Polymers characterisation

Those wishing to characterise polymers currently, need to use several analytical techniques to get all the information about a polymer's structure or chemistry. Within the Polymers, Composites and Spectroscopy Group we put an emphasis on the use of vibrational spectroscopy (FTIR and Raman), thermal analysis (DSC and TGA), Small Angle X-ray and Neutron Scattering (SAXS and SANS), and x-ray diffraction (XRD) to provide information about the polymer systems we study.

We are particularly interested in

• the transport mechanisms of polymer systems
• the degradation mechanisms of polymeric systems
• the stretched polymer films and fibres behaviour of polymers
• the gelation mechanisms of polymers

The Polymers, Composites and Spectroscopy Group is currently involved in a number of projects around Polymer Characterisation.

Spectroscopy

The PCAS group has a extensive range of accessories which can be used to collect FTIR spectra from wide variety of sample types. Attenuated Total Reflectance Fourier Transform Infra Red (ATR-FTIR) spectroscopy can be used to study very small samples. This surface sensitive technique can provide information on coatings and laminates by presenting different sides of the sample to the beam, The PCAS group also uses ATR-FTIR routinely to follow the adsorption of water and other solvents into polymer films. This approach provides a wealth of information in addition to the rate of diffusion of the solvent species and can include information on polymer swelling and crystallinity and the interactions between the solvent and the polymer.

Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) is particularly suited to the analysis of powders and their mixtures. Coupled with the variable temperature accessory DRIFTS can provide important information about the transformation of organic molecules bound to mineral surfaces.

Fourier Transform Infrared Microscopy is another useful method of collecting infrared data and is routinely used to investigate actives and polymers used in the pharmaceutical industry. For example, it is possible to map the distribution of additives based on a diagnostic vibration of that additive.

Raman microscopy is often used in combination with infrared spectroscopy because the combined output provides extremely useful information concerning a sample. Raman microscopy can be used with minimal sample preparation and can be used to study solid materials in the presence of water. This has proven particularly useful in the in-situ study of hydrating cement pastes and underfilm corrosion.