Polymer analysis
Polymer analysis can determine
- mapping of chemical composition
- glass transition / crystallisation temperature
- thermal degradation products and mechanisms
- non-destructive depth profiling
- structure as a function of temperature
- in-situ reactions / modifications
Techniques
Infrared spectroscopy and Raman microscopy are complementary non-destructive techniques that can be used to uniquely identify different polymeric materials and structures. Within the MARS CIC we have many different sampling accessories which, 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 Synergic chemical analysis instrumentation that enables the chemical fingerprint of a material to be interrogated as it thermally degrades and ESEM enabling the structure of a polymeric material to be characterised 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 make up 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 other 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 surface to be characterised.