Polyurethane Foam Research Articles

Sustainable rigid polyurethane foam composites based on used palm oil and turkey feather fiber: structural, morphological, thermal, insulation and mechanical properties

Sustainable rigid polyurethane foam composites based on used palm oil and turkey feather fiber: structural, morphological, thermal, insulation and mechanical properties

Shear Strength Enhancement in Soil Using Polyurethane Foam Adhesive and Cement Injections

Shear Strength Enhancement in Soil Using Polyurethane Foam Adhesive and Cement Injections

Polyurethane foam adhesive with fly ash as a sustainable stabilizer

ABSTRACT This experimental research work investigates the role of polyurethane foam adhesive (PFA) in evaluating the unconfined compressive strength (UCS) of three different types of sands with varying maximum particle sizes (Dmax = 4.00 mm, 2.00 mm, and 0.63 mm) mixed with different proportions of fly ash (FA = 0%, 5%, 10%, and 15%). Moreover, this study includes the influence of the polymer percentages (PFc = 2%, 4%, 6%, and 8%) and particle size characteristics on the UCS of the tested materials. The obtained results indicate a significant increase in the UCS and ductility at a particular fly ash content (FA = 5%), where the increment of the polyurethane foam content from PFc = 2% to 8% induces an increasing of the UCS from 1.64 MPa to 5.28 MPa (a 3.2% increase). It is found that higher values of PFc = 8% and FA = 15% exhibit noticeable improvements and stabilization of the strength properties in the tested mixtures. Additionally, the UCS of the enhanced mixtures can be predicted using a newly introduced parameter called the polymer factor index (IPF), which considers the porosity and PFA content properties. The PFA-enhanced sand-fly ash mixtures offer a promising and innovative solution in many geotechnical engineering applications due to their reliable mechanical performances.

Novosorb® BTM- history, production and application in challenging wounds

Novosorb® Biodegradable Temporising Matrix (BTM) is an entirely synthetic dermal matrix that is gaining popularity in the management of challenging wounds. Not only does it provide a framework in which to grow an organised neodermis, it is also especially resistant to infection. Today, the matrix is available as a 2 mm thick open cell polyurethane foam with a non-degrading sealing membrane. Its current form is the result of numerous in vitro and in vivo experiments that examined its shape, biodegradation, inflammatory response, and cytotoxicity. Clinical data on the use of BTM in a variety of cases is novel and presents early insights into its ability to foster wound healing where otherwise improbable. This review presents the history and development of Novosorb® BTM as well as all the currently available clinical data on its efficacy in difficult wounds such as: major burns, necrotising soft tissue infection, chronic wounds and in non graftable wound beds.

Experimental and Numerical Analysis of the Impact Resistance of Polyurethane Foam Aluminum-Concrete Sandwich Structures

The objective of this research paper is to examine the shock-absorption capabilities of sandwich structures that utilize polyurethane foam and aluminum as energy-absorbing materials. A series of drop weight impact tests were conducted on sandwich structures comprising polyurethane foam, aluminum, and concrete. The investigation encompasses variations in the thickness of the polyurethane foam-aluminum absorption layer, the impact height, and different structural combinations, coupled with numerical simulations. Results indicate that as the thickness of the polyurethane foam-aluminum energy absorption layer increases, the energy absorbed by the composite structure also increases. However, the rate of this increase tapers off as the layer thickness continues to grow. The impact height influences energy absorption within a defined range, enabling optimal utilization of the deformation and energy absorption capacities of the polyurethane foam-aluminum layer. Notably, the double-sandwich structure outperforms the single-sandwich structure in terms of impact resistance. The incorporation of the polyurethane foam-aluminum sandwich structure significantly enhances the impact resilience of concrete. Among the tested configurations, the double-sandwich structure composed of polyurethane foam, aluminum, and concrete exhibits the optimal absorption performance. Nevertheless, the layered nature of the structure significantly increases its construction complexity, potentially impacting the practical feasibility of utilizing the polyurethane foam-aluminum-concrete composite structure in real-world applications.

