Characterization of Biodegradable and Oxo-Biodegradable Plastic Bags

Importance of the Topic

Plastic waste derived from petroleum-based polymers resists natural degradation and contributes to environmental pollution and microplastic formation. Oxo-biodegradable and biodegradable alternatives aim to accelerate breakdown or introduce renewable components like starch. Reliable analytical methods are essential to verify material composition, environmental claims and optimize formulations for waste management.

Objectives and Overview of the Study

This study evaluates three oxo-biodegradable (O-BD), two biodegradable (BD) and one conventional polyethylene (PE) shopping bags to:

• Identify polymer types and inorganic additives
• Measure thermal melting behavior and crystallinity
• Quantify degradation fractions and residual ash

Methodology

Samples were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) to detect functional groups and fillers, Differential Scanning Calorimetry (DSC) according to ISO 11357-3 for melting temperature and crystallinity, and Thermogravimetric Analysis (TGA) following ASTM E1131 to determine moisture/volatile content, combustible polymer fraction and inorganic residue.

Instrumentation

• FTIR: IRSpirit with diamond ATR accessory (QATR-S), 4000–500 cm–1, 4 cm–1 resolution, 16 scans
• DSC: Shimadzu DSC-60 Plus under nitrogen, heating/cooling cycles between 30 °C and 180 °C
• TGA: Shimadzu DTG-60 (DTA–TGA) in nitrogen and air, 10 °C/min across defined temperature ranges

Key Results and Discussion

FTIR revealed that two O-BD bags and one BD bag contained PE signals plus CaCO₃ filler peaks, while a third O-BD matched pure PE and one BD bag showed starch-specific bands. DSC showed melting points near 130–134 °C and crystallinity above 56% for all PE-containing samples; the starch-based bag lacked a PE melting transition. TGA profiles indicated:

• PE and the pure-like O-BD sample degraded almost entirely as polymer with negligible residue
• O-BD1, O-BD2 and BD1 contained 5–8% inorganic ash, consistent with fillers or catalysts
• BD2 exhibited ∼11% moisture loss and ∼75% polymer/starch decomposition, plus ∼10% carbonaceous and 3.8% ash fractions

Benefits and Practical Applications

The integrated FTIR/DSC/TGA workflow enables rapid, non-destructive verification of biodegradable and oxo-biodegradable bag formulations, detection of inorganic additives, and assessment of melt and degradation properties. This supports quality control, regulatory compliance and the development of sustainable packaging.

Future Trends and Applications

Future advances may combine thermal analysis with evolved gas detection for detailed degradation pathways, explore novel bio-based fillers beyond starch, and implement high-throughput screening tools to tailor additive loads for specific composting profiles and environmental conditions.

Conclusion

FTIR, DSC and TGA successfully differentiated conventional PE from oxo-biodegradable and biodegradable bags, uncovering differences in filler content and polymer matrices. One oxo-biodegradable sample lacked expected additives, highlighting the need for standardized material certification. This analytical strategy lays the groundwork for reliable evaluation of eco-friendly plastics.

References

• Finzi-Quintão CM et al. Macromol Symp, 2016.
• Adamcová D et al. J Eco Eng, 2016.
• Sreekumar PA et al. Polym Eng Sci, 2012.
• ISO 11357-3, Plastics—DSC.
• ASTM E1131, Thermogravimetry.
• Wunderlich B. Thermal Analysis of Polymeric Materials, 2005.
• Wahyuningtiyas NE et al. J Mech Eng Sci Tech, 2017.