Polyurethane Foam Formulations Research Articles

Reticulated vitreous carbon from polyurethane foam–clay composites

Reticulated vitreous carbon foams were prepared by carbonizing polyurethane precursor foams which were first infused with furfuryl alcohol. The cell size and the fraction of open cells of the precursor foam were controlled by the addition of clay in the polyurethane foam formulation. Addition of clay permitted control of the cell size of carbon foams. The higher open cell content in foams with clay permitted uniform infusion of furfuryl alcohol in the precursor, and thus more uniform carbon foams of higher density. These foams had a lower electrical resistance as compared to foams without clay.

High Throughput Screening of Rigid Polyisocyanurate Foam Formulations: Quantitative Characterization of Isocyanurate Yield via the Adiabatic Temperature Method

To reduce the time-to-market, a high throughput experimentation (HTE) method has been introduced at Bayer MaterialScience for the rapid development and optimization of polyurethane (PU) foam formulations and for the fast screening of new PU raw materials. The foam processor developed for this purpose allows automated PU foam production on a scale of 0.4 L, which is ten times smaller than the usual lab-scale foam volume. In order to optimize formulations for the increasing polyisocyanurate (PIR) foam market, a rapid in situ method has additionally been developed that is able to quantify isocyanurate concentration and yield. This method, the adiabatic temperature method (ATM), is based on the temperature profile measured within the foam bun in the HTE foam processor. By comparison with attenuated total reflection (ATR)-FTIR spectra of the cured foams, it is shown that the isocyanurate concentration found in the 0.4 L foams is comparable with that of larger foams typically used in the laboratory (ca. 5 L). This demonstrates that the 0.4 L foams can be used to investigate the trimerization of isocyanates to form isocyanurate. The suitability of the ATM is demonstrated and verified by ATR-FTIR spectroscopy for the influence of the index on isocyanurate yield and concentration for a pentane blown and a water co-blown PIR formulation. Isocyanurate yield is shown to be negligible at indices close to 100 but increases to an almost constant level at higher indices, the height of which depends on the type of the formulation. A level of approximately 70% has been observed for the physically blown formulations, whereas the water co-blown formulations only reach a level of around 40%. Due to the successful implementation of the ATM, Bayer MaterialScience is increasingly using high throughput experimentation to optimize PIR recipes and to examine new raw materials and additives for polyisocyanurate foams. This has led to an increase in the efficiency of our polyurethane research and opened up possibilities that were not available to us before.

Oxypropylation of Lignins and Preparation of Rigid Polyurethane Foams from the Ensuing Polyols

AbstractSummary: Different lignins were converted into polyols by a chain extension reaction with propylene oxide (PO). Thus, soda lignin from Alfa (Stipa tenacissima) (SL), organosolv lignin from hardwoods (OL), kraft lignin (KL) from softwood and oxidized organosolv lignin (OOL) were oxypropylated in a batch reactor at 180 °C in the presence of KOH as catalyst. The ensuing polyols were characterized by FTIR and 1H NMR spectroscopy, which showed that they had incorporated poly(propylene oxide) grafts into their structure. Their viscosity varied from 5 mPa · s to infinity, depending on the Lignin/PO ratio and their hydroxy index was in the range of 100–200, which made them suitable for rigid polyurethane foam (RPU) formulations. The RPUs thus obtained had a Tg of ca. 60 °C and a thermal conductivity of ≈20 mW/m · K before ageing and ≈25 mW/m · K after accelerated ageing for 10 d at 70 °C. The analyses of the gases inside the cells showed that these were mostly closed, since the partial pressure did not decrease significantly with ageing.Photograph of polyurethane foam made from OLOP.magnified imagePhotograph of polyurethane foam made from OLOP.

