The practical applications associated with each technology are so numerous that it would be impractical to even attempt to list or describe them. Therefore, for each of the TA technologies we have mentioned, we will briefly outline some of its potential special applications in coating chemists.
The information obtained by DTA and DSC is roughly the same, the difference is that the information given by DSC is qualitative and quantitative. Differential thermal analysis (DSC) and differential thermal analysis (DTA) have been widely used to study the temperature and phase transition properties of materials heated under different atmospheres. The oxidative stability of various substances is easily characterized. Polymers evaluated are frequently analyzed for flammability and subambient phase transitions.
Coatings often have characteristic transitions, including glass transitions (transitions associated with changes in specific heat), exothermic reactions caused by physical or chemical reactions (such as crystallization or crosslinking reactions), melting, volatilization, decomposition, phase change, oxidation or thermal decomposition. DSC has the ability to quantify the heat of reaction and is useful for determining the relative heat of combustion of flame retardants and untreated materials. The effectiveness of flame retardants can also be assessed.
The kinetic parameters of the chemical reactions were derived from the DSC data. The study was carried out by isothermal method and heating method. These methods use the rate of thermal evolution as a measurement parameter. The classic epoxy amine reaction helps to simulate the production method, by first determining the reaction kinetics, minimizing the raw materials and reaction time to obtain a good product. Furthermore, since aging or oxidation is an exothermic reaction, this technique has been used to study the long-term stability of coatings.
As an analytical tool, the application of thermogravimetric analysis is mainly to determine the change of sample mass with time and temperature. Isothermal and non-isothermal methods were used. For the analysis of coatings, measurements of non-volatility and thermal stability are usually performed. However, as with DSC, decomposition kinetics, accelerated aging, and oxidative stabilization can be performed. Unlike DSC, which heats by conduction, TGA heats by convection and radiation. Therefore, the temperature sensor is located close to the sample to obtain true temperature readings.
Applications including estimation of polymer decomposition, polymer lifetime, differentiation of flame retardant polymers from untreated polymers of the same type, and drying kinetics have been reported.
For coating analysis, compositional analysis can help determine why changes in performance occur. For example, the weight loss curves of materials with apparently identical compositions behave differently in one formula. In further research, we observed that the weight loss of one material occurred at a slightly different temperature and in a different pattern, suggesting a difference in the material.
With the continuous strengthening of the control of organic volatiles in coatings, TGA can be used to determine the content of volatile organic compounds in coatings. As with DSC, thermal or long-term degradation stability of coatings based on one resin or another can be performed as a formulation tool.
The application of TMA is related to the size of the sample as a function of time and temperature. Information such as coating and substrate compatibility, elastomer performance in harsh environments, and adhesion of one material to another (such as multilayer packaging or bake-on coatings on metal substrates) are available.
A direct application of TMA in coating technology is dilatometry, ie the determination of the coefficient of thermal expansion. It is especially useful when identifying two different coatings.
The application of DMA provides information on transition temperature, curing phenomena and mechanical properties. These properties include impact resistance and even sound absorption. The technique measures how a material behaves when it deforms under cyclic stress. Another approach to DMA testing is to measure the viscoelastic response of a material to cyclic loading. Applications range from viscoelasticity measurements to crosslinking kinetics. Modulus values such as flexural, Young's and shear provide information on the material stiffness, while mechanical damping relates to the energy dissipated as heat during deformation.
In terms of coating technology, DMA can be applied to the study of film properties, such as curing process and film forming process. Various properties around the glass transition point can be investigated. For example, in thermoplastics, increasing the rubber modulus usually means increasing the molecular weight. In thermosets, increasing rubbery modulus values indicate higher crosslink density.
In order to obtain faster, more reliable and more novel information, TA is constantly improving. For example, in most TGA decomposition measurements, the heating rate is held constant over the decomposition range, self-compensating for internal cooling. A device that can simultaneously examine TGA and DSC data on the same sample.
The weight loss that occurs in overlapping temperature regions is resolved by rate-adjusted maximum resolution TGA. Overlap can be seen using the first derivative of the TGA signal. As with the previously mentioned techniques, the TA can be coupled to a mass spectrometer or infrared spectrometer to analyze the effluent output of the TA instrument. Modulated DSC is an innovation with higher sensitivity, higher resolution, more complete analysis, and easy data interpretation.
DMA currently has multiple degradation modes, including single and double cantilever, three-point bending, shear intercalation, compression, and tension. Provide frequency multiplexing from 0.01 to 200hz.
We try to describe the enormous capabilities of TA. This technique is at its best when multiple instruments are used in research or production problems. Combined, these devices can provide insight into the relationship between formulation, processing, and coating performance.
