Properties exhibited by polymeric materials are controlled by the microstructure (crystallinity and orientation) developed during their processing. Conventional manufacturing uses trial-and-error procedure to modify the process parameters to obtain desired properties in the films.  Real-time monitoring offers better control and optimization of the process. First, real-time process measurements were successfully conducted during single and multilayer blown film extrusion of polyolefins using miniature Raman probes, video-tracer technique and infrared pyrometer. Molecular transformation observed from the Raman spectrum collected at different axial locations from the die exit to the nip rolls in the blown film line was used to estimate crystallinity and orientation development during the process and coupled to different process parameters: blow-up ratios and take-up ratios to understand the effect of stress on the crystallization growth-rate.<br/> <br/>Since Raman spectroscopy is not a direct measurement technique for microstructure, simultaneous Raman spectroscopy and X-ray diffraction were conducted during the blown film process. This first-of-a-kind real-time measurement in a blown film line indicated that crystallinity and orientation data obtained from the two independent techniques were consistent and thus established Raman spectroscopy as an economical and viable process monitoring tool.

Real-time microstructural monitoring during the blown film extrusion of polyolefins

251st National Meeting (2016)

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