Analysis of recycled PET products by Pyrolysis-GC-TOFMS
MSTips No. 480
Introduction
The Circular economy is a global initiative that aims to realize a sustainable society by reducing the consumption of natural resources and maximizing the use of existing resources. Polymer (plastic) recycling is an important technology for achieving this. For example, many PET (polyethylene terephthalate) bottles are reused as PET bottles through horizontal recycling, but some are used for different products through cascade recycling (=downcycling). In addition, upcycling to use them in higher value products is also actively carried out. In these recycling process, evaluation of materials and products is important for stable quality, and Pyrolysis-GC-MS is commonly used as an analytical method.
In this MSTips, we will introduce an application of recycled PET products analysis using the high-performance gas chromatograph time-of-flight mass spectrometer "JMS-T2000GC" and unknown compounds structure analysis software "msFineAnalysis AI".
Experiment
As the sample, standard PET bottle and commercially available recycled PET product (buffer sheet) were used. 0.2 mg of each was weighed and measured using Pyrolysis-GC-MS. EI and FI (field ionization) methods were used for ionization. The obtained data were analyzed using two-sample comparison of msFineAnalysis AI. Table 1 shows details of the measurement conditions.
Table 1 Measurement conditions
Results
Figure 1 shows the TIC chromatograms of the EI measurement results. The major pyrolysis products of PET, such as benzoic acid and vinyl benzoate, were detected in both samples. In addition to these, several other peaks were detected in the recycled PET product.
Figure 1 TIC chromatograms
Figure 2 shows the result window of two-sample comparison of msFineAnalysis AI.
Figure 2 Result window of two-sample comparison
Table 2 shows the peak list, and Figure 3 shows the structural formulas of the compounds that were strongly detected in the recycled PET products (=Red group) . Methyl acrylate, styrene, and their hybrid trimers were identified, suggesting that recycled PET products may contain methyl acrylate-styrene (MS) copolymers.
Table 2 Peak list
Figure 3 Structural formulas (Red : strong in recycled PET product)
Conclusion
PET bottles and recycled PET product were analyzed using two-sample comparison of msFineAnalysis AI. As a result, it was confirmed that recycled PET products may contain MS copolymer. This recycled PET product is a thin and high-performance buffer sheet, which corresponds to upcycling. It was thought that MS copolymer was blended to improve moldability and weather resistance.
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