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This work presents the cell structure and selected properties of polyurethane (PUR) foams, based on two types of hydroxylated used cooking oil and additionally modified with three different flame retardants. Bio-polyols from municipal waste oil with different chemical structures were obtained by transesterification with triethanolamine (UCO_TEA) and diethylene glycol (UCO_DEG). Next, these bio-polyols were used to prepare open-cell polyurethane foams of very low apparent densities for thermal insulation applications. In order to obtain foams with reduced flammability, the PUR systems were modified with different amounts (10–30 parts per hundred polyol by weight—php) of flame retardants: TCPP (tris(1-chloro-2-propyl)phosphate), TEP (triethyl phosphate), and DMPP (dimethyl propylphosphonate). The flame retardants caused a decrease of the PUR formulations reactivity. The apparent densities of all the foams were comparable in the range 12–15 kg/m3. The lowest coefficients of thermal conductivity were measured for the open-cell PUR foams modified with DMPP. The lowest values of heat release rate were found for the foams based on the UCO_TEA and UCO_DEG bio-polyols that were modified with 30 php of DMPP.

We report on rigid polyurethane (PUR) foams prepared using different contents of a mixture of two bio-polyols (20–40 php). The bio-polyols were obtained through epoxidation and a ring opening reaction. Different chemical structures of the bio-polyols resulted from the use of 1-hexanol and 1,6-hexanediol as opening agents. The bio-polyols were characterized by hydroxyl values of 104 and 250 mgKOH/g and viscosities of 643 and 5128 mPa·s, respectively. Next, the influence of the bio-polyols on the foaming process of PUR systems as well as the foam properties was evaluated. The bio-foams modified with different contents of the bio-polyols were next compared with a reference foam obtained using a polyether petrochemical polyol. The effect of the apparent density reduction as a result of replacing the petrochemical polyol was minimized by decreasing the water content in the formulation. It was found that the modification of the recipe by changing the content of water, acting as a chemical foaming agent, did not affect the foaming process. However, the introduction of the bio-polyols mixture limited the reactivity of the systems by reducing the maximum temperature of the foaming process. The bio-materials with comparable apparent densities to that of the reference material were characterized by similar values of the thermal conductivity coefficient and a decrease in their mechanical strengths. A deterioration of mechanical properties was caused by the plasticization of the polyurethane matrices with the bio-polyols containing dangling chains. However, all materials were dimensionally stable at room temperature.

With its excellent biocompatibility, biodegradability, and antimicrobial activity, chitosan is a promising scaffold material for hard-tissue engineering. Yet, pristine chitosan foams typically lack the strength and porosity required for such use. Here we present a simple emulsion-templating approach to fabricate pristine chitosan foams with optimized strength and porosity. Sodium dodecyl sulfate (SDS), a widely used biocompatible anionic surfactant, was employed at trace levels to aid polymerization. The foams display a dual-scale pore morphology. Cavities of 150–300 μm are separated by around 50 μm thick chitosan walls containing large interconnecting openings. The walls are further populated with meso- and macropores of 50–500 nm. This architecture should support cell attachment and growth, facilitate proliferation, and enhance nutrient transport and metabolic exchange. The structure yields high surface area (up to 10 m2 g−1). Mechanically, the thick-walled cavities impart both elastic recovery and high compressive resistance (255 kPa at 40% strain from foams polymerized with 4% chitosan). A preliminary drug-release study using vancomycin confirmed excellent loading and sustained release.

The main strategy of the European Commission in the field of the building industry assumes a reduction of greenhouse gas emissions by up to 20% by 2020 and by up to 80% by 2050. In order to meet these conditions, it is necessary to develop not only efficient thermal insulation materials, but also more environmentally friendly ones. This paper describes an experiment in which two types of bio-polyols were obtained using transesterification of used cooking oil with triethanolamine (UCO_TEA) and diethylene glycol (UCO_DEG). The bio-polyols were next used to prepare low-density rigid polyurethane (PUR) foams. It was found that the bio-polyols increased the reactivity of the PUR systems, regardless of their chemical structures. The reactivity of the system modified with 60% of the diethylene glycol-based bio-polyol was higher than in the case of the reference system. The bio-foams exhibited apparent densities of 41–45 kg/m3, homogeneous cellular structures and advantageous values of the coefficient of thermal conductivity. It was observed that the higher functionality of bio-polyol UCO_TEA compared with UCO_DEG had a beneficial effect on the mechanical and thermal properties of the bio-foams. The most promising results were obtained in the case of the foams modified in 60% with the bio-polyol based on triethanoloamine. In conclusion, this approach, utilizing used cooking oil in the synthesis of high-value thermal insulating materials, provides a sustainable municipal waste recycling solution.

This article compares the properties of closed-cell PUR bio-foams produced on a laboratory scale and on an industrial scale. In the formulation used, the polyol premix contained 40 wt.% of a bio-polyol based on rapeseed oil. Selected useful properties of the foams obtained on the two scales and the use of one-step and spraying methods were compared. In the case of the spraying method, the experimental system was compared to a commercial one. Given the possibility of applying the bio-foams in insulation systems for cryogenic and liquefied natural gas (LNG) applications, a compressive strength analysis of the foams was carried out at room temperature as well as at −196 °C. It was found that the foams modified with the bio-polyol were characterized by a higher compressive strength at low temperatures than commercial foams based on a petrochemical polyol.

