Characterization of Biodegradable and Oxo-Biodegradable Plastic Bags

Significance of the Topic

The accumulation of conventional plastic waste poses a serious environmental threat due to its persistence and formation of microplastics. Oxo-biodegradable and biodegradable alternatives have emerged to reduce this impact. Reliable analytical characterization is essential to verify material composition, guide quality control and support environmental regulation.

Objectives and Overview

This study evaluates commercially available plastic bags labeled as oxo-biodegradable (O-BD) or biodegradable (BD) and one conventional polyethylene (PE) bag. The goal is to demonstrate how combined FTIR, DSC and TGA techniques can distinguish material types, detect fillers or additives, and assess polymer structure.

Methodology and Instrumentation

• FTIR: Shimadzu IRSpirit with diamond ATR accessory; spectrum range 4000–500 cm-1, resolution 4 cm-1, 16 scans per sample.
• DSC: Shimadzu DSC-60 Plus under nitrogen flow; heating from ambient to 180 °C at 20 °C/min, hold, cooling at –20 °C/min, second heating cycle to determine melting temperature and crystallinity per ISO 11357-3.
• TGA: Shimadzu DTG-60 following ASTM E1131; 20 mg samples in alumina pans, heating at 10 °C/min through defined volatile, polymeric, combustible and ash stages under nitrogen and air.

Main Results and Discussion

• FTIR revealed that two O-BD samples and one BD sample contain calcium carbonate filler, while one O-BD bag (O-BD3) matched pure PE spectra. Another BD sample (BD2) exhibited characteristic starch peaks.
• DSC analysis showed melting temperatures around 130–134 °C and crystallinity similar to PE for all samples except BD2, which lacked a melting transition due to its starch content.
• TGA results for PE and O-BD3 indicated nearly complete polymer decomposition by 600 °C with minimal residues. O-BD1 and O-BD2 exhibited 86–89% polymer mass loss, 5% non-volatile carbon and 6–8% ash, suggesting presence of fillers or catalysts. BD2 displayed high moisture loss (~11%), cellulose decomposition (~75%) and carbon residues (~10%).

Benefits and Practical Applications

This multi-technique approach allows rapid verification of biodegradable or oxo-biodegradable claims, detection of inorganic fillers and assessment of polymer purity. It supports material certification, regulatory compliance checks and product development in packaging and environmental monitoring.

Future Trends and Potential Applications

Advances may include coupling FTIR-imaging, modulated DSC and evolved gas analysis for deeper insight into degradation pathways. Portable spectrometers and on-line TGA systems could enable in-field screening. Data analytics and machine learning may further enhance discrimination of complex polymer blends and fillers.

Conclusion

The integration of FTIR, DSC and TGA provides a robust framework to distinguish biodegradable, oxo-biodegradable and conventional plastic materials. This methodology uncovers mislabeled products, quantifies filler content and elucidates thermal behavior, offering valuable tools for quality control and environmental research.

References

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