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

The aim of this research is the production of polyurethane (PU) foams with biopolyols from liquefied oil palm mesocarp fibre (OPMF) and renewable monomer. Liquefaction of OPMF was studied using polyhydric alcohol (PA) which is PEG-400 as liquefaction solvents in conventional glass flask. In the second part of this paper was obtained the PU foams which presented good results when compared with commercial foams and include polyols from of fossil fuels. PU foams were prepared by mixing liquefied OPMF biopolyol, renewable monomer from waste cooking, additives and methylene diphenyl diisocyanate (MDI). Water was used as an environmental friendly blowing agent. The factors that influence the cell structure of foams (i.e., catalyst, surfactant, dosage of blowing agent, and mass ratio of biopolyol to renewable monomer were studied. The synthesized PU foams were characterized by FTIR and SEM. The formulation of the PU foams should be improved, but the results show that is possible the use biopolyols and renewable monomer to produce industrial foams with lower cost.The aim of this research is the production of polyurethane (PU) foams with biopolyols from liquefied oil palm mesocarp fibre (OPMF) and renewable monomer. Liquefaction of OPMF was studied using polyhydric alcohol (PA) which is PEG-400 as liquefaction solvents in conventional glass flask. In the second part of this paper was obtained the PU foams which presented good results when compared with commercial foams and include polyols from of fossil fuels. PU foams were prepared by mixing liquefied OPMF biopolyol, renewable monomer from waste cooking, additives and methylene diphenyl diisocyanate (MDI). Water was used as an environmental friendly blowing agent. The factors that influence the cell structure of foams (i.e., catalyst, surfactant, dosage of blowing agent, and mass ratio of biopolyol to renewable monomer were studied. The synthesized PU foams were characterized by FTIR and SEM. The formulation of the PU foams should be improved, but the results show that is possible the use biopolyols and renewable ...

This study investigates the morphology and mechanical properties of polyurethane (PU) foams with varying flexibility levels compared to polyborodimethylsiloxane-based polyurethane (PBDMS-PU) foam (D3O) under low strain rates. While PU foams are widely used for impact protection and cushioning, their performance varies based on processing parameters and material composition. However, a systematic comparison of their energy dissipation and recovery under cyclic loading is lacking. This study addresses this gap by analyzing the processing-structure-property relationships of these materials to determine whether PU foams can replicate D3O’s mechanical behavior. PU foams were synthesized using polyether polyols, acrylic polyols, and 4,4′-diphenylmethane diisocyanate (pMDI), with water as the blowing agent. Characterization techniques, including SEM, TGA, and cyclic compression tests, were utilized. The results show that semi-flexible PU foams exhibit pore structures and densities similar to D3O, while rigid PU foams demonstrate 62% higher density and 35–40% greater compressive strength, leading to superior mechanical performance. D3O maintains >95% recovery after 10 compression cycles and exhibits stable energy dissipation, with only a 5–10% drop in peak stress after repeated loading, comparable to semi-flexible PU foams. However, D3O has lower thermal stability (T 30 = 357°C) than PU foams (T 30 = 366–370°C), despite enhanced high-temperature resistance (T 50 > 390°C). This study highlights the tunability of PU foams for energy absorption applications, providing insights for optimizing their mechanical and thermal properties.

