Fully Automated Instrument for Solution Viscosity in Polymeric Materials

Developed by Polymer Char, The Intrinsic Viscosity Analyser, IVA, is a reliable and automated instrument for intrinsic viscosity analysis of polymeric materials, which sometimes demand temperatures of up to 200 ºC for dissolution. A wide range of polymers, even the most crystalline ones, can be analysed with convenience and safety in this instrument.

The IVA proposes a precise and convenient approach to IV measurement as a result of the automation of all the analytical procedures, from filling of the vials to the reporting of the results. Under software control, the instrument takes care of adding solvent to the vials, controlling the exact dissolution time for each vial, injecting each solution, and rinsing the capillary lines. No solvent needs to be handled by the analyst at any time and no vapours are released to the atmosphere because the system is airtight at all times.

Accuracy is further achieved by sample care protocols implemented to maintain the sample’s integrity throughout the dissolution and measurement processes. A purge of the vial’s atmosphere with an inert gas (nitrogen) is performed before dissolution to minimise oxidation. The vials then remain in an external tray at room temperature before the software schedules their transfer to the dissolution oven. In addition, efficient heat transfer to the vial, together with a gentle shaking without magnets, and preheating the solvent prior to its delivery to the vial, help to shorten the time required for dissolution. This minimises oxidative and thermal degradation ensuring that accurate IV is measured, even for the most challenging, ultrahigh molar mass materials and oxidation‑prone polymers, such as polypropylene.

The viscosity measurement is performed by the built-in two capillary viscometer placed inside an oven with extremely precise and stable temperature control (0.01 ºC). The instrument fluidic design is rather simple, having a single valve inside the oven, which results in high reliability. Moreover, the IV results obtained by IVA are in agreement with the ISO 1628-3:2010 method.

A new run can be immediately started after finishing the previous one, achieving a throughput of 40 samples a day in standard operation conditions. Unlike the glass capillaries used in Ubbelohde viscometers, the IVA stainless steel capillaries and tubing do not require additional washing or rinsing, and provide robust and precise viscosity values over time.

The IVA can be used with different solvents for analysing a wide variety of polymers. When analysing polyolefins or other polymers containing significant C-H content, the instrument can incorporate the Infrared detector IR4. With this on-line detector, the injected polymer mass is accurately quantified, which results in improved precision and accuracy of IV results.