The separation and analysis of additives in polymers

This chapter describes the extraction, separation, identification and estimation of various organic and inorganic additives and polymeric materials in a range of plastic formulations such as poly(vinyl chloride), polypropylene, polyamide and polytetrafluoroethylene. It will concentrate primarily on their fractionation into, typically  

The extraction techniques employed will include solvent dissolution and extraction, centrifugation, polymer precipitation, filtration and ashing. Details will be given of the identification of these fractions using IR spectroscopy, pyrolysis/GC, HPLC, mass spectrometry and NMR spectroscopy, often after further separation using either specific solvents or TLC [21]. All IR spectra are recorded over the region 4000-667 cm (2.5-15.0 xm). 

The estimation of individual components by gravimetric techniques, IR spectroscopy, UV-visible spectroscopy, HPLC or titrimetry will be described. 

The basic principles of solvent extraction, etc., for the analysis of plastics formulations are well established and documented [1 ] and are still valid today. However, changes and improvements have been made, particularly in the fields of separation science and spectroscopy, to incorporate new ideas and instrumentation and to accommodate new additives. Despite such trends as robotics, the need for an experienced practical plastics analyst working at a bench using solvents, extraction flasks and beakers still exists. 

One theme running through this chapter will be that of method validation and the measurement of precision by way of calculated estimated standard deviations (sd) and coefficients of variance (cv) using check samples of known formulation and a collection of reference polymers and additives of known provenance. This approach not only will be necessary for any laboratories seeking accreditation such as BS5750 or NAM AS, particularly as a means of demonstrating to external auditors the competence of 

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