共查询到20条相似文献,搜索用时 31 毫秒
1.
Motori A. Montanari G. C. Saccani A. Peruzzotti F. 《Journal of Thermal Analysis and Calorimetry》2003,72(3):1159-1166
Two thermal analysis techniques (isothermal differential calorimetry and isothermal thermogravimetric analysis) are used as
analytical methods for short-term thermal endurance characterization of polymeric materials, used for electrical insulation.
These techniques are applied to commercial grade ethylene-propylene rubber and polyvinyl chloride. It is shown that thermogravimetric
analysis provides very satisfactory results, independently of the degradation reactions which take place in the material.
Calorimetry proves to be effective only for polymers (such as polyolefins) in which oxidation is the largely prevailing degradation
mechanism in the test and service temperature ranges.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG/FT-IR) was used to investigate the stabilizing action
of 3-(2,4-dibromophenylazo)-9-(2,3-epoxypropane)carbazole on the degradation of poly(vinyl chloride) (PVC). It was found that
this secondary stabilizer increases the initial temperature of hydrogen chloride evolution (the main process responsible for
PVC decomposition), thereby allowing its application for novel PVC systems with enhanced thermal stability. The application
of TG/FT-IR technique for study of the thermal properties of polymeric materials offers additional characterization options
in comparison with thermogravimetry, if used alone.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Acid and thermal treatments of lateritic bauxites 总被引:1,自引:0,他引:1
H2SO4 and HCl processes accompanied by thermal treatments at different stages are described for the industrial extraction of alumina
from lateritic clay minerals, especially from kaolinite, an important component of lateritic bauxites. The effects of calcination
at high temperatures on the pretreatments of the raw lateritic materials, as well as on the thermal transformations of the
products (salts) resulting from the acid treatments of lateritic bauxites are analyzed. Beside energetic considerations, separation
methods of Al from Fe and from other lateritic-metallic components are emphasized in the extraction and purification processes.
The mechanism of a controlled HCl-extracting treatment performed on iron-bearing kaolinite is described, as well as its characterization
by IR and DTA ad hoc methods, enabling to distinguish between Al and Fe in the structure of lateritic kaolinite. The location
and quantification of Al in the structure of lateritic goethite is also considered.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Barontini F. Marsanich K. Cozzani V. 《Journal of Thermal Analysis and Calorimetry》2004,78(2):599-619
The TG-FTIR technique was used in the present study to investigate the thermal degradation behaviour of materials containing
brominated flame retardants under fire conditions. Time-temperature profiles and oxygen concentrations typical of selected
fire scenarios were reproduced in the thermogravimetric analyzer, while the characterization of the gaseous products generated
was performed by the simultaneous FTIR analysis. FTIR analysis combined with the use of specific calibration procedures allowed
the quantitative estimation of the gaseous products evolved as a function of experimental conditions. The results obtained
allowed the straightforward assessment and the comparison of the quantities of hydrogen bromide formed in the oxidation and
thermal degradation of pure brominated flame retardants and of flame retarded materials of industrial interest. Hydrogen bromide
yields resulted dependent on the experimental conditions used, such as oxygen concentration and heating rate. Although TG-FTIR
experiments only provide a representation of the actual heterogeneous combustion products in real fire conditions, the coupled
TG-FTIR technique proved to be a straightforward experimental methodology allowing one to obtain reference data on the nature
and quantities of the macropollutants generated in a fire.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Y. Pelovski 《Journal of Thermal Analysis and Calorimetry》2000,60(1):53-58
The development of equipment for thermal analysis has opened up new areas for applications in science, industrial practice
and environment studies. On the basis of the literature and information from equipment producers, the directions for the use
of thermal analysis in research and practice are classified. Special attention is paid to the possibilities of controlling
environmental pollution, and the stability and other properties of intermediate and final industrial products. It is stressed
that DSC and DTA systems can be successfully applied to determine enthalpy changes in raw materials and products as control
tests for their application. The advantages of coupled thermal systems for complex studies and the control of raw materials,
products and wastes are described.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
M. Lalia-Kantouri 《Journal of Thermal Analysis and Calorimetry》1998,52(3):1063-1075
The history of the Hellenic Society of Thermal Analysis (HSTA) is outlined. A review of thermal activities in Greece is presented,
concentrating on polymeric and inorganic materials, minerals and pharmaceuticals. Some examples are given.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Degradation of polymeric materials used in nuclear power plants (NPP), especially polymeric cable insulation materials, in
the course of their service can be monitored by measuring their properties by DSC, mainly oxidative induction time — OIT.
The studied materials were in-laboratory aged by applying main stressors that act in NPP — ionising radiation and temperature.
