Decomposition processes of the quenched Zn-Al alloys were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the stabilities o...Decomposition processes of the quenched Zn-Al alloys were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the stabilities of supersaturated solid solution (SSS) of Zn-Al alloy and α' phase formed by quenching would reduce with the increase of Zn content and the precipitation of η-Zn phases even when aging at ambient temperature, so that the exothermic precipitation peak in DSC curve would disappear. The activation energy of the η-Zn precipitation and the reaction enthalpy were calculated and measured. The kinetics of α' decomposition or η-Zn formation was determined by XRD. The microstructure change during aging was observed by TEM.展开更多
The non-isothermal heating process of Mg-Sn powder mixture was studied by differential scanning calorimetry(DSC) technique and the synthesis kinetics of Mg2Sn was evaluated by the model-free and model-fitting methods....The non-isothermal heating process of Mg-Sn powder mixture was studied by differential scanning calorimetry(DSC) technique and the synthesis kinetics of Mg2Sn was evaluated by the model-free and model-fitting methods.The activation energy and conversion function of Mg2Sn synthesis reaction are calculated to be 281.7 kJ/mol and g(α)=[-ln(1-α)] 1/4,respectively.The reaction mechanism of 2Mg+Sn→Mg2Sn under non-isothermal condition is regarded as "nucleation and growth" .During the non-isothermal heating process,the phase transformation occurred in the Mg-Sn powder mixture was analyzed by XRD and the microstructure evolution of Mg2Sn was observed by optical microscopy,which is in good agreement with the reaction mechanism of 2Mg+Sn→ Mg2Sn deduced from the kinetic evaluation.展开更多
The differential scanning calorimetric (DSC)curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. T...The differential scanning calorimetric (DSC)curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. The curves show that the energy is released continuously as temperature rise to 70℃. Some thermodynamic and kinetic parameters of the energy release of the mitochondria have been obtained. The presented results showed that the mitochondria from cytoplasmic male sterile rice released more heat and they had higher energy barrier, less rate, and more complicated mechanism than that of their fertile lines in the energy release process.展开更多
In this paper the measurement of crystallinity(C)ofacrylic copolymer(PAC),by Swelling Differential Scan-ning Calorimetry(SDSC)is discussed.Common DSC isonly used for measuring the crystallinity of polymers withmelting...In this paper the measurement of crystallinity(C)ofacrylic copolymer(PAC),by Swelling Differential Scan-ning Calorimetry(SDSC)is discussed.Common DSC isonly used for measuring the crystallinity of polymers withmelting point,(T_m),below their decomposition temper-ature,(T_d).As temperature rises,polymers with swell-ing agent added become swollen and dissolved,goingthrough whole process of breaking solid structures.Thus,SDSC makes it possible to measure the crystallini-ty of polymers even with T_d below T_m.But the C mea-sured by WAXD and the total endothermal melting(swelling)heat in SDSC thermograms,(△H_l),are notlinearly correlated.It has been found that,instead of the△H_l,△H_l’obtained from the △H_l by subtracting the en-dothermal heat,△H_l,and the C measured by WAXDare linearly correlated.On the basis of this linear rela-tion,the unknown C of another PAC sample is measuredby SDSC.The result is in good accordance with thatmeasured by WAXD.展开更多
Differential scanning calorimetry (DSC) provides easy screening for thermal hazard evaluation. Here, we investigate the difference between using glass and stainless-steel vessels on the DSC measurement of exothermic d...Differential scanning calorimetry (DSC) provides easy screening for thermal hazard evaluation. Here, we investigate the difference between using glass and stainless-steel vessels on the DSC measurement of exothermic decomposition energy (QDSC) for 41 chemical substances (containing nitro, halogen, peroxide, and sulfur groups, and hydrazine bonds). Two borosilicate glass vessels (capillary and ampule) and one stainless-steel vessel were used. All QDSC values obtained were investigated with reference to the permissible fluctuation range specified by the ASTM (American Society for Testing and Materials) international Both glass vessels produced very similar QDSC values, despite different sample scales. The QDSC values obtained with the glass vessels were generally roughly within the variation tolerance range of the stainless-steel vessel. Notable exceptions were halogen- or sulfur-containing compounds;these exhibited smaller QDSC values with glass vessels in almost all cases. We will investigate whether certain structures in compounds react with stainless steel. The vessel material choice is crucial in evaluating the true reactivity of a substance.展开更多
