Polymer analysis: acid value, hydroxyl value, and isocyanates by titration
11/19/2015

Polymer pellets for spectroscopic analysis

Potentiometric titration is ideally suited for titrating functional groups in monomers, in particular monomeric mono- and polyacids as well as polyols. Application Bulletin 200 describes the determination of the acid value, hydroxyl value, and isocyanate value by automatic potentiometric titration. The acid and hydroxyl value are determined according to ASTM, the isocyanate value is measured according to ISO.

Titrations of functional groups in monomers, in particular monomeric mono- and polyacids as well as polyols, are mostly carried out in nonaqueous, nonpolar solutions. Hence, they are accompanied by very little potential change, leading to flat and erratic titration curves. 

Metrohm has developed suitable instrumentation and sensors (e.g., the Metrohm Solvotrode) enabling endpoints to be determined in these low-conductivity media. The following applications are described in Application Bulletin 200:

  • Acid number in accordance with ASTM D4662-93 and ISO 2114:1996
  • Hydroxyl number in accordance with ASTM E1899-08 and DIN 53240-2
  • Isocyanates according to DIN 53185 and DIN EN ISO 14896
An on-demand demand webinar provides in-depth information on titration solutions for difficult polymer samples.

Downloads