The dependence of OIT on radiation and thermal degradation of polymeric material was determined. The OIT values have been
compared to elongation at break as a property that directly reflects the functionality of the studied material. The comparison
of monitored OIT of real cable samples taken from NPP with dependencies on how the OIT values change with the elongation at
break, makes possible to establish the extent of cable degradation. This method can be considered as a suitable and effective
technique for lifetime assessment not only of cable insulations but also of many other plastics.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
R. Kunze D. Neubert K. Brademann-Jock U. Erhardt 《Journal of Thermal Analysis and Calorimetry》1998,53(1):27-33
A simultaneous thermal analysis/mass spectroscopy system was used for the determination of halogenated hydrocarbons in polymeric
foam insulation materials. The investigation of ten different polymeric foams show that this equipment is a sensitive and
reliable tool for the identification and determination of the bubbling agent. The results are compared with the Purge and
Trap method.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
As a part of our continuing interest in the preparation of multifunctional polymeric materials and evaluation of their potential in biomedical and environmental field, a survey on new polymeric systems susceptible to bioerosion and/or biodegradation attack is presented. In particular attention has been focused on the preparation and characterization of the following classes of polymeric materials: 1) hydroxyl-containing polyesters; 2) functionalized cyclodextrins; 3) hydrophilic polymers containing carboxylic groups; 4) hydrogels for the release of phytodrugs; 5) hybrid polymeric materials; 6) synthetic and semisynthetic polyfunctional polymeric materials for the removal of uremic toxins. A few examples of the use of these polymers in the controlled release of drugs and as coadjuvants in the chronic renal failure treatment will be also presented. 相似文献
10.
S. Cebulak B. Smieja-Król S. Duber M. Misz A. W. Morawski 《Journal of Thermal Analysis and Calorimetry》2004,77(1):201-206
The paper presents the applicability of Oxyreactive Thermal Analysis (OTA) for the investigation of different kinds of carbon
matter. For comparative reasons and more precise interpretation, along with OTA some physico-chemical properties of analyzed
materials were used as the methods commonly applied for the investigations.
The carbon materials of both natural (anthracites, graphite and diamonds) and synthetic origin (active carbon, glass carbon,
expanded graphite, soot and synthetic diamonds) were investigated.
It was stated that there is close relationship between structure parameters and physico-chemical properties and the thermal
reactivity within the investigated groups of carbon matters. The results show that OTA can be accepted as a good investigative
way for such materials.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Balek V. Šubrt J. Mitsuhashi T. Beckman I. N. Györyová K. 《Journal of Thermal Analysis and Calorimetry》2002,67(1):15-35
The paper reviews the actual state of the development and use of emanation thermal analysis (ETA). Examples of its recent applications are presented. The advantages of ETA in the microstructure characterization of materials under in situ conditions of their heat treatment are outlined.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
12.
Inverse numerical techniques have been applied in a range of different thermal studies in the past. These techniques require
measurements of boundary conditions and temperatures at known position within the sample in order to determine thermal properties
of the material of interest. Typically, they have been applied to highly specific applications and designs. In the current
work the authors have designed a novel instrument in order to measure apparent specific heats of a range of different materials
during continuous heating. Measurements of surface heat flux, surface and centre temperatures of the sample were obtained
under controlled heating for temperatures of up to 1000°C. Measured data was used to quantify specific and latent heats by
employing inverse numerical modelling technique. The instrument was calibrated with calorimetric calibration materials and
results were compared with the literature values. The average experimental error was estimated to be approximately 0.9% for
the reaction peak temperatures and 1.7% for the latent heats. Detailed experimental and calculation procedures as well as
measured results of specific heat and enthalpy for a number of materials are presented here.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
A. Zanier 《Journal of Thermal Analysis and Calorimetry》1999,56(3):1389-1396
Although thermogravimetric analysis (TG) has become an indispensable tool for the analysis and characterization of materials,
its scope is limited as no information is obtained about the qualitative aspects of the evolved gases during the thermal decomposition.
For processes involving mass loss, a powerful technique to provide this missing information is Fourier transform infrared
spectroscopy (FT-IR) in combination with TG. It supplies a comprehensive understanding of thermal events in a reliable and
meaningful way as data are obtained from a single sample under the same conditions.
The coupling TG/FT-IR is used in fuel analysis for the identification of residual volatiles, to determine their sequence of
release and to resolve thermogravimetric curves. In this work, the usefulness of TG/FT-IR for characterizing middle distillate
fuel residues is illustrated with some typical examples of recent application. A Bio-Rad FTS 25 FT-IR spectrometer coupled
with a TA Instruments TGA 2950 thermogravimetric analyzer was used for data aquisition.
