共查询到20条相似文献,搜索用时 31 毫秒
1.
Uzma K. H. Bangi A. Parvathy Rao H. Hirashima A. Venkateswara Rao 《Journal of Sol-Gel Science and Technology》2009,50(1):87-97
Experimental results on the physico-chemical properties of ambiently dried sodium silicate based aerogels catalyzed with various
acids are reported. The aerogels were prepared by hydrolysis and polycondensation of sodium silicate followed by subsequent
washings, surface chemical modification and ambient pressure drying using 10 various acid catalysts consisting of strong and
weak acids. The strength and concentration of acids have the major effect on the gelation of sol and hence the physico-chemical
properties of the silica aerogels. Strong acids such as HCl, HNO3 and H2SO4 resulted in shrunk (70–95%) aerogels whereas weak acids such as citric and tartaric acids resulted in less shrunk (34–50%)
aerogels. The physical properties of silica aerogels were studied by measuring bulk density, volume shrinkage (%), porosity
(%), pore volume, thermal conductivity, contact angle with water, Transmission Electron Microscopy (TEM), Atomic Absorption
Spectroscopy (AAS), Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric-Differential Thermal (TG-DT) analyses
and N2 adsorption–desorption BET surface analyzer. The best quality silica aerogels in terms of low density (0.086 g/cm3), low volume shrinkage (34%), high porosity (95%), low thermal conductivity (0.09 W/m K) and hydrophobic (148°) were obtained
for molar ratio of Na2SiO3:H2O:citric acid:TMCS at 1:146.67:0.72:9.46 with 20 min gelation time. The resulting aerogels exhibited the thermal stability
up to around 420 °C. 相似文献
2.
Je Kyun Lee George L. Gould Wendell Rhine 《Journal of Sol-Gel Science and Technology》2009,49(2):209-220
Less fragile lightweight nanostructured polyurea based organic aerogels were prepared via a simple sol–gel processing and
supercritical drying method. The uniform polyurea wet gels were first prepared at room temperature and atmospheric pressure
by reacting different isocyanates with polyamines using a tertiary amine (triethylamine) catalyst. Gelation kinetics, uniformity
of wet gel, and properties of aerogel products were significantly affected by both target density (i.e., solid content) and
equivalent weight (EW) ratio of the isocyanate resin and polyamine hardener. A supercritical carbon dioxide (CO2) drying method was used to extract solvent from wet polyurea gels to afford nanoporous aerogels. The thermal conductivity
values of polyurea based aerogel were measured at pressures from ambient to 0.075 torr and at temperatures from room temperature
to −120 °C under a pressure of 8 torr. The polyurea based aerogel samples demonstrated high porosities, low thermal conductivity
values, hydrophobicity properties, relatively high thermal decomposition temperature (~270 °C) and low degassing property
and were less dusty than silica aerogels. We found that the low thermal conductivities of polyurea based aerogels were associated
with their small pore sizes. These polyurea based aerogels are very promising candidates for cryogenic insulation applications
and as a thermal insulation component of spacesuits. 相似文献
3.
Guangwu Liu Bin Zhou Xingyuan Ni Jun Shen Guangming Wu Ai Du Guoqing Zu 《Journal of Sol-Gel Science and Technology》2012,62(2):126-133
The experimental results of thermal process on the microstructural and physical properties of ambient pressure dried hydrophobic
silica aerogel monoliths are reported and discussed. With sodium silicate as precursor, ethanol/hexamethyldisiloxane/hydrochloric
acid as surface modification agent, the crack-free and high hydrophobic silica aerogel monoliths was obtained possessing the
properties as low density (0.096 g/cm3), high surface area (651 m2/g), high hydrophobicity (~147°) and low thermal conductivity (0.0217 Wm/K). Silica aerogels maintained hydrophobic behavior
up to 430 °C. After a thermal process changing from room temperature to 300 °C, the hydrophobicity remained unchanged (~128°),
of which the porosity was 95.69% and specific density about 0.094 g/cm3. After high temperature treatment (300–500 °C), the density of final product decreased from 0.094 to 0.089 g/cm3 and porosity increased to 96.33%. With surface area of 466 m2/g, porosity of 91.21% and density about 0.113 g/cm3, silica aerogels were at a good state at 800 °C. Thermal conductivities at desired temperatures were analyzed by the transient
plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.0217 to 0.0981 Wm/K
as temperature increased to 800 °C, revealed an excellent heat insulation effect during thermal process. 相似文献
4.
