Search Results (127)

This study explores the potential of pine bark—a highly accessible and underexploited by-product of forestry and food processing—as a renewable raw material for rigid polyurethane (PUR) foam production. Under optimal extraction conditions, water-soluble extractives rich in carbohydrates were isolated from biomass with a yield of 25% and subsequently condensed with propylene carbonate (PC) to produce bio-based polyols. The polyols synthesized at a PC/OH molar ratio ranging from 1 to 5 were incorporated into rigid PUR foam formulations as substitutes for commercial polyether polyols. The foams containing bio-polyols synthesized at a PC/OH ratio of 3 demonstrated the highest compressive strength and thermal insulation performance, exceeding those of the reference material by 30% and 9%, respectively, and exhibited enhanced thermo-oxidative stability. Incorporation of extracted bark up to 10 wt% as a filler in the PUR matrix led to a decrease in mechanical properties to the level of the reference foam and a 19% reduction in thermal insulation capacity, without affecting the closed-cell content. Cone calorimetry revealed that both filled and unfilled bio-polyol-based PUR foams exhibited lower degradation rate, heat release rate, and total smoke release compared with the reference material, indicating reduced flammability and a lower tendency toward fire propagation. Full article

The development of bio-based polyurethane foams has become a key direction in polymer materials research, driven by the need to replace petrochemical raw materials with renewable alternatives. This study investigates the synthesis and characterization of open-cell polyurethane foams produced using mixed bio-polyols derived from radish seed oil and tall oil in various mass ratios. For comparison, reference foams based on a radish seed oil polyol, tall oil-based polyol and a petrochemical polyol were also prepared. The influence of the polyol composition on the foaming behavior, cell structure, apparent density, mechanical properties, and thermal conductivity of the resulting foams was analyzed. Full article

Rigid polyurethane foams obtained using different amounts of biopolyol synthesized via transesterification of rapeseed oil with triethanolamine were subjected to glycolysis in order to obtain rebiopolyols. It was demonstrated that the biopolyol content in the parent foam influences both the chemical structure and the properties of the recovered rebiopolyols. FTIR and GPC analyses confirmed changes in the proportions of urethane, ester, and ether linkages. They also revealed the release of free triethanolamine and the formation of monoglycerides resulting from partial cleavage of fatty acid ester groups originally present in the biopolyol. Increasing the biopolyol content led to a reduction in the viscosity and the number-average molecular weight, along with an increase in the amine number. The rebiopolyols were preliminarily evaluated in polyurethane formulations, and FOAMAT measurements indicated an increase in the foaming reactivity with a higher amine content. Complete replacement of the petrochemical polyol with rebiopolyols was possible only when the starting foam contained up to 50 wt% biopolyol, while higher biopolyol contents resulted in excessive reactivity. These results demonstrate that the biopolyol content in the foam subjected to glycolysis is the key factor determining the suitability of rebiopolyols for reuse in the synthesis of new polyurethane foams. Full article

This study presents a complete and zero-waste valorization strategy for barley straw through the synthesis of bio-polyols and the concurrent utilization of its cellulose fraction as lignin-containing cellulose nanofibers (LCNF) for the development of bio-based polyurethane (PU) foams. Two types of bio-polyols were prepared: one derived from lignin isolated via biomass fractionation, named lignin bio-polyol (LBP), and another obtained directly from unfractionated barley straw, called straw bio-polyol (SBP), thereby incorporating all lignocellulosic constituents into a single reactive matrix. LCNF, produced from the same feedstock, was incorporated at different loadings to achieve full biomass utilization and reinforce the polyurethane foam structure. Foams prepared with LBP exhibited lower density and a more homogeneous structure, whereas those synthesized with SBP developed a stiffer, more crosslinked network. The incorporation of LCNF generally increased apparent density and mechanical performance, with optimal reinforcement at 3 wt.% in foams with SBP and 5 wt.% in LBP foams, corresponding to a 62.5 and 121% enhancement in compressive strength relative to their respective control foams. Moreover, the use of barley straw bio-polyol shifted some thermal degradation peaks toward higher temperatures, evidencing improved thermal resistance. Overall, this dual-route strategy provides a sustainable and versatile methodology for the comprehensive valorization of lignocellulosic biomass, enabling a systematic understanding of the role of each structural component in polyurethane foam synthesis. The resulting materials offer a renewable, low-impact pathway toward high-performance polymeric materials. Full article

