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1.
M. Thirumal Dipak Khastgir Nikhil K Singha B. S. Manjunath Y. P. Naik 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):704-712
Water blown rigid polyurethane foams (PUF) with organoclay/organically modified nanoclay (ONC) were prepared and their properties such as density, mechanical, morphological, insulation, thermal and flame retardant properties were studied. In this investigation, the ONC content was varied from 1 to 10 parts per hundred of polyol (php) by weight. It was observed that the compressive strength of ONC filled PUF increased up to 3 php of ONC loading and then it decreased. Wide angle X-ray diffraction and transmission electron microscopy studies indicated the exfoliated dispersion of ONC in PUF. The thermal conductivity of ONC filled PUF decreases up to 5 php and then increases. The glass transition temperature (Tg) of PUF decreases on loading of ONC. The TGA analysis shows that there is slight increase in degradation temperature with increase in ONC loading. The flame retardant properties (LOI and flame spread rate) are improved slightly on addition (3 php) of ONC filled PUF. 相似文献
2.
E. Malhotra N. K. Kaushik G. S. Sodhi 《Journal of Thermal Analysis and Calorimetry》2001,65(3):859-864
Ionic chelate complexes of kojic acid(I) and hafnium(IV) of the type [(η5-C5H5)2HfL]+[MCl3]– (II)[HL=kojic acid; M=Zn(II), Cd(II), Hg(II), Cu(II)] have been synthesised and characterised by spectral studies (IR, UV, 1H NMR and 13CNMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have been carried out for these complexes
and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated.
The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves,
the heat of reaction has been calculated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
通过模型化合物ArOArCOArArCOArOAr(Ar为苯基或1,4-亚苯基)的全优化模型,得到芳环之间的平均二面角为37.5°,由其结构参数建立了刚性链聚芳醚酮(砜)类均聚物分子结构与其熔点及玻璃化温度的关系式,据此较好地了预测了新品种均聚物的热性能。 相似文献
4.
Mohammad Ghalambaz Seyed Abdollah Mansouri Mehryan Kasra Ayoubi Ayoubloo Ahmad Hajjar Mohamad El Kadri Obai Younis Mohsen Saffari Pour Christopher Hulme-Smith 《Molecules (Basel, Switzerland)》2021,26(5)
Thermal energy storage units conventionally have the drawback of slow charging response. Thus, heat transfer enhancement techniques are required to reduce charging time. Using nanoadditives is a promising approach to enhance the heat transfer and energy storage response time of materials that store heat by undergoing a reversible phase change, so-called phase change materials. In the present study, a combination of such materials enhanced with the addition of nanometer-scale graphene oxide particles (called nano-enhanced phase change materials) and a layer of a copper foam is proposed to improve the thermal performance of a shell-and-tube latent heat thermal energy storage (LHTES) unit filled with capric acid. Both graphene oxide and copper nanoparticles were tested as the nanometer-scale additives. A geometrically nonuniform layer of copper foam was placed over the hot tube inside the unit. The metal foam layer can improve heat transfer with an increase of the composite thermal conductivity. However, it suppressed the natural convection flows and could reduce heat transfer in the molten regions. Thus, a metal foam layer with a nonuniform shape can maximize thermal conductivity in conduction-dominant regions and minimize its adverse impacts on natural convection flows. The heat transfer was modeled using partial differential equations for conservations of momentum and heat. The finite element method was used to solve the partial differential equations. A backward differential formula was used to control the accuracy and convergence of the solution automatically. Mesh adaptation was applied to increase the mesh resolution at the interface between phases and improve the quality and stability of the solution. The impact of the eccentricity and porosity of the metal foam layer and the volume fraction of nanoparticles on the energy storage and the thermal performance of the LHTES unit was addressed. The layer of the metal foam notably improves the response time of the LHTES unit, and a 10% eccentricity of the porous layer toward the bottom improved the response time of the LHTES unit by 50%. The presence of nanoadditives could reduce the response time (melting time) of the LHTES unit by 12%, and copper nanoparticles were slightly better than graphene oxide particles in terms of heat transfer enhancement. The design parameters of the eccentricity, porosity, and volume fraction of nanoparticles had minimal impact on the thermal energy storage capacity of the LHTES unit, while their impact on the melting time (response time) was significant. Thus, a combination of the enhancement method could practically reduce the thermal charging time of an LHTES unit without a significant increase in its size. 相似文献
5.
