Thermogravimetric Analysis (TGA)

Thermogravimetric, or thermal analysis (TGA or TG) measures changes in sample weight in a controlled thermal environment as a function of temperature or time. The changes in sample weight (mass) can be a result of alterations in chemical or physical properties and can be detected to a fraction of a microgram. TGA is useful for investigating thermal stability of solid or liquid materials under conditions of ramping temperature in an inert gas atmosphere or in an oxidative gas atmosphere. TGA can also be conducted at constant temperature to evaluate thermal stability of materials over a specific time period. For example, potential VOC emission from pesticides can be measured at constant temperature for determining the amount and rate of mass loss over a specified time period.

Coupling the TGA to a spectrophotometer allows the study of volatile species and pyrolysis products, which can lead to discovering how a compound or formulation degrades and what components it contains. For example, TGA coupled with mass spectroscopy (MS) can provide specific information on chemical structure for identifying additives, contaminants and composition of blends and copolymers (TGA-EGA.)

Ideal Uses of TGA

Thermal stability/degradation
Quantitation of volatiles/moisture
Screening of additives
Evolved gas analysis (TGA with MS or TGA with FTIR (TGA-EGA)
Vaporization or sublimation
Deformulation of organic/inorganic mixtures (e.g., ink, paste, polymer composites)
Loss on drying
Residue/filler content
Decomposition kinetics

Strengths

Small sample size
Analysis of solids and liquids with minimal sample preparation
Qualitative or quantitative analysis
Detection of multiple mass loss thermal events from physical and chemical changes of materials
Separation of overlapping mass loss thermal events (High Resolution TGA)

Limitations

Evolved products are identified only when the TGA is connected to a spectrophotometer (e.g. TGA/MS or TGA/FTIR). This technique is available at EAG Laboratories in some supporting locations

TGA Technical Specifications

Signal Detected: Mass change and temperature
Maximum Sample Weight: 1 gram
Temperature Range: Ambient to 1000°C (1100°C available at some supporting locations TG-DTA)
Controlled Heating Rate: 0.01 to 100°C/minute
Weighing Precision: +/-0.01%

The following are available options that are offered at some supporting locations:

High Resolution TGA
Evolved Gas Analysis TG-EGA
TGA/MS Analysis
TGA/FTIR Analysis
1100°C Upper Temperature Limit
Simultaneous thermal analysis (STA): Combined TGA and Differential Thermal Analysis measurements in a single instrument: TG-DTA