热重分析(TGA)完全版资料

分解动力学
• The Effect of Reactive or Corrosive Atmospheres
on Materials
反应或腐蚀气氛对材料的影响
• Moisture and Volatiles Content of Materials
材料水分和挥发份含量
3
Mechanisms of Weight Change in TGA
350
400
450
500
550
600
Temperature (°C)
10
TGA: Baseline Considerations
• Good way to quantify how the TGA/SDT is working. • Especially important for measuring small weight
100 µL
100 µL
Platinum and Aluminum pans have attached wire bail.
250 µL
500 µL
Ceramic pans have removable wire bail.
15
Weight (%)
Effect of Sample Size
100
450
500
550
600
Temperature (°C)
2.5°C/min 5°C/min 10°C/min 20°C/min
650
700
Universal V3.7A TA Instruments
21
Time to Complete Degradation
120
100
2.5°C/min 5°C/min 10°C/min 20°C/minj
80
60
Weight (%)
40
20
源自文库
0
-20
20
40
60
80
100
120
140
160
180
Time (min)
Universal V3.7A TA Instruments
22
Q5000 IR – High-Heating Rate TGA Analysis
23
Typical Applications
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
pin-hole lid
13
TGA: Sample Pan Selection
• Platinum (useful for most materials)
Easy to Clean Nonporous Alloys with most metals
• Alumina (Ceramic)
Corrosives/Inorganics Large samples
• Aluminum (TGA) (designed for one-time use)
Lower cost Lower temperature limit (<=600°C)
14
TGA: Sample Pans - Types/Sizes
Platinum Aluminum
Ceramic
50 µL
•Thermal Stability •Compositional Analysis •Oxidative Stability
24
Thermal Stability of Polymers
100
PVC
80
PMMA
60
PET
40
LDPE
20
Method Log: 1:Select gas: 1 - N2 2: Ramp 20.00 °C/min to 650.00 °C 3: Select gas: 2 - Air 4: Ramp 20.00 °C/min to 1000.00 °C
18
Pan Shape Effect – Amorphous PMMA
120
100
365.01癈 369.13癈
80
Weight (%)
60
4.6mg; spread evenly
40
4.6mg; in tall S.S. pan (150 mg)
20
0
-20 0
100
200
300
400
500
Temperature (癈 )
losses associated with volatilization or small amounts of residue.
• Run clean, empty, tared pan, over temperature
range of interest, at desired heating rate.
0
40 0
-1
100
200
300
400
500
600
Temperature (°C)
9
Effect of Oxygen on Copper Oxalate Decomposition
46
45
Weight (%)
44
High Oxygen
43
Medium Oxygen
42
Low Oxygen
41
300
•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
• Thermal Stability of Materials
热稳定性
• Oxidative Stability of Materials
氧化稳定性
• Composition of Multi-component Systems 组成
• Estimated Lifetime of a Product
产品寿命
• Decomposition Kinetics of Materials
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).
650.00°C 55.59%
PEEK
650.00°C 14.32%
Weight (%)
0 50
650.00°C 5.928%
250
450
650
850
1050
40
20
0
0
100
200
300
400
500
600
Temperature (癈 )
Universal V3.8A TA Instruments
20
Shift in Onset with Ramp Rate
120
100
524.26°C 563.82°C
80
60
Weight (%)
40
20
0
-20
400
热重分析(TGA)
Theory & Applications
120 100
80 60 40 20
0
12.57% Water (0.8753mg)
6
19.47% Carbon Monoxide (1.355mg)
4
30.07% Carbon Dioxide (2.093mg)
2
0
-2
200
400
600
EGA Furnace
8
Test for Oxygen Contamination of N2 Purge Gas
120
3
Copper Oxalate
320.79°C
+
100
2
Weight (%) [------------] Deriv. Weight (%/°C)
80
1
60 10 minute N2 pre-purge
Weight (%)
Effect of Heating Rate
100
80
60
40
20
0
0
100
200
300
400
Temperature (°C)
Polystyrene 20°C/min Polystyrene 10°C/min Polystyrene 5°C/min Polystyrene 1°C/min
• Plot weight in µg vs. temperature.
11
TGA: Accurate Residuals
120
Polyolefin
4
100
2 80
60
0
Expanded Scale
0.28%
Weight (%)
40 -2
20
Baseline
0
-20 0
200
400
600
800
1000
500
600
17
Mass Effect – Semi-crystalline PE
120
436.28癈 457.57癈
100
80
Weight (%)
60
0.492mg
40
48.422mg
20
0
-20 0
100
200
300
400
500
600
Temperature (癈 )
Universal V3.8A TA Instruments
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
Standard Furnace
60ml/min
Temperature (°C)
Universal V3.9A TA Instrume1n2ts
TGA: Sample Preparation (cont.)
• Use brass tweezers to eliminate static effects • Tare a clean sample pan before every run • Distribute sample evenly over bottom of pan • Liquid samples - use hermetic pan with a
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
80
60
40
20
0
0
100
200
300
400
Temperature (°C)
Polystyrene 17.6 mg Polystyrene 10.2 mg Polystyrene 5.4 mg Polystyrene 2.7 mg
500
600
Universal V4.2D TA Instruments 16
800
1000
Temperature (°C)
Universal V3.4A TA Instruments
Weight (%) 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.
Universal V3.8A TA Instruments
19
Sample Morphology Effects – PET
120
419.58癈 424.58癈
100
80
Weight (%)
60
2.9 2m.9gm; ga;mamoorrpphhoouussPEPTET
2.8 mg2.;8smegm; cir-ycsrtaylslintaelPlinETe PET
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