A single scan has been performed in Differential Scanning Calorimetry (DSC) at a heating rate of 15oC/min under non-isothermal conditions to investigate the crystallization kinetics of glassy Se90Sb10-xAgx alloys (whe...A single scan has been performed in Differential Scanning Calorimetry (DSC) at a heating rate of 15oC/min under non-isothermal conditions to investigate the crystallization kinetics of glassy Se90Sb10-xAgx alloys (where x = 2, 4, 6, 8). For this purpose, Handerson’s theory based on non-isothermal method for thermal analysis of single-scan DSC data has been used. The activation energy of crystallization and order parameter has been determined and composition dependence of these parameters has been discussed.展开更多
Nanocomposites were fabricated by using a commercial two part epoxy as a matrix and multiwalled carbon nanotubes, graphite fibers and boron nitride platelets as filler materials. Multiwalled carbon nanotubes (MWCNTs) ...Nanocomposites were fabricated by using a commercial two part epoxy as a matrix and multiwalled carbon nanotubes, graphite fibers and boron nitride platelets as filler materials. Multiwalled carbon nanotubes (MWCNTs) that were produced by chemical vapor deposition were found to produce nanocomposites with better thermal diffusivity and thermal conductivity than the MWCNTs that were produced by the combustion method. Compared to the MWCNTs produced by both methods and graphite fibers, boron nitride produced nanocomposites with the highest thermal conductivity. Specific heat capacity was measured by using differential scanning calorimetry and thermal diffusivity was measured by using the laser flash.展开更多
Background:Differential scanning calorimetry as a method of investigating and monitoring the kinetics of herbal medicinal plants.Some instrumental and experimental aspects are discussed.Methods:A brief survey is made ...Background:Differential scanning calorimetry as a method of investigating and monitoring the kinetics of herbal medicinal plants.Some instrumental and experimental aspects are discussed.Methods:A brief survey is made of herbal medicinal plants and results of differential scanning calorimetry studies are reviewed and this discussion is presented the effects of the instrumental conditions like heating rate and the sample conditions like sample particle size,sample mass,sample purity,sample stability in the melting region and property of impurities.Conclusion:This study suggests that application of differential scanning calorimetry to study the interpretation on herbal medicinal drugs.展开更多
A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene t...A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene terephthalate) resins were selected as the samples containing different catalysts. The relationships between the parameters obtained from the known Avrami equation and from one in the present paper were discussed. A method for applying the equation to determine the kinetic parameters from a constant heating and a constant cooling curve was proposed.展开更多
HOT-DIPPING Zn+5% Al + (0.01%-0.2%) RE alloy on steel surface by the gas reductionmethod is a new technology. Owing to its good anti-corrosive and forming properties as wellas good technical periormances, the coating ...HOT-DIPPING Zn+5% Al + (0.01%-0.2%) RE alloy on steel surface by the gas reductionmethod is a new technology. Owing to its good anti-corrosive and forming properties as wellas good technical periormances, the coating attracts wide interest and has been put into indus-trial production rapidly. The authors successfully produced the coating by the electrolytic ac-tivity aid agent method and put it into industrial production. The products have been used inthe electric power and railway engineerings. Results show that the anti-corrosive展开更多
Seven typical components in municipal solid wastes (MSWs)--paper,food,textile,wood,straw,plastic and rubber were chosen as the thermogravimetric analysis samples in this paper to study the pyrolysis characteristics. B...Seven typical components in municipal solid wastes (MSWs)--paper,food,textile,wood,straw,plastic and rubber were chosen as the thermogravimetric analysis samples in this paper to study the pyrolysis characteristics. By the thermogravimetry and differential scanning calorimetry (TG-DSC) analysis,pyrolysis characteristics of MSWs’ components and pyrolysis endothermal enthalpy were obtained.The kinetic parameters of pyrolysis were determined with the Doyle method and a multi-stage first order pyrolysis model was proposed.The simulated results by this model showed good agreement with the TG experimental data.The pyrolysis characteristics provide significant parameters to a new concept of circulating fluidized bed incinerator,which can simultaneously restrain the high-temperature HCl corrosion and emission of dioxins.展开更多
