Synthesis Of Polyurethane Foams Research Articles

Utilization of Neem Seed Oil as Surfactant in the Production of Flexible and Rigid Polyurethane Foam

Extraction and processing of polyether polyols derived from petrochemicals, commonly used as surfactants during polyurethane foam (PUF) production, contribute to carbon emissions and raises the issue of long-term sustainability given that petrochemicals are non-renewable resources. Here, 5 mg and 4 mg of neem seed oil are employed to form flexible and rigid PUF, classified purposefully based on their divergent usage. To find an environmentally friendly replacement, flexible PUF whose mass, volume, density, compression, tensile strength, cream time, foam rise and rising time are 0.0047 kg m3, 16.52 kg/m3, 8.10%, 39.28 kN/m2, 60s, 10s and 60s is formed by mixing 1.25 kg polyol, 5mg silicon oil and 10g calcium carbonate (CaCO3). Likewise, by mixing 1.2 kg polyol, 4mg silicon oil and 8g CaCO3, a rigid PUF with 0.005kg, m3, 16.2 kg/m3, 8.15%, 40.72 kN/m2, 50s, 15 cm and 58s key, physical and mechanical property as respectively listed under the flexible PUF formulation is produced. Both foams were produced using equal amounts of toluene diisocyanate, water, stannous octoate and methylene chloride, resulting in PUF that can be used in insulation, cushioning and construction support applications based on their characteristic height, density, tensile strength and compressive strength. As the surfactant, neem seed oil's potential in the synthesis of PUF cannot be overemphasized. The study of the kinetics of PUF production is limited and should trigger the adoption of biobased surfactants for industrial applications in the future.

Liquefaction optimization of grape pulp using response surface methodology for biopolyol production and bio-based polyurethane foam synthesis.

Both environmental and economic disadvantages of using petroleum-based products have been forcing researchers to work on environmentally friendly, sustainable, and economical alternatives. The purpose of this study is to optimize the solvothermal liquefaction process of grape pomace using response surface methodology coupled with a central composite design. After investigating the physicochemical properties of the liquified products (biopolyol) in detail, a bio-based rigid polyurethane foam (RPUF) was synthesized and characterized. The hydroxyl and acid numbers and viscosity values of all the biopolyols were analyzed. According to variance analysis results (%95 confidence range), both the reaction temperature and catalyst loading were determined as significant parameters on the liquefaction yield (LY). The model was validated experimentally in the following reaction conditions: 4.25% catalyst loading, 50 min reaction time, and 165 °C reaction temperature, which yields an LY of 81.3%. The biopolyols produced by the validation experiment display similar characteristics (hydroxyl number: 470.5 mg KOH/g; acid number: 2.31 mg KOH/g; viscosity: 1785 cP at 25 °C) to those of commercial polyols widely preferred in the production of polyurethane foam. The physicochemical properties of bio-based foam obtained from the biopolyol were determined and the thermal conductivity, closed-cell content, apparent density, and compressive strength values of bio-based RPUF were 31.3 mW/m·K, 71.1%, 33.4 kg/m3, and 105.3 kPa, respectively.

Current Progress in Research into Environmentally Friendly Rigid Polyurethane Foams.

Polyurethane foams are materials characterized by low density and thermal conductivity and can therefore be used as thermal insulation materials. They are synthesized from toxic and environmentally unfriendly petrochemicals called isocyanates and polyols, which react with each other to form a urethane group via the displacement of the movable hydrogen atom of the -OH group of the alcohol to the nitrogen atom of the isocyanate group. The following work describes the synthesis of polyurethane foams, focusing on using environmentally friendly materials, such as polyols derived from plant sources or modifiers, to strengthen the foam interface derived from plant precipitation containing cellulose derived from paper waste. The polyurethane foam industry is looking for new sources of materials to replace the currently used petrochemical products. The solutions described are proving to be an innovative and promising area capable of changing the face of current PU foam synthesis.

Mn(III) O^N^O Complexes as Water-tolerant and Environmentally Benign Catalysts for Polyurethane Foam Synthesis.