The enhancement of mechanical and thermal properties of rigid polyurethane foam (RPUF) achieved through a cost‐effective and sustainable approach remains an ongoing interest in both industry and academia. In this study, water‐blown rigid polyurethane (PU) foams based on crude glycerol (CG) polyol are developed and halloysite nanotubes (HN) and microcrystalline cellulose (MC) with different loadings of 1.0, 3.0, and 5.0% are incorporated to improve the performance of the foams, respectively. Effects of different loadings of HN or MC on the viscosity of CG polyols and the foaming process are investigated. CG‐based polyurethane (CGPU) foams and their foam composites (CG‐HN PU foams and CG‐MC PU foams) are characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results reveal that HN is easier to disperse uniformly in the CG polyol than MC and CGPU foams with 1.0% of HN and MC shows significantly improved performance. Their compressive strength increases by 3.8 and 12.5%, respectively, as the HN and MC loadings increases from 0 to 1.0%. The thermal conductivities of CG PU foams reinforced with 1.0% of HN and MC are 37.79 and 37.94 mWm−1K−1, which are lower than that (38.24 mWm−1K−1) of CGPU foams without the addition of fillers. Moreover, compared to CGPU foams, both CG‐HN PU foams and CG‐MC PU foams show improved thermal stabilities, and the latter is higher than the former.Practical Applications: Different fillers (HN and MC) are used to reinforce the CG‐based polyurethane, and water‐blown rigid PU biofoam composites with improved properties are prepared. The use of fillers (HN and MC) has the potential for the production of advanced CG‐based rigid PU foams.Water‐blown rigid crude glycerol‐based polyurethane foams (PU) reinforced with halloysite nanotubes (HN) and microcrystalline cellulose (MC). The results reveal that HN is easier to disperse uniformly in the CG polyol than MC and CGPU foams with 1.0% of HN and MC show significantly improved performance. The thermal conductivities of CG PU foams reinforced with 1.0% of HN and MC are 37.79 and 37.94 mWm−1K−1, which are lower than that of CGPU foams without the addition of fillers. Moreover, compared to CGPU foams, both CG‐HN PU foams and CG‐MC PU foams show improved thermal stabilities.

Studies have been carried out on the removal of radioactive cobalt (60Co) from synthetic intermediate level waste (ILW) and decontamination waste using neat polyurethane (PU) foam as well as n-tributyl phosphate–polyurethane (TBP–PU) foam. The radioactive cobalt has been extracted on the PU foam as cobalt thiocyanate from the ILW. Maximum removal of cobalt has been observed when the concentration of thiocyanate in the solution is about 0.4 M. Cobalt can be separated from decontamination waste containing ethylenediaminetetraacetic acid (EDTA) and iron(II). The extent of extraction of cobalt is slow and the separation of iron and cobalt is better with the neat PU foam compared to the TBP–PU foam. The presence of iron in the decontamination waste facilitates the extraction of cobalt thiocyanate on the PU foam. Column studies have been carried out in order to extend these studies to the plant scale. The capacities of the PU foams for cobalt have been determined. The effect of density and the surface area of PU foam have been investigated. Fourier Transform Infrared (FT-IR) spectral studies have been conducted to find out the interaction between PU foam and cobalt thiocyanate species.

As a non-metallic composite material, widely applied in industry, rigid polyurethane (PUR) foams require knowledge of their dielectric properties. In experimental determination of PUR foams’ dielectric properties protection of one-side capacitive sensor’s active area from adverse effects caused by the PUR foams’ test objects has to be ensured. In the given study, the impact of polytetrafluoroethylene (PTFE) films, thickness 0.20 mm and 0.04 mm, in covering or simulated coating the active area of one-side access capacitive sensor’ electrodes on the experimentally determined true dielectric permittivity spectra of rigid PUR foams is estimated. Penetration depth of the low frequency excitation field into PTFE and PUR foams is determined experimentally. Experiments are made in order to evaluate the difference between measurements on single PUR foams’ samples and on complex samples “PUR foams + PTFE film” with two calibration modes. A modification factor and a small modification criterion are defined and values of modifications are estimated in numerical calculations. Conclusions about possible practical applications of PTFE films in dielectric permittivity measurements of rigid PUR foams with one-side access capacitive sensor are made.

Polyol derived from soybean oil was made from crude soybean oil by epoxidization and hydroxylation. Soy‐based polyurethane (PU) foams were prepared by the in‐situ reaction of methylene diphenyl diisocyanate (MDI) polyurea prepolymer and soy‐based polyol. A free‐rise method was developed to prepare the sustainable PU foams for use in automotive and bedding cushions. In this study, three petroleum‐based PU foams were compared with two soy‐based PU foams in terms of their foam characterizations and properties. Soy‐based PU foams were made with soy‐based polyols with different hydroxyl values. Soy‐based PU foams had higher Tg (glass transition temperature) and worse cryogenic properties than petroleum‐based PU foams. Bio‐foams had lower thermal degradation temperatures in the urethane degradation due to natural molecular chains with lower thermal stability than petroleum skeletons. However, these foams had good thermal degradation at a high temperature stage because of MDI polyurea prepolymer, which had superior thermal stability than toluene diisocyanate adducts in petroleum‐based PU foams. In addition, soy‐based polyol, with high hydroxyl value, contributed PU foam with superior tensile and higher elongation, but lower compressive strength and modulus. Nonetheless, bio‐foam made with high hydroxyl valued soy‐based polyol had smaller and better distributed cell size than that using low hydroxyl soy‐based polyol. Soy‐based polyol with high hydroxyl value also contributed the bio‐foam with thinner cell walls compared to that with low hydroxyl value, whereas, petroleum‐based PU foams had no variations in cell thickness and cell distributions.

