The known methods of determining polyethylene glycol (PEG) or the total amount of PEG with the ethoxylated amines (EOA) in viscose or the spinning bath fail to give satisfactory results in the man-made fibre industry for several reasons. For example, the gravimetric method of determining PEG in viscose with si]icotungstic acid /I/ gives a large relative error owing to the presence of impurities in the viscose. To eliminate the influence of these impurities the analysis must be carried out on inert viscose, i.e. on viscose devoid of modifying agents and surface-active substances~ but this is impracticable at many fibre plants owing to a lack of facilities for obtaining samples of inert viscose. The method of determining PEG with phosphomolybdic acid or with an acidifying mixture /2,3/, viz. H2SO 4 + K2Cr207, suffers from the same disadvantage.
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