Developments in Differential Scanning Calorimetry
From oceans to industries, the applications keep expanding
Millions of tons of microplastics—pieces less than five millimeters long—pollute the world’s oceans, and differential scanning calorimetry (DSC) can identify this debris. In fact, DSC can be used in a range of studies of polymers and plastics. Effectively applying DSC, though, depends on a combination of hardware and software. Today’s platforms offer many advances, including higher sensitivity, which allows measurements on smaller samples, built-in autosamplers that provide automation, and various analytical packages.
One example of DSC used in the study of microplastics is research conducted by scientists in Egypt, in which the technology was applied to water samples from the Mediterranean coast. With their DSC-based screening method, the researchers identified 10 types of microplastic in the samples. Similarly, scientists in Brazil analyzed hospital waste with DSC and found that polymers made up almost 99 percent of the waste produced from medical devices. These studies provide just a glimpse of how DSC can be used.
DSC can also be applied to a variety of more general tasks. As examples, César Leyva Porras, a tenured technician at the Centro de Investigación en Materiales Avanzados (CIMAV) in Chihuahua, Mexico, mentions using DSC to determine the melting temperature and heat of fusion to calculate the degree of crystallization in polymers and the glass transition temperature (Tg) in carbohydrate polymers. When asked what features matter most in a DSC device, Leyva Porras points out temperature and signal stability, temperature range for determining Tg below room temperature, and modulated features. For instrument advances, Leyva Porras would like to work with modulated DSC combined with thermogravimetric analysis.
Seeking better software
Beyond hardware, DSC requires software to analyze the data, and most vendors provide analysis packages. As an example, Mettler Toledo’s STARe software provides six methods for determining a sample’s specific heat capacity. Some vendors even run training sessions on making the most of their software packages.
In addition, commercial software packages can be enhanced with add-ons. As an example, TA Instruments (a Waters company) developed its TRIOS software for DSC, and the company offers various add-ons for thermal kinetics, such as a rheology polymer library. Some DSC software also focuses on simplification. With Hitachi’s NEXTA DSC platforms, for example, the software guides users through the process to make it easy even for beginners when using standard methods of DSC.
Still, some scientists prefer to develop their own analytical tools. At the Institut Laue-Langevin in Grenoble, France, for example, scientific coordinator of the Partnership of Soft Condensed Matter PSCM Leonardo Chiappisi and Aline Cisse, a PhD student in his group, created their own DSC software called pyDSC to handle a large amount of data in a short time. This simple Python-based script automatically performs much of the basic DSC analysis. The authors describe the script’s capabilities as basic corrections of raw-DSC, including the correction for the blank and solvent signal. Plus, anyone can use this free and open-source software, which works on any operating system running Python.
Identifying and characterizing plastics and polymers applies to so many areas of research and industry that many scientists and engineers benefit from advances in DSC—from the device itself to its related analytical software. It is promising to see scientists like Chiappisi and his colleagues writing scripts that make it easier to use this thermoanalytical technique. Such scientist-driven projects can further expand where and how DSC gets used, such as in tracking microplastic pollution around the world.