On-line viscometer controls polymer composition

For Polyacryl Iran Corporation, the benefits of the Hydramotion XL7 on-line viscometer were evident as soon as it was installed: the acrylic fibre quality is now tightly controlled

Founded in August 1974, Polyacryl Iran Corporation is the largest and most advanced man-made fibre manufacturer in Iran, producing over 95000 tonnes of polyester and acrylic fibre each year.

Acrylic fibre is easily washed, resistant to oils and chemicals, readily dyeable and quick drying - properties which make it very suitable for a wide range of knitted, woven and pile fabrics for clothing, blankets, upholstery, carpets, hosiery, sail covers and many other materials.

Polyacryl Iran produces acrylic fibre by dissolving a precise quantity of polyacrylonitrile powder in dimethylformamide and extruding the solution through a spinneret (die).

As the polymer solution leaves the spinneret the solvent is evaporated by heated nitrogen, so the fibres solidify and can be collected on a take-up wheel.

The viscosity of the polymer solution is a direct reflection of its polyacrylonitrile content, which determines the properties of the product fibre.

Viscosity can therefore be used as a control parameter to ensure that the composition of the solution is correct.

Before discovering Hydramotion, Polyacryl Iran was having trouble with viscosity measurement.

Not only was the company's previous instrument inaccurate, it also required constant maintenance and frequent repair, which made it an expensive part of the process.

Hydramotion supplied two XL7-103 on-line viscometers, both of which have been integrated into the process control system.

Although the polymer solution is highly viscous (up to 300,000 centipoise), these high-range instruments have given Polyacryl exactly what it needed: a reliable means of keeping the percentage of polyacrylonitrile in the solution to within the required +/-0.5%.

"The installation was very easy", commented Dr R Saghafian of Polyacryl Iran, "and the viscometer itself is very easy to use".

With the "fit-and-forget" XL7 units in place, the composition of the polymer solution is now tightly controlled.

Consistent product quality is assured while costly maintenance problems have become a thing of the past.

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