The results obtained demonstrate the utility of this combined technique in determining the decomposition pathway of tarry
materials at various stages of pyrolysis, thereby allowing new insights into the complex thermal behaviour of hydrocarbon
residual systems.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
J. Podìbradská R. Černý J. Drchalová P. Rovnaníková J. Šesták 《Journal of Thermal Analysis and Calorimetry》2004,77(1):85-97
Methods of thermal analysis are employed in a study of the high-temperature properties of three different types of glass fiber
reinforced cement composites together with the measurements of their thermal and hygric parameters. First, basic TG and DTG
measurements are carried out to get the first insight into the high-temperature behavior of the analyzed materials. Then,
mercury porosimetry and scanning electron microscopy of specimens subjected to the temperatures of 600 and 800°C are performed
and compared to the reference specimens not exposed to any thermal load. Finally, measurements of thermal and hygric parameters
of the studied materials are done and matched with the results of the material characterization experiments. Three main effects
are found to influence the thermal and hygric properties of the analyzed materials. The first is the decomposition of the
cement matrix, which is clearly a negative factor. The second is the positive effect of the presence of fibers that could
partially keep the cement matrix together even after significant decomposition of cement hydration products. The third important
factor affecting the thermal and hygric properties is the composition of the particular materials. The application of vermiculite
aggregates instead of sand is found to be clearly positive because of its porous character leading to the bulk density decrease
without worsening the other properties. Also, wollastonite aggregates are a better choice than sand because of its fibrous
character that could partially magnify the effect of fiber reinforcement.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Núñez Regueira Lisardo Núñez M. R. Villanueva M. Rial B. 《Journal of Thermal Analysis and Calorimetry》2002,70(1):29-35
The influence of agents originated in a municipal landfill on the thermal degradation of a polymeric system composed of a
diglycidyl ether of bisphenol A (n=0) and 1,2-diaminecyclohexane was studied by thermogravimetric analysis (TG) in order to obtain the lifetime of this material
before and after being attacked. The different data obtained were analyzed to check the resistance of these materials to chemical
attack and the possibility of their use as coating materials in plants where those reagents were present. At the optimum temperature
of service for this material, 373.16 K, the lifetimes obtained from the experimental results were 2633 years and 2135 years,
respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Ye J. Kojima N. Furuya K. Munakata F. Okada A. 《Journal of Thermal Analysis and Calorimetry》2002,69(3):1031-1036
A micro-thermal analysis technique was applied to investigate advanced silicon nitride materials, which exhibit high thermal
conductivity. Local thermal properties in the microstructure were evaluated, and the grain boundaries were observed to have
lower thermal conductance than the Si3N4 grains. It was found that thermal conductance both in the grains and boundaries was lowered by the addition of the sintering
aid Al2O3, which is soluble in Si3N4 grains. This indicates that high thermal conductivity in silicon nitride ceramics is achieved both by grain growth, leading
to a reduction in boundary density, and by eliminating soluble elements in silicon nitride grains.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
A modified thermoanalyzer for investigation ferromagnetic materials as metals and alloys is described. Conventional analog
phase detection technique is replaced by specialized digital one which added some new outstanding features of the instrumentation.
Samples of the material can be investigated simultaneously by three methods: differential thermal analysis (DTA), thermal
dilatometry (TD) and thermomagnetometry (TMAG).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Mark H. P. M. van Lieshout Hans-Gerd Janssen Carel A. Cramers Martin J. J. Hetem Huub J. P. Schalk 《Journal of separation science》1996,19(4):193-199
Thermal treatment hyphenated with gas chromatography is a versatile and powerful tool in the study of polymer characterization. An inexpensive system where thermal treatment at different temperatures occurs inside a Programmable Temperature Vaporization injector (PTV) is described. The samples investigated, commercial plastics, are complex mixtures that contain several polymers and additives. These plastics as well as their pure constituents are subjected to multi-step thermal treatment. The individual chromatograms of the various constituents of the polymeric sample are correlated with those of the final material in order to identify additives (thermal desorption) and degradation products (pyrolysis). Results obtained with the new method indicate the interesting potentials of the technique for the characterization of polymer compositions. Reproducibility of absolute and relative peak areas has been considered and found to be acceptable. The absence of a heated transfer line and switching valves, which are always present in conventional set-ups, eliminates the risk of losses of high molecular weight components. Further advantages of the technique proposed are simplicity, versatility, and its inexpensive nature. 相似文献
19.
Vito Gigante Laura Aliotta Maria Beatrice Coltelli Patrizia Cinelli Luigi Botta Francesco Paolo La Mantia Andrea Lazzeri 《Journal of polymer science. Part A, Polymer chemistry》2020,58(23):3264-3282
The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheological perspective. An optimized PLA/PBAT ratio was chosen as the polymeric basis to obtain a biodegradable formulation by adding a biobased plasticizer and appropriate fillers to produce a micrometer film with tailored flexibility and tear resistance. The processing technology involved flat-die extrusion, followed by calendering. The tearing resistance of the produced film was investigated, and the results were compared with literature data. A study on the essential work of fracture was implemented to explore the mode III out-of-plane fracture resistance starting from a trouser tear test. 相似文献
20.
Pérez-Maqueda L. A. Balek V. Poyato J. Pérez-Rodríquez J. L. Šubrt J. Bountsewa I. M. Beckman I. N. Málek Z. 《Journal of Thermal Analysis and Calorimetry》2003,71(3):715-726
Emanation thermal analysis (ETA), thermogravimetry, DTA and XRD were used in thermal characterization of natural vermiculite
(Santa Olalla, Huelva, Spain) and of Na+- and - exchanged vermiculite samples during heating in air in the range 25-1100°C. A good agreement between the results of
these methods was found. Changes in the radon release rate measured by ETA, which reflected the decrease and collapse of the
interlayer space after the release of water as well as the formation of new crystalline phases were evaluated using a mathematical
model. The model used for the evaluation was found suitable for the quantitative characterization of microstructure changes
during in situ conditions of heating of vermiculite samples.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献