Differential scanning calorimetry （DSC） is one of the few techniques that allow direct determination of enthalpy values for binding reactions and conformational transitions in biomolecules. It provides the thermody-...Differential scanning calorimetry （DSC） is one of the few techniques that allow direct determination of enthalpy values for binding reactions and conformational transitions in biomolecules. It provides the thermody- namics information of the biomolecules which consists of Gibbs free energy, enthalpy and entropy in a straightfor- ward manner that enables deep understanding of the structure function relationship in biomolecules such as the folding/unfolding of protein and DNA, and ligand bindings. This review provides an up to date overview of the applications of DSC in biomolecular study such as the bovine serum albumin denaturation study, the relationship between the melting point of lysozyme and the scanning rate. We also introduce the recent advances of the development of micro-electro-mechanic-system （MEMS） based DSCs.展开更多
文摘Decomposition processes of the quenched Zn-Al alloys were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the stabilities of supersaturated solid solution (SSS) of Zn-Al alloy and α' phase formed by quenching would reduce with the increase of Zn content and the precipitation of η-Zn phases even when aging at ambient temperature, so that the exothermic precipitation peak in DSC curve would disappear. The activation energy of the η-Zn precipitation and the reaction enthalpy were calculated and measured. The kinetics of α' decomposition or η-Zn formation was determined by XRD. The microstructure change during aging was observed by TEM.
基金Project(2007CB613706)supported by the National Basic Research Program of ChinaProject(0330005412901)supported the Key Disciplines Development of Beijing Municipality("Resources,Environment and Recycling Economy"Interdisciplinary),ChinaProject(X0104001200905)supported by the Scientific Research Foundation for the New Doctoral Teachers,Beijing University of Technology,China
文摘The non-isothermal heating process of Mg-Sn powder mixture was studied by differential scanning calorimetry(DSC) technique and the synthesis kinetics of Mg2Sn was evaluated by the model-free and model-fitting methods.The activation energy and conversion function of Mg2Sn synthesis reaction are calculated to be 281.7 kJ/mol and g(α)=[-ln(1-α)] 1/4,respectively.The reaction mechanism of 2Mg+Sn→Mg2Sn under non-isothermal condition is regarded as "nucleation and growth" .During the non-isothermal heating process,the phase transformation occurred in the Mg-Sn powder mixture was analyzed by XRD and the microstructure evolution of Mg2Sn was observed by optical microscopy,which is in good agreement with the reaction mechanism of 2Mg+Sn→ Mg2Sn deduced from the kinetic evaluation.
文摘The differential scanning calorimetric (DSC)curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. The curves show that the energy is released continuously as temperature rise to 70℃. Some thermodynamic and kinetic parameters of the energy release of the mitochondria have been obtained. The presented results showed that the mitochondria from cytoplasmic male sterile rice released more heat and they had higher energy barrier, less rate, and more complicated mechanism than that of their fertile lines in the energy release process.
文摘In this paper the measurement of crystallinity(C)ofacrylic copolymer(PAC),by Swelling Differential Scan-ning Calorimetry(SDSC)is discussed.Common DSC isonly used for measuring the crystallinity of polymers withmelting point,(T_m),below their decomposition temper-ature,(T_d).As temperature rises,polymers with swell-ing agent added become swollen and dissolved,goingthrough whole process of breaking solid structures.Thus,SDSC makes it possible to measure the crystallini-ty of polymers even with T_d below T_m.But the C mea-sured by WAXD and the total endothermal melting(swelling)heat in SDSC thermograms,(△H_l),are notlinearly correlated.It has been found that,instead of the△H_l,△H_l’obtained from the △H_l by subtracting the en-dothermal heat,△H_l,and the C measured by WAXDare linearly correlated.On the basis of this linear rela-tion,the unknown C of another PAC sample is measuredby SDSC.The result is in good accordance with thatmeasured by WAXD.