Rigid polyurethane (PUR) and polyisocyanurate (PIR) foams are widely used as thermal insulation materials due to their excellent thermal conductivity and low density. However, fire resistance remains a critical property determining their safe application in construction, transportation, and energy systems. This study provides a comparative overview of the fire behavior of PUR and PIR foams, focusing on structural aspects, decomposition mechanisms, flame retardancy, and performance of emission of toxic gases during the combustion process. Despite extensive studies on PUR and PIR foams, systematic comparative investigations addressing the combined influence of recycled PET-based polyester polyols, isocyanurate content, and fire-related properties-including thermal degradation, heat release, and toxic gas emissions-remain limited. PIR foams, characterized by higher isocyanate indices and the presence of isocyanurate rings, show superior thermal stability, reduced heat release rates, and enhanced char formation compared with PUR foams. Experimental analysis of thermal degradation (TGA/DTG) and heat release (cone calorimetry) confirms that PIR foams demonstrate higher resistance to ignition and slower fire propagation. The results emphasize the critical role of molecular architecture and crosslink density in shaping the fire performance of rigid foams, highlighting PIR systems as advanced insulation solutions for applications requiring stringent fire safety standards. The PIR foam was prepared using a polyester polyol derived from recycled PET, which could help in achieving better fire properties during the combustion process. Compared with PUR foams, PIR foams exhibited an approximately 50% reduction in peak heat release rate, an increase in char yield from about 3 wt.% to over 22 wt.%, and a shift of the main thermal degradation peak by approximately 55 °C toward higher temperatures, indicating substantially enhanced fire resistance.

One of the biggest disadvantages of rigid polyurethane (PU) foams is its low thermal resistance, high flammability and high smoke production. Greatest advantage of this thermal insulation material is its low thermal conductivity (λ), which at 18-28 mW/(m•K) is superior to other materials. To lower the flammability of PU foams, different flame retardants (FR) are used. Usually, industrially viable are halogenated liquid FRs but recent trends in EU regulations show that they are not desirable any more. Main concern is toxicity of smoke and health hazard form volatiles in PU foam materials. Development of intumescent passive fire protection for foam materials would answer problems with flammability without using halogenated FRs. It is possible to add expandable graphite (EG) into PU foam structure but this increases the thermal conductivity greatly. Thus, the main advantage of PU foam is lost. To decrease the flammability of PU foams, three different contents 3%; 9% and 15% of EG were added to PU foam formulation. Sample with 15% of EG increased λ of PU foam from 24.0 to 30.0 mW/(m•K). This paper describes the study where PU foam developed from renewable resources is protected with thermally expandable intumescent mat from Technical Fibre Products Ltd. (TFP) as an alternative to EG added into PU material. TFP produces range of mineral fibre mats with EG that produce passive fire barrier. Two type mats were used to develop sandwich-type PU foams. Also, synergy effect of non-halogenated FR, dimethyl propyl phosphate and EG was studied. Flammability of developed materials was assessed using Cone Calorimeter equipment. Density, thermal conductivity, compression strength and modulus of elasticity were tested for developed PU foams. PU foam morphology was assessed from scanning electron microscopy images.

The utilization of vegetable oil in producing bio-based polyol, as an alternative replacement to petroleum-based polyol in making polyurethane (PU) foam has gained a lot of interest due to its finite supply and low production cost. In this study, bio-based polyol using coconut oil as raw material produced PU foam as thermal insulation material. The vegetable oil-based polyol was prepared using a two-step method, while PU foams were prepared by the free-rise method. In order to enhance the thermal properties of the produce PU foams, phase change material (PCM) was added to the PU foam formulation. FTIR spectra result showed peaks at 2920 cm-1 and 2850-1, which signifies the CH2 asymmetric stretching, indicating that n-octadecane was successfully incorporated into PU foams. Moreover, heat flow meter (HFM) and thermo-gravimetric analysis (TGA) show PU foam with 1% n-octadecane shows better thermal properties than other produced PU foams. Furthermore, the universal testing machine (UTM) result shows an enhancement in the mechanical properties of the produced PU foam. These results demonstrate that the addition of n-octadecane to the PU foam formulation improved the mechanical properties of PU foams while enhancing their thermal properties.

