期刊文献+
共找到21篇文章
< 1 2 >
每页显示 20 50 100
Matrix-Material Fabrication Technique and Thermogravimetric Analysis of Banana Fiber Reinforced Polypropylene Composites
1
作者 Nazrul Islam M.A Gafur 《Journal of Building Material Science》 2023年第2期15-24,共10页
From the environmental consideration,it would be very interesting to use natural fibers such as banana,jute or coir as reinforcement materials instead of artificial fibers or any kind of synthetic materials.Natural fi... From the environmental consideration,it would be very interesting to use natural fibers such as banana,jute or coir as reinforcement materials instead of artificial fibers or any kind of synthetic materials.Natural fibers have many advantages over synthetic ones.Polypropylene banana fiber composites(PPBC)are prepared using untreated and alkali-treated banana fibers at 10-25%by weight of the fiber loading.The thermal properties of polypropylene natural fiber composites are very important for technological uses.Thermogravimetric measurements show that the incorporation of banana fiber into PP enhances the thermal stability of composites containing treated fibers,in comparison with untreated fibers.A composite of biodegradable polypropylene(PP)reinforced with short banana natural fibers was prepared by melt blending followed by a hot press molding system.The thermal properties of matrix materials were studied using thermogravimetric analyzers TGA units.It is observed that the introduction of short banana fibers slightly improved the thermo oxidative stability of PP-banana composites.Physical and chemical changes occurred through dehydration,phase transition,molecular orientation,crystallinity disruption,oxidation and decomposition,and incorporation of several functional groups.Systematic investigations of the thermal behavior of polymers in gas,vacuum or inert atmosphere give the knowledge of how change takes place in polymers.To understand such changes thermogravimetric analysis(TGA)and thermal analysis(TG)were performed.It is observed reinforcement of short banana fiber leads to little improvement in the thermooxidative stability of PPBC.Due to the enhancement of thermo-mechanical properties,such composites may be used as building materials namely roof materials,selling materials and many other engineering applications. 展开更多
关键词 Polypropylene banana composites(PPBC) Natural fiber Oxidative stability Thermogravimetric analysis(tga) DECOMPOSITION
下载PDF
Characterized the Microalgae (Chlorella and Spirulina) and Macro Algae by Using TGA and Bomb Calorific Meter for the Biomass Energy Application 被引量:1
2
作者 An-Peng Chen Shuichi Torii 《Journal of Mechanics Engineering and Automation》 2015年第12期691-696,共6页
Biomass usually is noticed a composition of various types of waste materials that can be utilized as useful form of energy alternative to the conventional fossil fuels. However, this new kind of energy has not met its... Biomass usually is noticed a composition of various types of waste materials that can be utilized as useful form of energy alternative to the conventional fossil fuels. However, this new kind of energy has not met its full potential in production of energy, especially electricity generation due to its lower performance in terms of thermal efficiency. Algae (included Microalgae & Macroalgae) are widely used for multi-application developments such as fishery aquaculture, food/nutrient supplement, cosmetics, and biomass energy. Microalgae have been treated as the source of bio-fuel. In this paper, we selected the two types of freshwater microalgae "Chlorella Vulgaris" & "Spirulina" and macro algae (Laminariaceae) as the main materials and we analyzed TGA (thermal gravity analysis) and calorific values (heat of combustion). We found the calorific values are 1,000-5,000 KC/KG and TGA results show that the microalgae decrease rapidly after reached 300 ℃. The results in this paper will be used as a reference material for microalgae multi-oriental energy application and biomass composition proximate and ultimate research development in the future. 展开更多
关键词 Biomass energy MICROALGAE tga (thermal gravity analysis combustion.