Flexible polyurethane foam (PUF) is a vital material across diverse applications, and its global market is projected to continue growing. Driven by regulatory and consumer demand for sustainable materials, the PUF industry is exploring alternatives to petroleum-derived raw materials, such as vegetable oil-derived bio-polyols. Although bio-based alternatives to fossil-derived foams have been developed, their environmental benefits remain to be fully assessed. Therefore, this study evaluates the environmental performance of flexible PUF production by comparing a conventional fossil-based formulation with a bio-based alternative using a cradle-to-gate Life Cycle Assessment (LCA). The bio-based PUF reduced global warming (6%), fossil resource scarcity (9%), and mineral resource scarcity (6%), but caused significant increases in freshwater eutrophication (91%) and marine eutrophication (19%), mainly due to agricultural processes associated with soybean cultivation. Regardless of the formulation, polyol and toluene diisocyanate production were identified as major environmental hotspots. These results highlight both the decarbonization potential and the trade-offs of bio-based raw materials, underlining the complexity of achieving sustainable PUF production. Overall, the findings provide quantitative insights to guide more sustainable design and sourcing strategies for flexible PUF in the transition from fossil to renewable feedstocks. Full article

In the described studies, raw material from chemically recycled petrochemical foam and biobased polyurethane foams (100% of rapeseed oil polyol were used in polyol premix) were utilised in order to obtain viscoelastic foams. The recycled foams exhibited differences in chemical structure, resulting in the formation of four different repolyols. The obtained repolyols were employed as replacements for 10 to 30 wt.% of the petrochemical polyol in the mixture utilised to produce viscoelastic polyurethane foams. It was determined that the chemical structure of the polyol utilised for the foam’s initial production influences the properties of the repolyols obtained and thus also the properties of the viscoelastic foams obtained using them. It was found that foams obtained with the addition of 10 wt.% repolyols were characterized by the best properties among the obtained modified foams, comparable or even better than in the case of petrochemical reference foam. The apparent density of such foams was about 70 kg/m³. Depending on the type of repolyol used, the hardness of the foams ranged from 2 to 8 kPa, and the comfort factor was between 2.5 and 5.0. The foams obtained were characterised by their ability to absorb energy, as evidenced by a resilience of no more than 10% in most cases. However, increasing the percentage of repolyol in the reaction mixture caused too many changes in the structure of the polymer chains, disrupting the arrangement of rigid and elastic segments, which caused the hardness to increase significantly, and the foams were therefore more susceptible to permanent deformation. Full article

Rigid polyurethane foams (RPUFs) are essential polymeric materials, prized for their low density, high mechanical strength, and superior thermal insulation, making them indispensable in construction, refrigeration, and transportation. Despite these advantages, their highly porous, carbon-rich structure renders them intrinsically flammable, promoting rapid flame spread, intense heat release, and the generation of toxic smoke. Traditional strategies to reduce flammability have primarily focused on incorporating additive or reactive flame retardants into the foam matrix, which can effectively suppress combustion but often compromise mechanical integrity, suffer from migration or compatibility issues, and involve complex synthesis routes. Despite recent progress, the long-term stability, scalability, and durability of surface flame-retardant coatings for RPUFs remain underexplored, limiting their practical application in industrial environments. Recent advances have emphasized the development of surface-engineered flame-retardant coatings, including intumescent systems, inorganic–organic hybrids, bio-inspired materials, and nanostructured composites. These coatings form protective interfaces that inhibit ignition, restrict heat and mass transfer, promote char formation, and suppress smoke without altering the intrinsic properties of RPUFs. Emerging deposition methods, such as layer-by-layer assembly, spray coating, ultraviolet (UV) curing, and brush application, enable precise control over thickness, uniformity, and adhesion, enhancing durability and multifunctionality. Integrating bio-based and hybrid approaches further offers environmentally friendly and sustainable solutions. Collectively, these developments demonstrate the potential of surface-engineered coatings to achieve high-efficiency flame retardancy while preserving thermal and mechanical performance, providing a pathway for safe, multifunctional, and industrially viable RPUFs. Full article

