We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Thermally driven polymer disentanglement: An overlooked Key pathway in PBAT-microplastic aging during composting
Summary
This study discovered that high composting temperatures directly cause biodegradable PBAT microplastic particles to age and fragment by disentangling their polymer chains — a physical process that had been overlooked because degradation was assumed to be microbially driven. This means that industrial composting may not safely eliminate biodegradable plastics but instead accelerate their breakdown into smaller, potentially more hazardous nanoplastic particles.
The aging of microplastics (MPs) during composting is traditionally attributed to microbially driven biodegradation. However, the direct role of heat on MPs in composting has not been fundamentally understood. Here, we reveal for the first time that the composting heat drives MPs aging by directly disentangling polymer chains. We conducted a comparative experiment between hyperthermophilic composting (HTC) and thermophilic composting (TC), and combined it with molecular dynamics simulations and the Boruta machine-learning algorithm. During the early stage of HTC (90°C), van der Waals forces between PBAT molecular chains decreased to -2616.36 kcal/mol, the free volume fraction increased to 14.38 %, and the hydroxyl radical diffusion coefficient increased to 5.38 × 10 Å/ps. In addition to molecular chain disentanglement, composting aging resulted in significant changes in surface physicochemical properties of PBAT-MPs. Elemental analysis showed an increased surface oxidation degree, with the C/O ratio decreasing from 2.67 to 1.78 in HTC (compared to 2.02 in TC). After the molecular chain disentanglement, HTC further facilitated the development of a plastisphere core microbiota (Oceanobacillus and unclassified_f_Bacillaceae reached relative abundances of 9.19 % and 20.31 %), which boosted microbial degradation efficiency during late stage. We confirm that the direct disentangling effect induced by high temperature is pivotal for the aging process within the high-molecular-weight fractions of PBAT-MPs. These results revise the microorganism-dominant aging paradigm in composting, demonstrating that thermal energy directly disentangles polymeric molecular chains to drive MPs aging. This study provided new insights into the underlying mechanisms governing MPs aging in composting environments.
Sign in to start a discussion.
More Papers Like This
The Polymer-Plastisphere-Function Nexus Links to Divergent Biodegradation of Microplastics During Composting.
Researchers found a fundamental dichotomy in microplastic biodegradation during thermophilic composting, where biodegradable polymers (PLA, PBS, PBAT) underwent rapid degradation driven by selective microbial community assembly shaped by polymer chemistry, while conventional plastics resisted breakdown despite similar composting conditions.
Biodegradable microplastics (BMPs): a new cause for concern?
This review examined whether biodegradable microplastics present new environmental hazards, finding that many biodegradable polymers degrade slowly under real environmental conditions and can release toxic additives, and that the assumption of biodegradability does not eliminate microplastic pollution risks unless composting conditions are actively managed.
Effect of weathering on the release of secondary microplastic fragments and dissolved organics from microplastics
Researchers systematically investigated how different weathering conditions affect the release of secondary microplastics and dissolved organic carbon from PVC, polyethylene, and biodegradable PBAT plastics. The study found that biodegradable PBAT released the highest amounts of secondary particles and organic carbon, and that combined UV and mechanical aging produced the most significant degradation, enhancing particle release by up to 72% compared to either method alone.
Hybrid mechanism of microplastics degradation via biological and chemical process during composting
Researchers explored how composting can degrade microplastics through combined biological and chemical processes. They found that pre-aged microplastics broke down about three times faster than non-aged ones during composting, with microorganisms and chemical oxidation working together to accelerate degradation. The study suggests that composting may offer a practical approach for reducing microplastic contamination in organic waste streams.
Secondary microplastics formation and colonized microorganisms on the surface of conventional and degradable plastic granules during long-term UV aging in various environmental media
Researchers compared how biodegradable and conventional plastics generate secondary microplastics and develop bacterial biofilms during long-term UV aging. Biodegradable PBAT plastic produced significantly more secondary microplastic fragments than conventional PVC after 90 days of weathering. The study also found that aged microplastics harbored genes related to human pathogens, raising concerns that biodegradable plastics may actually pose greater ecological risks than expected.