下载PDF
Dielectric and Thermal Analysis of a Shrub Leaf for the Modeling of Forest Fire
3
作者 Khadidja Khelloufi Yamina Baara +2 位作者 Nouredine Zekri Claudia Pinto Domingos Xavier Viegas 《Journal of Environmental Science and Engineering(A)》 2017年第11期552-560,共9页
Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on t... Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on the behavior of the bio-physical properties of vegetation associated to combustion. An experimental study to analyze the structure of a leaf of Laurel shrub at different biological stages is presented; it allows following the structural exchanges induced on the leaf by the effect of increasing temperature. For this purpose, both dielectric and TGA (Thermogravimetric Analysis)/DTA (Differentialthermal Analysis) was performed to a better understanding of the pyrolysis phenomenon. The results obtained provide information on the process of thermal degradation caused by fire. The evolution of the leaf impedance as a function of the applied frequency characterizes the moisture loss in plant species during pyrolysis. The dielectric response confirms the proposition to the equivalent circuit of the leaf as a composite of liquid and solid parts. The TGA/DTA results detected the behaviour of the solid parts in the fire under a constant heating rate, and were able to show all the transformation subjected by the Laurel leaf until ignition and all the gases released during it. 展开更多
关键词 Impedance spectroscopy tga/DTA analysis PYROLYSIS modeling forest fire.
下载PDF
Non-isothermal oxidation and ignition prediction of Ti-Cr alloys 被引量:6
4
作者 弭光宝 黄秀松 +3 位作者 李培杰 曹京霞 黄旭 曹春晓 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第10期2409-2415,共7页
The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and... The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influencing mechanism of chromium on the oxidation resistance of Ti-Cr alloys was discussed. The results show that the oxidation resistance of the alloys decreases with Cr below a critical chromium content wC and increases above wC; above 1000 K, the oxidation kinetics obeys parabolic rule and titanium dominates the oxidation process; after oxidation, the oxygen-diffusing layer is present in the alloy matrix, the oxide scale is mainly composed of rutile whose internal layer is rich in chromium, and chromium oxides separated out from TiO2 near the alloy-oxide interface improve the oxidation resistance. Ignition of metals and alloys is a fast non-isothermal oxidation process and the oxidation mechanism of Ti-Cr alloys during ignition is predicted. 展开更多
关键词 Ti-Cr alloy non-isothermal oxidation thermogravimetric analysis tga oxide scale microstructure IGNITION
下载PDF
THERMAL DEGRADATION OF POLY(ARYLENE SULFIDE SULFONE)/NMETHYLPYRROLIDONE CRYSTAL SOLVATE 被引量:3
5
作者 杨杰 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2010年第1期85-91,共7页
The thermal degradation of poly(arylene sulfide sulfone)/N-methylpyrrolidone (PASS/NMP) crystal solvate was studied by thermogravimetric analysis (TGA) and was compared with pure PASS in order to determine the w... The thermal degradation of poly(arylene sulfide sulfone)/N-methylpyrrolidone (PASS/NMP) crystal solvate was studied by thermogravimetric analysis (TGA) and was compared with pure PASS in order to determine the way in which the formation of the crystal solvate affected the thermal properties of the polymer. The activation energy of the solid state process was determined using Kissinger's method, which does not require knowledge of the reaction mechanism (RM), to be 174.18 kJ/mol which was lower than that for pure PASS (E = 214 kJ/mol). The study of master curves together with interpretation of integral methods, allows confirmation that the thermal degradation mechanism for PASS in the crystal solvate system is a decelerated Rn type, which is a solid-state process based on a phase boundary controlled reaction, in the conversion range considered. Whereas, the pure PASS follows a decelerated Dn thermodegradation mechanism in the same conversion range. 展开更多
关键词 Poly(arylene sulfide sulfone) Crystal solvate Thermal degradation Thermogravimetric analysis tga).
