Process monitoring of polymer melts using in-line spectroscopy

Abstract

Over the last decade, there has been an increased drive in the polymer industry toward the development of in-line monitoring techniques for analysis of melt processing. Manufacture of high material volumes combined with stringent quality-control restrictions and the requirement for tailored end-user products, have made the implementation of analytical methods essential for measurement of material characteristics. This paper presents the application of a range of spectroscopic techniques for in-line analysis of polymer extrusion processes. Fourier transform near-infrared (FT-NIR), Raman and fluorescence spectroscopy have been successfully implemented as tools to monitor a range of processing characteristics including copolymer melt and additive composition, material residence time distribution and degree of polymerization. In combination with partial least squares (PLS) chemometric analysis, these spectroscopic techniques are demonstrated to be sensitive and robust tools for monitoring a wide range of chemical and physical parameters at high-temperature and pressure in a polymerprocessing environment.

Effect of processing parameters on the morphology development during extrusion of polyethylene tape: An in-line small-angle X-ray scattering (SAXS) study

“…Spectroscopic, ultrasonic and X-ray scattering techniques have proven invaluable to monitor structure development, composition and material properties during processing [17][18][19][20][21][22].…”

In-line NIR spectroscopy for the understanding of polymer–drug interaction during pharmaceutical hot-melt extrusion

“…Further, NIR spectroscopy has been used to monitor the ethylene vinylacetate copolymer composition in the extrusion die during single screw extrusion [19][20][21] , and for the quantification of the copolymer composition in a polypropylene and ethylene vinyl acetate blend [22] during twin screw extrusion. NIR has also been applied to measure the polymer melt flow index [21] in single screw extrusion and to detect and quantify small amounts of Irganox in polypropylene [23] and Mg(OH) 2 in LDPE [20] and HDPE [24] during twin screw extrusion. Further, NIR spectroscopy was used to monitor the content of pulverised chalk in polypropylene [22] , to quantify the melamin cyanurate concentration in polyamid 12 [25] and to quantify the composition of a PE/PS blend [25] during twin screw extrusion.…”

Raman spectroscopy for the in-line polymer–drug quantification and solid state characterization during a pharmaceutical hot-melt extrusion process

“…Raman spectroscopy enables rapid, non-destructive and in-line measurements, and has previously been used during hot-melt extrusion (single screw extrusion) to monitor EVA copolymer melt composition [7,8] , to analyze film formulations [9] , and to monitor the composition of a series of highdensity polyethylene (HDPE)/polypropylene (PP) blends [10,11] . It has also been implemented in a twin screw extrusion process to determine the concentration of Irganox additive in polypropylene [12] .…”