General Analysis of Miscellaneous Elements in a Polyurethane Elastomer

GENERAL ANALYSIS OF MISCELLANEOUS ELEMENTS IN A POLYURETHANE ELASTOMER 

The previously described procedures are the most commonly used ones for polyurethane characterization by analysis however, sometimes it is necessary for completeness to carry out analytical procedures for the identification of the less usual elements that may be present as a result of residual catalysts from the manufacture of intermediates or finished 

Total chlorides can be determined by the Schoniger method, which is rapid and utilizes small samples, and by the Wickbold method, which can be utilized for polymers as solids or liquids which may be aspirated into the combustion chamber as solutions in a suitable solvent. The Paar bomb or Wickbold combustion techniques are particularly amenable to the analysis of urethanes. 

For trace metals the method is usually to employ wet-ashing or dry-ashing techniques. The ashed residue is solubilized by the desired solvent, followed by colorimetric, polarographic, or emission spectroscopic techniques. Atomic absorption can also be used with many polymers analyzed directly after a proper solution is prepared, without prior ashing. For polymers that are difficult to solubilize or that provide a solution too viscous to aspirate into the flame, partial degradation by hydrolysis, thermal treatment or solvent extraction may be used to effectively alleviate these difficulties. 

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