In this work, we engineered a corn-straw-based bio-foam material under the inspiration of the intrinsic morphology of the corn stem. The explosion pretreatment was applied to obtain a fibrillated cellulose starting material rich in lignin. The in situ esterification of cellulose was adopted to improve the cross-linking network of the as-developed foam bio-material. The esterification of lignin was observed in the same procedure, which provides a better cross-linking interaction. The esterified corn-straw-derived bio-foam material showed excellent elastic resilience performance with an elastic recovery ratio of 83% and an elastic modulus of 20 kPa. Meanwhile, with surface modification by hexachlorocyclotriphosphazene-functionalized lignin as the flame retardant (Lig-HCCP), the as-obtained bio-foam material demonstrated quite a good flame retardancy (with 27.3% of the LOI), as well as a heat insulation property. The corn-straw-derived bio-foam material is prospected to be a potential substitution packaging material for widely used petroleum-derived products. This work provides a new value-added application of the abundant agricultural straw biomass resources.

This study explores the acoustic properties of composite biomaterials using a polylactic acid (PLA) matrix reinforced by plant fibers for sound insulation applications. Acoustic tests evaluated the absorption coefficient, reflection factor, and characteristic impedance, examining various configurations with different thicknesses of the composite biomaterial. The combinations of PLA/grape stem and PLA/wood straw were analyzed for their acoustic behaviors. Grape stems and wood straw were chosen because they are abundant, undervalued waste materials, especially in Italian regions like Tuscany. Therefore, using these materials in composite biomaterials could offer opportunities for valorization. The findings highlight the impact of plant fiber characteristics on acoustic properties, emphasizing the need to optimize these factors for desired acoustic outcomes. The results suggest implications for developing eco-friendly construction materials that balance environmental sustainability with performance requirements. This investigation contributes to the ongoing discourse on sustainable material utilization for acoustic purposes, reinforcing the potential for innovative and environmentally conscious building solutions.

Driven by the urgent need to identify sustainable alternatives to petroleum-based plastic packaging, this study evaluates the environmental performance of mycelium bio-foam (MBF) as a substitute for expanded polystyrene (EPS) in protecting a 32-inch flat-screen television (32-TV). A cradle-to-grave life cycle assessment (LCA) was conducted using OpenLCA software and the ELCD database to compare the impacts of MBF and EPS. The results indicate that MBF packaging offers lower environmental impacts overall, particularly during raw material acquisition, manufacturing, and end-of-life management stages. Global warming potential (GWP) (kg CO 2 eq) for MBF50, MBF100, and MBF150 was 1.32, 2.16, and 3.24, respectively, significantly lower than EPS at 3.35 kg CO 2 eq. Similarly, human non-carcinogenic toxicity (kg 1,4-DCB) values were 4.3, 6.2, and 9.3 for MBF variants, compared to 9.3 for EPS. In the transportation phase, MBF incurred higher global warming impacts (0.9 × 10 –3 to 2.8 × 10 –3 kg CO 2 eq) than EPS (0.4 × 10 –3 kg CO 2 eq) due to its higher weight. However, these emissions are offset by MBF’s biodegradability and potential for circularity. The findings underscore the importance of optimizing MBF packaging weight and design to enhance both environmental and economic viability. MBF emerges as a promising sustainable alternative to EPS, though continued innovation in material engineering and packaging design remains essential. Promoting the environmental benefits and cost-effectiveness of MBF packaging is key to accelerating its market adoption. Graphical abstract Highlights This study compared the environmental impact of Mycelium Bio-Foam (MBF) and Expanded Polystyrene (EPS) packaging for a 32-inch TV using Life Cycle Assessment (LCA). MBF generally outperformed EPS, showing lower impacts in raw material acquisition, manufacturing, and end-of-life due to its biodegradability and renewable feedstock. The GWP of MBF was 1.32 kg CO 2 compared to 3.35 kg CO 2 for EPS. MBF’s heavier weight increased transportation emissions, resulting in higher GWP (0.9*10 − 3 kg CO 2 ) compared to EPS (0.4*10 − 3 kg CO 2 ). Optimizing MBF density is crucial for enhancing its sustainability and competitiveness. The research highlights the potential of MBF as a viable, eco-friendly alternative to EPS.

AbstractReliance on harmless and renewable resources to mitigate process environmental footprint has become increasingly important for the design and operation of sustainable processes. One challenge that is prevalent in marine water surface contamination concerns treatment and recovery from oil spills where efforts are needed to design emergency units adapted to marine conditions. Potential candidates are naturally-grown porous loofa (bio-foam) materials which can be integrated in floating units transportable to the contamination area. For this purpose, a hexapod platform motion simulator was employed to emulate sea-driven floating movements of a column packed with two loofa bio-foam packings (dense and open-cell samples) and operated in cocurrent gas-liquid upflow mode. The column hydrodynamic behaviour was monitored by means of capacitance wire mesh sensors and electrical capacitance tomography for various inclination and rolling parameters. In the case of dense bio-foam packing, the relatively even distribution of gas and liquid in the vertical bed tended to degrade as the bed tilted up to 15°. Column rolling prompted fluid displacements in bed crosswise planes inducing notable amplitude oscillations of the local liquid saturation. Kerosene exhibited a strong foaming behavior with promotion of earlier inception of pulsing flow as a function of column inclination as compared to water.