Improving Your Product's Performance With Thermal Analysis

Improving Your Product's Performance With Thermal Analysis
7 min read
23 February 2023

To optimize your product's performance, you must understand the material properties that change when it's heated or cooled. Thermal analysis is an important technique for measuring these changes.

Calorimetric methods, such as differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA) can help you determine fundamental properties of a material over specific temperature ranges.

Heat Capacity

Heat capacity is a measure of the amount of energy that is needed to raise the temperature of an object by one degree. This measurement is often used in calorimetry experiments to determine how much heat is required to change the enthalpy of a combustion reaction.

It is a characteristic of materials, and it varies with the material and its phase. It is a very useful property to know because it helps us understand how much energy we need to heat an object of a certain mass by one degree Celsius or Kelvin, and how long this process will take under a given supply.

Specific heat capacity is the amount of energy it takes to raise the temperature of a gram of a substance by one degree degC, or one kelvin. It is usually referred to as Cs (sometimes pronounced as s), and it can also be symbolized by capital C with a subscript s, as in the case of water, or by capital C with a subscript m for molar heat capacity, which is the capacity of a substance when measured in moles.

The exact value of the heat capacity of a substance can be difficult to estimate, but it is a very useful characteristic to know when measuring an object in narrow ranges of temperature and pressure, as it allows us to trust that a given amount of heat input will change the temperature of a sample in those conditions with negligible error.

Melting Point

A melting point is a temperature at which a solid can be transformed into a liquid. It's important to know the melting point of your product, as it can influence a lot of other chemical characteristics.

Melting points are determined by heating a sample to the desired temperature using a specialized furnace. The temperature is then monitored by measuring the melting points of capillaries attached to a heating stand.

The difference between boiling points and melting points, in addition to the change of entropy and enthalpy, is that for melting, the molecules are unpacked from their ordered arrays into a loosely-bonded liquid, while with boiling, they remain firmly attached to each other. This is due to the fact that a molecule's shape allows it to pack tightly together and be compacted into one stable object.

It is therefore not surprising that a molecule's shape can have an effect on its boiling point, and also on the trend of its melting point. For example, toluene has a significantly higher boiling point than benzene, because toluene is much larger and more dense than benzene.

Similarly, the symmetry of a molecule can have an impact on its melting point, as high molecular symmetry is associated with higher melting points in organic chemistry. This is because it is more difficult to arrange symmetrical molecules in fully regular arrays, thus melting will be more difficult and will likely occur at a lower temperature than with low-symmetry compounds.

Temperature Transitions

When a product is exposed to a different temperature, its properties can change. This is especially true when using thermosets or amorphous polymers. It can affect how the material behaves, whether it will be hard or soft, and how it reorients itself.

The temperature at which a material changes form is known as the transition temperature. This is usually the point where a material switches from one crystalline state to another. For example, rhombic sulfur changes into monoclinic sulfur when heated above 95.6 degC; cooled below that point, it returns to rhombic sulfur.

This transition temperature is important for a wide range of applications, including biomedical devices that must be implanted at the body’s surface. It is also a factor in the development of materials that are used for cryoprotectant technology, which can be applied to frozen cells and tissue during cellular preservation or transplantation.

If you have a high-temperature polymer you are thinking about using for an application, it is vital to understand its glass transition temperature and how the material will be affected by additives and the cooling-ratio. This will help you select the best materials for your product.

The thermal analysis of a product can be a complex process, so it is essential to work with a lab that has experience with testing a variety of polymers. The lab can determine the right combination of tests for your specific application and ensure that the results provide you with the information you need to make the best decision for your product’s performance.

Weight Loss

Thermal analysis is a wide-ranging term that refers to the measurement of changes in physical or chemical properties triggered by heating or cooling. This is a critical step in the development of a quality-controlled product.

A popular technique to characterize the thermal stability of polymers is thermogravimetric analysis (TGA). This method measures weight loss as a function of temperature. The onset of weight loss is often used to define the upper temperature limit for thermal stability.

Thermogravimetric analysis is also a great technique for detecting the presence of volatile components that can lead to a product's breakdown. As a sample is heated, it will undergo various decomposition steps, each of which can result in a different volatile component. The resulting volatiles can then be chemically identified by a gas-phase IR cell.

This method is also a good candidate for solvate and hydrate analysis, as it can help identify the concentration of a solvent residue. It can also be used to determine the kinetics of decomposition and the level of dissolved oxygen.

High resolution TGA, or Hi-Res TGA, is an extension of conventional TGA that allows for the use of higher heating rates during regions with no weight loss and automatically lowers the heating rate as the sample experiences a weight loss transition. This can help improve separation of overlapping or poorly defined weight loss events, as well as enhance resolution of the derivative peaks.

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