Soybean oil auto applications: Developing flexible polyurethane foam formulations containing functionalized soybean oil for automotive applications

Industrial BiotechnologyVol. 1, No. 1 MethodsSoybean oil auto applications: Developing flexible polyurethane foam formulations containing functionalized soybean oil for automotive applicationsDeborah F. Mielewski, Cynthia M. Flanigan, Christine Perry, Matthew J. Zaluzec, and Paul C. KillgoarDeborah F. MielewskiSearch for more papers by this author, Cynthia M. FlaniganSearch for more papers by this author, Christine PerrySearch for more papers by this author, Matthew J. ZaluzecSearch for more papers by this author, and Paul C. KillgoarSearch for more papers by this authorPublished Online:16 May 2005https://doi.org/10.1089/ind.2005.1.32AboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byPolyurethane Foams Reinforced with Biobased Materials: Properties and ApplicationsCurrent Applied Polymer Science, Vol. 3, No. 1Polyurethane Composite Foams in High-Performance Applications: A Review26 June 2017 | Polymer-Plastics Technology and Engineering, Vol. 57, No. 4Renewable polyols for advanced polyurethane foams from diverse biomass resources1 January 2018 | Polymer Chemistry, Vol. 9, No. 32Characterization of flexible polyurethane foams based on soybean-based polyolsJournal of Applied Polymer Science, Vol. 112, No. 1Water-blown rigid and flexible polyurethane foams containing epoxidized soybean oil triglycerides1 January 2008 | Journal of Applied Polymer Science, Vol. 109, No. 1Preparation of high hydroxyl equivalent weight polyols from vegetable oilsIndustrial Crops and Products, Vol. 27, No. 3High-value oils from plantsThe Plant Journal, Vol. 54, No. 4Production of new soy-based polyols by enzyme hydrolysis of bodied soybean oilIndustrial Crops and Products, Vol. 25, No. 2Selective hydrolysis of epoxidized soybean oil by commercially available lipases: Effects of epoxy group on the enzymatic hydrolysisJournal of Molecular Catalysis B: Enzymatic, Vol. 41, No. 1-2Natural nanotubes enhance biodegradable and biocompatible nanocomposites; Nanotubes in halloysite clay may provide increased strength and new capabilities for consumer product, packaging, medical, and other applications Aaron L. Wagner, Sarah Cooper, and Michael Riedlinger6 October 2005 | Industrial Biotechnology, Vol. 1, No. 3 Volume 1Issue 1Mar 2005 InformationCopyright 2005, Mary Ann Liebert, Inc.To cite this article:Deborah F. Mielewski, Cynthia M. Flanigan, Christine Perry, Matthew J. Zaluzec, and Paul C. Killgoar.Soybean oil auto applications: Developing flexible polyurethane foam formulations containing functionalized soybean oil for automotive applications.Industrial Biotechnology.Mar 2005.32-34.http://doi.org/10.1089/ind.2005.1.32Published in Volume: 1 Issue 1: May 16, 2005PDF download

Thermal stability and fire properties of conventional flexible polyurethane foam formulations

Polyurethane foams are widely used in many industrial applications, including automotive, upholstered furniture and mattresses, insulating panels for building. Depending on the desired application, polyurethane foams can be produced using many different chemicals and formulations. The physical properties of flexible polyurethane foams depend on their composition. They will be closely related to the characteristics of the polyol used, to the stoichiometry (polyol/isocyanate), to the quantity of catalysts and surfactants and to the water content (and so to the density). By its chemical nature, a polyurethane is very flammable. The flammability of polyurethane foams is an important industrial issue. This paper deals with the influence of the composition of conventional flexible PU foams on their thermal stability and fire behaviour.

Modeling of polyurethane foam formation

AbstractPolymeric foams are widely used both as structural and as thermal insulating material. Few detailed data about the process of foam growth are reported in the literature, especially for recently developed polyurethane formulations that involve the use of a volatile organic compound instead of the banned chlorofluorocarbons (CFCs). In this work, a dedicated device was realized that allows experimental data collection for polymeric foams growth in terms of temperature and density profiles. For modeling and simulation purposes, a model reported in the literature was modified by improving, in particular, the description of the vapor–liquid phase equilibrium for the system blowing agent/polymer mixture. Simulation of the collected experimental data was performed by this model after the determination of the kinetic parameters for the occurring reaction between polyol and isocyanate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1875–1886, 2004