Ray L. Frost János Kristóf Erzsébet Horváth 《Journal of Thermal Analysis and Calorimetry》2009,98(3):749-755
Controlled rate thermal analysis (CRTA) technology offers better resolution and a more detailed interpretation of the decomposition
processes of a clay mineral such as sepiolite via approaching equilibrium conditions of decomposition through the elimination
of the slow transfer of heat to the sample as a controlling parameter on the process of decomposition. Constant-rate decomposition
processes of non-isothermal nature reveal changes in the sepiolite as the sepiolite is converted to an anhydride. In the dynamic
experiment two dehydration steps are observed over the ~20–170 and 170–350 °C temperature range. In the dynamic experiment
three dehydroxylation steps are observed over the temperature ranges 201–337, 337–638 and 638–982 °C. The CRTA technology
enables the separation of the thermal decomposition steps. 相似文献
5.
Digambar Y. Nadargi Sanjay S. Latthe A. Venkateswara Rao 《Journal of Sol-Gel Science and Technology》2009,49(1):53-59
The properties of silica aerogels are highly dependent on the post-treatment steps like gel washing, gel aging and gel drying.
The experimental results of the studies on one of the post-treatment steps i.e. gel aging effect on the physical and microstructural
properties of methyltrimethoxysilane (MTMS) based silica aerogels, are reported. These hybrid aerogels were prepared by two
step sol–gel process followed by supercritical drying. The molar ratio of MeOH/MTMS (M) was varied from 7 to 35 by keeping
the H2O/MTMS (W) molar ratio constant at 4. The as prepared alcogels of different molar ratios were aged from 0 to 5 days. It was
observed that 2 days of gel aging period is the optimum gel aging period for good quality aerogels in terms of low density,
less volume shrinkage and high porosity. The well tailored network matrix with low density (0.04 g/cm3), less volume shrinkage (4.5%), low thermal conductivity (0.05 W/mK) and high porosity (98.84 %) was obtained for 2 days
of gel aging period of M = 35. Further, the gelation time varied from 8 to 1 h depending on the M values. The gelation time was being more for lesser
M values. The aerogels were characterized by bulk density, porosity, volume shrinkage, thermal conductivity, Scanning Electron
Microscopy and the Fourier Transform Infrared spectroscopy. 相似文献
6.
Thermoanalytical investigations TGA/DTG/DSC of polyamide–imide enamel after thermal ageing have been presented. The lifetimes
at 260, 270, 280, 290, 300 °C were determined. The thermograms of the enamels after attaining of their lifetimes much depend
on the ageing temperature. The temperatures of 5% loss of mass that much increase after thermal ageing appear the most sensitive
indicator of ageing rate. The residue of mass at 800 °C increases after ageing, even to 27%, due to diffusion of copper ions
from the conductor into enamel during annealing. The copper contents in aged coatings could be also an indicator of ageing
rate. 相似文献
7.
Anna Rita Campanelli Aldo Domenicano Fabio Ramondo István Hargittai 《Structural chemistry》2011,22(2):361-369
The molecular structure of triphenylsilane has been investigated by gas-phase electron diffraction and theoretical calculations.
The electron diffraction intensities from a previous study (Rozsondai B, Hargittai I, J Organomet Chem 334:269, 1987) have
been reanalyzed using geometrical constraints and initial values of vibrational amplitudes from calculations. The free molecule
has a chiral, propeller-like equilibrium conformation of C
3 symmetry, with a twist angle of the phenyl groups τ = 39° ± 3°; the two enantiomeric conformers easily interconvert via three
possible pathways. The low-frequency vibrational modes indicate that the three phenyl groups undergo large-amplitude torsional
and out-of-plane bending vibrations about their respective Si–C bonds. Least-squares refinement of a model accounting for
the bending vibrations gives the following bond distances and angles with estimated total errors: r
g(Si–C) = 1.874 ± 0.004 ?, 〈r
g(C–C)〉 = 1.402 ± 0.003 ?, 〈r
g(C–H)〉 = 1.102 ± 0.003 ?, and ∠aC–Si–H = 108.6° ± 0.4°. Electron diffraction studies and MO calculations show that the lengths of the Si–C bonds in H4−n
SiPh
n
molecules (n = 1–4) increase gradually with n, due to π → σ*(Si–C) delocalization. They also show that the mean lengths of the ring C–C bonds are about 0.003 ? larger
than in unsubstituted benzene, due to a one hundredth angstrom lengthening of the Cipso–Cortho bonds caused by silicon substitution. A small increase of r(Si–H) and decrease of the ipso angle with increasing number of phenyl groups is also revealed by the calculations. 相似文献
8.
