Thermo-analysis of Preparation Processfor Electron Trapping Materials

The heated process of raw materials for electron trapping materials (ETM) is investigated by thermo-analysis method. The temperature ranges of raw materials experienced some physical and chemical change processes, such as dehydration, organic solvent removal, crystal sulphur burning, oxidation of alkaline earth sulfides and solid phase reaction (rare earth doped) and so on, are obtained. The experimental results also show that the presence of trace oxygen in shielded gas is very harmful to prepare the ETM.The raw material thermo-analysis results provide very important experimental reference for optimizing the ETM preparation techniques.

热分解率(TGA)评定汽油清净剂控制发动机沉积物的理论和实践

阐述了依据清净剂及其加剂汽油的热稳定性预测其控制发动机沉积物的可行性。用热分解率(TGA)从购自汽车售后市场8款清净剂中挑选2款特定热稳定性的清净剂,分别按规定浓度添加在2台试验车的汽油中进行1000 km道路试验。结果表明,这2款清净剂控制CCD、IVD及PFID的实际效能与其由TGA热稳定性预测的清净效能完全吻合,因此TGA能有效取代清净剂台架试验评定。

热失重法(TGA)预测汽油清净剂控制发动机沉积物的研究

阐述了依据清净剂及其加剂汽油的热稳定性预测其控制发动机沉积物的可行性。用热失重法(TGA)从8款清净剂中挑选2款特定热稳定性的清净剂,分别按规定浓度添加在2台试验车的汽油中进行1 000 km道路试验。结果表明,这2款清净剂控制CCD(燃烧室沉积物)、IVD(进气阀沉积物)及PFID(喷油嘴沉积物)的实际效能与TGA(热失重分析)预测效能完全吻合,因此认为TGA能有效取代清净剂台架试验评定。

THERMAL DEGRADATION OF POLY(ARYLENE SULFIDE SULFONE)/NMETHYLPYRROLIDONE CRYSTAL SOLVATE

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.

Thermal Stability and Decomposition Kinetics of Polysuccinimide

The thermal stability and decomposition kinetics of polysuccinimide (PSI) were investigated using analyzer DTG-60 under high purity nitrogen atmosphere at different heating rates (3, 6, 9, 12 K/min). The thermal decomposition mechanism of PSI was determined by Coats-Redfern method. The kinetic parameters such as activation energy (E), pre-exponential factor (A) and reaction order (n) were calculated by Flynn-Wall-Ozawa and Kissinger methods. The results show that the thermal decomposition of PSI under nitrogen atmosphere mainly occurs in the temperature range of 619.15-693.15 K, the reaction order (n) was , the activation energy (E) and pre-exponential factor (A) were obtained to be 106.585 kJ/mol and 4.644 × 109 min-1, the integral and differential forms of the thermal decomposition mechanism of PSI were found to be and , respectively. The results play an important role in understanding the thermodynamic properties of polysuccinimide.

Comparison of burn rate and thermal decomposition of AP as oxidizer and PVC and HTPB as fuel binder based composite solid propellants

In the present investigation an effort has been made to understand the thermal decomposition and burn rate characteristics of AP as oxidizer and PVC and HTPB as fuel binder in composite solid propellant. The burning rate study has been carried out at ambient and different pressures of 2.068 Mpa, 4.760 Mpa,6.895 Mpa. The mechanism of thermal decomposition of each composition have also been determined by NETZSCH simultaneous thermal analyser, comprising differential scanning calorimeter(DSC) and thermo-gravimetric analyser(TGA). An effort has been made to study the burn rate and decomposition of fuel binder and oxidizer in presence of Fe_2O_3 and also their overall impact on combustion of propellant.

Optical, Thermal and Nonlinear Properties of Tristhiourea Lanthanum Nitrate

The single crystals of tristhiourea lanthanum nitrate (TTLaN) have been grown by solution growth using slow evaporation technique. The optical study revealed that the crystal has high transmission with lower cut-off wavelength of 235.78 nm. The EDAX analysis confirmed the grown compound elements. The presence of functional groups was identified through Fourier transform-infrared technique. The thermal stability of the crystal was determined from thermo gravimetric and differential thermal analysis curve. The second harmonic generation behavior of TTLaN crystal was tested by Kurtz-Perry powder technique. This single novel semiorganic crystal of TTLaN showed very good optical transmission property, high thermal stability and large non-linearity nature.

