The Cebe Research Group is an experimental condensed matter physics lab studying polymeric materials. We utilize an array of experimental techniques to investigate the behavior and properties of commercial and specialty polymers, with an emphasis on thermal analysis. You can see our current projects here:
Differential Scanning Calorimetry (DSC)
In a DSC experiment a material is heated or cooled at a specified rate, and the change in heat flow of the sample is measured. Using this data, we can determine the heat capacity of the material, which is a fundamental thermodynamic property that relates the amount of energy in a material with its temperature. Standard phase transitions such as melting and crystallization are readily apparent in the heat capacity data provided by DSC, as well as more exotic transitions such as the glass transition.
Thermogravimetry (TG) is a powerful tool for investigating the thermal stability of a material. A TG experiment involves placing a material on a high precision balance inside a furnace, and increasing the temperature. As the sample heats up it will undergo chemical degradation, and lose mass which is constantly measured throughout the experiment. Thus it is possible to determine the maximum operating temperature of a material. We use TG to assess not only thermal stability, but to characterize materials using their degradation “fingerprint,” and to investigate the presence of solvents such as water in our materials.
Fourier Transform Infrared Spectroscopy (FTIR)
FTIR is a powerful tool we use to characterize a material’s chemical and structure compositon. When exposed to infrared radiation of a specific wavelength, the chemical bonds of a material can absorb that radiation and vibrate. Exposing the material to a large swath of the infrared spectrum can reveal many of these characteristic vibrations, allowing us to “fingerprint” the material. FTIR is especially valuable for investigating crystalline structures, as it is sensitive to different crystal phases or polymorphism.
Wide Angle X-ray Diffraction (WAXD or WAXS)
X-ray diffraction is a technique whereby a material is hit with a directed beam of X-rays. The X-rays will scatter off the material, and from the scatterring pattern the microstructure of the material can be determined. We use wide angle X-ray diffraction in our work with semi-crystalline polymers to determine crystallographic phase and orientation in the material, as well as a means of determining the overall crystal fraction.
Scanning Electron Microscopy (SEM)
Due to the electron’s Compton wavelength being shorter than optical light, electron microscopes can resolve objects that would normally be blurry blobs in an optical microscope. Scanning Electron Microscopy allows us to see objects microns in diameter, all the way down to a few hundred nanometers. SEM is an ideal tool for our work in characterizing electrospun nanofibers, as well as polymer nanocomposites.
Polarized Optical Microscopy (POM)
For imaging microscopic objects, optical microscopy is a phenomenal technique. Add to that the ability to use polarized light, and you have polarized optical microscopy. Polymer crystals are birefringent, which allows us to see polymer cyrstals using POM. When used in conjunction with our hot stage, we can see the polymer crystals form and grow in a material with POM.
Dielectric Relaxation Spectroscopy (DRS)
Dielectric Relaxation Spectroscopy allows us to probe the relaxation dynamics of polymer systems. By exposing our materials to an oscillating electric field at various frequencies, and various temperatures, we are able to measure the relaxation time distributions of the polymer dipoles. DRS is used to investigate the glass forming properties of our materials, as well quantify the conductivity of a material.