(657c) In-Line Near-Infrared Spectroscopy for Optimization of Radical Modification Reactions of Polyolefins

Many analytical challenges are associated with in-line reaction monitoring to support continuous process optimization. To that end, techniques such as Raman, rheology, and IR¹spectroscopy have been recently applied for the monitoring of flowing streams in "real time". In the present work, NIR was selected because it is a non-destructive technique, compatible with the used chemicals, substantially cheaper/more readily available, and it does not require the use of solvents.

Several monomers were successfully grafted onto polyolefins in an intermeshing co-rotating twin-screw extruder via radical modifications. This study demonstrates the use of in-line NIR in monitoring radical reactions in order to optimize process conditions for obtaining higher grafting efficiencies (GE).

Besides grafting, side reactions are observed resulting in low grafting efficiencies. Reducing the monomer concentration as well as increasing the mixing level by improving the screw design was shown to suppress side reactions and results into higher grafting efficiencies. It was also observed that initiator concentration controls the overall conversion, degree of grafting (DG) as well as side reactions.

References

^{1 J.A. Covas, O.S. Carneiro, J.M. Maia, S.A. Filipe, A.V. Machado, Evolution for chemistry, morphology and rheology of various polymer systems along a twin-screw extruder, The Canadian Journal of Chemical Engineering 80 (2002) 1065â??1074.}