采用非限定烤燃试验,测定了高固含量改性双基推进剂药柱的热爆炸临界温度,讨论了固含量与临界温度的关系及临界温度的尺度效应;通过高压热分解研究,获得了高固体含量推进剂热分解反应非等温动力学参数,探讨了固含量对临界温度的影响机...采用非限定烤燃试验,测定了高固含量改性双基推进剂药柱的热爆炸临界温度,讨论了固含量与临界温度的关系及临界温度的尺度效应;通过高压热分解研究,获得了高固体含量推进剂热分解反应非等温动力学参数,探讨了固含量对临界温度的影响机理。结果表明,固含量由0%增加至50%,热爆炸临界温度由134.5℃上升到156.1℃,3 MPa压力下第一热分解峰温由201.8℃上升到206.2℃(β=10℃/min),表明热稳定性增加;长径比为1的GLX-4药柱临界温度与直径的对数呈线性关系。此外,随着固含量升高,热分解活化能由161.0 k J/mol升高到181.9 k J/mol,揭示了烤燃试验热获得的爆炸临界温度升高这一现象的高压热分解动力学理论依据。展开更多
Recycled polyethylene terephthalate (RPET) and recycle polypropylene (RPP) blends filled with a renewable filler, i.e. cockleshell-derived CaCO3 (CS) were prepared as an environmental friendly thermoplastic composite....Recycled polyethylene terephthalate (RPET) and recycle polypropylene (RPP) blends filled with a renewable filler, i.e. cockleshell-derived CaCO3 (CS) were prepared as an environmental friendly thermoplastic composite. The effects of CS particle size and content on thermal stability, mechanical performance and flame retardant properties of the blends were investigated. Thermogravimetric analysis was performed to elucidate the thermal decomposition kinetics of the filled composites. The iso-conversion of the Flynn-Wall-Ozawa was developed by the second order polynomial function for thermal oxidative degradation of the blends while peak derivative temperature from the Kissinger method was able to verify the mechanism of degradation in these blends. The results indicated that both CS and commercial grade CaCO3 improved thermal stability and enhanced the stiffness as well as impact performance of the blends. However, this could only be achieved when high filler content was present in the RPET/RPP blends.展开更多
A thermal gravimetric method is described for evaluating the kinetics of cell size-dependent decomposition and lifetime estima- tion for microcellular tissue engineering scaffolds made of biodegradable polylactic acid...A thermal gravimetric method is described for evaluating the kinetics of cell size-dependent decomposition and lifetime estima- tion for microcellular tissue engineering scaffolds made of biodegradable polylactic acid(PLA)foams.PLA foam cell sizes from 550 to 20?m were fabricated experimentally using a solvent-free solid-state foaming technique under saturation pressures from 1 to 5 MPa.The thermal properties of the PLA foams with respect to the cell sizes were measured using thermal gravimetric analy- sis in a nitrogen atmosphere and the activation energy and pre-exponential factor were derived to evaluate the decomposition ki- netics and estimate lifetime.It was found that small cell sizes can be achieved under high saturation pressures and that the thermal stability of PLA decreases after the fabrication process.The cell size-dependent thermal stability and degradation rate indicate that a PLA foam of larger cell sizes has a shorter degradation time,a few tenths that of the PLA raw material,at a temperature of 37°C. The results suggest that it is feasible to optimize fabrication parameters to obtain appropriate cell sizes and lifetimes that satisfy the application requirements for various organs.This study provides the basis for precise scaffold design and quantitative analysis of PLA foams in tissue engineering applications.展开更多
The thermal decomposition process of KAI(SO4)2’ 12H2O and its kinetics has been studied by TG-DTG. By Dollimore method, D3 is defined as the second step of thermal decomposition kinetic model and its kinetic equation...The thermal decomposition process of KAI(SO4)2’ 12H2O and its kinetics has been studied by TG-DTG. By Dollimore method, D3 is defined as the second step of thermal decomposition kinetic model and its kinetic equation is da/dT = (l /P) CT '(3/2(l - a)2/3[ 1- (l - a)1/3] - 1 ). At the same time, it has been found that the apparent activation energy E increases with the increases of fraction of conversion a and the absolute temperature T, and then it shows that a linear relationship with the temperature T has been obtained.展开更多