In this study, polyurethane (PU) foams were manufactured using kraft lignin and castor oil as bio-based polyols by replacing 5–20 wt% and 10–100 wt% of conventional polyol, respectively. To investigate the effects of unmodified bio-based polyols on PU foam production, reactivity and morphology within PU composites was analyzed as well as mechanical and thermal properties of the resulting foams. Bio-based PU foam production was carried out after characterizing the reagents used in the foaming process (including hydroxyl group content, molecular weight distribution, and viscosity). To compare the resulting bio-based PU foams, control foam were produced without any bio-based polyol under the same experimental conditions. For lignin-incorporated PU foams, two types, LPU and lpu, were manufactured with index ratio of 1.01 and 1.3, respectively. The compressive strength of LPU foams increased with lignin content from 5 wt% (LPU5: 147 kPa) to 20 wt% (LPU20: 207 kPa), although it remained lower than that of the control foam (PU0: 326 kPa). Similarly, the compressive strength of lpu foams was lower than that of the control foam (pu0: 441 kPa), with values of 164 kPa (lpu5), 163 kPa (lpu10), 167 kPa (lpu15), and 147 kPa (lpu20). At 10 wt% lignin content, both foams (LPU10 and lpu10) exhibited the smallest and most homogenous pore sizes and structures. For castor oil-incorporated PU foams with an index of 1.01, denoted as CPU, increasing castor oil content resulted in larger cell sizes and void fractions, transitioning to an open-cell structure and decreasing the compressive strength of the foams from 284 kPa (CPU10) to 23 kPa (CPU100). Fourier transform infrared (FT-IR) results indicated the formation of characteristic urethane linkages in PU foams and confirmed that bio-based polyols were less reactive with isocyanate compared to traditional polyol. Thermogravimetric analysis (TGA) showed that incorporating lignin and castor oil affected the thermal decomposition behavior. The thermal stability of lignin-incorporated PU foams improved as the lignin content increased with char yields increasing from 11.5 wt% (LPU5) to 15.8 wt% (LPU20) and from 12.4 wt% (lpu5) to 17.5 wt% (lpu20). Conversely, the addition of castor oil resulted in decreased thermal stability, with char yields decreasing from 10.6 wt% (CPU10) to 4.2 wt% (CPU100). This research provides a comprehensive understanding of PU foams incorporating unmodified biomass-derived polyols (lignin and castor oil), suggesting their potential for value-added utilization as bio-based products.

In the last years, increasing interest has been paid to polyurethane (PU) foams with open porosity to be used as scaffold in numerous tissue engineering applications. In fact, they possess good cyto- and biocompatibility, and they can be synthesized with tunable chemico-physical and mechanical properties by varying the base reagents used for their synthesis (polyol, isocyanate, and expanding agent) and the stoichiometric ratio between them. The aim of this work was to design and develop novel PU foams with high open porosity and tunable physical and mechanical properties by varying the polyol composition and the stoichiometric ratio between the base reagents. PU foams were synthesized by a one step gas foaming method (stoichiometric and not stoichiometric foams), by reacting a polyol mixture ad hoc set up with MDI prepolymer, using Fe-AA as catalyst, and water as expanding agent. Different polyol mixtures were prepared by varying the ratio between the main polyol components, e.g. a polyether-polyol (component A), a polyether-polyol containing styrene (component B), and an amine-based tetrafunctional polyether-polyol (component C). The PU foams were characterized by SEM, micro-CT, ATR-FTIR analysis, and evaluation of density, water uptake, and mechanical properties by uniaxial compressive tests in dry and wet conditions. Polyol composition do not affect PU foam open porosity, while the pore size and water uptake increase with the increase of components B and C. All the foams show higher compressive properties in dry than in wet state, due to the plasticizing effect of water. PU foams synthesized with an excess of diisocyanate are significantly stiffer than the stoichiometric ones. In addition the compressive properties of the PU foams are mostly affected by the amine-based tetrafunctional component, that causes a higher level of cross-linking, stiffness and strenght. Preliminary tests show no cytotoxic effects for all the tested PU foams.

