ioiţescu Gabriela Vlase T. Vlase G. Ilia N. Doca 《Journal of Thermal Analysis and Calorimetry》2009,96(3):937-942
The synthesis of four types of hydroxyapatite synthesized from calcium chloride and four different organic phosphites is presented.
The method of synthesis chosen is the sol–gel route, which has a number of advantages compared to other methods, like the
intimate contact between reactants and the milder synthesis conditions. The samples were thermally treated, the TG/DTG/DTA
curves being obtained at four heating rates, namely: 7, 10, 12 and 15 °C min−1. The samples were characterized before and after the thermal treatment using FT-IR analysis. The FT-IR spectra certified
that the formed compounds represent hydroxyapatite. Based on the information from the TG curves and IR spectra interpretation,
a reaction mechanism was proposed. 相似文献
16.
17.
Thermal
degradation of wood treated with flame retardants 总被引:2,自引:0,他引:2
Wood,
one of the most flammable materials, was treated with various compounds containing
nitrogen, phosphorus, halogens, and boron. For a study of flame retardance
from the standpoint of thermal degradation, the samples were subjected to
thermogravimetry (TG), differential thermal analysis (DTA) and differential
thermogravimetry (DTG) in nitrogen to determine if there were any characteristic
correlations between thermal degradation behaviors and the level of flame
retardance. From the resulting data, kinetic parameters for different stages
of thermal degradation are obtained using the method of Broido. The energies
of activation for the decomposition of samples are found to be from 72 to
109 kJ mol–1. For wood and modified wood,
the char yields are found to increase from 10.2 to 30.2%, LOI from 18 to 36.5,
which indicates that the flame retardance of wood treated with compounds is
improved. The flame retardant mechanism of different compounds has also been
proposed. 相似文献
18.
This study investigates the effect of ammonium bromide and/or ammonium chloride as nondurable finishes on the flammability
of 100% cotton fabric, (woven construction, weighing 144 g m−2). The laundered bone-dried, weighed fabrics were impregnated with suitable concentrations of aqueous ammonium bromide and/or
ammonium chloride solutions by means of squeeze rolls and dried at 110°C for 30 min. Afterwards they were cooled in a desiccator,
re-weighed with an analytical precision and kept under ordinary conditions before the fulfillment of the vertical flame test.
The optimum add-on values to impart flame retardancy expressed in g anhydrous ammonium bromide and ammonium chloride per 100
g fabrics were individually obtained to be about 3.5–3.89 and 17.31–17.99%, respectively.
Thermogravimetric analysis (TG/DTG) of pure cotton and the salts treated fabrics were fulfilled and their curves were compared
and commented. The results obtained comply with free radical theory, and also proved the superiority of ammonium bromide for
the impartation of flame-retardancy in regard to ammonium chloride. 相似文献
19.
Sahra C. Lemos Silmar J. S. Franchi Adelino V. G. Netto Antonio E. Mauro Oswaldo Treu-Filho Regina C. G. Frem Eduardo Tonon de Almeida Cláudia Torres 《Journal of Thermal Analysis and Calorimetry》2011,106(2):391-397
This work describes the synthesis, characterization, and the thermal behavior investigation of four palladium(II) complexes
with general formulae [PdX2(mba)2], in which mba = N-methylbenzylamine and X = OAc− (1), Cl− (2), Br− (3) or I− (4). The complexes were characterized by elemental analysis, infrared vibrational spectroscopy, and 1H nuclear magnetic resonance. The stoichiometry of the complexes was established by means of elemental analysis and thermogravimetry
(TG). TG/DTA curves showed that the thermodecomposition of the four complexes occurred in 3–4 steps, leading to metallic palladium
as final residue. The palladium content found in all curves was in agreement with the mass percentages calculated for the
complexes. The following thermal stability sequence was found: 3 > 2 > 4 > 1. The geometry optimization of 1, 2, 3, and 4, calculated using the DFT/B3LYP method, yielded a slightly distorted square planar environment around the Pd(II) ion made
by two anionic groups and two nitrogen atoms from the mba ligand (N1 and N2), in a trans-relationship. 相似文献
20.
Marcelo Kobelnik Douglas Lopes Cassimiro Diógenes dos Santos Dias Clóvis Augusto Ribeiro Marisa Spirandeli Crespi 《Journal of Thermal Analysis and Calorimetry》2011,106(3):711-715
The jerivá is a well-known fruit, which belongs to the Arecaceae family, Syagrus romanzoffiana species frequently found in Brazil. Extraction of the jerivá oil was carried out, and the fatty acid profile of this oil
indicates the linoleic and oleic acid presence, around 29.35 and 28.89%, respectively. Thermogravimetry (TG), derivative thermogravimetry
(DTG), and differential scanning calorimetry (DSC) were used to characterize this oil. Additionally, this oil was evaluated
by DSC from 25 to −80 °C, and the crystallization behavior was verified. Details concerning the thermal behavior as well as
data of kinetic parameters of these stages have been described here. The obtained data were evaluated, and the values were
plotted in activation energy (E
a/kJ mol−1) in function of the conversion degree (α). 相似文献