文摘采用非限定烤燃试验,测定了高固含量改性双基推进剂药柱的热爆炸临界温度,讨论了固含量与临界温度的关系及临界温度的尺度效应;通过高压热分解研究,获得了高固体含量推进剂热分解反应非等温动力学参数,探讨了固含量对临界温度的影响机理。结果表明,固含量由0%增加至50%,热爆炸临界温度由134.5℃上升到156.1℃,3 MPa压力下第一热分解峰温由201.8℃上升到206.2℃(β=10℃/min),表明热稳定性增加;长径比为1的GLX-4药柱临界温度与直径的对数呈线性关系。此外,随着固含量升高,热分解活化能由161.0 k J/mol升高到181.9 k J/mol,揭示了烤燃试验热获得的爆炸临界温度升高这一现象的高压热分解动力学理论依据。
文摘Recycled polyethylene terephthalate (RPET) and recycle polypropylene (RPP) blends filled with a renewable filler, i.e. cockleshell-derived CaCO3 (CS) were prepared as an environmental friendly thermoplastic composite. The effects of CS particle size and content on thermal stability, mechanical performance and flame retardant properties of the blends were investigated. Thermogravimetric analysis was performed to elucidate the thermal decomposition kinetics of the filled composites. The iso-conversion of the Flynn-Wall-Ozawa was developed by the second order polynomial function for thermal oxidative degradation of the blends while peak derivative temperature from the Kissinger method was able to verify the mechanism of degradation in these blends. The results indicated that both CS and commercial grade CaCO3 improved thermal stability and enhanced the stiffness as well as impact performance of the blends. However, this could only be achieved when high filler content was present in the RPET/RPP blends.
基金supported by the National Basic Research Program of China(2011CB707900)the National Natural Science Foundation of China(10974098)+1 种基金the Natural Science Foundation of Jiangsu Province(BK2009407)the Doctoral Fund of the Ministry of Education of China(20093207120003)
文摘A thermal gravimetric method is described for evaluating the kinetics of cell size-dependent decomposition and lifetime estima- tion for microcellular tissue engineering scaffolds made of biodegradable polylactic acid(PLA)foams.PLA foam cell sizes from 550 to 20?m were fabricated experimentally using a solvent-free solid-state foaming technique under saturation pressures from 1 to 5 MPa.The thermal properties of the PLA foams with respect to the cell sizes were measured using thermal gravimetric analy- sis in a nitrogen atmosphere and the activation energy and pre-exponential factor were derived to evaluate the decomposition ki- netics and estimate lifetime.It was found that small cell sizes can be achieved under high saturation pressures and that the thermal stability of PLA decreases after the fabrication process.The cell size-dependent thermal stability and degradation rate indicate that a PLA foam of larger cell sizes has a shorter degradation time,a few tenths that of the PLA raw material,at a temperature of 37°C. The results suggest that it is feasible to optimize fabrication parameters to obtain appropriate cell sizes and lifetimes that satisfy the application requirements for various organs.This study provides the basis for precise scaffold design and quantitative analysis of PLA foams in tissue engineering applications.
文摘The thermal decomposition process of KAI(SO4)2’ 12H2O and its kinetics has been studied by TG-DTG. By Dollimore method, D3 is defined as the second step of thermal decomposition kinetic model and its kinetic equation is da/dT = (l /P) CT '(3/2(l - a)2/3[ 1- (l - a)1/3] - 1 ). At the same time, it has been found that the apparent activation energy E increases with the increases of fraction of conversion a and the absolute temperature T, and then it shows that a linear relationship with the temperature T has been obtained.
文摘为了解超细六硝基艹氐(HN S)的热分解性能,通过DSC-TG实验研究HN S-Ⅳ的热分解过程,用K iss inger法和O zaw a法计算了HN S-Ⅳ热分解反应动力学参数。结果表明,HN S-Ⅳ的热稳定性与HN S-Ⅱ相当。K iss inger法和O zaw a法得到的HN S-Ⅳ分解表观活化能分别为221.4 kJ/m o l和220.3 kJ/m o l,比静态气氛下HN S-Ⅱ热分解反应的表观活化能减小27 kJ/m o l。
