Engineers from Rosemount Analytical were involved in the evaluation of techniques to provide process control of the Tyvek spinning process
Applications for the DuPont Tyvek spunbonded polyethylene materials are increasing rapidly, and the production plant in Luxembourg is being expanded to meet demand.
Tyvek is a family of tough durable, non-woven sheet products, formed by spinning continuous fine HDPE fibres, which are then laid in a random web and bonded together, using heat and pressure.
By varying the spinning and bonding conditions used in the manufacturing process, different grades of Tyvek can be produced, from hard paper-like materials to softer textiles.
Engineers from Rosemount Analytical were involved in the evaluation of techniques to provide process control of the spinning process, in co-operation with the DuPont process engineers.
Raman spectroscopy offered on-line analysis of the composition of the spinning agents used, and initial measurements were made in the Rosemount European Technology Centre at Hasselroth, Germany, on a Process Raman Analyser unit installed there to assist in such customer evaluation work.
The results were positive - the Raman Analyser from Rosemount Analytical provided the information required to control the fibre spinning process, and two Raman analyser units have been purchased by DuPont for installation on the expanded Tyvek production plant.
This is the first installation of a Rosemount Raman Process analyser on-line in this type of manufacturing and production line environment in Europe.
Raman spectrometry is a technique that uses the interaction between monochromatic (laser) light and analyte molecules in the monitored process.
A small proportion of the light entering the sample is scattered at the molecular level.
Most light is scattered elastically, ie there is no energy exchange.
This is known as Rayleigh scattering.
But some light photons exchange energy with the molecules - resulting in a shift in the wavelength and a change in the internal molecular (vibrational) energy of the analyte.
This inelastic scattering is known as the Raman effect.
The wavelength shifts are characteristic of the analyte molecular structure and the scattered light intensity at the shifted wavelengths can be used to determine analyte concentration.
The Process Raman Analyser (PRA) from Rosemount Analytical is ruggedly built to be at home in a process environment, and has unique Sure raw data processing software to ensure stable and repeatable performance.
The dual beam design provides dynamic wavelength stabilisation and, together with the photometric calibration routine, standardises instrument response.
The PRA can be 'simul-plexed' to take separate measurements at several process points simultaneously, reducing the number of analysers needed for multipoint installations.
The Raman probes are connected to the central analyser with fibre-optic cables.
Smart diagnostics monitor the analyser status and standard laser safety features ensure personnel safety.
Operating, interfacing and networking use standard communications protocols.
