A Review of Online Real-Time Process Analyses of Melt-State Polymer Using the Near-Infrared Spectroscopy and Chemometrics

Abstract

This review describes the online process monitoring of the melt-state polymer by near-infrared (NIR) spectroscopy and chemometrics. The spectra of linear low-density polyethylene (LLDPE), random polypropylene (RPP), block polypropylene (BPP), and ethylene-vinylacetate (EVA) copolymer in melt states measured by an online monitoring system with a Fourier transform near-infrared spectrometer are discussed. The calibration models for the density of LLDPE, the content of ethylene copolymers in RPP and BPP, and vinylacetate concentration (VA) in EVA copolymers using partial least squares regression are reported. The continuous monitoring of the LLDPE density at the real plant is described as an example of online monitoring using NIR spectroscopy and chemometrics. For the precise prediction of VA in EVA, a combination method using regression and discrimination was inducted. Three compensation methods for the effect of the temperature change in the RPP and BPP samples are shown. Conventional calibration transfer methods are introduced, and a practical calibration transfer method using two samples and its performance are reported using BPP and RPP spectra. Moreover, the possibility of a calibration correction method using one sample for the realization of long-term traceability is indicated by the example of the relocation.

Recent Prospects in the Inline Monitoring of Nanocomposites and Nanocoatings by Optical Technologies

“…Instead, several spectroscopic techniques have already been applied for inline monitoring of the extrusion process, such as ultrasound, Raman, UV-VIS (ultra-violet-visible) and NIR (near-infrared) spectroscopy, demonstrating that they were suitable non-invasive methods for process control without time consuming analysis and sampling, while inserting optical probes in the polymer stream [17,18,19,20]. This has often been coupled with other methods.…”

“…The nanoparticles’ dispersion is generally characterized offline through the use of electron microscopy [14,15], X-ray diffraction etc., whereas nanocoating thickness is commonly assessed by electron microscopy or profilometry [16]. As reported in this review, a number of efforts, generally based on the insertion of optical probes, have also been undertaken to continuously monitor the processing of nanocomposites in order to help optimise the dispersion of nanoparticles [17,18,19,20] and/or the thickness of nanocoatings, which are key to the resulting performance.…”

A UV-Vis spectroscopic method for monitoring of additive particle properties during polymer compounding

“…Content (w/w %) of Magnesium Hydroxide in low density polyethylene (LDPE) was monitored during an extrusion process by near infrared (NIR) spectroscopy (Barnes and Sibley 2007). For the most part these studies used some form of multivariate data (MVDA) analysis in order to extract the relevant data from the measurements, the use of MVDA and chemometrics for extrusion monitoring is relatively widespread in the modern literature (Rohe et al 1999;Alig et al 2005;Becker and Eisenreich 2005;Vigh et al 2014;Watari 2014).…”

Use of Near-Infrared–Mid-Infrared Dual-Wavelength Spectrometry to Obtain Two-Dimensional Difference Spectra of Sesame Oil as Inactive Drug Ingredient

“…Because of these features, NIR spectroscopy has recently become an indispensable technique for the quantitative and qualitative analysis of real-time process monitoring and quality control in a variety of industries. 1–7 The use of NIR spectroscopy has now spread to multiple fields, such as agriculture, foods, polymers, petroleum, and pharmaceuticals. 4…”

“…Because of these features, NIR spectroscopy has recently become an indispensable technique for the quantitative and qualitative analysis of real-time process monitoring and quality control in a variety of industries. [1][2][3][4][5][6][7] The use of NIR spectroscopy has now spread to multiple fields, such as agriculture, foods, polymers, petroleum, and pharmaceuticals. 4 Recently, there has been an increase in an interest in process analytical technology (PAT) because a guide for industry PAT was issued from the U.S. Food and Drug Administration (FDA) in 2004.…”