The experimental results by using various exchanging solvents in the preparation of two step (acid and base) processed ambient
pressure dried hydrophobic silica aerogels, are reported. Silica alcogels were prepared by hydrolysis with oxalic acid and
condensation with NH4OH of ethanol diluted tetraethylorthosilicate (TEOS) precursor and hexamethyldisilazane(HMDZ) methylating agent. The exchanging
solvents used were: hexane, cyclohexane, heptane, benzene, toluene and xylene. The physical properties such as % of volume
shrinkage, density, pore volume, % of porosity, thermal conductivity, % of optical transmission, surface area, pore size distribution
and contact angle (θ) of the silica aerogels with water, were measured as a function of EtOH/TEOS molar ratios (R) for all the exchanging solvents. It was found that the physical and hydrophobic properties of the silica aerogels strongly
depend on the nature of the solvent and R. Heptane solvent resulted in highly transparent (≈90% optical transmission at 700 nm for 1 cm thick sample), low density
(≈0.060 g/cm3), low thermal conductive (≈0.070 W/m·K), high % of porosity (97%), high surface area (750 m2/g), uniform porosity and hydrophobic (θ ≈ 160°) aerogels compared to other solvents. On the otherhand, xylene resulted in aerogels with higher hydrophobicity (θ ≈ 172°) among other solvents. 相似文献
9.
Interest in improving the optical transmission of sodium silicate-based aerogels by ambient pressure drying led to the synthesis of aerogels using a two-step sol–gel process. To produce optically transparent silica aerogel granules, NH4F (1 M) and HCl (4 M) were used as hydrolyzing and condensation catalysts, respectively. The silica aerogels were characterized by their bulk density, porosity (%), contact angle and thermal conductivity. Optical transmission of as synthesized aerogels was studied by comparing the photos of aerogel granules. Scanning electron microscopic study showed the presence of fractal structures in these aerogels. The degree of transparency in two step sol–gel process-based aerogels is higher than the conventional single step aerogels. The N2 adsorption–desorption analysis depicts that the two step sol–gel based aerogels have large surface areas. Optically transparent silica aerogels with a low density of ∼0.125 g/cc, low thermal conductivity of ∼0.128 W/mK and higher Brunauer, Emmett, and Teller surface area of ∼425 m2/g were obtained by using NH4F (1 M), HCl (4 M), and a molar ratio of Na2SiO3::H2O::trimethylchlorosilane of 1::146.67::9.46. The aerogels retained their hydrophobicity up to 500 °C. 相似文献
10.
Pooja Sawant S. Varma B. N. Wani S. R. Bharadwaj 《Journal of Thermal Analysis and Calorimetry》2012,107(1):189-195
In this article, the role of the preparation route and calcinations temperature on the thermal expansion and conductivity
of BaCe0.8Y0.2O3−δ (BCY) has been studied. In particular, the samples were synthesized by means of the solid-state reaction and by a sol–gel
route. BCY has been suggested as proton conducting electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs).
Proton conductivity strongly depends on the densification of the material as well as the crystal structure, which is generally
influenced by the preparation procedure. It was found that a single phase material could be achieved at 1000 °C for the samples
prepared through the sol–gel route with ~96% packing density. In case of ceramic route, single phase could be obtained at
higher temperatures (1200 °C) and does not lead to good density values. The ceramic synthesis produces BCY material in cubic
symmetry where as the gel–citrate complexation route leads to homogenous orthorhombic BCY. The conductivity measurements of
sample synthesized by two different routes were investigated by means of impedance spectroscopy and electron microscopy. A
comparative study of thermal expansion behavior of BCY synthesized by different route was carried out. 相似文献
11.