Biodegradable Polyurethane Foams Based on Polyols Obtained from Cellulose and Its Hydroxypropyl Derivative

Three methods of cellulose-derived polyol synthesis were elaborated. The suitable substrates were (hydroxypropyl)cellulose or cellulose, which were hydroxyalkylated in reactions with glycidol and ethylene carbonate in triethylene glycol or in water. The products were characterized by IR, 1H NMR, and MALDI ToF spectroscopies. For all polyols, IR spectra showed strong bands at 1060 cm−1 from the ether group formed upon the ring opening of GL and EC. The polyol obtained from (hydroxypropyl)cellulose in the triethylene glycol solvent was accompanied by oligomeric products of glycol hydroxyalkylation and oligomeric glycidol. The polyol obtained by the hydroxyalkylation of cellulose with glycidol and ethylene carbonate in the water contained units of hydroxyalkylated cellulose and products of hydroxyalkylation of water. The physical properties of the obtained polyols, like density, viscosity, and surface tension, were determined. The polyols were then used to obtain rigid polyurethane foams. The foams have apparent density, water uptake, and polymerization shrinkage similar to classic rigid PUFs. The foams showed advantageous thermal resistance in comparison with classic ones. After thermal exposure, their compressive strength improved. The biodegradation of the obtained materials was tested by a respirometric method in standard soil conditions by the measurement of biological oxygen demand and also using the cellulases or the enzymes responsible for cellulose degradation. It has been found that polyols are totally biodegradable within one month of exposure, while the foams obtained thereof are at least 50% biodegraded in the same conditions. The enzymatic biodegradation of the PUFs by the action of microbial cellulase was confirmed.

A new green rigid polyurethane foam based on modified palm oil: Preliminary study of their potential for marine buoy applications

AbstractThis study demonstrates a new green rigid polyurethane (PU) based on modified palm oil (MPO) for marine buoy applications. The bio‐polyol based on palm oil was synthesized using hydrogen peroxide and formic acid. The foam formation was by kinetic foaming reaction. The MPO‐based PU foams made with increased water content had closed cells that grew larger with water content to provide a low‐density foam. The resistance to flammability of PU foam was improved by adding triphenyl phosphate (TPP). The PU foam with increased TPP content had enlarged cells, increased water absorption and decreased compressive strength. In addition, carbon black (CB)‐containing foam had uniform, large foam cells, comparatively high density, higher compressive strength, and low water absorption. Moreover, a high CB content gave shorter extinguishing time for PU foam. The PU foams were investigated for buoyancy and compared with a commercial PU foam buoy. The commercial buoy had lower density, providing better‐floating performance than PU foam. Interestingly, CB_8 had an elevated density, but low water absorption rate, similar to the commercial buoy PU foam. The investigations showed that the PU foam from MPO is eco‐friendly, and the buoyancy performance of that foam is improved on adding TPP or CB.

In-depth mechanistic insights into Au nanoparticles based polyurethane foams as a selective and efficient dispersive solid phase microextractor for textile dyes from water: performance and reusability study

ABSTRACT Herein, a simple, superhydrophobic, superoleeophilic and low cost microextractor Au nanparticles (Au NPs) based polyurethane (PUFs) solid platform (Au NPs/PUFs) has been developed as a promising sorbent for removal and recovery of Congo red (CR) textile dye from water bodies. The sorbent was characterised using UV-visible and SEM techniques. The procedure relied complete dye retention from the aqueous solution at pH 5.0–5.5 onto an Au NP/PUF extractor. Analytical assessments revealed that the Au NPs/PUFs combination significantly improves mass transfer of dye and enhances creation of active sites for CR retention. CR sorption by the sorbent fitted well with intra-particle diffusion and pseudo first-order kinetic models (R2 = 0.990). The enthalpy change, ΔH (37.8 kJ mol−1) indicates that dye extraction is endothermic whereas the entropy change, ΔS0 (116.6 J mol−1K−1), reveals a significant change in the entropy during dye uptake. The free energy change ΔG (3.12 kJ mol−1 at 298 K) of CR sorption indicated that the dye retention was not spontaneous at all temperatures. A twofold sorption mechanism involving absorption accompanying ‘solvent extraction’ and/or ‘weak ion exchange’, combined with surface adsorption of dye is proposed. Sorbent packed mini column demonstrated effective percent removal and recovery (101.8%) of CR from water samples using acetone or NaOH as an eluting agent. The study expands the utility of Au NPs/PUFs for reusability and spectrophotometric sensing of trace levels of CR in water. The key attention also includes integrating PUFs utility by improving the selectivity and sensing properties towards textile dyes.

