Methods for the determination of the molecular weight of nylons are described. The active end groups of alcohol-soluble nylons are determined either potentiometrically or conductometrically. The amine end groups of alcohol-insoluble, phenol-soluble nylons may be determined by conductometric titration in the solvent phenol-alcohol-water. Carboxyl end groups of the latter nylons are determined by dissolving the polymer in benzyl alcohol at 175°C. and titrating with potassium hydroxide, using phenolphthalein as indicator.
not pyrophoric and did not regain their black color or pyrophoric property by allowing them to cool in an atmosphere of hydrogen.
SummaryNickel salts are reduced by sodium, potassium or calcium to free nickel. It is pyrophoric and an excellent catalyst for the reaction between sodium (potassium or calcium) and ammonia. Small amounts of nickel amide are formed when the nickel salt is present in excess. The reactivity of the nickel is greater when calcium is the reducing metal. The pyrophoric property appears to be due to adsorbed hydrogen. Cincinnati, Ohio
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