Effect of a cold delignification prior to determination of the IEC 60450 viscometric degree of polymerization of cellulosic insulation materials

The objective of this work is to propose a sample preparation procedure implementing a preliminary cold delignification (CD) for the IEC 60450 DPv determination in order to be able to dissolve any sample independently of its history (new, dried, or aged). This work shows that a cold delignification enables the full dissolution of samples known to be reluctant to it. The cold delignification is compared to other strategies known to ease the dissolution as a mechanical pretreatment, increasing the time of dispersion in water or of dissolution in the solvent. The comparison is conducted on new cellulosic pulp samples. A cold delignification enables the full dissolution of the sample after only 30 minutes of dissolution in the solvent and induces a DPv loss of 2.3%. On the other hand, extending the dissolution time in the solvent from 30 minutes to 4h leads to a DPv loss of 13%.