Exploring Urea Phase Connectivity in Molded Flexible Polyurethane Foam Formulations Using LiBr as a Probe

Lithium bromide (LiBr) was incorporated in formulations based on molded flexible polyurethane foams in order to alter systematically the phase separation behavior and thus give insight into urea phase connectivity. The formulations of the materials generated were similar to those of molded flexible polyurethane foams except that a surfactant and a low molecular weight cross-linking agent (such as diethanol amine) were not used. The resulting materials were evaluated by using the techniques of atomic force microscopy (AFM), SAXS, and DSC. Atomic force microscopy and SAXS were used to demonstrate that the materials with and without LiBr were microphase separated and possessed average interdomain spacings of ca. 90 Å, typical of flexible polyurethane foams. AFM phase images also showed that incorporation of LiBr reduced the urea phase aggregation, which is known to take place in flexible polyurethane foams, and led to a more homogeneous distribution of the urea microdomains in the soft polyol phase. Addition of LiBr also decreased the regularity in segmental packing of the hard segments, as was noted by using WAXS. DSC scans revealed that inspite of the significantly different morphologies noted for the samples with different LiBr contents, soft-segment mobility, as reflected by its Tg, remained unaffected on including this additive at the concentrations investigated. Interaction of LiBr with diethyl ether (DEE), 1,3-dimethylurea (DMU) and a model urethane (1,3-dimethylcarbamate) (URET) also was estimated by quantum mechanical calculations (QMC) by using density functional theory (DFT). For DMU and URET, QMC indicated a strong interaction of the Li+ ion with ether and carbonyl oxygens, and of the Br− with the (N–H) protons. Interaction energies of Li+ with DEE (O… · ·Li+), URET (C = O… · ·Li+), and DMU (C = O… · ·Li+) complexes were calculated to be –201, –239 and –272 kJ/mole, respectively. Interaction energies of DEE, URET, and DMU complexes with LiBr were calculated to be –198, –620, and –691 kJ/mole, respectively, suggesting that the interaction of the salt was predominantly with the hard segments (urea and urethane) and not with the polyether soft segments.

Exploring macro- and microlevel connectivity of the urea phase in slabstock flexible polyurethane foam formulations using lithium chloride as a probe

Urea phase connectivity has been probed by systematically varying the hard segment content, and lithium chloride content, in a series of plaques based on slabstock flexible polyurethane foams. The plaque formulations are identical to those of slabstock polyurethane foams with the exception that a surfactant is not utilized. Small angle X-ray scattering (SAXS) is used to demonstrate that all materials investigated are microphase separated with similar interdomain spacings, irrespective of hard segment content (21–37 wt%) or LiCl content. Several complimentary characterization techniques are employed to reveal that urea phase connectivity is present at different length scales. Macrolevel connectivity, or connectivity of the large-scale urea rich aggregates typically observed in flexible slabstock polyurethane foams, is probed using SAXS, TEM, and atomic force microscopy. These techniques collectively show that the urea aggregation increases as the hard segment content is increased. Incorporation of LiCl is shown to systematically reduce the urea aggregation behavior, thus leading to a loss in the macroconnectivity of the urea phase. Wide angle X-ray scattering is used to probe the regularity in segmental packing, or the microlevel connectivity between the hard segments, which is observed to decrease systematically on addition of LiCl. The loss in microlevel connectivity is suggested to increase chain slippage, and leads to increased rates of stress-relaxation for the samples containing LiCl. Materials containing LiCl also display relatively short rubbery plateaus as compared to their counterparts which do not contain the additive. Modulus values, as obtained at ambient conditions by stress-strain analyses, are found to be a stronger function of LiCl content when the hard segment content is higher.

