Company: GÖTTFERT
Intrinsic viscosity
A simple method is described to determine the intrinsic viscosity IV. This is done via a correlation process, entirely without chemical solvents. The process is particularly suitable for PET and polyamides.
Introduction
The intrinsic viscosity (IV or η) describes the structural and rheological properties of highly concentrated solutions and polymer melts in cm³/g. It is used to characterise the average molecular weight of PET and PA-based plastics.
Method
The correlation relationship must be determined representatively, uniquely, from measured melt indexes or melt viscosities and intrinsic viscosities. This data set should include at least three pairs of values (IV value and melt index or melt viscosity).
Model calculations show a correlation between measured and calculated IV and IVRheo intrinsic viscosities. This correlation relationship is a straight line equation with the two constants A and B.
These are then used to calculate the intrinsic viscosity.
The constants apply in each case to one test weight or one shear rate, assuming that the same procedure was always carried out.
Procedure in 3 steps
- An IV value is calculated per weight from the mean value of the MI measurement or from the viscosity.
- Model calculations show a correlation between measured and calculated IV and IVRheo intrinsic viscosities.
- The correlation relationship is a straight line equation with 2 constants A and B. The constants A and B of the correlation relationship must first be determined so that the calculation of IV can then be carried out.
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Rheological testing equipment since 1962
GÖTTFERT Werkstoff-Prüfmaschinen GmbH was founded in 1962 by Prof. Dr. Otto Göttfert. In the second generation, his son Dr Axel Göttfert took over as sole managing director.
On the world market, the medium-sized company is known as one of the leading companies in the niche area of rheological testing equipment. The innovative rheological systems are used worldwide in laboratories as well as in production.
To be closer to many customers, a subsidiary was opened in Rock Hill, South Carolina, USA, in 1989. In 2011, GOETTFERT (China) Limited was founded with headquarters in Beijing and Shanghai.
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