The acoustic, thermal, and mechanical performances of sawdust-reinforced polyurethane (PU) foam are investigated for different thicknesses and varying mesh sizes. Acoustic properties are explored using a combination of impedance tube testing and mathematical modeling with the Johnson–Champoux–Allard–Lafarge (JCAL) model, a simplified JCAL model and a model of non-uniform cylindrical pores with a log-normal radius distribution (NUPSD). Thermal Insulation and mechanical properties are determined by measuring the effective thermal conductivity (K_eff) and by tensile strength tests, respectively. Compared with pure PU foam, the presence of sawdust matches noise reduction coefficients (NRC) and increases sound absorption averages (SAA) by nearly 10%. Increasing thickness and width of backing air gap have the usual effects of improving low- and mid-frequency absorption and shifting resonance peaks toward lower frequencies. As well as superior acoustic performance, samples with Mesh 16 sawdust reinforcement provide both useful insulation (K_eff = 0.044 W/mK) and tensile strength (~0.06 MPa), confirming their multifunctionality. Although the JCAL model provides reasonable fits to the sound absorption data, some of the fitted parameter values are unphysical. Predictions of the NUPSD model are relatively poor but improve with sample thickness and after fiber addition. Full article

The influence of both mixing pressure and substrate temperature on the structure and properties of spray polyurethane foams produced with a high content (80%) of tall oil-based polyol was investigated. The use of a renewable feedstock such as tall oil polyol aligns with the principles of sustainable development by reducing the carbon footprint and minimizing the environmental impact of the production process. The research focused on identifying the relationships between process parameters and the resulting materials’ thermal insulation properties, physico-mechanical performance, thermal behavior, cellular structure, and chemical composition. The results demonstrated that increasing the mixing pressure (from 12.5 to 17.5 MPa) and substrate temperature (from 40 to 55 °C) led to a reduction in average pore diameter, an increase in closed-cell content up to 94.5% and improved structural homogeneity. The thermal conductivity coefficient (λ) ranged from 18.55 to 22.30 mW·m⁻¹·K⁻¹ while apparent density varied between 44.0 and 45.5 kg·m⁻³. Higher mixing pressure positively affected compressive strength, whereas elevated substrate temperature reduced this parameter. Brittleness, water uptake, and dimensional stability remained at favorable levels and showed no significant correlation with processing conditions. These findings confirm the high quality of the materials and highlight their potential as sustainable, environmentally friendly insulation foams. Full article

This study investigates the use of bio-based polyurethane foams (PUFs) containing phase change material (PCM) microparticles as a sustainable alternative for the automotive sector. These foams are synthesized using polyols derived from waste cooking oil (WCO), aligning with circular economy principles. To evaluate the thermophysical properties of these materials and, more in general, their thermal behavior, the use of non-destructive thermographic techniques has been proposed. This technique enables a rapid, full-field thermal analysis without physical contact, making it especially suitable for porous and heterogeneous structures like foams. As a reference, both virgin and foams with PCM were characterized in terms of density and thermal conductivity using well-established methods. Then, Lock-in thermography has been used as the first attempt technique to investigate variations in thermal behavior due to different thermophysical material properties based on the thermal response in transmission configuration. The thermographic approach proves to be an effective tool not only for assessing thermal behavior but also for supporting quality control and process optimization of sustainable polymeric materials. Full article

This systematic literature review explores recent advancements in polymer-based composite materials designed for thermal insulation in automotive applications, with a particular focus on sustainability, performance optimization, and scalability. The methodology follows PRISMA 2020 guidelines and includes a comprehensive bibliometric and thematic analysis of 229 peer-reviewed articles published over the past 15 years across major databases (Scopus, Web of Science, ScienceDirect, MDPI). The findings are structured around four central research questions addressing (1) the functional role of insulation in automotive systems; (2) criteria for selecting suitable polymer systems; (3) optimization strategies involving nanostructuring, self-healing, and additive manufacturing; and (4) future research directions involving smart polymers, bioinspired architectures, and AI-driven design. Results show that epoxy resins, polyurethane, silicones, and polymeric foams offer distinct advantages depending on the specific application, yet each presents trade-offs between thermal resistance, recyclability, processing complexity, and ecological impact. Comparative evaluation tables and bibliometric mapping (VOSviewer) reveal an emerging research trend toward hybrid systems that combine bio-based matrices with functional nanofillers. The study concludes that no single material system is universally optimal, but rather that tailored solutions integrating performance, sustainability, and cost-effectiveness are essential for next-generation automotive thermal insulation. Full article