下载PDF
Synthesis and Application of Sodium-carboxymethylcellulose Type Superplasticizer in Cement Mortars 被引量:1
6
作者 LU Gaolei HAN Fuqin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2019年第4期811-817,共7页
The polymeric admixture, the sodium-carboxymethylcellulose(CMC)/poly sodium p-styrene sulfonate(PSS)/poly vinyl acetate(PVAc) was synthesized and applied in cement mortars. The polymer was tested by FTIR and SEM, and ... The polymeric admixture, the sodium-carboxymethylcellulose(CMC)/poly sodium p-styrene sulfonate(PSS)/poly vinyl acetate(PVAc) was synthesized and applied in cement mortars. The polymer was tested by FTIR and SEM, and the results indicate that the ideal molecular structure is synthesized. The effect of addition amount of polymeric admixture and water-to-cement ratio on mechanical properties of cement mortars was studied. The polymer-modified mortars under the optimum water cement ratio and optimum polymer cement ratio, the flexural strength of polymer-modified mortars are 1.45, 1.21, and 1.17 times higher than the plain cement mortar at age of 3, 7, and 28 d, respectively.The compressive strength of polymer-modified mortars at age of 3, 7, and 28 d are 1.55, 1.40, and 1.2941 times higher than that of the plain cement mortar,respectively. Scanning electron microscope(SEM), FTIR and TG were used to analyze the effect of polymer emulsion on cement hydration reaction. The results show that the polymer emulsion can promote the hydration reaction of cement. 展开更多
关键词 CELLULOSE cement MORTAR mechanical properties THERMOGRAVIMETRIC analysis(tga)
下载PDF
Synthesis and Properties of Chiral Polyurethane Elastomers Using Tartaric Acids
7
作者 Kazunori Kizuka Shin-Ichi Inoue 《Open Journal of Organic Polymer Materials》 CAS 2016年第1期38-52,共15页
The polyaddition of isocyanate and polyol to form polyurethane elastomers has rarely been applied to the construction of chiral polyurethane elastomers. Hence, the introduction of chiral units via polyaddition remains... The polyaddition of isocyanate and polyol to form polyurethane elastomers has rarely been applied to the construction of chiral polyurethane elastomers. Hence, the introduction of chiral units via polyaddition remains a challenging subject in polymer chemistry. In this study, the synthesis of chiral polyurethane elastomers using an aromatic isocyanate, polyols (polyether and polyester polyols), and L(+)-, D(&#8722)-, or meso-tartaric acid by a one-shot method is investigated. The polymers are characterized using FTIR and NMR spectroscopy, and their thermal properties are investigated by TGA, DMA, and DSC analyses. The optical activities of the polymers are confirmed by rotation. The use of chiral tartaric acids is essential to obtain the desired chiral polyurethane elastomers. 展开更多
关键词 CHIRAL Polyurethane Elastomers Tartaric Acid Differential Scanning Calorimetry (DSC) Thermogravimetric analysis (tga)
下载PDF
An Investigation of Thermomechanical Behavior of Tunisian Luffa Sponges’ Fibers
8
作者 Khaled Kharrati Madiha Salhi +1 位作者 Jemaa Sliman Ridha Abdeljabar 《Materials Sciences and Applications》 CAS 2022年第10期519-531,共13页
This work is realized in the context of valorizing natural and local resources, in particular, luffa plant fruit (luffa sponge). The raw fibers of the luffa sponge have a short lifetime. Hence, when they are chemicall... This work is realized in the context of valorizing natural and local resources, in particular, luffa plant fruit (luffa sponge). The raw fibers of the luffa sponge have a short lifetime. Hence, when they are chemically treated, it constitutes a solution is prepared to limit their degradation in the long term and to improve their mechanical characteristics. Therefore, this paper studies the effect of the chemical treatment on the mechanical properties of the luffa sponge’s fibers (fibers of luffa Sponge). The chemical process consists of dipping a brunch of luffa in various concentrations of sodium hydroxide (NaOH) at different time intervals and at different temperature conditions. The luffa sponge’s fibers were mechanical. Characterized before and after the treatment, mechanically (micro traction test). It has been shown that an optimum of 61% increase in mechanical properties (tensile strength) has been reached in the following conditions: treatment with 1% concentration for 90 min at 50&deg;C. 展开更多
关键词 Luffa Sponge’s Fibers Chemical Treatment Thermogravimetric analysis (tga) X-Ray Diffraction Spectrum Infrared Spectroscopy (IR) Mechanical Characteristics Tensile Strength
下载PDF
