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乙烯-醋酸乙烯酯-乙烯醇三元共聚物性质的研究
以乙烯-醋酸乙烯酯共聚物(EVA)为原料,通过控制VA的水解程度制得一系列不同组成的乙烯-醋酸乙烯酯-乙烯醇三元共聚物.研究表明:随水解程度的增加共聚物的结晶性越来越好.在一定水解度范围内共聚物具有良好的综合力学性能,是一种新型的热塑性弹性体....
2020-09-25 09:10:57浏览：60
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聚酯的热分析与热分解动力学的研究
基于热分析动力学理论,在单一升温速率下采用差示扫描量热法(DSC)和热重分析(TG)对两种PET(a-PET和b-PET)试样在空气中的热解过程进行研究.通过考察DSC曲线得到两种PET的玻璃化转变温度(Tg)、熔点(Tm)、结晶温度(Tc)和结晶度等,得到结果:a-PET和b-PET的玻璃化转变温度分别为80.70℃和93.81℃,熔点分别为261.41℃和260.31℃,结晶温度分别为128.28℃和229.59℃,结晶度分别为27.76%和31.17%.通过Freeman-Carroll方法计算不同试样各阶段热解反应的活化能、反应级数和指前因子.结果表明:PET有两个主要的热解阶段,第一阶段在340～445℃温度区间中,a-PET的活化能、反应级数和指前因子分别为141.00kJ·mol-1和0.65、4.97E+9 min-1;b-PET的活化能、反应级数和指前因子分别为167.128 kJ/mol、0.39和4.33E+11 min-1;第二阶段在515～561℃温度区间内,a-PET的活化能、反应级数和指前因子分别为106.48 kJ/mol、0.66和2.2E+6 min-1;b-PET的活化能、反应级数和指前因子分别为123.04kJ/mol,0.70和1.05E+7 min-1....
2020-09-02 20:01:33浏览：154
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CuBiAl合金相变动力学研究
采用DSC法研究了CuBiAl合金组织中α(Cu)+γ2(Al4Cu9)→β(AlCu3)的相变动力学.结果表明,该合金以10℃/min升温时的相变温度为562.12℃,合金的相变表观激活能为1 145.75 kJ/mol,相变起始激活能为2 744.58kJ/mol,随着相变体积分数的增加,其相变激活能逐渐减小.并在此基础上绘制了相变的体积分数与温度之间的关系曲线....
2020-08-31 10:42:30浏览：66
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TNAE的合成和热分解动力学
以尿素和乙二醛为原料,经缩合、硝化和水解反应合成了含能化合物TNAE.用差示扫描量热法(DSC)研究了TNAE的热行为,测定了TNAE在不同升温速率(5、10、15、20和25 K/min)下的分解峰温.用Kissinger和Ozawa方法计算了TNAE放热分解反应的表观活化能(Ek和Eo)和指前因子(A),用热力学方程计算了TNAE放热分解反应的的活化焓(△H≠)、活化熵(△S≠)和活化吉布斯自由能(△G≠).结果表明,TNAE对热不稳定,△H≠、△S≠和△G≠值分别为147.93 kJ/mol、54.52J/(K· mol)、125.86 kJ/mol....
2020-08-30 18:25:27浏览：44
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DNAN在RDX中的非等温结晶动力学
采用差示扫描量热仪研究了2,4-二硝基苯甲醚(DNAN)在RDX中的非等温结晶行为,运用多种数学模型对DNAN的结晶动力学进行数据处理.结果表明,RDX能够降低过冷度,消除自加热.由Avrami方程计算得到了DNAN结晶动力学的Avrami 指数为2.34,确定了结晶过程的机理函数g(α).由Avrami-Ozawa方程获得了Ozawa指数为0.77.由Hu-Zhao-Gao-Zhao方程获得了结晶动力学参数活化能为214.99 kJ·mol-1....
2020-08-30 18:25:27浏览：57
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表面修饰聚乙二醇粒子的非等温结晶过程
采用乙基纤维素对聚乙二醇(PEG)粒子进行表面修饰,通过对修饰后PEG粒子和未修饰PEG粒子进行差示扫描量热(DSC)测试,研究PEG材料尺寸对非等温结晶过程的影响.结果发现:表面修饰PEG粒子在球晶生长碰到皮材时结晶结束,而未修饰PEG粒子在球晶生长一段时间后相互碰撞挤压直到填满所有空隙后结晶才结束;表面修饰后结晶半时间和结晶最快时间变短;表面修饰PEG粒子和未修饰PEG粒子在尺寸小于400μm时,表面修饰PEG粒子的结晶峰峰位向高温移动....
2020-07-10 14:39:05浏览：47
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Characterization of water-in-crude oil emulsions in oil spill response
The formation of water-in-crude oil emulsions occurs when crude oils are spilled into sea. The water-in-crude oil emulsionssignificantly change the properties of the spilled crude oils and in turn influence the choices made relating to oil spill countermeasures. Thewater-in-crude oil emulsions were characterized using various techniques in this study. The environmental scanning electron microscopyobservation of water droplets in the emulsions is also presented. It is a powerful tool in emulsion observations....
2020-07-08 21:52:19浏览：81
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Water permeability parameters of dermal fibroblast employed in tissue engineering in subzero tempera
Fibroblast is a crucial kind of cell in the construction of the tissue engineered dermal equivalent. In order to optimize the cryopreservation protocols of the tissue- engineered dermis, the characteristics of dermal fibroblast in subzero temperatures are required, which include the water permeability of the cell membrane and the apparent activation energy. Using the differential scanning calorimeter (DSC), the volumetric shrinkage during freezing of human dermal fibroblast suspensions was obtained at the cooling rate of 5℃·min-1 in the presence of extracellular ice. To ensure the presence of extracellular ice, a small quantity of ice nucleation bacteria (INA bacteria), pseudomonas syringae was added in the samples. And based on the Karlsson's model, a nonlinear- least-squares curve fitting technique was implemented to calculate the cryogenic parameters. At the reference temperature TR (= 0℃), the water permeability of membrane Lpg = 0.578μm·min-1·atm-1 and the apparent activation energy ELP = 308.8 kJ·mol-1. These parameters were then used to simulate water transport of fibroblast during constant cooling at rates between 0.01―50℃·min-1. The simulation results were analyzed to predict the amount of water left in the cell after dehydration and the "optimal cooling rate" for fibroblast cryopreservation. For the dermal fibroblast with DMEM solution, a cooling rate of 4.6℃·min-1 was optimal....
2020-07-08 21:52:19浏览：75
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木材热解特性和动力学研究
选取杉木、花梨木和水曲柳为样品,对其在不同升温速率下进行了TG、DTG和DSC分析.将木材的热解过程分为四个阶段,分析了每个阶段的化学物理变化以及热效应的变化,研究了不同升温速率对热解过程的影响,并建立试样的热解模型,求出了其动力学参数,有助于着火机理、火蔓延机理、阻燃机理的研究....
2020-06-12 14:56:35浏览：1426
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木材热解特性和动力学研究
选取杉木、花梨木和水曲柳为样品,对其在不同升温速率下进行了TG、DTG和DSC分析.将木材的热解过程分为四个阶段,分析了每个阶段的化学物理变化以及热效应的变化,研究了不同升温速率对热解过程的影响,并建立试样的热解模型,求出了其动力学参数,有助于着火机理、火蔓延机理、阻燃机理的研究....
2020-03-24 09:12:12浏览：1427
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