Polyurethanes are synthesized on industrial scale by the reaction of diisocyanates with diols in the presence of catalysts which are commonly based on tin complexes and amines. However, due to the toxicity and volatility of these tin catalysts and amines, there is the need to develop new catalysts that are more environmentally benign. Herein, we report the synthesis of O^N^O pincer-ligated Mn(III) and Fe(III) complexes that serve as suitable catalysts for urethane formation and are stable to hydrolysis as predicted by computations and observed experimentally. The O^N^O pincer scaffold is vital to the activity of these catalysts, simultaneously ensuring increased solubility in the reaction medium as well as providing a stable framework upon dissociation of co-ligands in the catalytic cycle. In silico mechanistic investigations for urethane formation show that the stabilization of active species in square-planar geometries enabled by these O^N^O ligands permit the simultaneous coordination of alcohol and isocyanate in suitable configuration at the metal center.

Influence of the Microcrystalline Cellulose Dispersion Method on the Structure and Properties of Rigid Polyurethane Foam Composites

Abstract This paper investigates the reinforcement of rigid polyurethane foams with microcrystalline cellulose to improve their mechanical and thermal properties. In this work, microcrystalline cellulose was added to polyol and was dispersed using two methods: calendering and ultrasounds. As a result of the study, it was found that the addition of micro cellulose to the polyol mixture used for the synthesis of polyurethane foam changes the properties of the final product. A crucial aspect is how it is added to the mixture. When adding microcrystalline cellulose particles, better results were obtained for particles dispersed using ultrasound. The most beneficial changes were obtained for the sample with 2php cellulose. The most significant reduction in average pore size was shown, which has a beneficial effect on the insulating properties of polyurethane foam. In addition, an increase in mechanical properties was also noted. Both properties are highly desirable in many applications.

Polyols and Polyurethane Foams Based on Water-Soluble Chitosan.

At present, majority of polyols used in the synthesis of polyurethane foams are of petrochemical origin. The decreasing availability of crude oil imposes the necessity to convert other naturally existing resources, such as plant oils, carbohydrates, starch, or cellulose, as substrates for polyols. Within these natural resources, chitosan is a promising candidate. In this paper, we have attempted to use biopolymeric chitosan to obtain polyols and rigid polyurethane foams. Four methods of polyol synthesis from water-soluble chitosan functionalized by reactions of hydroxyalkylation with glycidol and ethylene carbonate with variable environment were elaborated. The chitosan-derived polyols can be obtained in water in the presence of glycerol or in no-solvent conditions. The products were characterized by IR, 1H-NMR, and MALDI-TOF methods. Their properties, such as density, viscosity, surface tension, and hydroxyl numbers, were determined. Polyurethane foams were obtained from hydroxyalkylated chitosan. The foaming of hydroxyalkylated chitosan with 4,4'-diphenylmethane diisocyanate, water, and triethylamine as catalysts was optimized. The four types of foams obtained were characterized by physical parameters such as apparent density, water uptake, dimension stability, thermal conductivity coefficient, compressive strength, and heat resistance at 150 and 175 °C. It has been found that the obtained materials had most of the properties similar to those of classic rigid polyurethane foams, except for an increased thermal resistance up to 175 °C. The chitosan-based polyols and polyurethane foams obtained from them are biodegradable: the polyol is completely biodegraded, while the PUF obtained thereof is 52% biodegradable within 28 days in the soil biodegradation oxygen demand test.

Impact of Various Catalysts on Transesterification of Used Cooking Oil and Foaming Processes of Polyurethane Systems.

The search for new sources of raw materials that can be used in the synthesis of polyurethanes and other polymer groups is extremely important. Currently, according to the principles of green chemistry and a circular economy, waste materials with a high reuse potential are being sought. This article presents a way of obtaining used-cooking-oil-based compounds capable of participating in the reaction of polyurethane creation. The transesterification reaction can be carried out using a variety of homo- and heterogeneous acid or base catalysts. Here, we looked at the impact of selected catalysts on the course of transesterification reactions, the composition of the post-reaction mixture and the possibility of using the products in polyurethane foam synthesis. The raw materials and the products were analyzed by means of gel permeation chromatography, FTIR spectroscopy and 1H NMR. The polyurethane foam formation process was analyzed using a FOAMAT® apparatus.

A study on coconut fatty acid diethanolamide-based polyurethane foams.