Ann M. Anderson Mary K. Carroll Emily C. Green Jason T. Melville Michael S. Bono 《Journal of Sol-Gel Science and Technology》2010,53(2):199-207
Hydrophobic silica aerogels have been prepared using the rapid supercritical extraction (RSCE) technique. The RSCE technique
is a one-step methanol supercritical extraction method for producing aerogel monoliths in 3 to 8 h. Standard aerogels were
prepared from a tetramethoxysilane (TMOS) recipe with a molar ratio of TMOS:MeOH:H2O:NH4OH of 1.0:12.0:4.0:7.4 × 10−3. Hydrophobic aerogels were prepared using the same recipe except the TMOS was replaced with a mixture of TMOS and one of
the following organosilane co-precursors: methytrimethoxysilane (MTMS), ethyltrimethoxysilane (ETMS), or propyltrimeth-oxysilane
(PTMS). Results show that, by increasing the amount of catalyst and increasing gelation time, monolithic aerogels can be prepared
out of volume mixtures including up to 75% MTMS, 50% ETMS or 50% PTMS in 7.5–15 h. As the amount of co-precursor is increased
the aerogels become more hydrophobic (sessile tests with water droplets yield contact angles up to 155°) and less transparent
(transmission through a 12.2-mm thick sample decreases from 83 to 50% at 800 nm). The skeletal and bulk density decrease and
the surface area increases (550–760 m2/g) when TMOS is substituted with increasing amounts of MTMS. The amount of co-precursor does not affect the thermal conductivity.
SEM imaging shows significant differences in the nanostructure for the most hydrophobic surfaces. 相似文献
12.
Zou Hantao Yi Changhai Wang Luoxin Liu Hongtao Xu Weilin 《Journal of Thermal Analysis and Calorimetry》2009,97(3):929-935
Thermogravimetric (TG), differential thermal analysis (DTA) and thermal degradation kinetics, FTIR and X-ray diffraction (XRD)
analysis of synthesized glycine–montmorillonite (Gly–MMT) and montmorillonite bound dipeptide (Gly–Gly–MMT) along with pure
Na–MMT samples have been performed. TG analysis at the temperature range 25–250 °C showed a mass loss for pure Na–MMT, Gly–MMT
and Gly–Gly–MMT of about 8.0%, 4.0% and 2.0%, respectively. DTA curves show the endothermic reaction at 136, 211 and 678 °C
in pure Na–MMT whereas Gly–MMT shows the exothermic reaction at 322 and 404 °C and that of Gly–Gly–MMT at 371 °C. The activation
energies of the first order thermal degradation reaction were found to be 1.64 and 9.78 kJ mol−1 for Gly–MMT and Gly–Gly–MMT, respectively. FTIR analyses indicate that the intercalated compounds decomposed at the temperature
more than 250 °C in Gly–MMT and at 250 °C in Gly–Gly–MMT. 相似文献
13.
Bansi Lal Sasmita K. Patro Shivani Singh 《Journal of Sol-Gel Science and Technology》2010,56(3):340-344
Bismuth silicon oxide (Bi12SiO20, BSO) nano crystalline powder was prepared by sol–gel technique using bismuth nitrate and tetraethyl orthosilicate as starting
materials. The prepared samples were sintered at various temperatures (750 °C maximum) and characteristic sillenite single
cubic phase with crystallite size ~38 nm (calculated from room temperature powder XRD measurements) was realized at 750 °C
sintering temperature. SEM analysis showed that the powder contains the nano-sized particles with almost spherical morphology.
The observed frequencies in room temperature FTIR spectrum could be assigned to Bi–O, Si–O and Bi–O–Si bonds. The FWHM (full
width at half maximum) of the diffraction peaks decreased while the intensity of FTIR absorption lines increased with the
increase in the sintering temperature indicating better bond formation and crystallization. The thermograph of the samples
recorded in the temperature range 50–1,000 °C showed almost no weight loss after ~575 °C further confirmed the conclusion
arrived at from XRD and FTIR analysis. The samples sintered at 750 °C showed about 50% absorbance in 400–600 nm region which
was consistent with the pale yellow color of the sample. Broad blue emission centered ~478 nm was observed when excited by
350 nm radiation from a Xe-lamp. The intensity of this broad emission band increased while its FWHM decreased with the increase
in sintering temperature. Self-trapped excitons could be responsible for this emission. 相似文献
14.