Organophosphate Esters and Polybrominated Diphenyl Ethers in Vehicle Dust: Concentrations, Sources, and Health Risk Assessment

Background: The primary flame retardants in vehicles, organophosphates (OPEs) and polybrominated diphenyl ethers (PBDEs), volatilize and accumulate in the enclosed vehicle environment, posing potential health risks. Amidst the rising number of vehicles, the scrutiny of persistent organic pollutants like OPEs and PBDEs in vehicles is increasing. This study investigates occupational and nonoccupational population exposure to specific OPEs (TnBP, TBOEP, TEHP, TCEP, TCiPP, TDCiPP, TPhP, EHDPP) and PBDEs (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, BDE-209) in vehicle dust. Methods: Data on OPEs and PBDEs in vehicle dust were sourced from PubMed and Web of Science. We applied PCA and PMF to identify pollutant sources and assessed health risks using the hazard index (HI) and carcinogenic risk (CR) methods. Monte Carlo simulations were conducted for uncertainty analysis, evaluating variable contributions to the results. Results: The predominant OPE in dust samples was TDCiPP (mean value: 4.34 × 104 ng g−1), and the main PBDE was BDE-209 (mean value: 1.52 × 104 ng g−1). Potential sources of OPEs in vehicle dust include polyvinyl chloride (PVC) upholstery, polyurethane foam (PUF) seats, electronics, carpet wear, hydraulic oil, and plastic wear in the brake system. PBDE sources likely include automotive parts, PVC upholstery, seats, carpets, and electronics. The 90th percentile HI and CR values for occupational and nonoccupational populations exposed to OPEs and PBDEs indicate that the noncarcinogenic and carcinogenic risks are relatively low. A sensitivity analysis showed that the pollutant concentration, time in the vehicle, exposure frequency, and duration significantly influence health risks. Conclusions: The health risks to both occupational and nonoccupational populations from exposure to OPEs and PBDEs in vehicle dust are relatively low.

Enhancing flame retardancy of flexible polyurethane foams through one-step coassembled nanocoatings

Enhancing flame retardancy of flexible polyurethane foams through one-step coassembled nanocoatings

Historical Evolution and Current Developments in Building Thermal Insulation Materials—A Review

The European Climate Law mandates a 55% reduction in CO2 emissions by 2030, intending to achieve climate neutrality by 2050. To meet these targets, there is a strong focus on reducing energy consumption in buildings, particularly for heating and cooling, which are the primary drivers of energy use and greenhouse gas emissions. As a result, the demand for energy-efficient and sustainable buildings is increasing, and thermal insulation plays a crucial role in minimizing energy consumption for both winter heating and summer cooling. This review explores the historical development of thermal insulation materials, beginning with natural options such as straw, wool, and clay, progressing to materials like cork, asbestos, and mineral wool, and culminating in synthetic insulators such as fiberglass and polystyrene. The review also examines innovative materials like polyurethane foam, vacuum insulation panels, and cement foams enhanced with phase change materials. Additionally, it highlights the renewed interest in environmentally friendly materials like cellulose, hemp, and sheep wool. The current challenges in developing sustainable, high-performance building solutions are discussed, including the implementation of the 6R principles for insulating materials. Finally, the review not only traces the historical evolution of insulation materials but also provides various classifications and summarizes emerging aspects in the field.