Thermogravimetric Analysis and Thermal Ageing of Crosslinked Nitrile Rubber/Poly(ethylene-co-vinyl Acetate) Blends 总被引:1,自引:0,他引:1
Varghese H. Bhagawan S. S. Thomas S. 《Journal of Thermal Analysis and Calorimetry》2001,63(3):749-763
The thermal behaviour of nitrile rubber (NBR)/poly(ethylene-co-vinyl acetate) (EVA) blends was studied by thermogravimetry.
The effects of blend ratio, different crosslinking systems (sulphur, peroxide and mixed), various fillers (silica, clay and
carbon black) and filler loading on the thermal properties were evaluated. It was found that the initial decomposition temperature
increased with the addition of NBR to EVA. Among the various crosslinking systems studied, the peroxide cured system showed
the highest initial decomposition temperature. This is associated with the high bond dissociation energy of C–C linkages.
The addition of fillers improved the thermal stability of the blend. The mass loss at different temperatures and activation
energy of degradation were also studied. The thermal ageing of these blends was carried out at 50 and 100°C for 72 h. It was
seen that the properties are not affected by the mild ageing condition. Also, the peroxide cured system was found to exhibit
better retention in properties, than other crosslinking systems.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methylglutarates were prepared as solids with general formula MC6 H8 O4 ×n H2 O, where n =0–8. Their solubilities in water at 293 K were determined (7.0×10−2 −4.2×10−3 mol dm−3 ). The IR spectra were recorded and thermal decomposition in air was investigated. The IR spectra suggest that the carboxylate
groups are mono- or bidentate. During heating the hydrated complexes lose some water molecules in one (Mn, Co, Ni, Cu) or
two steps (Cd) and then mono- (Cu) or dihydrates (Mn, Co, Ni) decompose to oxides directly (Mn, Cu, Co) or with intermediate
formation of free metals (Co, Ni). Anhydrous Zn(II) complex decomposes directly to the oxide ZnO.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
The thermal stabilities of 5-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) were studied in air and
nitrogen atmospheres. The complexes were obtained as mono-, di-, tetra-and pentahydrates with a metal to ligand ratio of 1:2
and with colours typical for M2+ ions (Mn-slightly pink, Co-pink, Ni-green, Cu-blue and Zn-white) and as polycrystalline compounds. When heated they dehydrate
to form anhydrous salts which nextare decomposed to the oxides of the respective metals in air while in nitrogen to the mixtures
of metal oxides and oxychlorides and carbon. The most thermally stable in air, nitrogen and argon atmospheres is 5-chloro-2-methoxybenzoate
of Cu(II) while the least thermally stable is that of Co(II).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Thermal studies on some organotin(IV) complexes with piperidine and 2-aminopyridine dithiocarbamates
The complexes of piperidine dithiocarbamate, 2-aminopyridine dithiocarbamate and organotin(IV) of the type R3Sn(L1), R2Sn(L1)2, R3Sn(L2), R2Sn(L2)2, [R=C6H5CH2 (benzyl), p-ClC6H4CH2 (p-chlorobenzyl), L
1=sodium piperidine dithiocarbamate and L
2=sodium 2-aminopyridine dithiocarbamate] have been synthesised and characterised by spectral studies (IR, UV, 1H NMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have beeen carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated. 相似文献
9.
10.
酞侧基聚芳醚酮的热学性能谢红卫,李滨耀(中国科学院长春应用化学研究所长春130022)关键词酞侧基聚芳醚酮,pvT行为,导热系数,定压比热容酞侧基聚芳醚酮(PEK-C)具有较高的玻璃化转变温度,其流变加工性能和力学性能已被广泛研究[1~3],被证明是... 相似文献
11.
本文通过考虑容器和试样内存在温度梯度这一事实,成功地解释了实际DTA曲线上的相变终点,并就相变前后试样的热容量不同这一普遍情况,推导出计算热焓的广义Speil公式。 相似文献
12.
