热分析91887.ppt

Chapter 1 热分析 1.1 简介 研究物质性能随温度变化而变化的方法都可以归结为热分析方法。最常用的热分析方法列于表1中。 Table 1. Most frequently used thermal analysis techniques Continued: Continued: 各种热分析方法中以两种为主，即TG 和 DTA(DSC), 它们各种用途在表2和表3中作了部分例举。表4给出了DTA和DSC的热量变化方向。 Table 2. Some applications of thermogravimetry Continued: 8.蒸发和升华的速率 9.吸水吸湿研究 10.相图分析 11.聚合物热氧化分解 12.爆炸物分解 13.重量分析 14.反应动力学研究 15.新化合物的发现 16.汽化热测定和蒸汽压 17.?吸收、解吸曲线 18. 居里温度测定 Table 3. Some applications of DTA and DSC 催化剂 聚合物材料 润滑油 油脂 配位化合物 碳水化合物 氨基酸和蛋白质 金属氢氧化物 金属和非金属氧化物 煤 木材和相关物质 天然产物 粘土和矿物质 金属和合金 土壤 生物材料 无定形材料 水泥 半导体 医药品 爆炸物 相图 反应动力学 固体反应 脱水反应 辐射损伤 吸收热 反应热 聚合热 升华热 溶剂解离 固－气反应 居里点测试 纯度分析 热稳定性 氧化稳定性 玻璃化温度 危害评价 导热系数 比热 Continued: 1.2 Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) 1.2.1 Principle of DTA/DSC 经典 DTA 和 热流型 DSC, 功率 补偿DSC. Continued: They generally consist of (a) a furnace or heating device, (b) a sample holder, (c) a low-level dc amplifier, (d) a differential temperature detector, (e) a furnace temperature programmer, (f) a recorder, and (g) control equipment for maintaining a suitable atmosphere in the furnace and sample holder. For classical DTA: 1.The sample and reference materials are inserted into identical environments; 2.The temperatures of the sample and the reference are measured by thermocouples mounted in contact with sample and reference; 3.?T=TS-TR=R ?H, or d(?T )/dt=RdH/dt, R is the heat resistance of the system For heat flux DSC and power compaensation DSC: 1.?The temperature sensors were placed outside, but close to, the sample and reference in order to eliminate the thermal resistance R; 2.?There is a thermal lag between sample and sensor. For power compensation DSC: 1.The sample and the reference are contained in separate but identical holders with separate heaters and Pt resistance temperature sensors; 2.?The energy differences are measured directly; 3.The sample and the reference keep a same temperature. 1.2.2 实验技术 1, 样品和参比 样品: 可以是液体和固体，但不能是气体 Reference: ?-Al2O3 for DTA, nothing