Physical and Mechanical Properties of Indian Oyster Mushroom Mycelium/Sawdust Composites for Biodegradable Packaging Materials

Mycelium-based composite (MBC) offers an excellent sustainable alternative to hydrocarbon-based materials, especially styrofoam for packaging, due to its abundance of fungal mycelium that grows quickly on agricultural substrates, its biodegradable and its lightweight. The mycelium of a commercial mushroom species, Pleurotus ostreatus (PO), is used to fabricate MBC for packaging materials. Another species, Pleurotus pulmonarius (PP), prefers warmer weather, making it more common in tropical countries. Nevertheless, there is a lack of studies of PP mycelium-based composites and their mechanical and physical properties. This study investigated the physical and mechanical properties of PP mycelium/sawdust composite and compared to PO mycelium/sawdust composite. The results showed that the average density of PP/sawdust and PO/sawdust composites were 292.14 and 272.17 kg/m3, respectively, which fell within the range of low-density polyurethane foam. The final mass gain due to water absorption into PO/sawdust specimens was 144.04%, 1.41 times lower than PP/sawdust specimens. Furthermore, PP/sawdust composite exhibited 7.5 times faster water absorption rate than PO/sawdust composite, indicating that PO/sawdust had better water resistance. The PP/sawdust composite produced an equivalent compressive modulus to the PO/sawdust composite under compression up to 1.34 MPa of maximum value. Thus, the PP/sawdust composite showed excellent potential for substitution of biodegradable packages made from PO/sawdust composite as they contributed the equivalent strength; however, the PO/sawdust composite exhibited superior water resistance to the PP/sawdust composite. Consequently, PO/sawdust should be more advantageous if the biodegradable packaging is required to be of strength as high as the low-density polyurethane foam and of compatible water resistance.

Shape Memory Polyurethane Foams With Tunable Mechanical Properties and Radiation Tolerance for Breast Repair and Reconstruction.

This study developed a shape memory polyurethane foam (SM-PUF) with tunable mechanical properties and exceptional radiation tolerance for potentially implanting tissue defects after mastectomy. The PUFs were synthesized via an insitu foaming strategy using water as a foaming agent, incorporating 4,4'-diphenylmethane diisocyanate (MDI) as the rigid segment and both polyoxytetramethylene glycol and polycaprolactone as the soft segment. The resultant PUFs possess an open-cell structure with a pore size of 30 ~ 800 μm, which achieves a compressive stress of 0.04 MPa under 70% compression strain and a tensile elongation of 667.9%. PUFs exhibit body temperature (37°C)-responsive softening and shape memory abilities, with recovery and fixation ratios reaching 88% and 98%, respectively. It was verified that PUFs can resist 40 Gy radiotherapy without changing their mechanical properties and biocompatibility. This study introduces an innovative approach to produce customizable foam for the reconstruction of implant prostheses for the breast.

Primary Stability of Zirconia Dental Implants with Cylindrical and Tapered Designs Across Varying Bone Densities: An In Vitro Evaluation

Background: While titanium implants are widely recognized for their clinical success, zirconia implants have emerged as a metal-free alternative. This study aimed to evaluate the influence of zirconia implant macrogeometry and bone density on primary implant stability. Methods: Two types of zirconia implants were tested—the Neodent® Zi Ceramic Implant and the Straumann® PURE Ceramic Implant, that were placed into polyurethane foam blocks mimicking different bone densities (10 PCF, 15 PCF, 20 PCF, 30 PCF, and 40 PCF). Each implant type was inserted and removed multiple times, with primary stability measured using resonance frequency analysis via the Osstell® Beacon device. Statistical tests, including the Shapiro–Wilk test, t-tests, the Mann–Whitney U test, and the Kruskal–Wallis test, were applied, with significance set at 5% (p < 0.05). Results: The tapered Neodent® Zi Ceramic Implant consistently showed higher ISQ values across all foam densities compared to the Straumann® PURE Ceramic Implant (p = 0.035). Additionally, lower-density foams exhibited lower stability scores (p < 0.05). Conclusion: The study concludes that both the macrogeometry of zirconia implants and bone density significantly affect primary implant stability. Specifically, tapered implants demonstrated higher stability than cylindrical designs, suggesting that implant macrogeometry and bone density should be considered for optimal primary stability in clinical settings.

