As sustainability becomes a global priority, biodegradable plastics are increasingly used as alternatives to conventional petroleum-based materials. However, understanding the actual polymer composition of commercially available biodegradable products is critical for evaluating their environmental impact, performance, and degradation behavior.
In this technical study, Evolved Gas Analysis–Mass Spectrometry (EGA-MS) is applied to analyze a commercially available biodegradable plastic shopping bag. Using a multi-functional pyrolyzer coupled with GC/MS, the thermal decomposition behavior and polymer constituents of the material are clearly identified.
Background
Biodegradable plastics are plastics that fully decompose to naturally existing small molecules through the actions of living microorganisms and enzymes. The use of biodegradable plastics will contribute to sustainability and reduction of the environmental impact associated with disposal of petroleum-based plastics. This note reports the analysis of a commercially available biodegradable plastic shopping bag (Fig. 1) by evolved gas analysis (EGA)-MS.
Experimental
The unprinted part of a biodegradable plastic bag was cut into small pieces using a utility knife and was placed in an Eco-Cup LF as a sample. The analysis was done using a GC/MS system with a Multi-Shot Pyrolyzer (EGA/PY-3030D) which was directly interfaced with the GC injector. A deactivated metal tube (UAD™-2.5N) was used to connect the GC injector to the MS detector. EGA thermogram was obtained by EGA-MS measurement.
Results
In the EGA thermogram shown in Fig. 2 (a), a broad peak at 420 ºC was observed. The EGA thermogram is divided into three zones, and the averaged mass spectra of Zones B and C are respectively shown in Fig. 2 (b) and (c). The averaged mass spectrum of Zone B is similar to the mass spectrum of PLA standard; therefore, species in Zone B is ascribed to PLA. Major peaks in the mass spectrum of Zone C correspond to those of PBSA and PBT as shown in Fig. 2 (c). However, the prominent peak at m/z 73 in PBSA is absent, and further investigation is required.
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References: This technical note was developed by Frontier Laboratories Ltd. 4-16-20 Saikon, Koriyama, Fukushima, 963-8862 JAPAN. www.frontier-lab.com