Abstract

The escalating accumulation of persistent plastic waste necessitates the transition to sustainable materials, with bio-based and/or biodegradable polymers increasingly adopted for applications, such as forestry tree shelters, where retrieval is costly and impractical. However, the true environmental fate and long-term stability of these complex bio-based and/or biodegradable polymer products remain uncertain. This uncertainty is exacerbated by reliance on conventional degradation assessments that employ indirect metrics (e.g., carbonyl index, CO$_2$ evolution) under ideal laboratory conditions, often failing to predict performance in the heterogeneous and complex natural environment. This research addressed this critical analytical gap by establishing a high-resolution, untargeted chemical framework for the molecular characterisation and early detection of degradation in field-deployed bio-based and/or biodegradable polymers. The current investigation focused on applying advanced pyrolytic techniques to overcome these limitations. The methodology involved evaluating Pyrolysis-Comprehensive Multidimensional Gas Chromatography-Mass Spectrometry (Py-GC$\times$GC-MS), demonstrating its superior chromatographic resolution compared to conventional Py-GC-MS. Crucially, the Py-GC-MS workflow successfully provided definitive chemical identification and differentiation of structurally similar polymers, polybutylene succinate and polybutylene succinate-co-adipate, which FTIR was unable to attain. The established Py-GC-MS methodology was then applied to a suite of commercially available, multi-component biodegradable tree shelters retrieved after one and two years of deployment in real-world field sites. The use of untargeted chemometric analysis, involving multivariate and univariate analysis, successfully separated deployed samples from controls and identified subtle, statistically significant chemical changes linked to environmental exposure. These early degradation indicators included the appearance of specific photo-oxidation products in control polyolefin samples, the loss or depletion of low-abundance additives in some deployed shelters, and the increase in degradation intermediates consistent with hydrolysis of ester-based materials.The study provides a robust, molecular-level foundation for the chemical analysis of bio-based and/or biodegradable polymers end-of-life characteristics. The applied analytical framework offers a powerful tool for industry and policymakers to compliment the biodegradability certifications, enabling the accurate assessment of material fate, the validation of end-of-life claims with structural and chemical certainty, and the prediction of bio-based and/or biodegradable polymer environmental persistence.

Awarding Institution(s)

University of Plymouth

Supervisor

Michael Wilde, Richard Thompson, Tom Hutchinson, Katie Jones

Document Type

Thesis

Publication Date

2026

Embargo Period

2026-06-16

Deposit Date

June 2026

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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