Effect of Polymer Properties on the Biodegradation of Polyurethane Microplastics

Abstract

The release of fragments from plastic products, that is, secondary microplastics, is a major concern in the context of the global plastic pollution. Currently available (thermoplastic) polyurethanes [(T)PU] are not biodegradable and therefore should be recycled. However, the ester bond in (T)PUs might be sufficiently hydrolysable to enable at least partial biodegradation of polyurethane particles. Here, we investigated biodegradation in compost of different types of (T)PU to gain insights into their fragmentation and biodegradation mechanisms. The studied (T)PUs varied regarding the chemistry of their polymer backbone (aromatic/aliphatic), hard phase content, cross-linking degree, and presence of a hydrolysis-stabilizing additive. We developed and validated an efficient and non-destructive polymer particle extraction process for partially biodegraded (T)PUs based on ultrasonication and density separation. Our results showed that biodegradation rates and extents decreased with increasing crosslinking density and hard-segment content. We found that the presence of a hydrolysis stabilizer reduced (T)PU fragmentation while not affecting the conversion of (T)PU carbon into CO 2 . We propose a biodegradation mechanism for (T)PUs that includes both mother particle shrinkage by surface erosion and fragmentation. The presented results help to understand structure−degradation relationships of (T)PUs and support recycling strategies.

Fragmentation and Mineralization of a Compostable Aromatic–Aliphatic Polyester during Industrial Composting

“…For fragment extraction, we tested very gentle processes with olive oil on partially biodegraded PU-polyester, but biodegradation diminished the hydrophobicity of the polymer as driving force for extraction efficiency. Here, we combined sonication to deagglomerate plastic fragments attached to other compost particles, oxidation to remove the organic background and to ensure proper identification by Raman spectra, and density separation to remove Fenton residue and compost inorganic components (Figure S2).…”

“…Protocols developed for characterization of conventional microplastics 17 require validation and possibly adaptation for soil-biodegradable and compostable plastics, because these plastics may inadvertently degrade during the sample preparation procedures. 18,19 certified compostable materials have proven to positively impact the amount of biowaste collected and its quality, 20−22 but their interim fragmentation must be addressed properly.…”

“…Compostable plastics could enable diverting organic wastes from landfill and incineration, reducing plastic contamination in the organic waste stream and with that support the goals of the EU Green Deal. , Certified industrially compostable plastics are designed to deliver performance during application, e.g., as food packaging or as bags for biowaste collection, and to biodegrade in their intended end of life. ,, The inevitable loss of structural integrity of a plastic article during composting incurs a potential to disintegrate into micro- and nanoplastic fragments, also as an interim phase of biodegradation. − Studies have investigated the presence of fragments from both conventional and biodegradable plastics in compost or soil. − However, systematic studies with blank and spike controls are still missing. Protocols developed for characterization of conventional microplastics require validation and possibly adaptation for soil-biodegradable and compostable plastics, because these plastics may inadvertently degrade during the sample preparation procedures. , In summary, certified compostable materials have proven to positively impact the amount of biowaste collected and its quality, − but their interim fragmentation must be addressed properly.…”

Synthesis of Poly(ether carbonate)-Based Polyurethane for Biodegradable–Recyclable Pressure Sensors

“…In the second stage, which is from the 29th to the 103rd day, the biodegradation process became slightly moderate but continued until the end of the test. The biodegradation rate of BPPU in this paper is compared to the results from published literature ,− ,− on BPURs as shown in Figure c, where different colors are used to represent diverse degradation environments. In this case, red is soil burying, , purple represents immersion in physiological saline, yellow stands for composting, ,, orange is adding lipase to PBS, ,, and green refers to only PBS. , It is encouraging to see that the synthesized BPPU by this work has better biodegradability than the previous reports in terms of time and degree of biodegradation.…”

The performance of and promotion strategies for degradable polymers in triboelectric nanogenerators

“…PU can be broken down by bacteria, fungi, or enzymes, 144 and chemical agents like acidic or alkaline solutions can destroy it. 145 Lee and associates 146 prepared PU-based e-skin with controlled degradation performance by using a mixture of highly crystalline poly (1,4-butylene adipate) (HTPBA) and low crystalline PCL diol. Detecting electronic skin as a friction layer in the TENG is well done after self-healing and anti-aging experiments, presenting steadfast generation durability.…”