The possibility of using coconut fatty acid diethanolamide, a derivate from coconut oil as a bio-based polyol for the synthesis of polyurethane foam was explored. The intrinsic tertiary amine moiety in this polyol (p-CFAD) endowed an auto-catalytic effect in the synthesis process of polyurethane foams, combined with a shorter cream and gelation time compared to the fossil-based polyol 3152. H-nuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectrometry (FTIR) were conducted to characterize the chemical structural features of the p-CFAD, and rheology measurement showed the shear-thinning behavior due to the branched structure. A thermal conductivity comparable to the commercial rigid polyurethane foam was achieved when 40wt% fossil-based polyol 3152 was substituted with the bio-based p-CFAD. With the increased content of the p-CFAD, a transition of the physical properties from rigid PU foam to soft PU foam was observed. Scanning electron microscopy (SEM) revealed the occurrence of the interconnected pores on the cell walls with the increase of the added p-CFAD, implying the possibility of regulating the cellular structure and foam properties via the incorporation of the p-CFAD. Results showed the feasibility of using p-CFAD as a potential polyol in the development of bio-based polyurethane foams with high performance.

Eco‐friendly blowing agent, HCFO‐1233zd, for the synthesis of polyurethane foam as cryogenic insulation

AbstractPolyurethane foam is an insulating material, which is adopted in various industrial fields owing to its high compressive strength, low thermal conductivity, and excellent impact resistance. The most important additive in the synthesis process of the polyurethane foam is the blowing agent because it significantly affects the cell structure and density. HFC‐245fa, the most widely used blowing agent, is expected to be terminated under strict environmental regulations owing to its high global warming potential. This study synthesizes a new eco‐friendly polyurethane foam with HCFO‐1223zd in the density range of 90 to 190 kg/m3. After the synthesis process, the microstructural morphology of the HCFO‐1223zd blown polyurethane foam was observed using scanning electron microscopy. Additionally, the insulation performance was compared to conventional polyurethane foam. Furthermore, mechanical characteristics were investigated at 20 and −163°C temperatures. The results show that the HCFO‐1233zd blown polyurethane foam has superior mechanical and thermal properties compared to the conventional blowing agents.

Hardly Flammable Polyurethane Foams with 1,3-Pyrimidine Ring and Boron Atoms.

This work presents the results of research related to the determination of application possibilities of new oligoetherols with 1,3-pyrimidine rings and boron atoms in rigid polyurethane foam production. Oligoetherols were obtained from 1,3-bis(2-hydroxyethyl)uracil, boric acid, and ethylene carbonate. Their structure was determined by instrumental methods (IR, 1H-NMR and MALDI-ToF spectra) and the physicochemical and thermal properties were examined. Obtained oligoetherols were used for synthesis of polyurethane foams. Some properties of the foams, such as apparent density, water uptake, dimensions stability, thermal stability, compression strength, thermal conductivity, oxygen index, and horizontal burning were investigated. The introduction of boron atoms into the foam structure reduced their flammability, but unfortunately it had a negative effect on the water absorption of the obtained materials—the water absorption was higher compared to the boron-free foams. The obtained foams showed good thermal stability compared to classic, rigid polyurethane foams.

Rigid Polyurethane Foam Obtained from Enzymatic Glycerolysis: Evaluation of the Influence of Lipase on Biopolyol Composition and Polymer Characteristics

In this study, the synthesis of biopolyols derived from castor oil and glycerol was performed by enzymatic glycerolysis in a solvent-free system applying the lipases: Novozym® 435 (N435), from Candida antarctica fraction B, immobilized on macroporous anionic resin, and Eversa® Transform 2.0, a soluble formulation from Thermomyces lanuginosus. The biopolyols presented different conversion into mono- and diacylglycerol (MAG and DAG) owing to regioselectivity of the lipases. The resulting biopolyols were employed for the synthesis of polyurethane foams using different amounts of chemical blowing agent (water). The NCO source employed was polymeric methylene diphenyl diisocyanate (pMDI). The foams were compared, and the results showed that the PU foams obtained by using the biopolyol from lipase N435 presented uniform pore size and more desirable mechanical characteristics. Although this has arisen, the results obtained by using the lipase Eversa® Transform 2.0 showed the possibility of applying a low-cost enzyme to obtain biopolyols and foams, and there may be a possibility of competition with chemical catalysts.

A novel catalytic two-step process for the preparation of rigid polyurethane foams: synthesis, mechanism and computational studies

Synthesis of polyurethane foams catalyzed by sodium chloride both in prepolymer preparation and elongation step. The reaction mechanism involves the role of a proton shuttle between two terminal OH groups of PEG 400.

