In-Line Monitoring the Degradation of Polypropylene under Multiple Extrusions Based on Raman Spectroscopy

Abstract

Polymer degradation is a common problem in the extrusion process. In this work, Raman spectroscopy, a robust, rapid, and non-destructive tool for in-line monitoring, was utilized to in-line monitor the degradation of polypropylene (PP) under multiple extrusions. Raw spectra were pretreated by chemometrics methods to extract variations of spectra and eliminate noise. The variation of Raman intensity with the increasing number of extrusions was caused by the scission of PP chains and oxidative degradation, and the variation trend of Raman intensity indicated that long chains were more likely to be damaged by the extrusion. For the quantitative analysis of degradation, the partial least square was used to build a model to predict the degree of PP degradation measured by gel permeation chromatography (GPC). For the calibration set, the coefficient of determination (R2) and the root mean square error of cross-validation (RMSECV) were 0.9859 and 1.2676%, and for the prediction set, R2 and the root mean square error of prediction (RMSEP) were 0.9752 and 1.7228%, which demonstrated the accuracy of the proposed model. The in-line Raman spectroscopy combined with the chemometrics methods was proved to be an accurate and highly effective tool, which can monitor the degradation of polymer in real time.

On the Mechanical Response of Silicon Dioxide Nanofiller Concentration on Fused Filament Fabrication 3D Printed Isotactic Polypropylene Nanocomposites

“…For all nanocomposites, characteristic PP Raman peaks could be seen, as has been reported elsewhere [ 39 ]. More specific, the characteristic fingerprints of PP are located at ca.…”

“…More specific, the characteristic fingerprints of PP are located at ca. 385, 810, 868, 967, 1036, 1168 and 1221 cm −1 (C–C stretching vibration), 1250 and 1320 cm −1 (CH deformation vibration), 1334 and 1454 cm −1 (–CH 2 of the PP backbone macromolecular chains), 1361–1385 cm −1 (–CH 3 deformation vibrations of PP chains, as well as the –CH 3 side group rocking vibration) [ 39 ], and 2721, 2837, 2875 and 2962 cm −1 (CH 3 symmetric and asymmetric stretching vibration) [ 40 ]. The spectra of PP/SiO 2 nanocomposites at the different SiO 2 wt.% filler loading exhibit some peaks attributed to the incorporated SiO 2 NP vibrational modes, indicated more clearly in Figure 7 b. Namely, peaks at ca.…”

Sustainable Additive Manufacturing: Mechanical Response of Polypropylene over Multiple Recycling Processes

“…PP is a semi-crystalline material, and this makes it prone to different behavior regarding the percentage of crystallinity. The crystallinity percentage is affected by parameters, such as the temperature and the cooling rate of the material during the recycling procedure [27]. Polymeric chains are reoriented or shortened inside the material and this may cause a more brittle or ductile behavior.…”

Optimization of the Filler Concentration on Fused Filament Fabrication 3D Printed Polypropylene with Titanium Dioxide Nanocomposites

“…More specifically, the characteristic fingerprints of PP are located at ca. 385, 810, 868, 967, 1036, 1168, and 1221 cm −1 (C–C stretching vibration); 1250 and 1320 cm −1 (CH deformation vibration); 1334 and 1454 cm −1 (–CH 2 of the PP backbone macromolecular chains); 1361–1385 cm −1 (–CH 3 deformation vibrations of PP chains, as well as the –CH 3 side group rocking vibration) [ 33 ]; and 2721, 2837, 2875, and 2962 cm −1 (CH 3 symmetric and asymmetric stretching vibration) [ 34 ]. The spectra of the PP/TiO 2 nanocomposites at the different TiO 2 wt.% filler loadings exhibited some additional peaks attributed to the TiO 2 nano crystallites’ vibrational modes, indicated more clearly in Figure 7 b. Namely, the peaks at ca.…”