Polyurethane foams are widely used polymers. Their end-of-life is largely managed through landfilling and incineration, causing environmental concerns and resource loss. Hydrothermal carbonization and hydrothermal liquefaction have recently emerged as promising thermochemical approaches to valorise polyurethanes waste into value added products. This study presents a systematic investigation of the effects of operating parameters on hydrochars (HCs) yields and properties, using a rigid polyurethane foam as feedstock. Product yields were rationalized using the Severity Value (SV) parameter and the obtained HCs were characterized by ultimate analysis, FTIR, SEM and thermogravimetric analysis. An increase in SV led to a reduction of HCs yields, whereas the effect of the feedstock to solvent ratio exhibited only a minor influence. Ultimate analysis revealed decreased H/C and O/C ratios in all HCs, while the nitrogen content increased in all samples compared to PUR, suggesting their potential application as nitrogen-doped carbon materials. All produced HCs exhibited HHVs higher than that of PUR (27.59 MJ/kg), indicating energy densification. The calculated combustion parameters indicated that HCs exhibit lower reactivity and a slower, more controlled combustion process compared to PUR. These results together with their positioning in the coal-like regions of the Van Krevelen diagram, suggest their potential use as solid fuels. The liquid phases recovered for each test were rich in value-added compounds, including aromatic heterocycles. Overall, these findings offer valuable insights for advancing circular economy strategies in PUR waste management, highlighting the potential of HTC and HTL to simultaneously produce energy-dense solid fuels and value-added platform chemicals. • Hydrothermal treatments were applied to recycle rigid polyurethane foam waste. • The operating parameters strongly influence hydrochar yields and properties • An inverse relationship is observed between severity values and hydrochar yields • Hydrochar has potential applications as nitrogen doped material and solid fuel • Organic phase is rich in compounds with potential applications as chemicals

Instability analysis of circumferential and radial yielding structures in high in-situ stress soft rock tunnels based on polyurethane foam

Release kinetics and environmental risks of TCPP from polyurethane foam microplastics: Insights from artificial seawater to natural estuarine water.

Comparative performance of material conductivity on anaerobic digestion of palm oil mill effluent under varying Feed-to-Inoculum ratios.

Application of plant-based by-products in the design of sustainable formed-in-place polyurethane foam gaskets

Analysis of the thermal properties of sprayed polyurethane foams with and without aerogel incorporation

Sustainable tannic acid-based polyurethane foam for enhanced microplastic removal and antibacterial water purification

Harnessing on-demand homo- and heterogeneous topological rearrangement for solid-state reprocessing of dynamic crosslinked polyurethane foams

New strategies for reducing flammability and toxic smoke emission in rigid polyurethane foams

Enhanced interlaminar adhesion and stab resistance in recycled composites using waste prepreg and milled waste polyurethane foam

X-rays to Probe Compression across Scales in Rigid Polyurethane Foams: Molecular Simulations and Synchrotron Experiments

Deammonification, which is based on partial nitritation and anammox (PN/A), is a well-established sidestream treatment for nitrogen removal. However, transferring deammonification to mainstream wastewater treatment remains challenging due to low temperatures, the need to retain slow-growing anammox bacteria (AnAOB), and their competition for nitrite with nitrite-oxidizing bacteria (NOB) and heterotrophic denitrifiers. This work investigates cubic polyurethane foam carriers to promote growth and retention of AnAOB. A moving bed biofilm reactor (MBBR) and an integrated fixed-film activated sludge (IFAS) reactor were compared over a three-year experimental period at lab-scale. The feasibility of the biofilm carriers for deammonification was first evaluated under sidestream conditions, followed by a stepwise transition to mainstream operational conditions. The impact of operational parameters, including dissolved oxygen concentration, pH value, and aeration strategy, was evaluated with respect to the activity of aerobic ammonium-oxidizing bacteria (AOB), NOB, and AnAOB, as well as nitrogen removal rates. Deammonification reached nitrogen removal rates of 0.04–0.12 kg N m−3 d−1 (IFAS reactor) and 0.02–0.28 kg N m−3 d−1 (MBBR) at subphases with reactor bulk concentrations above 60 mg NH4-N L−1. Highest nitrogen removal degrees of 77 ± 6% (IFAS) and 76 ± 5% (MBBR) were achieved at reactor bulk concentrations of 96 mg NH4 L−1 and 97 mg NH4 L−1, respectively. Lower concentrations triggered NOB activity in both reactors, leading to an increase in nitrate concentration up to 22 mg NO3-N L−1. AOB and AnAOB activities were on average 6-fold higher on the carriers compared to suspended biomass throughout all experimental phases, demonstrating the feasibility of using cubic polyurethane foam carriers for deammonification. This was also confirmed by fluorescence in-situ hybridization (FISH) measurements. Median nitrogen removal rates over all experimental phases of 0.07 kg N m−3 d−1 for the IFAS reactor and 0.05 kg N m−3 d−1 for the MBBR were achieved, which are comparable to conventional activated sludge systems performing nitrogen removal via nitrification–denitrification. While at lower nitrogen concentrations, the IFAS reactor yielded superior nitrogen removal rates, peak nitrogen removal rates of 0.28 kg N m−3 d−1 were measured in the MBBR configuration. However, controlling NOB activity at lower temperatures and concentrations remains a challenge in MBBR and IFAS configurations. In our study, in the IFAS reactor NOB activities were visible on fewer days than in MBBR. At mainstream-like conditions, higher nitrogen removal rates of IFAS (0.09–0.12 kg N m−3 d−1) were achieved compared to the MBBR (0.06–0.09 kg N m−3 d−1). This demonstrates the advantage of the IFAS reactor in treating mainstream wastewater via deammonification. As an autotrophic nitrogen removal process, the implementation of deammonification in the mainstream of municipal wastewater treatment plants enables enhanced recovery of biogas from sewage organic matter. The latter would otherwise be consumed during the conventional nitrification-denitrification pathway. Consequently, the overall energy balance for wastewater treatment can be improved, contributing to a more environmentally sustainable process.