Rare earth elements have been widely used in many areas. Rare earth complex bearing an amino acid was synthesized to study the influence and the long-term effect of rare earth elements on environment and human beings,because amino acid is the basic unit of the living things. Previous work on these kinds of comidex is focused on synthesis and characterization of them. But thermodynamic data have seldom been reported. Here we present the thermod~nRmle study of [ Ho (Thr)(H20 )5]Cl3. The heat capecity of Holmium complex with threonine,[Ho(Thr)(H2O)5]Cl3,was measured with an automatic adiabatic calorimeter in the temperature range from 79K to 330K and no thermal anomaly was found in this range,Thermodynamic functions relative to standard state 298.15K were derived from the heat capactiy data.Thermal decomposition behavior of the complex in nitrogen atmosphere in the range from 300K to 900K was studied by thermogravimetric(TG) technique and a possible decompostion mechanism was proposed according to the TG-DTG results. 相似文献
13.
Complexes of Cr(III):Cu(II) with the glyoxylate dianion as ligand were synthesized in the range of cation atomic ratios (0.01–8):1.0.
The results of non-isothermal analysis of the synthesized compounds correlated with the results of IR and UV-VIS spectroscopy,
and gas chromatography of the volatile products of the decomposition allowed the formulation of a mechanism for the decomposition
of the complex with Cr(III):Cu(II)=2:1 and the assumption that the other complexes are mixtures of this with the homopolynuclear
complexes of Cr(III) and Cu(II), depending on the ratio of the cations Cr(III):Cu(II).
The thermal conversion of the complexes takes place at relatively low temperatures, with partial transformation of the ligand
into oxalate and of the oxide mixture into CuCrO4.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
N. Voyer A. Soisnard Sara J. Palmer W. N. Martens R. L. Frost 《Journal of Thermal Analysis and Calorimetry》2009,96(2):481-485
Zn-Al hydrotalcites and Cu-Al hydrotalcites were synthesised by coprecipitation method and analysed by X-ray diffraction (XRD)
and thermal analysis coupled with mass spectroscopy. These methods provide a measure of the thermal stability of the hydrotalcite.
The XRD patterns demonstrate similar patterns to that of the reference patterns but present impurities attributed to Zn(OH)2 and Cu(OH)2. The analysis shows that the d003 peak for the Zn-Al hydrotalcite gives a spacing in the interlayer of 7.59 ? and the estimation
of the particle size by using the Debye-Scherrer equation and the width of the d003 peak is 590 ?. In the case of the Cu-Al
hydrotalcite, the d003 spacing is 7.57 ? and the size of the diffracting particles was determined to be 225 ?.
The thermal decomposition steps can be broken down into 4 sections for both of these hydrotalcites. The first step decomposition
below 100°C is caused by the dehydration of some water absorbed. The second stage shows two major steps attributed to the
dehydroxylation of the hydrotalcite. In the next stage, the gas CO2 is liberated over a temperature range of 150°C. The last reactions occur over 400°C and involved CO2 evolution in the decomposition of the compounds produced during the dehydroxylation of the hydrotalcite. 相似文献
15.
首先采用格氏试剂法合成了甲基三苯乙炔基硅烷(MTPES),通过傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)对其结构进行了表征。然后以MTPES和4,4’-二叠氮甲基联苯(BAMBP)为原料制备了新型聚三唑树脂(MPTA)。利用FT-IR和差示扫描量热(DSC)研究了MPTA树脂的固化行为,通过动态力学热分析(DMA)和热重分析(TG)研究了炔基与叠氮基配比对树脂热性能的影响,并通过测试凝胶时间随贮存时间的变化研究了树脂及其四氢呋喃(THF)溶液的贮存稳定性。结果表明,固化后的树脂玻璃化转变温度(Tg)达到236℃,在氮气中的5%热失重温度(T_(d5))在320℃左右。MPTA树脂在35℃和25℃下分别贮存7d和20d后,100℃下树脂的凝胶时间分别为40min和25min,MPTA树脂的THF溶液在同样条件下贮存28d后,凝胶时间分别为54min和61min,具有比现有聚三唑树脂更好的贮存稳定性。单向T700碳纤维-MPTA复合材料常温下的弯曲强度为1 660 MPa,弯曲模量为129 GPa,150℃下的弯曲强度保留率为70%。 相似文献
16.