A Comparative Investigation of Lead Sulfate and Lead Oxide Sulfate Study of Morphology and Thermal Decomposition

The compound lead oxide sulfate PbSO4.PbO was prepared in our laboratory. The Thermal behavior of PbSO4 was studied using techniques of Thermogravimetry under air atmosphere from 25 to 1200°C. The identity of both compounds was confirmed by XRD technique. Results obtained using both techniques support same decomposition stages for this compound. The electron microscopic investigations are made by SEM and TEM. The compound is characterized by XRD and the purity was determined by analytical Methods. Also a series of thermogravimetric analysis is made and the ideal condition is determined to convert this compound to pure lead oxide.

Thermal Studies of Commercial Low Calorie Sweeteners

This paper presents the thermal analysis of artificial sweeteners, and natural sugar substitutes. Thermal analysis was done on commercial compositions of sweeteners using simultaneous DSC/TGA (SDT). Heat flow, and mass vs. temperature and time thermograms, along with DSC peak enthalpies and transition temperatures are reported. A number of the sweeteners were found to undergo transitions and reactions before or at 190°C (375°F, normal baking temperatures) and all dextrose containing sweeteners show an endothermic peak around 80°C due to the liberation of bound water molecules. The major components of sweeteners studied were found to be generally thermostable at or below 100°C.

Thermal Characterization and Lifetime Estimation of the Humus Lombricospt

Through this study, the humus produced in the breeding place of Universidad Autonoma de Occidente was thermally characterized. The humus was submitted to a heating program controlled by the Differential Scanning Calorimetry (DSC) technique to characterize the type of transition, Thermogravimetry (TGA) to study the equilibrium of phasesand Mass Spectrometry (MS) coupled to TGA to identify detached elements in a temperature range. The temperature range used in this study was 30℃ ℃. The energy required for the water desorption in the humus has been found in this study. The humus showed a quick desorption between 30℃ ≤ TDesorption ≤ 110℃ at a heating rate of 10℃/min and presented decomposition around 250℃. Moreover, the kinetics of the desorption of the humus was studied to obtain the activation energy three TGA measures for three different heating rates. The average activation energy was about 26 kJ/Mol. This result was carried out to obtain an estimation of the desorption time of water in the range from room temperature to the decomposition temperature around 350℃.

TGA2常见故障分析及管理维护

介绍了TGA2热重分析仪的工作原理和操作条件,结合仪器在使用过程中出现的问题及故障进行了分析和探讨,提出了合理的解决方案,并提出了有效的仪器管理维护办法,延长仪器的使用寿命,减少故障率,更好的为科研工作服务。

生物酶预处理对桐木脱色的影响

【目的】探讨二代生物复合酶对桐木的漂白效果和影响规律,为桐木脱色和生物学改良及桐木制浆的发展提供理论基础和科学依据。【方法】以兰考泡桐为试验材料,采用纤维素二代生物复合酶CTEC2进行预处理,控制预处理时间(60、75、90和105 min)、温度(30、50和70℃)和pH(3、5和7)等因素,分析预处理前后样品色差、化学组分等变化;利用TGA/DSC3型热重同步分析仪探究泡桐木材热降解性能;使用电镜扫描(SEM)观察预处理前后样品纤维微观形态变化;通过X射线衍射测定预处理泡桐木材结晶度,分析不同预处理条件对样品结晶的影响。【结果】1)颜色测定表明,在温度50℃、pH为7的条件下,CTEC2预处理105 min泡桐木材漂白脱色效果最好,亮度和白度均有所提高,且随着预处理时间延长,漂白效果更好;2)组分测定表明,在温度50℃、pH为7的条件下,CTEC2预处理泡桐木材效果最好,纤维素相对含量增加10.76%、半纤维素含量减少11.13%、酸溶木质素含量减少3.05%、酸不溶木质素含量减少4.22%、抽提物含量减少1.15%;3)从TGA曲线可知,经预处理的泡桐木材最大质量损失速率对应的温度有所增加,热稳定性有所上升;从SEM图像可知,预处理可有效破坏木质纤维素结构;从XRD可知,经预处理的泡桐木材纤维素结晶度有所提高。【结论】纤维素二代生物复合酶CTEC2可使泡桐木材主要化学组分发生变化,降低木质素、半纤维素和抽提物等含量,从而达到漂白脱色效果。泡桐木材漂白预处理的最佳条件为温度50℃、pH 7、预处理时间105 min。

