Polymer Identification and Analysis

Commercial polymers typically include a base polymer and a number of other components such as anti-oxidants, UV stabilisers, colour masterbatch, inorganic fillers, glass and carbon fibres, plasticisers, processing aids and cross-linking agents to name a few.

A wide range of analytical techniques are available to identify the type of polymer and determine the composition which can be used in:

• Identification of unknown materials
• To establish whether or not the specified material has been used
• Compare materials
• Predicting differences in performance based on differences in composition
• Assess the variation and quality of materials
• Conformance to regulations and directives

Analytical techniques routinely used by Sandberg include: Fourier Transform Infrared Spectroscopy (FTIR); UV Spectroscopy; Atomic Absorbtion Spectroscopy (AAS); Differential Scanning Calorimetry (DSC); Thermogravimetric Analysis (TGA) and Mass Spectrometry.

Fourier Transform Infrared Spectroscopy (FTIR)

FTIR is one of the most important techniques used in the identification and analysis of polymers. Typical applications of FTIR in polymers include:

• Identification of the polymer type to ensure that the correct or specified type of polymer has been used for the application or to identify unknown polymer materials
• To investigate the composition of copolymers and polymer blends
• To investigate and identify polymer degradation mechanisms, such as hydrolysis of polyurethane or oxidation of polyethylene
• To identify substances that have migrated to the surface of the polymer, such as phthalate plasticisers in PVC

UV Spectroscopy

This techniques is used to identify material components that absorb in the UV range. In polymers it is mainly used for the identification and quantification of antioxidants and UV stabilisers, that have characteristic absorption peaks, such as butylated hydroxy toluene.

It can also be used to identify coloured derivatives of additives that are associated with discolouration and staining problems, such as phenolic yellowing associated with phenolic antioxidants.

Atomic Absorbtion Spectroscopy (AAS)

AAS is used for the identification and quantification of specific metals. Applications of AAS in polymers include:

• Determination of heavy metal content, such as the lead content in paint.
• Identification of metal content to establish conformance to regulations such as WEEE and ROHS
• Investigating the cause of polymer degradation , since trace amounts of some metals can act as catalysts in polymer degradation mechanisms
• Identification of contamination
• Establishing if counterfeit materials have been used
• Investigating interaction between polymers and metals