On the issue of urea phase connectivity in formulations based on molded flexible polyurethane foams

AbstractLithium chloride was added to systematically alter the phase separation behavior, and hence, the nature of urea phase connectivity, in a series of plaques based on molded flexible polyurethane foam formulations. The plaques prepared were found to possess varied levels of urea phase connectivity that was examined at different length scales using several characterization techniques. SAXS, TEM, and t‐AFM were used to show that addition of LiCl systematically reduced the formation of the urea aggregate structures typically observed in flexible polyurethane foam formulations and thus led to a loss in urea phase connectivity at the macrolevel. SAXS, DSC, and DMA revealed that formulations with and without LiCl exhibited similar interdomain spacings and soft segment glass transitions, suggesting that incorporation of LiCl did not prevent the plaques from undergoing partial microphase separation. WAXS demonstrated that addition of LiCl led to a loss in the local ordering of the hard segments within the microdomains, i.e., it led to a reduction of microlevel connectivity or the regularity in segmental packing of the urea phase. High‐magnification t‐AFM images showed that increasing the LiCl content dispersed the urea component more homogeneously and in a more uniform manner in the polyol matrix, and thus altered the connectivity of the urea phase at the microdomain level. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2956–2967, 2002

Identification and Quantitation of Urea Precipitates in Flexible Polyurethane Foam Formulations by X-ray Spectromicroscopy

Scanning transmission X-ray microscopy (STXM) and atomic force microscopy have been used to study the morphology and chemical composition of macrophase-segregated block copolymers in plaque formulations based on water-blown flexible polyurethane foams. Although there has been a large body of indirect evidence indicating that the observed macrophase-segregated features in water-rich polyurethane foams are due principally to urea components, this work provides the first direct, spatially resolved spectroscopic proof to support this hypothesis. The STXM results are consistent with a segregation model where urea segments segregate, forming enriched phases with the majority of the polyether- polyol and urethane groups at the chain ends of the urea hard segments. Chemical mapping of the urea, urethane, and polyether distribution about the urea-rich segregated phases showed that the urea concentration changes gradually (across several hundred nanometers) in a butylene oxide-based foam. This mapping also showed the urea-rich segregated phases present as a partial network in an ethylene oxide/propylene oxide sample.

Rigid polyurethane foams with poly(ethylene terephthalate)/triethanolamine recycling products

A product of the chemical degradation of poly(ethylene terephthalate) (PET) with triethanolamine was used as a polyol component for rigid polyurethane foam synthesis. Miscibility of the product with water, some polar organic solvents and commercial polyols was investigated. Viscosities of the product as a function of temperature as well as in solutions with water and the polyols were examined. The PET chemical recycling product was used instead of the commercial polyol in rigid polyurethane foam formulation. Technological times were defined for the process of the foam synthesis. These foams have density of about 30 kg/m3, compression strength in a range of RC = 80–160 kPa and thermal conductivity coefficient λ = 0.028–0.038 W/m K. Rigid polyurethane foams prepared from the product of PET degradation with triethanolamine can be considered as insulation materials. Copyright © 1999 John Wiley & Sons, Ltd.

The Influence of Silicone Surfactants on the Dispersion and Reactivity of Water in Flexible Slabstock Polyurethane Foam

In polyurethane foam formulations, the limited compatibility of water with polyol and isocyanate can lead to liquid-liquid dispersions, but the kinetic consequence of phase separation in these systems has been poorly understood. In the present study, the reagent compatibility and reactivity of model polyurethane formulations have been evaluated through a combination of ATR-FTIR spectroscopy, chemical titration, and optical microscopy. Kinetic experiments have revealed that phase separation reduces substantially the rate of water/isocyanate reaction. Using a reactive polyurethane model system, blowing and gelling reaction profiles for catalysts with and without the presence of surfactant were obtained. Mass loss rate-of-rise experiments on actual foam with and without surfactant were also conducted. Water titration experiments have indicated that silicone surfactants can induce phase separation of water, but do not effect the ultimate water solubility limit in the model formulations. Although the surfactants improve dispersion of reagents in these systems, no increases in reaction rates are observed in either model systems or actual foams.