Objective: Excess wound exudate can cause tissue maceration and delayed healing. Fluctuating exudate levels, combined with the impact of gravity, increase dressing leakage risk, affecting patient quality of life. Bacteria and proteases found in hard-to-heal (chronic) wounds pose additional barriers to healing if not promptly removed. Absorbent dressings must therefore address these multiple challenges, and so were explored in this series of preclinical investigations. Method: Standard in vitro absorbency tests were conducted to compare the performance of several dressings with a new advanced five-layer silicone polyurethane foam dressing with superabsorbent particles (ASFS). Dressing functionality was explored using clinically relevant test conditions, including the impact of gravity and fluid bolus events on absorbency, combined with the dressing's ability to absorb and retain bacteria and proteases. Results: ASFS demonstrated superior performance across standard absorbency tests versus most of the alternative absorbent dressings and outperformed a comparator five-layer silicone foam dressing with superabsorbent fibres (SFD) in run-off testing. Under clinically relevant dynamic bolus conditions, including gravitational challenge, no leakage was observed with ASFS, whereas dressing failure due to fluid spill or leakage was observed with SFD. ASFS was also shown to retain matrix metalloproteinases and the majority of bacteria, even under increasing fluid volumes. Conclusion: Functionality of absorbent wound dressings in both standard and clinically relevant tests is critical to support healthcare professionals’ decision-making in selecting optimal interventions for their patients’ wounds. Effective exudate management combined with removal of bacteria and proteases by the new ASFS dressing supports healthcare professional and patient confidence in continuing with daily activities, with the potential for fewer dressing changes and associated resource benefits, warranting further evaluation in clinical practice.

For the past quarter century, polyurethane foam (PUF) disk-based passive air samplers (PASs) have grown as a pivotal tool in research and monitoring of persistent organic pollutants and emerging chemicals in ambient air in both the gas phase and on ambient particulate matter. Their low cost and ease of use have facilitated deployment at the regional and global scales. Modifications to the PUF-PAS have expanded its use for more specific purposes, such as the sorbent-impregnated PUF-PAS (SIP-PAS), which improves sorptive capacity for more volatile chemicals, and the passive dry deposition (PAS-DD) sampler, which captures larger particles and enables estimation of gas and particle deposition. This review summarizes studies characterizing uptake rates and partition coefficients of PUF disks for a wide range of compounds and evaluations of sampler design and performance. It synthesizes applications of PUF-PAS, SIP-PAS, and PAS-DD from 2000 to 2024 across diverse topics: ambient air measurements, indoor air quality, source emissions, health, and, most recently, biodiversity. Approximately 650 publications employing PUF disk-based PASs are summarized herein, demonstrating their increasing use and diversification. On the horizon, we envisage that the PUF-PAS will continue to transform and integrate fields of science and inform policy.

Micro-ecological islands provide unique habitats for microbes and play a crucial role in the functioning of aquatic ecosystems. Microbes settle on these micro-ecological islands, forming distinct microbial communities. Previous studies have provided some understanding of the colonization processes and regulatory mechanisms of protozoa in microbial communities. However, these islands are also subject to colonization by a variety of microbes beyond protozoa, and comprehensive cross-kingdom studies and their potential mechanisms remain largely unexplored. Using polyurethane foam units (PFU) to simulate micro-ecological islands, we studied the colonization dynamics of microbes in two distinct aquatic ecosystems, the Yangtze River and East Lake. Over 10-day colonization survey was conducted, we applied eDNA-PFU technology combined with metagenomic sequencing to comprehensively identify species present in the microbial communities, including bacteria, fungi, flagellates, protozoa, and metazoa. We found that microeukaryotes, rather than prokaryotes, were the primary colonizers in these two aquatic ecosystems. Our study reveals a colonization process of microeukaryotes in PFUs, profoundly influenced by their motility modes. Additionally, we propose a hypothetical food web framework within micro-ecological islands that maintains community stability, representing the most fundamental biological interactions. Overall, this study enriches our understanding of micro-ecological islands and provides deeper insights into the colonization processes and regulatory mechanisms of microbial communities. It highlights the practical significance of micro-ecological islands in biological resource management, environmental protection, and biodiversity conservation.

