Spectroscopic characterisation of polymers and nanocomposites
Polymer analysis can provide
- maps of chemical composition
- glass transition / crystallisation temperature
- thermal degradation products and mechanisms
- non-destructive depth profiling
- structure as a function of temperature
- data regarding in-situ reactions / modifications
Infrared spectroscopy and Raman microscopy are complementary non-destructive techniques that can be used to uniquely identify different polymeric materials and structures. We have a substantial range of different sampling accessories which, when used in conjunction with the state of the art infrared spectrometers, can provide valuable information about the material under investigation. Often these methods require little or no sample preparation.
Infrared spectroscopy is frequently used in industry for problem solving, research and product development and QC. We also have a sophisticated thermal analysis facility (TG-MS, TG-GC- MS) that enables the chemical fingerprint of a material to be interrogated as it thermally degrades and electron microscopes which can visualise the structure of a polymeric material over a wide range of temperatures without carbon or gold coating.
How Infrared spectroscopy works
A beam of infrared light is passed through the sample (via a substrate in the case of reflection measurements) and the loss (via absorption) of energy at characteristic wavelengths (called a spectrum) is recorded. The spectrum contains information about the chemical composition and the morphology of the material. The use of apertures to mask down the size of the beam enables microscopic samples to be analysed. Different sampling accessories can be used to obtain spectral information from the upper few microns of the sample.
How Raman microscopy works
Raman spectra are generated when light (usually from a laser beam) is incoherently scattered by a sample. The instrument is usually attached to a microscope which not only helps us to characterise the outer region of a sample, but also by moving the sample into and out of focus, different depths into the material can be analysed. This is known as confocal microscopy and involves the clever use of optics to prevent light from outside the focal plane contributing to the spectrum. For example, we can focus quite specifically into a polymer/polymer interface and completely block out the surrounding areas.
Confocal Raman microscopy can be used to analyse buried inclusions in polymer films as well as the interface of a polymer laminate. Also the high spatial resolution (less than 1mm) allows maps of heterogeneous surfaces to be characterised.