POLYAMIDE (PA) Relative Viscosity & Viscosity Number

The RPV-1 Gen. 2 Polymer Viscometer is suitable for the determination of Relative Viscosity and/or the Viscosity Number of Polyamide (PA) also referred to as nylon. Today this polymer is used in airbags, carpet, automotive components, pipes and many more applications. Most people will be familiar with the product from consumer textiles. Depending on the grade of nylon, it may be dissolved in Formic Acid, m-Cresol or sulphuric acid. The determination of the Viscosity Number provides a measure of the relative molecular mass of the polymer.

The RPV-1 Gen. 2 provides a complete solution for the solution viscosity of polyamides, including sample preparation, sample dissolution, flow time measurement and full reporting of results, as specified in ISO 1628 Part 1, ISO 307 and ASTM D789.

ISO 307 covers the determination of the Viscosity Number of a low 0.5% concentration of the polymer solution. Solvent and solution flow times are measured at 25 deg. C using the same size of suspended-level Ubbelohde type viscometer for both measurements. For Formic Acid a size 1 viscometer is used and a size 2 for Sulphuric Acid or m-Cresol. The method requires that two successive flow times are obtained within a 0.25% precision. For each polyamide sample, ISO 307 also requires at least two determinations of the viscosity number in order to meet the repeatability test criteria. The dual position RPV-1 (2) Gen. 2 is an ideal configuration as well as the four position RPV-1 (4) Gen. 2. The iSP-1 Sample Preparation system can be used in conjunction with the RPV-1 to prepare samples on a precise weight to weight basis. Dissolution is carried out either using a wrist action shaker (WAS) for samples dissolved in Formic Acid or Sulphuric Acid and a reaction block with stirring and heating at 90 to 100 deg. C with a programmable timer. (SD-BM).

ASTM D789 covers the determination of relative viscosity of a high 8.4% concentration of polyamide dissolved in 90% formic acid. For this method, the solvent and polymer solution will need to be measured in different sizes of viscometer. The RPV-1 (4) Gen. 2 is the ideal configuration integrated with the ISP-1 sample preparation system.