Potential use of black liquor as lignin source for synthesis of polyurethane foam

This study was conducted to recover lignin from black liquor for synthesis of lignin-based polyurethane foam (LPUF). To do so, lignin was precipitated from black liquor through acid precipitation at different pH values. The precipitated lignin samples were characterized by mid-infrared spectroscopy (MIR), thermogravimetric analysis (TGA), proton nuclear magnetic resonance (1H-NMR), and ultraviolet–visible (UV–Vis) spectroscopy (UV–Vis) techniques. After that, lignin sample with higher purification and lower molecular weight was selected for preparation of lignin polyol. Then, microwave-assisted liquefaction was employed to liquefy lignin sample. The obtained lignin polyol was used successfully to synthesize LPUF samples in different 4, 4′-diphenylmethane diisocyanate (MDI) indexes. The effect of MDI index on properties of LPUF samples was investigated through MIR, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and compressive strength tests. The results demonstrated that MDI content could change morphology of the prepared LPUF samples and caused reduction of cell size and more regularity of cellular structure. Also, thermal and mechanical properties of LPUF samples were found to be influenced by MDI index.

Polyol and polyurethane foam from cellulose hydrolysate

AbstractBACKGROUNDAt present the majority of polyurethanes, including polyurethane foams (PUF), are obtained from petrochemical substrates. However, green chemistry policy worldwide and restricted crude oil resources are driving the use of biological substrates to make polyurethanes. Widely available cellulose seems to meet the expectation of a polyol substrate for use in synthesizing polyurethane foams provided that it is converted first into liquid resin with free hydroxyl groups.RESULTSCellulose hydrolysate was functionalized with glycidol and ethylene carbonate to obtain polyol. The product was characterized by infrared and proton nuclear magnetic resonance spectroscopy and matrix‐assisted laser desorption ionization–time‐of‐flight spectrometry. The polyol then was used to obtain rigid polyurethane foam. The foam was characterized by physicochemical methods to determine apparent density, water uptake and polymerization shrinkage.CONCLUSIONSNew polyol was obtained from cellulose hydrolysate by reaction with glycidol and ethylene carbonate in the presence of potassium carbonate as catalyst without solvent. This polyol contains hydroxyalkylated cellulose units incorporated into its structure and is suitable for synthesis of polyurethane foams. The properties of the foam were close to those of typical rigid polyuerethane foams used in industry. The foam showed good thermal resistance. Thermal exposure of obtained foam results in increase of compression strength. © 2020 Society of Chemical Industry (SCI)

Glass bubble reinforced polyurethane foams with high mechanical strength for cryogenic temperature insulation

AbstractIn this study, glass bubble (GB) is added to polyurethane (PU) foams at different weight ratios—0, 0.25, 0.5, 0.75, and 1 wt% —to investigate the changes in the mechanical and thermal properties of the foam. By conducting several tests and measurements, the density, cell morphology, compressive strength, and thermal conductivity of the foam are studied. In particular, the effect of GB additives is examined by conducting compression tests at various temperatures (−163, −100, −40, and 20°C). Scanning electron microscopy and X‐ray microscope reveal that the foams exhibit higher stability below 0.5 wt%, which improves the thermal performance. On the other hand, the compressive strength of the foams increases for all weight ratios of GB, and it increases sharply at 0.75 wt%. In addition, the chemical interactions and the dispersion of additives in the PU matrix are investigated through Fourier transform infrared and X‐ray diffractions analysis. It is found that the synthesis of PU foams with GB nanoparticles is an efficient method for improving the mechanical properties and insulation performance of the foam for LNG insulation technology.

Implementation of Circular Economy Principles in the Synthesis of Polyurethane Foams.

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.

Utilization of Palm Olein-Based Polyol for Polyurethane Foam Sponge Synthesis: Potential as a Sorbent Material

Polyol was successfully synthesized from natural palm olein and was used as a starting material for polyurethane foam synthesis. FT-IR spectroscopy was used to confirm of each reaction in the multistep synthesis, including the transesterification, epoxidation, and reaction with ethylene glycol, ultimately producing palm olein-based polyol (POBP) and POBP-containing polyurethane foam. The morphological properties of the prepared foams were investigated by scanning electron microscopy. The foam cells were uniform in size and shape, and a coarse cell structure was observed. While the pristine polyurethane foam contained closed cells, the pore structure became more interconnected with the introduction of POBP. The thermal properties were studied by DSC and TGA. In the presence of POBP, the sample was found to be less thermally stable. Mechanical testing revealed that the tensile strength and Young’s modulus were decreased, while the elongation at break was increased, suggesting that POBP improved the flexibility of the polyurethane foam. This was in agreement with the observed microstructure. Introducing POBP into the polyurethane foam also decreased the water contact angle from 120° to 80°. However, the oil sorption properties were improved due to interconnected pores along the polyurethane foam structure. Its sorption properties for synthetic dyes (methyl orange and rhodamine B) were also evaluated, and superior sorption properties were found for methyl orange. In short, the polyurethane synthesized from POBP exhibited attractive properties as a sorbent material. The labels in figures (1,3,4,5,6,7,8,9) are not readable. Please provide a new figure with legible labels in Vector EPS or tiff / jpeg format with 600 dpi resolution.Yes, it was provided as a separated file.

