Dear Vishal Rimal,

There are three methods for valuation of thermal stability:

1. Thermogravimetric analysis (TGA)

2. Differential scanning calorimetry (DSC)

3. Differential thermal analysis (DTA)

Any of the thermal techniques can be used to assess thermal stability as mentioned above. The typical approach is to conduct isothermal tests at 4-5 temperatures, then construct an Arrhenius plot to determine stability vs temperature. We always compared those results with oven tests of macro samples to compare results, using discoloration or other change as the end point.

It should be noted that even PVC follows this simple process, because the first step is a dehydration step, which is first order. The fact that the decomposition is complex is not relevant, since the rate-limiting step is the dehydration step. So the entire process is well-represented by a simple Arrhenius technique.

Vishal Rimal

I would add another route and that controlled pyrolysis in a gas chromatograph. This is sometimes used to determine the type of polymer. For example:

https://www.sciencedirect.com/topics/chemistry/pyrolysis-gas-chromatography

Dear Vishal,

could you please elaborate what material you want to test? Do you want to test chemical or structural stability? Please elaborate a bit on your project. ASTM can be used as a guideline as well.

kind regards

Dear Vishal,

In addition to TGA analyses, you should consider DSC analyses.

Abrie Myburgh I'm working on the thermal stability of carbon dots. In view of the same I was looking for techniques other than TGA, DSC and DTA in order to evaluate its stability in high temperature environments.

In addition to TGA, DTA and DSC following methods are also recommended for characterization of stability, decomposition, deformation, conductivity, etc., under the influence of temperature or thermal properties.

Thermo Mechanical Analysis (TMA): A technique in which a deformation of the sample under non-oscillating stress is monitored against temperature.

Dynamic-Mechanical Analysis (DMA): change in mechanical properties under the dynamic stress and with temperature.

Dielectric Analysis (DEA): Change in conductivity with temperature.

The suitability of thermal techniques is often dependent upon the objectives to be measured and the nature of the materials.

Multiple thermal techniques are usually used for a proper understanding of the thermal responses of materials.

Dielectric Analysis (DEA) technique may be useful for your study.

Thermo-optical Analysis (TOA) method can also be tried. In this method, the visual observation of a sample using transmitted or reflected light by means of hot-stage microscopy or DSC microscopy. Method is generally used for the study of crystallization and melting processes and phase transitions.

Hi Vishal,

a challenging project indeed. You state that the C-dots will be subjected to high temperatures? Will the atmosphere be inert/oxidative/reducing? If you do have access to a SEM, (or micro XRD) you could perhaps monitor the changes the C-dots could undergo in time?

Differential scanning calorimeter (DSC):

Differential scanning calorimeter (DSC) can be used to measure thermal properties of a sample. DSC is used widely for examining polymeric materials to determine their thermal transitions. Important thermal transitions include the glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm). DSC is used to measure a number of characteristic properties of a solid sample. Using this technique it is possible to observe fusion and crystallization events as well as glass transition temperatures (Tg). DSC can also be used to study oxidation, as well as other chemical reactions. Glass transitions may occur as the temperature of an amorphous solid is increased. These transitions appear as a step in the baseline of the recorded DSC signal. This is due to the sample undergoing a change in heat capacity; no formal phase change occurs. As the temperature increases, an amorphous solid will become less viscous. At some point the molecules may obtain enough freedom of motion to spontaneously arrange themselves into a crystalline form. This is known as the crystallization temperature (Tc). This transition from amorphous solid to crystalline solid is an exothermic process, and results in a peak in the DSC signal. As the temperature increases the sample eventually reaches its melting temperature (Tm). The melting process results in an endothermic peak in the DSC curve. The ability to determine transition temperatures and enthalpies makes DSC a valuable tool in producing phase diagrams for various chemical systems. DSC is mostly used in the pharmaceutical and polymer industries. For the polymer chemist, DSC is a handy tool for studying curing processes, which allows the fine tuning of polymer properties. The cross-linking of polymer molecules that occurs in the curing process is exothermic, resulting in a negative peak in the DSC curve that usually appears soon after the glass transition.

Experiment Objectives:

To know glass transition temperatures (Tg)

To know as the crystallization temperature (Tc)

Melting temperature or point (Tm)

To know about heat (Energy) release and heat absorption

To determine the thermal stability

To identify the kinetics reaction of materials

To study the compatibility of polymer

Thermo-gravimetric Analyzer (TGA):

Thermo-gravimetric Analyzer (TGA) is used for the measurement of the rate of weight change in a material by increasing the temperature or isothermally as a function of time with controlled at the morphemic condition. These measurements are used to determine the decomposition of material & to predict the thermal stability of material up to 1000 C TGA detects the phase change of material due to decomposition, oxidation or dehydration. After testing from TGA we can characterize material and predict the estimated life of the material. Such as; degradation temperature, physical aging, and moisture determination.

This equipment is used to measure the:

Thermal stability of the material

Composition of multi-component

Oxidative stability of the material

The estimated lifetime of a product

Moisture & volatile contents of the material

Effect of Environment or reactive or corrosive atmospheres on materials

Decomposition kinetics of materials

Liquid samples

Melting Temperature

Abrie Myburgh we had introduced the novel synthesis of high thermal stability carbon dots in our previous manuscript and preliminary tests such as XRD, SEM that you've mentioned were done and established to be credible. The carbon dots were found to be highly stable at temperatures up-to 800°C. As part of our ongoing research I was curious to see if any additional techniques would help us further reinforce the mechanism and have a better outlook.

Hi

You try DMA, DTA, DSC are some of the testing methods

Aside TGA other popular tests are Differential Thermal Analysis (DTA), DSC and DMA. Like Rimal suggested you can also check for changes in XRD signal of materials treated at different temperatures.

I do agree with Moses and Vishal

I would add another route for check. It is the zeta (ζ)-potential which could control the thermal stability of the polymers then effectively of the materials.

https://books.google.az/books?id=U0OB6pQSlfsC&pg=PA184&lpg=PA184&dq=Excluding+TGA+which+other+test+can+I+consider+to+check+the+thermal+stability+of+a+material?&source=bl&ots=t8p8V8tI4U&sig=ACfU3U33HWu6T8Z1757TRAGS2i-7cGdp6g&hl=ru&sa=X&ved=2ahUKEwiy4NCEsaTqAhUDjqQKHWN1DeYQ6AEwAnoECAoQAQ#v=onepage&q=Excluding%20TGA%20which%20other%20test%20can%20I%20consider%20to%20check%20the%20thermal%20stability%20of%20a%20material%3F&f=false

What is thermal stability? How is this size defined? The measure of thermal stability of given material is one physical quantity or several quantities, such as for texture? I would avoid using such ambiguous terms.