Some Aspects of Matrix Formation of Flexible Polyurethane Foams

The reaction of liquid raw materials like isocyanates, polyols, and water, to build a structural polymer network is a very complex sequence of different chemical reactions. We can describe some of these essential processes by the use of a dynamic measurement of the viscosity during the course of the foaming reaction, on-line FTIR-spectrometry measurements and the determination of the curing behaviour. We employed a laboratory FT-IR system, that was interfaced to an optical fibre loop. The formation of the soluble and associated urea species, the decay of isocyanate groups and the development of urethane species during the polymerization reaction were studied by FT-IR. The onset of the formation of associated urea species is influenced by the chemical composition of the reacting mixture. For the viscosity measurements we used a rotational viscosimeter. The network development was shown by the determination of the viscosity profile. By extrapolation of the course of the indentation force over time, estimated after the demould of the flexible foam, we determined the green strength of the moulding and the vitrification of the foam at a frozen morphology. We also illustrated the dependence of the mechanical properties of flexible PU foams on the chemical structures formed during the reaction.

Formation of integral skin polyurethane foams

AbstractPolyurethane integral skin foams comprise a low density foamed core surrounded by a high density skin of the same material, and are made in a single molding operation. Polyurethane integral skin foams find wide application as structural materials, and the mechanical properties of such foams are significantly affected by the foam structure, which in turn is determined by the foaming process. An experimental and theoretical study of the foam formation process is presented. Experimental results show that increase in the mold wall temperature results in an increase in the upper skin thickness, a decrease in the lower skin thickness, and a decrease in the density of both skins. The core density increases with increasing wall temperature. Increase in the blowing agent concentration produces a small increase in the skin thickness. Computations based on the model of Marciano et al. [Polym. Eng. Sci., 26, 717 (1986)] are presented using an efficient numerical technique. Predictions of the model for the skin thickness, core density and pressure and temperature variation with time are in reasonable agreement with experimental data. The model, however, predicts higher skin densities than the experimental measurements. A modification of the initial condition of the model to account for the air bubbles dispersed during mixing gives better agreement between theory and experiment.

Glycols in polyurethane foam formulations with a starch–oil composite

A dry starch–oil composite was blended with each of three glycols; ethylene, polyethylene, and propylene, and then reacted with isocyanate to produce polyurethane foams. The liquid glycols permitted the dry composite to blend well with the other ingredients in the foam formulations. Infrared spectra confirmed the presence of urethane structures in the composite–glycol foams. Polyethylene glycol provided a slightly less dense foam than the other glycols in the composite–glycol products. Microscopy showed a greater number of larger cells in the composite–polyurethane glycol foams. Infrared spectra indicated essentially no qualitative differences in the composite–glycol foams with the three glycols. By prestaining starch with toluidene blue and oil with sudan red, the location of the starch and oil components of the milled composite were observed in the composite–propylene glycol foam. Intact flakes of the composite were observed in the foam. An apparent loss of mobility of oil in the composite–polyurethane foam, as evidenced by NMR analysis, is probably due to crosslinking by isocyanate diffusing into the flakes. Both the cell structure and uniformity of blending were improved by using these glycols rather than the polyester polyol described previously. J Appl Polym Sci 69: 957–964, 1998. Published 1998 John Wiley & Sons, Inc.

Glycols in polyurethane foam formulations with a starch-oil composite

A dry starch–oil composite was blended with each of three glycols; ethylene, polyethylene, and propylene, and then reacted with isocyanate to produce polyurethane foams. The liquid glycols permitted the dry composite to blend well with the other ingredients in the foam formulations. Infrared spectra confirmed the presence of urethane structures in the composite–glycol foams. Polyethylene glycol provided a slightly less dense foam than the other glycols in the composite–glycol products. Microscopy showed a greater number of larger cells in the composite–polyurethane glycol foams. Infrared spectra indicated essentially no qualitative differences in the composite–glycol foams with the three glycols. By prestaining starch with toluidene blue and oil with sudan red, the location of the starch and oil components of the milled composite were observed in the composite–propylene glycol foam. Intact flakes of the composite were observed in the foam. An apparent loss of mobility of oil in the composite–polyurethane foam, as evidenced by NMR analysis, is probably due to crosslinking by isocyanate diffusing into the flakes. Both the cell structure and uniformity of blending were improved by using these glycols rather than the polyester polyol described previously. J Appl Polym Sci 69: 957–964, 1998. Published 1998 John Wiley & Sons, Inc.