Recycled-based thermosetting material obtained from the decomposition of polyurethane foam wastes with castor oil

In this work, a castor-oil-based process for flexible polyurethane foam scrap decomposition was used to prepare a recycled-based polyurethane foam. Decomposed polyurethane (DP) and 4,4′ diphenylmethane diisocyanate (MDI) were polymerized at three distinct MDI/DP ratios (1.0/2.2, 1.0/2.7 and 1.0/3.2) and two curing times (15 and 50 min). The influence of castor oil on the decomposition process and subsequent synthesis of polyurethane foam were evaluated using Fourier transform infrared spectroscopy (FTIR). Further characterization of the final material was carried out through thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and mechanical testing. FTIR assessment showed the presence of multi-functional hydroxyl groups as a result of the decomposition process. TGA confirmed three thermal degradation zones between 160 ℃ and 535 ℃ indicating the degradation of non-reacted compounds as well as the presence of oligomers, fatty acid chains, and urethane network. Mechanical evaluation evidenced that the MDI/DP ratios had a significant effect on tensile properties. The addition of DP increased the elongation at break and reduced the tensile strength with a slight variation of curing time. From the perspective of pore size, SEM micrographs exhibited that cell size apparently decreased with the addition of the DP.

Characterization of Modified Polyurethane Foam Adsorbents for Mercury Adsorption Applications

The use of modified polyurethane foam adsorbents for mercury adsorption applications can reduce the impact of mercury pollution. This study aims to study the characteristics of adsorbents made from castor oil, MDI (Methylene diphenyl diisocyanate), glycerol, distilled water and modified by the addition of zeolite and bentonite. Polyurethane foam which has optimum performance is further characterized to determine physical and chemical properties, including: functional groups (FTIR), morphology (SEM) and area (BET). The results of FTIR Characterization showed that in polyurethane foams without modification there was a C = O group which is a typical group in the polyurethane group shown in wavenumber (1654-1516 cm−1, 1680-1514 cm−1, and 1593-1516 cm−1) Whereas in zeolite modified polyurethane foam there is a C = CH group with a wavenumber of 3008 cm−1 which is a typical group for zeolite whereas in bentonite there is a C = CH group with a wavenumber of 3007 cm−1 which is a typical group for bentonite. The results of SEM characterization show that zeolite modified polyurethane foam has a smooth and flat structure with small pores and polyurethane foam with bentonite has irregular or irregular particle shape. The average BET area obtained in the PUF modification is 1.3778 m2 g−1. Whereas for the smallest BET area obtained at synthetic PUF 19.1 gr + Zeolite 40% for 0.773 m2 g−1, the area is influenced by the comparison of composition from polyurethane foam synthesis.

Flame retardant and mechanical properties of expandable graphite/polyurethane foam composites containing iron phosphonate dopamine‐coated cellulose

AbstractAdditive‐type flame retardants used in polyurethane foams (PUFs) have low compatibility with the matrix and have a large particle size which reduces the mechanical strength. To overcome this, cellulose‐based additive‐type flame retardants were prepared. Microcrystalline cellulose (MCC) was grinded to a suitable size to be applying as a reinforcement for urethane foam. The ground MCC was coated with the mussel‐derived adhesive protein, dopamine, and formed the iron phosphonate coordination network on the surface. It was confirmed that the modification proceeded well by structural analysis by Fourier‐transform infrared spectrometer and morphology analysis by scanning electron microscope. In the synthesis of PUF, expandable graphite (EG) was added to obtain high flame retardancy. The PUF mixed with 3 wt% of ground MCC‐based flame retardant and 12 wt% of EG (GCF3) was found to have an excellent limiting oxygen index (LOI) of 25.3%, while the LOI of pure PUF was 19.3%. In particular, the compressive strength of GCF3 was remarkably enhanced (21 wt%) compared with the PUF containing 15 wt% of EG. This study produced a new additive‐type flame retardant to improve mechanical strength. This provides a simple and comprehensive solution for PUF applications requiring high flame retardancy and mechanical strength.