Cashew Nut Shell Liquid(CNSL)Based Bio-Derived Resin And Composites for Advanced Structural,Automotive,Electronic Packaging and Medical applications-A Review
9
作者 Padmanabhan Krishnan 《Organic Polymer Material Research》 2019年第2期9-13,共5页
As India is a world class producer of sugarcane,sugar beet,other tubers like potato and vegetables with starch,cashew and badam,castor oil and soybean,the quantum of bio resins and bio plastics that can be produced fr... As India is a world class producer of sugarcane,sugar beet,other tubers like potato and vegetables with starch,cashew and badam,castor oil and soybean,the quantum of bio resins and bio plastics that can be produced from these conventional,organic and genetically modified plants is immense.As on date,advanced and state of the art plastics and composites are being used in many applications as there is no incentive for farmers to produce plants and vegetables for the plastics and resins market exclusively.The use of advanced composites in varied applications escalates costs and shifts the material consumption that would deplete the natural resources,through excessive usage at one end and lack of demand for natural resources at the other end as bio derived composites become under-utilized.This review paper attempts to project the actual possibilities of the bio resin and bio plastic market in this country and provides the knowhow for the production of bio-phenolic cashew nut shell resin which are more than a substitute for the synthetically produced epoxies.Their true potentialities in composites product applications involving structural,thermal,electronic,pharmaceutical and petroleum engineering markets is discussed in this paper.A novel working model with an economically feasible option is also provided for those concerned about their safe disposal,recycling,reuse and conversion into useable fuel with virtually no impact to the environment.Cashew Nut Shell Liquid(CNSL)is an abundant natural source for synthesizing phenolic compounds.The excellent monomer,Cardanol is isolated from CNSL for polymer production.These are polymerized with aldehydes and acids at a particular mole fraction in the presence of catalysts like alkalis to convert into rigid resins.Differential Scanning Calorimetric(DSC)and Thermo Gravimetric Analysis(TGA)were studied for the thermal characterization of the synthesized CNSL Resins.Characterization of the synthesized resins was also carried out with respect to the evaluated mechanical properties such as hardness,strength,elastic modulus and fracture toughness.The synthesized CNSL resins yielded many interesting compositions with varied properties increasing the possibilities of various resin formulations which could be used for composites applications in vibrational damping.The electronic packaging applications of nano-composites with high dielectric strength produced with the CNSL matrix are also highlighted. 展开更多
关键词 CASHEW NUT Shell Liquid(CNSL)Resin Hardness Tensile Properties DSC Thermo Gravimetric analysis(tga) Fracture TOUGHNESS Vibration damping Natural frequencies Di-electric Constant Electronic packaging Genetic modification Waste plastics to fuel
下载PDF
Thermogravimetric analysis of bamboo-tar under different heating rates based on distributed activation energy model
10
作者 Huan Zhang Beibei Yan +4 位作者 Tingzhou Lei Tao Liu Jianjun Hu Yameng Li Guanyi Chen 《International Journal of Agricultural and Biological Engineering》 SCIE EI CAS 2018年第6期180-186,共7页
Carbon fiber is a kind of new polymer material with excellent mechanical properties and being applied widely.The process of carbon fiber prepared by bamboo tar,including extraction,condensation,spinning,oxidation and ... Carbon fiber is a kind of new polymer material with excellent mechanical properties and being applied widely.The process of carbon fiber prepared by bamboo tar,including extraction,condensation,spinning,oxidation and carbonation,is influenced by the pyrolysis kinetics significantly.In this paper,the thermogravimetric analysis(TGA)of bamboo tar produced in the process of pyrolysis and gasification of the bamboo which is known as Phylostachys sulphurea,was analyzed by the distributed activation energy model(DAEM)to understand the kinetic properties and parameters of bamboo tar.The thermogravimetric analysis of bamboo tar which is used as the raw material of carbon fiber was conducted under 5 different heating rates(i.e.5,10,15,30 and 50℃/min,etc.)in nitrogen atmosphere.The results show that the activation energy of bamboo tar and the exponential factor increased significantly with the increase of the heating rate,and the low heating rate is advantageous to the extraction of bamboo tar solvent and the thermal polycondensation,which can provide scientific reference for the optimization of carbon fiber technology.The thermal weight results show that the temperature range of bamboo tar being decomposed rapidly is 213℃-410℃.The ranges of the activation energy were calculated by DAEM,which have small difference in comparisons with five heating rates when the conversion rate is at 0.1-0.6 and the average value of the activation energy is 119 kJ/mol.The stability range of the activation energy is enlarged when the conversion rate is greater than 0.6 and heating rate increases. 展开更多