Formation of rigid polyurethane foams with semi-fluorinated diblock copolymeric surfactants

Semi-fluorinated diblock copolymers were employed as surfactants in the formation of water-blown closed cell rigid polyurethane foams by the ‘tube’-foam method. These fluorosurfactants consisted of a poly(methyl methacrylate) block and a poly[(1H,1H,2H,2H-perfluoroalkyl) methacrylate] block in which the perfluoroalkyl groups were either butyl or hexyl. As references, model foams were prepared with commercially applied siloxane surfactant, inert silica, and no surfactant. Foams based on the fluorosurfactants contained many small cells while the others showed larger and markedly more irregular cells. Scanning electron microscopy (SEM) and the average foam height (AFH) were used for characterization. SEM revealed that foam cell diameters as small as 100 μm could be realized when using fluorosurfactants in contrast to very large cell sizes and irregular shapes when a commercially available siloxane surfactant, an inert inorganic solid, or no surfactant at all were used. Furthermore, relatively large AFH-values were observed when only a semi-fluorinated diblock copolymer was used. However, the combination of siloxane surfactant with a fluorine-containing surfactant resulted in unparalleled high AFHs.

Water-blown flexible polyurethane foam extended with biomass materials

Soy protein isolate, soy fiber, and cornstarch (0–40% polyether polyol) were incorporated into a flexible polyurethane foam formulation. Stress–strain curves of the control foam and foams containing 10–20% biomass material exhibit a considerable plateau stress region but not for foams extended with 30–40% biomass materials. An increase in biomass material percentage increases foam density. An increase in initial water content decreases foam density. Foams extended with 30% soy protein isolate, as well as foams extended with 30% soy fiber, have notably greater resilience values than all other extended foams. The comfort factor increases with increasing percentage of biomass material in foam formulation. Foams containing 10–40% biomass materials display significantly lower values in compression-set than the control foam. &copy 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 695–703, 1997

Manufacture and use of pulverized flexible polyester polyurethane foam particles

AbstractCrucial process modifications were shown necessary to improve the economics of cryogenic grinding of flexible polyurethane (PU) foam. It is concluded that foam densification prior to cryogenic processing was essential to reduce insulation effects. In comparative studies of foam and densified foam, increasing the density to ∼800 kg/m3 resulted in dramatically reduced cryogen use and vastly improved output. Results indicated that cryogenic pulverization presents a significantly more economic solution than previously recognized. Particles produced by this method were added to foam formulations and effects of particle size and structure on compression properties and cell structure of resultant foams were studied. Particle sizes <100 μm gave similar compression properties and cell size to virgin foam at up to 10 parts by weight on 100 parts of polyol, but cell structure and compressive properties showed increasing divergence as particle size and addition concentration increased. Studies of alternative uses showed that the PU particles showed promise as fillers in rigid PU foam formulations and suggested an extending or reinforcing action in natural rubber vulcanizates.

The pyrolysis of para-toluene isocyanate

Para-toluene isocyanate is a major intermediate in the pyrolysis of aromatic di-isocyanates which are widely used in polyurethane foam formulations. The pyrolysis of para-toluene isocyanate (p-TI) has been studied quantitatively in a flow system at temperatures of 823K to 873K. Qualitative data on aromatic diisocyanate pyrolysis is also interpreted in the context of polyurethane degradation to isocyanates and nitriles. The major products in the decomposition of p-TI were benzonitrile, methylbenzonitrile, phenylisocyanate, toluene and benzene. The orders of the reactions and the Arrhenius parameters for the rate constants have been determined for these major products. Reasonable mechanisms have been derived for the formation of the major gaseous products and for the deposited char, which appears to be a polymer derived from para-methylbenzonitrile. The rate constant for the initiation reaction [Display omitted] has been determined (in units s−1) as log10k3 = 14.6(±1.2) - 303(±30) (kJ/mol)/2.303RT.