Nanocomposite ZnO–Ag thin film containing nano-sized Ag particles have been grown on glass substrate by spin-coating technique
using zinc acetate dihydrate as starting precursor in 2-propanol as solvent and monoethanolamine as stabilizer. Silver nanoparticles
were added in the ZnO sol using silver nitrate dissolved in ethanol-acetonitrile. Their structural, electrical, crystalline
size and optical properties were investigated as a function of preheating, annealing temperature and silver content. The results
indicated that the crystalline phase was increased with increase of annealing temperature up to 550 °C at optimum preheating
temperature of 275 °C. Thermal gravimetric differential thermal analysis results indicated that the decomposition of pure
ZnO and nanocomposite ZnO–Ag precursors occurred at 225 and 234 °C, respectively with formation of ZnO wurtzite crystals.
The scanning electron microscopy and atomic force microscopy revealed that the surface structure (the porosity and grain size)
of the ZnO–Ag thin film (the film thickness is about 379 nm) was changed compared to pure ZnO thin film. The result of transmission
electron microscopy showed that Ag particles were about 5 nm and ZnO particles 58 nm with uniform silver nanoclusters. Optical
absorption results indicated that optical absorption of ZnO–Ag thin films decreased with increase of annealing temperature.
Nanocomposite ZnO–Ag thin films with [Ag] = 0.068 M and [Ag] = 0.110 M showed an intense absorption band, whose maximum signals
appear at 430 nm which is not present in pure ZnO thin films. The result of X-ray photoelectron spectroscopy revealed that
the binding energy of Ag 3d5/2 for ZnO–Ag shifts remarkably to the lower binding energy compared to the pure metallic Ag due to the interaction between
Ag and ZnO. 相似文献
15.
Christian Schramm Beate Rinderer Richard Tessadri Heinz Duelli 《Journal of Sol-Gel Science and Technology》2010,53(3):579-586
Based on differential scanning calorimetry data, it was shown that the reaction of (3-triethoxysilylpropyl)succinic anhydride
and (3-amino)propyltriethoxysilane at 110 °C resulted in the formation of polyamic acid, whereas the thermal treatment at
220 °C led to the generation of an aliphatic monoimide-bridged polysilsesquioxane as proved by FT-IR. X-ray powder diffraction
studies showed a prominent reflection at 2θ = 6.66° (d = 1.32 nm) revealing that a crystalline area is formed. 29Si CP-MAS-NMR and 13C CP-TOSS-MAS-NMR measurements proved that no cleavage of the Si–C bond occurred, and a highly condensed material was obtained. 相似文献
16.
In this paper, the thermal behaviours of two organophosphorous compounds, N,N-dimethyl-N′,N′-diphenylphosphorodihydrazidic (NDD) and diphenyl amidophosphate (DPA), were studied by thermogravimetery (TG), differential
thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques under non-isothermal conditions. The results
showed that NDD melts about 185 °C before it decomposes. NDD decomposition occurs in two continuous steps, in the 190–410 °C
temperature range. First thermal degradation stage for NDD results a broad exothermic peak in the DTA curve that is continued
with a small exothermic peak at the end of decomposition process. On the other hand, applying TG-DTA techniques indicates
that DPA melts about 150 °C before it decomposes. This compound decomposes in the temperature range of 230 to 330 °C in two
steps. These steps are endothermic and exothermic, respectively. Activation energy and pre-exponential factor for the first
step of decomposition of each compound were found by means of Kissinger method and were verified by Ozawa–Flynn–Wall method.
Activation energy obtained by Kissinger method for the first stage of NDD and DPA decompositions are 138 and 170 KJ mol−1, respectively. Finally, the thermodynamic parameters (ΔG
#, ΔH
# and ΔS
#) for first step decomposition of investigated organophosphorous were determined. 相似文献
17.