关键词 bamboo tar carbon fiber thermogravimetric analysis(tga) distributed activation energy model(DAEM)
原文传递
Preparation and Characterization of Mesophase Pitch via Co-Carbonization of Waste Polyethylene/Petroleum Pitch 被引量:5
11
作者 Youliang Cheng Lu Yang +3 位作者 Tao Luo Changqing Fang Jian Su Jian Hui 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2015年第8期857-863,共7页
The low-cost petroleum pitch and waste polyethylene (WPE) were used as raw materials to prepare the mesophase pitch by co-carbonization method and the forming mechanization of mesophase pitch was also investigated. ... The low-cost petroleum pitch and waste polyethylene (WPE) were used as raw materials to prepare the mesophase pitch by co-carbonization method and the forming mechanization of mesophase pitch was also investigated. Polarized microscopy, softening point, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to characterize and analyze the properties and struc- ture of the mesophase pitch. The results showed that the carbonization yield of the modified pitch was high when 1-2 wt% WPE was added and the property of mesophase pitch (MP1-450-4 and MP2-450-4) prepared by thermal polymerization was excellent. Moreover, when the treatment temperature was above 420 ~C, the mesophase development of the modified pitch may be entire and 100% streamline texture mesophase can form. During the co-carbonization of WPEJpetroleum pitch, a large number of naphthenic structures and methylene bridges may be generated, which can improve the properties of the obtained mesophase pitch. 展开更多
关键词 Polarized light microscopy MICROSTRUCTURE PROPERTY Thermogravimetric analysis tga Formation mechanism
原文传递
Influence of Size of Hematite Powder on Its Reduction Kinetics by H_2 at Low Temperature 被引量:3
12
作者 PANG Jian-ming GUO Pei-min ZHAO Pei CAO Chao-zhen ZHANG Dian-wei 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2009年第5期7-11,共5页
The reduction kinetics and mechanisms of hematite ore with various particle sizes with hydrogen at low temperature were studied using the thermogravimetric analysis. At the same temperature, after the particle size of... The reduction kinetics and mechanisms of hematite ore with various particle sizes with hydrogen at low temperature were studied using the thermogravimetric analysis. At the same temperature, after the particle size of powder decreases from 107. 5μm to 2. 0 μm, the surface area of the powder and the contact area between the powder and gas increase, which makes the reduction process of hematite accelerate by about 8 times, and the apparent activation energy of the reduction reaction drops to 36.9 kJ/mol from 78. 3 kJ/mol because the activity of ore powder is improved by refining gradually. With the same reaction rate, the reaction temperature of 6.5 μm powder decreases by about 80 ℃ compared with that of 107. 5 μm powder. Thinner diffusion layer can also accelerate the reaction owing to powder refining. The higher the temperature, the greater is the peak of the reduction rate; at the same temperature, the greater the particle size, the smaller is the peak value of the reduction rate; both inner diffusion and interface chemical reaction play an important role in the whole reaction process. 展开更多
关键词 iron oxide low temperature reduction kinetics thermogravimetric analysis tga reduction mechanism
原文传递
Combustion characteristics of tannery sludge and volatilization of heavy metals in combustion 被引量:2
13
作者 Xu-guang JIANG Chun-yu LI Zhen-wei FEI Yong CHI Jian-hua YAN 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2010年第7期530-537,共8页
