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Standard: |
TAPPI |
Method: |
TAPPI T 509 |
Title: |
Hydrogen ion concentration (pH) of paper extracts
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TAPPI T 509 measures the hydrogen ion concentration of a cold aqueous extract (unfiltered) of paper, expressed in terms of pH value. It is suitable for writing, printing, and sized industrial papers, but is not intended for unbuffered types such as insulating and condenser papers. The determined values may not be exact in a fundamental sense and should not be interpreted in terms of solution theory. The pH values are empirically correlated with end use requirements and paper qualities. This method avoids change of acidity or alkalinity resulting from heat-induced hydrolysis. A hot water extraction method is described in TAPPI T 435. Surface pH measurement of paper is described in TAPPI T 529.
This method consists of a cold water (25 ± 5°C) extraction of the specimen for one hour followed by a pH measurement with a commercial pH meter.
The pH determination measures the extent to which the paper alters the hydrogen-hydroxyl equilibrium of pure water. The pH (acidity) may be important because of its effect on the permanence of the paper. Although the acidity may be determined as the amount of water soluble acidity by titration with alkali (TAPPI T 428 “Hot Water Extractable Acidity or Alkalinity of Paper”), the hydrogen ion concentration (pH) is more indicative of the stability of paper than is the total acidity.
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Please note:
SGS-IPS cannot sell or otherwise provide standards, specifications, or test procedures to third parties.