Lignin used in this work was isolated from sapele (Entandrophragma cylindricum) wood through a hybrid pulping process using soda/ethanol as pulping liquor and denoted soda-oxyethylated lignin (SOL). SOL was mixed with a polyethylene glycol (PEG)–glycerol mixture (80/20 v/v) as liquefying solvent with 98% wt. sulfur acid as catalyst, and the mixture was taken to boil at 140 °C for 2, 2.5, and 3 h. Three bio-polyols LBP1, LBP2, and LBP3 were obtained, and each of them exhibited a high proportion of -OH groups. Lignin-based polyurethane foams (LBPUFs) were prepared using the bio-polyols obtained with a toluene diisocyanate (TDI) prepolymer by the one-shot method. Gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and carbon-13 nuclear magnetic resonance spectroscopy (¹³C NMR) were used characterize lignin in order to determine viscosity, yield, and composition and to characterize their structure. The PEG-400–glycerol mixture was found to react with the lignin bio-polyols’ phenolic -OHs. The bio-polyols’ viscosity was found to increase as the liquefaction temperature increased, while simultaneously their molecular weights decreased. All the NCO groups were eliminated from the samples, which had high thermal stability as the liquefaction temperature increased, leading to a decrease in cell size, density, and crystallinity and an improvement in mechanical performance. Based on these properties, especially the presence of some aromatic rings in the bio-polyols, the foams produced can be useful in automotive applications and for floor carpets. Full article

In this study, we tested a flexible polyurethane (PU) foam, synthesized from bio-based components, for the removal of petroleum-derived fuels from water samples. The PU was synthesized via the prepolymer method through the reaction of PEG 400 with L-lysine ethyl ester diisocyanate (L-LDI), followed by chain extension with 2,5-bis(hydroxymethyl)furan (BHMF), a renewable platform molecule derived from carbohydrates. Freshwater and seawater samples were artificially contaminated with commercial diesel, gasoline, and kerosene. Batch adsorption experiments revealed that the total sorption capacity (S, g/g) of the PU was slightly higher for diesel in both water types, with values of 67 g/g in freshwater and 70 g/g in seawater. Sorption kinetic analysis indicated that the process follows a pseudo-second-order kinetic model, suggesting strong chemical interactions. Equilibrium data were fitted using Langmuir and Freundlich isotherm models, with the best fit achieved by the Langmuir model, supporting a monolayer adsorption mechanism on homogeneous surfaces. The PU foam can be regenerated up to 50 times by centrifugation, maintaining excellent performance. This study demonstrates a promising application of this sustainable and bio-based polyurethane foam for environmental remediation. Full article

This review examines the chemical functionalization of Camelina, hemp, and rapeseed oils for the development of sustainable bio-based resins. Key strategies, including epoxidation, acrylation, and click chemistry, are discussed in the context of tailoring molecular structure to enhance reactivity, compatibility, and material performance. Particular emphasis is placed on overcoming the inherent limitations of vegetable oil structures to enable their integration into high-performance polymer systems. The agricultural sustainability and environmental advantages of these feedstocks are also highlighted alongside the technical challenges associated with their chemical modification. Functionalized oils derived from Camelina, hemp, and rapeseed have been successfully applied in various resin systems, including protective coatings, pressure-sensitive adhesives, UV-curable oligomers, and polyurethane foams. These advances demonstrate their growing potential as renewable alternatives to petroleum-based polymers and underline the critical role of structure–property relationships in designing next-generation sustainable materials. Ultimately, the objective of this review is to distill the most effective functionalization pathways and design principles, thereby illustrating how Camelina, hemp, and rapeseed oils could serve as viable substitutes for petrochemical resins in future industrial applications. Full article

Bio-polyurethane foam was synthesized in this study using bio-polyol derived from liquefied waste wood as a sustainable alternative to petroleum-based polyols. It has been widely reported that polyurethane foams incorporating liquefied wood exhibit biodegradability when buried in soil, with assessments typically relying on CO₂ emission measurements in a close system. However, this method cannot obtain any chemical bonding breakage information of the bio-polyurethane foam. On the other hand, our study investigated the biodegradation process by employing an elemental composition analysis using a CHN coder and functional group analysis through Fourier transform infrared (FT-IR) spectroscopy to capture chemical structure changing. The results demonstrated that biodegradation occurs in three different stages over time, even in the absence of significant early-stage weight loss. The gradual breakdown of urethane bonds was confirmed through changes in the elemental composition and functional group ratios, providing a more detailed understanding of the degradation mechanism. These findings suggest highlighting the importance of complementary chemical analytical techniques for a more accurate evaluation. On the other hand, TG data showed that bio-polyurethane foams remained thermally stable even after biodegradation occurred. Full article