Degree of Polymerization via intrinsic viscosity
The determination of the average degree of polymerisation (DP) is carried out according to DIN EN 60450.
The measurement of DP is applied to new and aged cellulosic electrical insulation materials used for the production of transformers, cables and capacitors.
The samples are freed from oil by extraction using dichloromethane (DCM), dried, cut into small squares (approx. 1 mm x 1 mm) and the dry substance content is determined according to ISO 638:2008-10.
The prepared, weighed samples are shaken in copper(II) ethylenediamine hydroxide solution (CUEN solution) until the sample is completely dissolved, avoiding oxygen (air) contact, tempered and measured using an Ubbelohde viscometer. Based on the run-out times, the specific viscosity is measured, the intrinsic viscosity is derived and the DP is calculated from this.
The average degree of polymerisation (DP) of new papers is between 1200 and 1500, the DP of aged, unusable papers is around 150.
The method can also be used for chemically modified papers if these dissolve completely in the cuen.