P. Budrugeac Carmen Racles V. Cozan Maria Cazacu 《Journal of Thermal Analysis and Calorimetry》2008,92(1):263-269
Thermal and thermo-oxidative stability of some poly(siloxane-azomethine)s obtaining starting from bis(formyl-p-phenoxymethyl)tetramethyldisiloxane and different organic diamines have been investigated by TG+DTG+DSC simultaneous analyses
performed in argon flow and air static atmosphere, respectively. TG, DTG and DSC curves of each polymer showed three or four
successive degradation steps at different temperatures according to the composition of the sample and the gaseous atmosphere
in which the thermal analysis was performed. For each process, the following parameters were evaluated: total mass loss, temperature
corresponding to the maximum reaction rate, maximum reaction rate, temperature corresponding to certain mass loss. In order
to determine the thermal and thermo-oxidative stabilities of investigated polymers, the following values were determined:
T
x% — temperature corresponding to x% mass loss, and %Δm
T — mass loss at a given temperature T. The obtained orders of stability were correlated with the structure of investigated polymers. 相似文献
17.
Malhotra E. Kaushik N. K. Sodhi G. S. 《Journal of Thermal Analysis and Calorimetry》2002,68(1):215-222
A number of ionic chelate complexes of maltol(A) and hafnium(IV) the type[(η5−C5H5)2HfL]+[MCl3]− (B) [HL=maltol; M=Zn(II), Cd(II), Hg(II), Cu(II)]have been synthesized and characterized by spectral studies (IR, UV, 1H NMR and 13C NMR). The stoichiometry of the complexes has been confirmed by conductance measurements. Thermogravimetric (TG) and differential
thermal analytical (DTA) studies have been carried out for these complexes and from TG curves, the order, apparent activation
energy and apparent activation entropy of the thermal decomposition reactions have been elucidated .The order in each case
has been determined to be one and the degree of spontaneity and lability have been inferred from the apparent activation energy
and entropy, respectively. Thermal parameters have been correlated with some structural aspects of the complexes concerned.
From differential thermal analysis curves, the heat of reaction has been calculated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
A. Kula 《Journal of Thermal Analysis and Calorimetry》2002,68(3):957-964
Complexes of lanthanide(III) (La–Lu) and Y(III) with 1-hydroxy-2-naphthoic acid were obtained as crystalline compounds with
a general formula Ln[C10H6(OH)COO]3⋅nH2O:n=6 for La–Tm and Y, n=2 for Yb and n=0 for Lu. IR spectra of the prepared complexes were recorded, and their thermal decomposition in air were investigated. Spectroscopic
data suggest that in the coordination of metal-organic ligand only oxygen atoms from the carboxylate group take part. When
heated, the complexes decompose to the oxides Ln2O3, CeO2, Pr6O11 and Tb4O7 with intermediate formation of Ln(C11H7O3)(C11H6O3).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
Czakis-Sulikowska D. Czylkowska A. Radwańska-Doczekalska J. 《Journal of Thermal Analysis and Calorimetry》2000,63(2):387-395
The complexes with the empirical formula M(4-bipy)(ClCH2COO)2 ×nH2O (where: 4-bipy=4,4'-bipyridine, L=ClCH2 COO–, M (II)=Mn, Co, Ni, Cu) were prepared and characterized via the IR and electronic (VIS) spectra and conductivity measurements.
Thermal decomposition of these compounds was studied. During heating in air dehydration processes occur. The anhydrous compounds
decompose at high temperature to oxides. The principal volatile mass fragments correspond to: H2O, CO2, CH3Cl, HCl, Cl2 and other.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
Bartomiej Rogalewicz Alina Climova Ekaterina Pivovarova Jarosaw Sukiennik Kamila Czarnecka Pawe Szymaski Magorzata Szczesio Katarzyna Gas Maciej Sawicki Monika Pitucha Agnieszka Czylkowska 《Molecules (Basel, Switzerland)》2022,27(9)
A novel biologically active thiosemicarbazide derivative ligand L (N-[(phenylcarbamothioyl)amino]pyridine-3-carboxamide) and a series of its five metal(II) complexes, namely: [Co(L)Cl2], [Ni(L)Cl2(H2O)], [Cu(L)Cl2(H2O)], [Zn(L)Cl2] and [Cd(L)Cl2(H2O)] have been synthesized and thoroughly investigated. The physicochemical characterization of the newly obtained compounds has been performed using appropriate analytical techniques, such as 1H and l3C nuclear magnetic resonance (NMR), inductively coupled plasma (ICP), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and magnetic measurements. In order to study the pharmacokinetic profile of the compounds, ADMET analysis was performed. The in vitro studies revealed that the synthesized compounds exhibit potent biological activity against A549 human cancer cell line. 相似文献