热重分析(TGA)
Theory & Applications
120
6
12.57% Water (0.8753mg)
100
19.47% Carbon Monoxide (1.355mg)
4
80
Weight (%)
30.07% Carbon Dioxide (2.093mg)
2
60
0 40
20 0 200 400 600 800
-2 1000
Universal V3.4A TA Instruments
Temperature (°C)
Deriv. Weight (%/min)
TGA: The Technique
Thermo gravimetric Analysis (TGA) measures the amount and rate of change in the weight of a material as a function of temperature or time in a controlled atmosphere.
•样品在热环境中发生化学变化、分解、成分改变时可能伴随着重量的 变化。 •热重分析就是在不同的热条件（以恒定速度升温或等温条件下延长时 间）下对样品的质量变化加以测量的动态技术。
热重分析的结果用热重曲线或微分热重曲线表示。
2
What TGA Can Tell You
热稳定性 • Thermal Stability of Materials • Oxidative Stability of Materials 氧化稳定性 • Composition of Multi-component Systems 组成 产品寿命 • Estimated Lifetime of a Product 分解动力学 • Decomposition Kinetics of Materials • The Effect of Reactive or Corrosive Atmospheres 反应或腐蚀气氛对材料的影响 on Materials • Moisture and Volatiles Content of Materials
材料水分和挥发份含量
3
Mechanisms of Weight Change in TGA
Weight Loss:
Decomposition: The breaking apart of chemical bonds. Evaporation: The loss of volatiles with elevated temperature. Reduction: Interaction of sample to a reducing atmosphere (hydrogen, ammonia, etc). Desorption.
Weight Gain:
Oxidation: Interaction of the sample with an oxidizing atmosphere. Absorption. All of these are kinetic processes (i.e. there is a rate at which they occur).
4
TG曲线 积分型曲线
DTG曲线 微分型曲线
5
初始热分解 温度(B、G)
最大失重 速率温度
反应终了温 度(C、H)
6
影响热重测定的因素: Purge Gas
• TGA: Always purge through balance housing with dry inert gas • TGA: Only introduce reactive/corrosive gases through sample
area/furnace housing • Nitrogen most common. • Helium often provides best baseline but will make furnace work hard at high temperature. • Air can sometimes improve resolution because of differences in the oxidative stability (versus thermal stability) of components. 气氛不同反应机理的不同。
7
TGA: Purge Gas Flow
40ml/min 10ml/min
90ml/min
60ml/min Standard Furnace
EGA Furnace
8
Test for Oxygen Contamination of N2 Purge Gas
120 3
Copper Oxalate
320.79°C
+
100 Weight (%) 2 [------------] Deriv. Weight (%/°C)
9
80
1
60
10 minute N2 pre-purge
0
40 0 100 200 300 400 500 600 Temperature (°C)
-1
Effect of Oxygen on Copper Oxalate Decomposition
46 45 Weight (%) 44
High Oxygen
43
Medium Oxygen
42
Low Oxygen
41 300
350
400
450
500
550
600
Temperature (°C)
10