文摘Differential scanning calorimetry (DSC) provides easy screening for thermal hazard evaluation. Here, we investigate the difference between using glass and stainless-steel vessels on the DSC measurement of exothermic decomposition energy (QDSC) for 41 chemical substances (containing nitro, halogen, peroxide, and sulfur groups, and hydrazine bonds). Two borosilicate glass vessels (capillary and ampule) and one stainless-steel vessel were used. All QDSC values obtained were investigated with reference to the permissible fluctuation range specified by the ASTM (American Society for Testing and Materials) international Both glass vessels produced very similar QDSC values, despite different sample scales. The QDSC values obtained with the glass vessels were generally roughly within the variation tolerance range of the stainless-steel vessel. Notable exceptions were halogen- or sulfur-containing compounds;these exhibited smaller QDSC values with glass vessels in almost all cases. We will investigate whether certain structures in compounds react with stainless steel. The vessel material choice is crucial in evaluating the true reactivity of a substance.
文摘A single scan has been performed in Differential Scanning Calorimetry (DSC) at a heating rate of 15oC/min under non-isothermal conditions to investigate the crystallization kinetics of glassy Se90Sb10-xAgx alloys (where x = 2, 4, 6, 8). For this purpose, Handerson’s theory based on non-isothermal method for thermal analysis of single-scan DSC data has been used. The activation energy of crystallization and order parameter has been determined and composition dependence of these parameters has been discussed.
文摘Nanocomposites were fabricated by using a commercial two part epoxy as a matrix and multiwalled carbon nanotubes, graphite fibers and boron nitride platelets as filler materials. Multiwalled carbon nanotubes (MWCNTs) that were produced by chemical vapor deposition were found to produce nanocomposites with better thermal diffusivity and thermal conductivity than the MWCNTs that were produced by the combustion method. Compared to the MWCNTs produced by both methods and graphite fibers, boron nitride produced nanocomposites with the highest thermal conductivity. Specific heat capacity was measured by using differential scanning calorimetry and thermal diffusivity was measured by using the laser flash.
文摘Background:Differential scanning calorimetry as a method of investigating and monitoring the kinetics of herbal medicinal plants.Some instrumental and experimental aspects are discussed.Methods:A brief survey is made of herbal medicinal plants and results of differential scanning calorimetry studies are reviewed and this discussion is presented the effects of the instrumental conditions like heating rate and the sample conditions like sample particle size,sample mass,sample purity,sample stability in the melting region and property of impurities.Conclusion:This study suggests that application of differential scanning calorimetry to study the interpretation on herbal medicinal drugs.
文摘A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene terephthalate) resins were selected as the samples containing different catalysts. The relationships between the parameters obtained from the known Avrami equation and from one in the present paper were discussed. A method for applying the equation to determine the kinetic parameters from a constant heating and a constant cooling curve was proposed.
文摘HOT-DIPPING Zn+5% Al + (0.01%-0.2%) RE alloy on steel surface by the gas reductionmethod is a new technology. Owing to its good anti-corrosive and forming properties as wellas good technical periormances, the coating attracts wide interest and has been put into indus-trial production rapidly. The authors successfully produced the coating by the electrolytic ac-tivity aid agent method and put it into industrial production. The products have been used inthe electric power and railway engineerings. Results show that the anti-corrosive
文摘Seven typical components in municipal solid wastes (MSWs)--paper,food,textile,wood,straw,plastic and rubber were chosen as the thermogravimetric analysis samples in this paper to study the pyrolysis characteristics. By the thermogravimetry and differential scanning calorimetry (TG-DSC) analysis,pyrolysis characteristics of MSWs’ components and pyrolysis endothermal enthalpy were obtained.The kinetic parameters of pyrolysis were determined with the Doyle method and a multi-stage first order pyrolysis model was proposed.The simulated results by this model showed good agreement with the TG experimental data.The pyrolysis characteristics provide significant parameters to a new concept of circulating fluidized bed incinerator,which can simultaneously restrain the high-temperature HCl corrosion and emission of dioxins.
文摘Differential scanning calorimetry （DSC） is one of the few techniques that allow direct determination of enthalpy values for binding reactions and conformational transitions in biomolecules. It provides the thermody- namics information of the biomolecules which consists of Gibbs free energy, enthalpy and entropy in a straightfor- ward manner that enables deep understanding of the structure function relationship in biomolecules such as the folding/unfolding of protein and DNA, and ligand bindings. This review provides an up to date overview of the applications of DSC in biomolecular study such as the bovine serum albumin denaturation study, the relationship between the melting point of lysozyme and the scanning rate. We also introduce the recent advances of the development of micro-electro-mechanic-system （MEMS） based DSCs.