Jyoti L. Gurav A. Venkateswara Rao Digambar Y. Nadargi 《Journal of Sol-Gel Science and Technology》2009,50(3):275-280
The experimental results on the study of thermal conductivity and effect of humidity on HMDZ modified TEOS based aerogels
dried at ambient pressure, are reported. Silica sol was prepared by keeping the MeOH/TEOS molar ratio, Acidic water (Oxalic
acid) and basic water (NH4OH) concentrations constant at 16.5, 0.001 and 1 M, respectively throughout the experiments and the HMDZ/TEOS molar ratio
(h) was varied from 0.34 to 2.1. Finally, the surface modified wet gels were dried at an ambient pressure. The thermal conductivity
of the aerogel samples was measured. Further, the humidity study was carried out in 80% humid surrounding at 30 °C temperature
over 80 days. The best quality aerogels in terms of low bulk density, thermal conductivity and durability (no moisture absorption)
with an only 2% of weight gain were obtained for TEOS: MeOH: Acidic H2O: Basic H2O: HMDZ molar ratio at 1:16.5:0.81:0.50:0.681, respectively. The thermal stability and hydrophobicity of the aerogel have
been confirmed with Thermo gravimetric and Differential Thermal (TG–DT) analyses and Fourier Transform Infrared Spectroscopy
(FTIR), respectively. Microstructural studies were carried out by Scanning Electron microscopy (SEM). 相似文献
18.
W. P. C. de Klerk W. Colpa P. J. van Ekeren 《Journal of Thermal Analysis and Calorimetry》2006,85(1):203-207
The ageing
characteristics of pyrotechnic compositions are influenced not only by temperature,
but also by surrounding effects as humidity and vibrations. In this paper
the thermal stability of the pyrotechnic system magnesium–sodium nitrate
will be investigated.
In an inert helium atmosphere two steps
of mass loss, which were not completely separated from each other, were observed
in the temperature range from 65 to 265°C: a mass loss of about 15% between
65 and 160°C and about 34% between 160 and 265°C. It is assumed that
these two steps are caused by different processes. The separation between
the two steps was not or hardly detectable for measurements that were performed
in a nitrogen atmosphere. Using MS and FTIR (mass spectrometry/Fourier transform
infrared spectroscopy) the evolved gases were analysed. Only above about 170°C
evolving gases were detected (which means that during the first step no gases
were detectable). The detected gas mainly consists of CO2,
CO and N2O, with smaller amounts of NO2,
NO and possibly HCN. A third step of mass loss (8–9%) was observed above
314°C. The process which caused this step of mass loss is considered not
to contribute significantly to the ageing of the material at much lower temperatures
of maximum 80°C, which is of interest in view of the use of the materials. 相似文献
19.
In the present paper the experimental results of the effect of sol-gel processing temperature on the physical properties of
the TEOS based silica aerogels are reported and discussed. The aerogels were produced by the two step sol-gel process at various
temperatures in the range of 26–70∘;C followed by supercritical drying using methanol solvent extraction. A remarkable reduction in the gelation time was observed
from three and a half days at room temperature to a mere 18 hours at 50∘;C. The best quality aerogels in terms of low density and high optical transmission were obtained for 6 hours hydrolysis time.
The aerogels were characterized by the measurements of bulk density, volume shrinkage, porosity, refractive index and optical
transmission. Monolithic aerogels with ultra low density (∼0.018 g/cm3), extremely high porosity (∼99%) and optimum optical transmission at 700 nm (∼75%) were obtained for the molar ratio of TEOS:MeOH:acidic
water:basic water at 1:99:10.42:14.58 respectively. 相似文献
20.
S. C. Mojumdar L. Raki N. Mathis K. Schimdt S. Lang 《Journal of Thermal Analysis and Calorimetry》2006,85(1):119-124
A non-ionic polymer (poly(vinyl
alcohol) (PVA)) has been incorporated into the inorganic layers of calcium
silicate hydrate (C–S–H) during precipitation of quasicrystalline
C–S–H from aqueous solution. C–S–H and a C–S–H-polymer
nanocomposite (C–S–HPN) material were synthesized and characterized
by X-ray fluorescence (XRF), energy dispersive spectroscopy (EDS), 29Si
magic angle spinning nuclear magnetic resonance (29Si
MAS NMR) and 13C cross-polarization nuclear magnetic
resonance (13C CP NMR) spectroscopy, atomic force
microscopy (AFM), thermal conductivity, thermogravimetric analysis (TG) and
differential thermal analysis (DTA). Thermal conductivity of PVA, C–S–H
and C–S–HPN material was studied in the temperature range 25–50°C.
C–S–HPN materials exhibited the highest thermal conductivity at
25 and 50°C. The thermal conductivity increases from 25 to 50°C are
7.03, 17.46 and 14.85% for PVA, C–S–H and C–S–HPN
material, respectively. Three significant decomposition temperature ranges
were observed on the TG curve of C–S–HPN material. 相似文献