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Chemical Analysis of Polymers

• FT-IR - Fourier Transform Infrared Spectroscopy (FT-IR) is a popular tool for identifying and characterising poly
  mer materials and their additives. Independent Polymer Technology uses a Nicolet Impact 400 Fourier transform infrared bench driven by “Omnic” software. Spectra from unknown samples can be readily compared with extensive reference spectra using the library search facility, to aid identification.

Infrared Microscope (IR-Plan)

The infrared bench and software is also used to drive an infrared microscope. Infrared micro-spectroscopy is a powerful technique in problem solving – particularly for the identification of inclusions or defects in moulded parts or plastic films. The microscope can also be a valuable tool for forensic investigations when the available sample may be limited. See the case study on regrind contaminant identification

• DSC - Differential Scanning Calorimetry measures heat flow to a polymer. By monitoring the heat flow as a function of temperature phase transitions such a glass transition temperatures and crystalline melt temperatures can be characterised.

Thermal Analysis Suite including DSC, TGA and TMA

From a knowledge of both the glass transition temperature and crystalline melt properties information regarding the degree of crystallinity miscibility of blends and alloys and processing conditions for component manufacture can be gained. The technique can also be used to determine the thermal stability of polymers through determination of the OIT (oxidation induction time/temperature)

• TGA - Thermogravimetric Analysis (TGA) measures changes in the weight of a sample as a function of temperature and/or time. TGA is used to determine polymer degradation temperatures, residual solvent levels, absorbed moisture content, and the amount of inorganic (non-combustible) filler in polymer or composite material compositions. It can also assist in de-formulation of complex polymer products.

• TMA - This technique measures changes in the length or volume of a sample as a function of temperature and/or time. TMA is commonly used to determine thermal expansion coefficients and the glass transition temperature of polymer or composite materials. A weighted probe is placed on the surface of the specimen. The vertical movement of the probe is continuously monitored while the sample is heated at a controlled rate.

• Atomic force microscopy - AFM is a powerful surface imagining technique which uses a fine probe to scan the sample surface. Deflections of the probe are detected by a laser reflecting off the back surface of the probe tip and are used to characterise the surface topography of the sample. 

Glass Fibre on PTFE surface

This technique allows high resolution imaging of samples to the region of nano-meters with significant simplification of sample preparation in comparison to alternative techniques such as SEM. See other AFM examples