In this paper, a laboratory-scale (small) Steam Boiler was designed and developed for a small-scale polyurethane recycling machine. A small-sized polyurethane machine was developed for the recycling of polyurethane foams to reduce wastes in the polyurethane production industries and also to reuse old discarded foams after their useful lives. It has been observed from studies carried out in many foam manufacturing industries that the polyurethane foam wastes generated from various plant operations are enormous. Also, polyurethane (foam) products are everywhere in our homes, industries and automobiles and are always discarded after their useful lives. These wastes need to be recycled always in other for them not to get back into our ecosystems thereby polluting our environment because polyurethane foams are non-biodegradables and can remain in the environment for a very long time. However, only a few companies with strong financial capabilities are able to embark on this venture because of the high costs of machinery and large quantities of chemicals involved. The high costs of machinery and chemicals also deter cottage industries from participating in the recycling of old and discarded polyurethane foams. Therefore, there is a need to develop small-scale polyurethane foam waste recycling machines to reduce the costs of machinery and chemicals involved in the recycling thereby allowing more participation in the recycling process. The boiler is used to generate high-temperature steam for curing and better bonding of the shredded foams. The heating chamber of the machine consists of the steam boiler, and pressure hose to enable passage of steam from the steam boiler into the molding box. The total volume of the boiler is 2.5 Litres. The outlet steam temperature is 135 0C and 25 psi pressure. The heat rate is 1.52 kJ/s. The recycled foams were able to cure and bonded better with the addition of steam compared to without the steam. The percentage difference in I.F.D, Resilience, Tensile Stress and percent elongation are +0.56, -2.00, +85.45, and +68.39 respectively. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

Background: Polyurethane (PU) foams contained in construction and demolition wastes (CDW) represent a great environmental impact, since they usually end in landfill or incineration processes. The goal of this work is to develop a way to formulate PU foams, maintaining (or ever improving) their performance, by the re-use of those industrial wastes. This procedure will allow minimize both the volume of disposal to be treated by other ways and the amount of pristine raw material needed to produce new PU foams. Methods: In this work, new rigid and soft polyurethane (PU) foams have been formulated with addition of recycled PU foams coming from demolition of buildings. Density, Fourier transform infrared analysis, compression properties and thermal conductivity were measured to characterize the resulting foams. Results: The work showed that addition of filler coming from recycled PU foams should be limited to low percentages, in order to allow good foam evolution from the reactants. Thermal conductivity values of modified rigid foams are worse than those of pristine foam, which is undesirable for thermal insulation purposes; however, in the case of soft foams, this parameter improved to some extent with low levels of recycled PU foam addition. Conclusions: The studied procedure could contribute to reduce the thermal conductivity of pristine soft PU foam, which would be of interest for applications where thermal insulation matters.

Background: Polyurethane (PU) foams contained in construction and demolition wastes (CDW) represent a great environmental impact, since they usually end in landfill or incineration processes. The goal of this work is to develop a way to formulate PU foams, maintaining (or ever improving) their performance, by the re-use of those industrial wastes. This procedure will allow minimize both the volume of disposal to be treated by other ways and the amount of pristine raw material needed to produce new PU foams. Methods: In this work, new rigid and soft polyurethane (PU) foams have been formulated with addition of recycled PU foams coming from demolition of buildings. Density, Fourier transform infrared analysis, compression properties and thermal conductivity were measured to characterize the resulting foams. Results: The work showed that addition of filler coming from recycled PU foams should be limited to low percentages, in order to allow good foam evolution from the reactants. Thermal conductivity values of modified rigid foams are worse than those of pristine foam, which is undesirable for thermal insulation purposes; however, in the case of soft foams, this parameter improved to some extent with low levels of recycled PU foam addition. Conclusions: The studied procedure could contribute to reduce the thermal conductivity of pristine soft PU foam, which would be of interest for applications where thermal insulation matters.

Fluorescent polyurethane foams as sensory materials: Advances in isocyanate and non-isocyanate platforms for environmental and biological detection