Turning Corn Stalk Trashes into a Photothermal Agent for Interfacial Solar Water Evaporation for Sustainable Water Purification

Biomass‐based photothermal materials have a higher photothermal conversion efficiency and contribute significantly to improved solar water evaporation systems. This work aims to transform corn stalk (CS) trash into efficient photothermal materials with centralized and less‐contact area water supply systems to achieve enhanced interfacial heat accumulation. We successfully synthesized cornstalk biochar synthesized via pyrolysis to maintain the environmental concern and is deposited onto a scalable, and cost‐effective (<1$) polyurethane foam (triangle shape, where the tip plays the wick and centralized water supply). The detailed characterizations validate the porous structure of CS biochar‐coated PU foam (CSB@PU), and enhance interfacial heat accumulation up to 47.8 °C under 1 kW m−2 solar irradiation which is endowed via thermal management of polystyrene foam (PS). This reproducible interfacial heat accumulation and sustainable evaporator bestow a water evaporation rate of up to 1.38 kg m−2 h−1, and solar‐to‐vapor conversion efficiency (84%) under one sun which is more efficient than other biomass‐derived evaporators. Inductively coupled plasma‐optical emission spectroscopy analysis validates the reductions of primary (Na+, K+, Mg2+, and Ca2+) and heavy metal ion (Fe3+, Hg2+, Cd2+, and Pb2+) concentrations in condensate, insights the potential of CSB@PU to advance the water treatment technologies.

Properties of polyurethane foam/natural fibre composite for air conditioning insulation

ABSTRACT This study focuses on the fabrication of a biocomposite with insulating properties suitable for application in refrigeration pipe systems. The objective of this study was to utilise coconut husk and rice husk in a 1:1 ratio as reinforcement for flexible polyurethane foam. Biocomposites were made using hand mixing and casting technique reinforcement ratios of 5%, 10%, 15%, 20%, and 25% weight ratios from reinforcement husks. A thermal resistivity test, along with tensile test and water absorption measurements as a function of fibre content, was conducted according to ASTM standards. The study demonstrated that incorporating coconut and rice husks as reinforcement in polyurethane foam significantly improved the tensile properties of the composite material. The composite reinforced with 25% weight has been found to have highest tensile stress. In contrast, the thermal resistivity is observed to decrease as the fibre content is increased. A maximum thermal resistivity at 5% wt was found from the reinforcement. On the other hand, the amount of water absorption of the polymer compound increases with the increase in weight percentage of natural fibres. Based on these results, Flexible polyurethane foam reinforced with coconut husks and rice husks shows a promising solution for use as insulation for air conditioning pipes.

Development of High Performance Light Weight Concrete through incorporation of Steel Fibers onto Polyurethane Foam Concrete

A lightweight, high-performance concrete was developed using steel Fiber-reinforcement onto polyurethane foam (PUF) enhanced lightweight concrete. Fiber-reinforcement enhances strength parameters of concrete. But, the interaction between polyurethane foam’s ability to reduce density and the reinforcing effects of steel Fibers in terms of mechanical strength, shrinkage, chloride penetration, and crack resistance has not yet been explored. To overcome this limitation, investigations were done in this study to find compressive strength, split tensile strength, flexural strength, shrinkage, impact resistance, and chloride ion penetration on PUF incorporated with steel Fibers. Microstructural analysis was performed using scanning electron microscopy (SEM) to examine Fiber-concrete bonding. The results revealed that mixes with 1.5% steel Fiber content exhibit good performance, in terms of improved compressive and flexural strengths, impact resistance, and shrinkage reduction. Chloride penetration test results exhibited good chloride resistance in Fiber-reinforced mixes, making them suitable for use in corrosive environments. SEM analysis confirmed that the improved mechanical properties were largely due to enhanced Fiber-matrix bonding, which contributed to better crack control. Thus, this study was able to develop a Polyurethane foam light weight concrete incorporated with steel Fibers which could synergistically enhance its strength and durability characteristics.

Determining the Exposure Routes and Risk Assessment of Isocyanates in Indoor Environments.