Incineration is considered one of the most readily available techniques for sewage sludge disposal, including tannery sludge, which often contains significant amounts of volatile heavy metals. The combustion character... Incineration is considered one of the most readily available techniques for sewage sludge disposal, including tannery sludge, which often contains significant amounts of volatile heavy metals. The combustion characteristics and kinetic analysis of tannery sludge were investigated using thermogravimetric analysis (TGA) at a heating rate of 30 °C/min in 50–950 °C. In addition to confirming that tannery sludge has a high content of volatile material and ash, it was further discovered that almost all the zinc (Zn) in tannery sludge is volatilized at 900 °C. The degree of volatilization for heavy metals at 900 °C followed the order of Zn>Cd>Cu>Mn>Pb>Cr. Moreover, the volatilization of these heavy metals increased with temperature. It is thus concluded that, to avoid heavy metal volatization during incineration disposal, 800 °C is a reasonable incineration temperature. 展开更多
关键词 Tannery sludge COMBUSTION Heavy metal volatilization Thermogravimetric analysis (tga) Combustion kinetics
原文传递
Effects of Halloysite Nanotube Reinforcement in Expandable Graphite Based Intumescent Fire Retardant Coatings Developed Using Hybrid Epoxy Binder System 被引量:4
14
作者 Qandeel Fatima Gillan Faiz Ahmad +2 位作者 M.I.Abdul Mutalib Puteri S.M.Megat-Yusoff Sami Ullah 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2018年第11期1286-1296,共11页
In this study, the effects of halloysite nanotubes (HNTs) reinforcement in expandable graphite based intumescent fire retardant coatings (IFRCs) developed using a polydimethylsiloxane (PDMS)/phenol BA epoxy syst... In this study, the effects of halloysite nanotubes (HNTs) reinforcement in expandable graphite based intumescent fire retardant coatings (IFRCs) developed using a polydimethylsiloxane (PDMS)/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients (ammonium polyphosphate/melamine/boric acid/expandable graphite, APP/MEL/BA/EG). The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy (FESEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared analysis (FTIR). The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH(3), due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis (TGA) of intumescent coating formulations. Reference formulation, SH(0) with no filler, degraded at 300 ~C and lost 50% of its total mass but SH(3), due to synergistic effects between PDMS and HNTs, degraded above 400 ~C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect ofHNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings. 展开更多
关键词 Polydimethylsiloxane (PDMS) Halloysite nanotubes (HNTs) Intumescent fire retardant coatings (IFRC) Thermogravimetric analysis tga Transmission electron microscopy (TEM)
原文传递
In Situ TEM Observation of the Gasification and Growth of Carbon Nanotubes Using Iron Catalysts 被引量:2
15
作者 Xiaofeng Feng See Wee Chee +5 位作者 Renu Sharma Kai Liu Xu Xie Qunqing Li Shoushan Fan Kaili Jiang 《Nano Research》 SCIE EI CAS CSCD 2011年第8期767-779,共13页
We report the in situ transmission electron microscope (TEM) observation of the catalytic gasification and growth of carbon nanotubes (CNTs). It was found that iron catalysts can consume the CNTs when pumping out the ... We report the in situ transmission electron microscope (TEM) observation of the catalytic gasification and growth of carbon nanotubes (CNTs). It was found that iron catalysts can consume the CNTs when pumping out the precursor gas, acetylene, at the growth temperature, and reinitiate the growth when acetylene is re-introduced. The switching between gasification and growth of CNTs can be repeated many times with the same catalyst. To understand the phenomenon, thermogravimetric analysis (TGA) coupled with mass spectroscopy was used to study the mechanism involved. It was shown that the residual water molecules in the growth chamber of the TEM react with and remove carbon atoms of CNTs as carbon monoxide vapor under the action of the catalyst, when the precursor gas is pumped out. This result contributes to a better understanding of the water-assisted and oxygen-assisted synthesis of CNT arrays, and provides useful clues on how to extend the lifetime and improve the activity of the catalysts. 展开更多
关键词 Carbon nanotubes GASIFICATION GROWTH iron catalyst environmental transmission electron microscopy (ETEM) thermogravimetric analysis tga
原文传递
Effects of CuO Nanoparticles on Microstructure,Physical,Mechanical and Thermal Properties of Self-Compacting Cementitious Composites 被引量:2
16
作者 Ali Nazari Shadi Riahi 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2011年第1期81-92,共12页
