A testament to the march of scientific inquiry, thermogravimetry emerged through the integration of three individual inventions in the 19^th and 20^th centuries: the electric furnace, the thermocouple, and the microbalance. As a cornerstone of material science, chemistry, and various other industries, thermogravimetric analysis (TGA) has since developed in leaps and bounds. Today, TA Instruments are leading the way in TGA, and we welcome you to join us as we explore the workings and applications of this groundbreaking technique.¹

Thermogravimetric analysis is a technique in which changes in sample mass are measured as a function of time and temperature. This allows researchers to gain valuable insights into a wide range of material properties and behaviors, including thermal and oxidative stability, decomposition kinetics, moisture content, volatile components, the presence of multiple constituents, and the effects of reactive or corrosive environments. Additionally, TGA serves as a crucial tool for determining the decomposition temperature of substances, a parameter essential for designing effective experiments using differential scanning calorimetry (DSC).²

The basic setup of a TGA instrument includes a microbalance to measure the sample’s mass, a furnace to provide controlled heating, and a temperature sensor to monitor the temperature. During a TGA experiment, the sample is placed in a crucible or pan, which is then loaded onto the balance system. The temperature of the furnace is gradually increased at a constant rate. Typically an inert gas, such as nitrogen, or a reactive gas, such as oxygen, is used to purge the unit, depending upon the exact nature of the experiment. Various processes may occur within the sample as the temperature rises, such as decomposition, evaporation, and oxidation, resulting in a loss or gain of mass, which is detected by the balance system throughout the experiment.³

By analyzing the patterns in mass changes, researchers can infer important information about the sample’s stability, composition, and volatile content. TGA can also be performed under different pressures and atmospheric conditions, such as air, inert gases (e.g., nitrogen), vapors (e.g. steam), or reactive gases (e.g., oxygen), permitting researchers to investigate the effects of different environments on the sample’s behavior.

TA Instruments offers a suite of thermogravimetric analyzers, including Standard TGA systems and High-Pressure TGA systems, as described below:

Standard TGA Systems

These instruments are provided at a range of price points to suit research needs. The TGA 55, TA Instument’s most cost-effective analyzer, is designed for individuals seeking robustness and reliability without sacrificing performance. At its heart lies TA’s exclusive Tru-Mass™ Balance, ensuring unparalleled performance. With exceptional sensitivity, accuracy, and user-friendly operation, the TGA 55 is the perfect model for basic research and industrial labs.

Building upon the specifications of the TGA 55, the TGA 550 provides advanced options and configuration flexibility, such as Hi-Res™ TGA, MTGA™, DTA signal, and our latest addition, the 25-position autosampler. With its outstanding versatility and intuitive handling, the TGA 550 is ideal for research and multi-user laboratories.

Finally, crafted for unrivaled performance, TA Instruments offers the TGA 5500. Tailored for researchers demanding peak performance and a comprehensive battery of features, such as Hi-Res and MTGA, all standard, the TGA 5500 is engineered to optimize temperature precision and minimize signal drift, surpassing any competitive TGA, including those incorporating post-test data manipulation. An integrated electromagnet makes temperature calibration easy. Leveraging our patented IR furnace, the TGA 5500 executes the swiftest heating and cooling rates, thereby enhancing productivity.⁴

High-Pressure TGA Systems

Across numerous applications, materials are required to endure harsh environments as part of their regular operation, such as extreme pressures or exposure to reactive gases and steam. In these scenarios, conventional TGA may not deliver the desired level of analysis. By introducing an additional dimension—pressure—to the analysis, high-pressure thermogravimetric (HP-TGA) systems allow for the comprehensive evaluation of a material’s thermal stability, generating deeper insights into its performance under severe environmental conditions.

TA Instruments produce a variety of HP-TGA instruments, including the Discovery HPTGA 75, HP-TGA 750, and HP-TGA 7500. At the center of each lies an innovative top-loading magnetically levitated (MagLev) balance. By integrating multiple patented technologies, these instruments can function seamlessly under extreme conditions of high pressure and temperature.⁵

Thermogravimetric analysis has a diverse range of applications across various industries and fields of study. Some of the key areas where TGA finds application include:

Polymers: TGA analysis offers a means to test the stability and investigate the lifespan of common polymers, such as those found in wire insulation, as well as high-performance polymers used in the fields of aviation and automobile manufacturing. As a result, short-term experiments can be conducted to forecast polymer operational longevity.^6,7

Pharmaceutical: Analysis of moisture content and the stability of pharmaceutical formulations can be performed by TGA to ensure product quality and efficacy.⁸

Batteries: Battery separators, pivotal components of lithium-ion batteries, can be evaluated by TGA across an array of parameters, including stability, temperature-dependent mass loss, and filler content. TGA can also be used to assess decomposition kinetics and facilitate the estimation of the separator’s lifespan.⁹

Food Science: The application of TGA and DCS analysis provides valuable information for optimizing food quality, safety, and processing techniques in the food industry. For example, in cheese manufacturing, TGA and DSC have been used to understand the composition and physicochemical structure of materials, facilitating modeling and the determination of factors such as the ideal storage temperature.¹⁰

Thermogravimetric analysis has evolved continuously over the years with advancements such as Hi-Res™ which allows for enhancement of the resolution of multiple weight loss events without increasing the time of the experiment.

Modulated TGA further enhances TGA analysis by applying a sinusoidal temperature program to generate a response change in the sample. This approach offers improved kinetic analysis capabilities by determining activation energy in real time with just one run, overcoming the constraints of traditional techniques such as multiple experiments.¹¹

Evolved gas analysis (EGA) techniques, including TGA coupled with mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR), and gas chromatography-mass spectrometry (GCMS), enable the identification and quantification of gases evolved during TGA experiments. These techniques provide valuable information on decomposition mechanisms, product formation, and chemical reactions occurring in the sample, elucidating complex thermal behaviors and reaction pathways.

Thermogravimetric analysis reveals a detailed profile of material properties and behaviors, providing invaluable information across a spectrum of industries and research domains. Leading the charge in TGA technology, TA Instruments’ analyzers are poised to elevate product development, fortify quality control measures, and propel innovation into uncharted territories. Contact a member of the team today to find out more.