Isocyanates are used as raw materials for polyurethane foams, paints, and building materials. The isocyanates can cause acute adverse health effects such as irritation of the respiratory tract, skin, and eyes, and induce asthma and sick house syndrome. However, investigations into the potential sources and risk assessments of indoor isocyanates are limited. Thus, this study aimed to determine the sources and exposure routes of isocyanates and to assess their risk in indoor environments. The results showed that household products, such as infant chairs, mattresses, and polyurethane foam spray, used in indoor environments are potential sources of atmospheric isocyanic acids (ICA). Toluene diisocyanate and methyl isocyanate pose relatively high risks to indoor environments. Total concentrations of isocyanates ranged from 38.2 to 1570ngg-1 in infant chairs, mattresses, and spray polyurethane foams. The indoor products can be indoor sources of ICA because emission rates of ICA from household products were observed in all products (0.0536-1.37ngg-1 d-1). Field observations showed that isocyanate concentrations in house-dust samples ranged from 0.194±0.126 (ethyl isocyanate) to 70.1±67.8 (ICA)ngg-1. Atmospheric isocyanate concentrations ranged from 0.0030±0.020 (propyl isocyanate) to 26.0±14.3 (ICA)ng m-3. An estimation of human exposure demonstrated that air inhalation was the major route of isocyanate exposure. The minimum margin of exposure values of methyl isocyanate and toluene diisocyanate were 523 and 655, respectively, for children, indicating that they may pose a relatively high risk.

Investigating the Impact of Long-Term Use on Mattress Firmness and Sleep Quality—Preliminary Results

Mattress comfort, often associated with firmness, is a complex construct influenced by factors such as material composition, construction, and personal preference. In this short communication paper, we indirectly investigated the effects of long-term mattress use on its hardness and sleep quality by observing the changes in the mattress. A mechanical durability test was performed on two structurally different mattress samples (with polyurethane core and pocket spring core) using a modified method based on the EN 1957 standard, aiming to understand the long-term effects of mattress characteristics on sleep quality. Preliminary results confirm that the mattress samples can maintain firmness and support during long-term use. The polyurethane foam mattress experienced initial compression but quickly stabilized, while the pocket spring mattress showed slight softening, maintaining overall firmness. For the polyurethane mattress, after the initial drop, the hardness value stabilized, varying between 7.53 and 9.03 N/mm, and at the end of the test, it stopped at 8.60 N/mm. The firmness rating stabilized at 4.3, showing minimal fluctuation between 4.0 and 4.6 throughout the process, while the total height loss was 3.79 mm. The hardness value of pocket spring mattresses generally decreased with increasing test cycles (it started at 5.86 N/mm and ended at 5.21 N/mm). The firmness remained relatively stable, varying between 7.3 and 7.1, and the total height loss was only 2.86 mm. The findings suggest that the firmness of a mattress can be changed with its use, highlighting the need for further research on a larger number of samples in the direction of the long-term implications of these changes on sleep comfort.

Experimental and Simulation Study of Fiber-Reinforced and Foam-Filled Anti-Tetrachiral and Re-Entrant Structures

Negative Poisson's ratio (NPR) honeycomb structures exhibit excellent properties, including resistance to compression, impact resistance, and energy absorption. To better study NPR structures, this paper investigates two different methods to enhance the mechanical properties and energy absorption capabilities of re-entrant and anti-tetrachiral structures. Fiber reinforcement and polyurethane foam filling methods were used to address material enhancement issues, aiming to achieve structures with high specific energy absorption. Specimens were fabricated using selective laser sintering technology with three different material configurations, including nylon, carbon fiber-reinforced nylon, and glass fiber-reinforced nylon, for comparative analysis. Additionally, some specimens were filled with polyurethane foam. Quasi-static compression tests indicated that both glass fiber-reinforced nylon and foam filling significantly improved the material's stiffness, initial peak stress, and energy absorption, although the "auxetic" effect was weakened. Subsequently, finite element methods were used to simulate the deformation modes and mechanical properties of the two NPR structures, and the numerical results showed good agreement with the experimental results.