In the present study,split tensile strength of self-compacting concrete with different amount of CuO nanoparticles has been investigated.CuO nanoparticles with the average particle size of 15 nm were added partially t... In the present study,split tensile strength of self-compacting concrete with different amount of CuO nanoparticles has been investigated.CuO nanoparticles with the average particle size of 15 nm were added partially to self compacting concrete and split tensile strength of the specimens has been measured.The results indicate that CuO nanoparticles are able to improve the split tensile strength of self compacting concrete and recover the negative effects of polycarboxylate superplasticizer on split tensile strength.CuO nanoparticle as a partial replacement of cement up to 4 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH)2 amount at the early ages of hydration.The increase of the CuO nanoparticles more than 4 wt% causes the decrease of the split tensile strength because of unsuitable dispersion of nanoparticles in the concrete matrix.Accelerated peak appearance in conduction calorimetry tests,more weight loss in thermogravimetric analysis and more rapid appearance of related peaks to hydrated products in X-ray diffraction(XRD) results all also indicate that CuO nanoparticles up to4 wt% could improve the mechanical and physical properties of the specimens.Finally,CuO nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and few-harm pores. 展开更多
关键词 Self-compacting concrete(SCC) CuO nanoparticles Split tensile strength Thermogravimetric analysistga X-ray diffraction(XRD) Pore structure
原文传递
Lithium ion conduction and ion-polymer interaction in poly(vinyl pyrrolidone) based electrolytes blended with different plasticizers 被引量:2
17
作者 K.Kesavan Chithra M.Mathew S.Rajendran 《Chinese Chemical Letters》 SCIE CAS CSCD 2014年第11期1428-1434,共7页
Poly(ethylene oxide), poly(vinyl pyrrolidone)(PEO/PVP), lithium perchlorate salt(Li Cl O4) and different plasticizer based, gel polymer electrolytes were prepared by the solvent casting technique. XRD results ... Poly(ethylene oxide), poly(vinyl pyrrolidone)(PEO/PVP), lithium perchlorate salt(Li Cl O4) and different plasticizer based, gel polymer electrolytes were prepared by the solvent casting technique. XRD results show that the crystallinity decreases with the addition of different plasticizers. Consequently, there is an enhancement in the amorphousity of the samples responsible for the process of ion transport. FTIR spectroscopy is used to characterize the structure of the polymer and confirms the complexation of plasticizer with host polymer matrix. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. Among the various plasticizers, the ethylene carbonate(EC) based complex exhibits a maximum ionic conductivity value of the order of2.7279 10 4S cm 1. Thermal stability of the prepared electrolyte films shows that they can be used in batteries at elevated temperatures. PEO(72%)/PVP(8%)/Li Cl O4(8%)/EC(12%) has the maximum ionic conductivity value which is supported by the lowest optical band gap and lowest intensity in photoluminescence spectroscopy near 400–450 nm. Two and three dimensional topographic images of the sample having a maximum ionic conductivity show the presence of micropores. 展开更多
关键词 Polymers Thermogravimetric analysistga X-ray diffraction Luminescence Transport properties
原文传递
Thioether Functional Chain Extender for Thermoplastic Polyurethanes
18
作者 Zerrin Altιntas Emrah akmakι +1 位作者 M.Vezir Kahraman Nilhan Kayaman-Apohan 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2015年第6期850-856,共7页
In this study, a novel three functional chain extender (TATATRIOL) was synthesized from the reaction of 1,3,5- tri(prop-2-en-1-yl)-1,3,5-triazinane-2,4,6-trione (TATA) with 2-sulfanylethanol. Then new thermoplas... In this study, a novel three functional chain extender (TATATRIOL) was synthesized from the reaction of 1,3,5- tri(prop-2-en-1-yl)-1,3,5-triazinane-2,4,6-trione (TATA) with 2-sulfanylethanol. Then new thermoplastic polyurethanes (TPUs) were synthesized by a one-step bulk polymerization from the reaction of 1,1'-methanediylbis(4- isocyanatocyclohexane) (H12MDI), a poly(ethylene adipate) based polyester polyol and a chain extender. Butane-l,4-diol (BD) and the newly synthesized monomer, TATATRIOL, were used as chain extenders. The effects of TATATRIOL on the properties of the TPU were investigated and compared to those of the TPU prepared with BD. The TPUs which derived from the sulfur containing chain extender displayed lower modulus and high elongation at break values than the analogous TPUs derived from BD. Moreover sulfur containing TPUs exhibited higher thermal stability. 展开更多
关键词 Elastomers Thermogravimetric analysis tga Differential scanning calorimetry (DSC) Polyurethanes.