Metal-organic framework-integrated polyurethane foam dressing for active scavenging of pro-inflammatory chemokines in chronic wounds.

Carbon Nanofiber/Polydopamine/Fe ³⁺ Composite Aerogel Coatings as Gas–Solid Fire Barriers for Rigid Polyurethane Foams

Construction industry remains a major driver of global resource use and waste generation, therefore, identifying sustainable material alternatives is increasingly important. Recycled-textile-based insulation presents a promising pathway to support circular economy principles by diverting post-consumer waste from landfills and reducing reliance on virgin petrochemical materials. This study conducts a cradle-to-gate life cycle assessment (LCA) using SimaPro to compare polyurethane (PU) foam and recycled denim (cotton fiber) insulation. The system boundary includes raw material extraction, transportation, and manufacturing. A functional unit of 1 m2 of installed insulation with a thermal resistance of RSI = 1 m2·K/W at the factory gate ensures comparability, with mass-based results reported as secondary metrics. The results indicate that recycled denim exhibits higher embodied carbon per unit mass, despite lower production energy and lower cradle-to-gate impacts per installed area, reinforcing the need for a declared-unit-based comparison tied to thermal performance. Air leakage is evaluated separately as a complementary performance indicator influencing in-service energy behavior showing significantly lower air leakage for PU; but is not included in the cradle-to-gate normalization. However, it could be argued that materials with improved airtightness may enable the use of reduced insulation thickness while still achieving equivalent performance, thereby potentially lowering overall material demand. Nevertheless, recycled denim offers environmental advantages by reducing landfill waste and promoting resource conservation through material reuse. A transient coupled heat–moisture model in COMSOL Multiphysics, using climate data from Arizona and Florida, further reveals that denim absorbs more moisture than polyurethane. This leads to larger heat flux fluctuations, highlighting a trade-off between denim’s sustainability advantages and its reduced hygrothermal durability. Overall, these findings demonstrate the limitations of single-metric comparisons and emphasize the need for performance-based, multi-criteria assessments that integrate functional efficiency with circularity. Future research should incorporate occupant health and comfort to enable a more comprehensive evaluation of insulation sustainability.

This study examines the impact of varying isocyanate indices on the morphology and properties of bio-based viscoelastic polyurethane (VE PU) foams produced using high-pressure processing and moulding technology. Palm-based polyol, referred to herein as Pioneer E-135, was used as a sustainable alternative to petroleum-based polyol. VE PU foams were formulated with different isocyanate indices (71%, 75%, 79% and 83%) and their physical, mechanical and morphological characteristics were evaluated. Results indicated that the VE PU foam containing 10% Pioneer-E135 polyol and an isocyanate index of 83% exhibited superior mechanical properties compared to the VE PU foam with 100% petroleum-based polyol. The incorporation of 10% Pioneer-E135 polyol significantly enhanced the mechanical properties, including surface texture, morphology and load-bearing capacity, as indicated by indentation force deflection and sag factor measurements. Higher NCO indices contributed to increased tensile strength, tear strength, and ageing resistance, but resulted in lower density and reduced elongation at break. Overall, the optimised processing parameters enabled the successful production of high-quality, bio-based VE PU foams using high-pressure machine technology.

ABSTRACT The method for conducting heating tests on test specimens in a vertical orientation using a cone calorimeter is recommended in ISO 5660 Annex E. Although this standard defines the ignitor position, no experimental basis has been found. A previous study suggests that the specified position may not necessarily be optimal. Furthermore, the spark orientation is not specified in ISO 5660 Annex E, and no studies investigating the effect of ignitor spark have been found. Therefore, this study conducted cone calorimeter tests by varying the position and orientation of the ignitor spark to investigate their effects on experimental results. Three experimental series, (1) experiments with detailed variations in the ignitor position using flexible polyurethane foam as the test specimen, (2) experiments altering the ignitor orientation at representative ignitor positions using plywood as the test specimen, and (3) experiments using various materials for the test specimen at representative ignitor positions were conducted. In experimental series (3), two types of wooden materials, polyvinyl chloride board, and gypsum board with wallpaper were selected as test specimens. The experimental results were compared such as time to ignition, peak heat release rate, cumulative heat release, and surface temperature at ignition. The results indicated that the ignitor position recommended in ISO 5660 Annex E and a horizontal ignitor orientation (perpendicular to the airflow) are suitable for burning test materials and obtaining stable test results.