轨道车辆EVA电缆剩余寿命快速评估研究

随着科技的发展,我国的交通运输水平已处于世界前列,特别是轨道车辆的发展,为我国人员流通、物资运输和经济的发展作出重大贡献。轨道交通列车运行过程中,车辆内部运行控制信号及电力的输送保障至关重要。在轨道交通列车上使用的薄壁控制电缆的外层护套绝缘材料种类中,有一种为乙烯-醋酸乙烯共聚物(EVA),该材料在酸性、潮湿等恶劣条件下易发生黄变、开裂、鼓包等现象,从而影响电缆的剩余寿命,使得电缆出现传输异常,影响列车正常运行,严重时可能出现短路发生火灾造成重大事故及人员伤亡。为对轨道车辆用乙烯-醋酸乙烯共聚物(EVA)电缆的剩余寿命进行快速评估,文章采用热重分析法(TGA)研究了不同老化程度的EVA绝缘材料的热分解特性,计算出了其对应的热分解活化能。在此基础上,参照ASTM E 1877-00:2021标准中的方法建立了EVA绝缘材料的热寿命方程。研究结果表明:热分解特性能够用来评估轨道车辆用EVA电缆的实际老化情况,结合建立的热寿命方程能完成电缆使用状况的快速评估,与传统评估方法相比,该方法操作更加简单。

城市生活垃圾典型组分的热解动力学模型研究

对城市生活垃圾中的典型组分进行热重特性试验，根据热失重曲线得出了反应力学参数及反应速率控制方程，进而提出了一个通用的反应速率函数式，提出热解指数这个指标来表征垃圾的热解特性．结果表明：１垃圾组分中，塑料、橡胶、植物类厨余热解符合三段模型，其余组分符合二段热解模型，在不同的温度范围内，热解的反应机理是不同的，且反应动力学参数也不相同．２同一种组分，影响其反应速率的主要因素是反应动力学常数，升温速率改变时，反应速率方程中的函数式并不改变，改变的只是反应动力学常数．３在加热速率相同的情况下，塑料最容易热解，提高加热速率。

贝壳脱硫性能的动力学研究

采用热重分析仪和压汞仪对4种贝壳和一种石灰石在不同反应条件下的脱硫性能和孔结构进行了试验研究。随SO2浓度的增加、反应时间的增加,贝壳与石灰石的钙转化率增加。贝壳的脱硫效果优于石灰石,其最佳脱硫温度比石灰石的高:扇贝壳的约为1050℃,海螺和毛蚶壳约为1000℃,花蛤约为950℃,而石灰石的约为900℃。煅烧贝壳的内部孔径在0.2-10gm之间,比表面积在0.6459-1.1389 m2/g,而石灰型CaO的孔径集中在0.02-0.1μm,比表面积为12.2209 m2/g。孔分布良好的贝壳具有较好的脱硫动力学特性,脱硫剂的钙转化率较高。

不同生长期莲藕淀粉的凝胶特性、热重与核磁共振测定

对不同生长期的莲藕淀粉进行热重、莲藕及其淀粉凝胶的质构和莲藕淀粉的核磁共振的测定。结果表明:不同生长期莲藕淀粉的热分解速率随着成熟度而加快;随着莲藕成熟度的增加其破裂力与破裂能减少;不同生长期莲藕淀粉凝胶特性和淀粉与水分子的相互作用均有所不同。

生物质与煤共热解特性研究

选取4种典型生物质样品(麦秆、稻秆、木质素、造纸废液颗粒),将生物质样品与煤分别以1∶9、3∶7、5∶5的重量比例掺混。采用热重分析法,在相同升温速率下,对各掺混样品进行热解实验,探讨了生物质与煤热解特性的差异以及它们共热解时生物质对煤热解过程的影响。研究表明,生物质与煤的热解特性差异很大:生物质热解温度低,热解速度快,而煤相对热解速度慢,热解温度高;在生物质与煤混合热解时,总体热解特性分阶段呈现生物质和煤的热解特征;将各生物质样品与煤混合热解的实际微分曲线与按比例折算后曲线进行比较,得出实际微分曲线与折算曲线基本吻合,即生物质对煤的热解无明显影响。

生物质的热解过程及其动力学规律

采用热重分析法(TGA)对几种常见天然生物质(稻秆、麦秆、玉米秆)和其衍生物木质素、造纸废液颗粒等的热解过程及其动力学规律进行了研究.实验中加热速率分别为10,20,30℃/m in,终温为850℃.热解在氮气气氛下进行,并用高纯氮气作为保护气体.实验结果表明:天然生物质的非等温热解只有1个剧烈失重阶段,而木质素和造纸废液颗粒存在2个剧烈失重阶段.生物质比煤的热解起始温度低,热解速度快.随升温速率的提高,生物质的最大热解速度提高,对应的峰值温度升高,最终失重率呈下降趋势.生物质的热解机理满足三维扩散Jander方程,且随着升温速率的提高,其活化能增大.