原文传递
Synthesis and characterization of sodium-lithium niobate ceramic structures and their composites with biopolymers
19
作者 Thomas V.MATHEW Sunny KURIAKOSE 《Journal of Advanced Ceramics》 SCIE CAS 2013年第1期11-20,共10页
Ceramic powders of Na_(1−x)Li_(x)NbO_(3)(LNN)have been synthesized by an aqueous sol-gel route.These solid solutions were prepared from Na-Li-Nb precursor gel.The precursor was synthesized from Na-EDTA,Li-EDTA and Nb-... Ceramic powders of Na_(1−x)Li_(x)NbO_(3)(LNN)have been synthesized by an aqueous sol-gel route.These solid solutions were prepared from Na-Li-Nb precursor gel.The precursor was synthesized from Na-EDTA,Li-EDTA and Nb-citrate complexes and they acted as the source of Na,Li and Nb,respectively.Citric acid and ethylenediaminetetraacetic acid(EDTA)were used as the chelating agents for Na,Li and Nb.The precursor gel was calcinated on a muffle furnace at 750℃for one hour and this provided the ceramic structures.Composites of LNN-biopolymers were prepared by the encapsulation of the ceramic structures into the biopolymeric scaffolds.The ceramic structures and composites were characterized by FTIR,NMR,TG and SEM analysis. 展开更多
关键词 ceramic structures sol-gel chemistry ENCAPSULATION thermo gravimetric analysis(tga)
原文传递
A functional approach toward xerogel immobilization for encapsulation biocompatibility of Rhizobium toward biosensor
20
作者 Pooja Arora Sunita Sharma +2 位作者 Sib Krishna Ghoshal Neeraj Dilbaghi Ashok Chaudhury 《Frontiers in Biology》 CAS CSCD 2013年第6期626-631,共6页
Sol-gel derived silica has tremendous applications as a biocompatible scaffold for the immobilization of cells. The use of xerogel as a matrix in the blueprint of biosensors is an appealing proposition due to several ... Sol-gel derived silica has tremendous applications as a biocompatible scaffold for the immobilization of cells. The use of xerogel as a matrix in the blueprint of biosensors is an appealing proposition due to several inimitable characteristics of xerogels, primarily because of their high porous nature, amendable pore size, and exceptionally large internal surface area. Morphological (X-Ray Diffraction and Thermogravimmetric Analysis) and optical (Fourier Transform Infrared and UV-Vis absorption) studies of the silica matrices with entrapped Rhizobial (Rz) structure of the biomaterial has been made. Temporal and concentration dependent studies were conducted for impregnated samples; it showed that the response time for the new biosensor for determining the concentration of Rz is less than 20 min. In this work, first time a novel avenue to create a generic approach for the fabrication of biosensor has been created. 展开更多
关键词 BIOSENSOR Fourier Transform Infrared spectroscopy (FTIR) RHIZOBIUM Thermo Gravimmetric analysis tga sol-gel XEROGEL X-Ray Diffraction (XRD)
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部