Flammability Of Polyurethane Foam Research Articles

Flammability, Toxicity, and Microbiological Properties of Polyurethane Flexible Foams.

The aim of the research was to investigate the influence of calcium phosphinate (HPCA) and aluminum phosphinate (HPAL) in synergistic systems with organophosphorus compounds, i.e., diphenylcresyl phosphate (CDP) and trichloropropyl phosphate (TCPP), on the thermal stability, flammability, smoke density, and emission of toxic gases during the thermal decomposition of polyurethane (PUR) foams. Thermogravimetric analysis (TGA), along with cone calorimetry and microcalorimetry, were used to assess the influence of fillers on the thermal stability and flammability of PUR foams. The analysis of toxic gas products was performed with the use of a coupled TG-gas analyzer system. The optical density of gases was measured with the use of a smoke density chamber (SDC). The obtained results showed an increase in thermal stability and a decrease in the flammability of the PUR composites. However, the results regarding smoke and gas emissions, as well as toxic combustion by-products, present ambiguity. On one hand, the applied flame retardant systems in the form of PUR-HPCA-CDP and PUR-HPCA-TCPP led to a reduction in the concentration of CO and HCN in the gas by-products. On the other hand, they clearly increased the concentration of CO2, NOx, and smoke emissions. Microbiological studies indicated that the obtained foam material is completely safe for use and does not exhibit biocidal properties.

Highly dispersed red phosphorus produced by mechanical milling for enhanced flame retardancy of polyurethane-based foam

To improve the exothermic temperature and flammability of polyurethane foam (PUF), red phosphorus (RP) and diatomite (D) from mechanical milling were chosen as the flame retardants to be incorporated into the polyurethane/waterglass foam (PUHF). The maximum exothermic temperature and temperature distribution of PUF and PUHF were measured using an infrared thermal camera. The morphology and chemical structure of the flame retardants as well as the chemical structure, morphology, compressive strength, thermal stability and flame retardancy of different PUFs were comprehensively investigated by scanning electron microscope, energy dispersive spectrometer, Fourier transform infrared spectroscopy, X-ray diffraction, compression test, thermogravimetric analysis, limiting oxygen index, vertical burning combustion test, cone calorimetry and X-ray photoelectron spectroscopy. The obtained results showed that the maximum exothermic temperature and temperature distribution of PUHF were lower and more uniform than those of PUF. The addition of D increased the dispersion of RP in PUHF, and the uniform and closed pore structures and compressive property were well-retained. Moreover, RP/D/PUHF exhibited excellent thermal stability and flame retardant properties. In addition, a possible flame retardant mechanism of RP/D/PUHF was proposed.

Carbon dioxide adducts from DOPO‐grafted polyethylenimines as both blowing agents and flame retardants for polyurethanes

AbstractThe high risk of flammability of polyurethane foams (PUFs) and the high global warming potentials of polyurethane (PU) blowing agents rank key problems to be solved in PUF industry. Herein, 9,10‐dihydro‐9‐oxa‐10‐phosphenanthrene‐10‐oxide (DOPO)‐grafted polyethylenimines (PEIs) are synthesized via Atherton–Todd reaction, with grafting rate ranging from 13.3% to 28.3%. The grafted PEIs further react with CO2 to obtain corresponding CO2 adducts (DOPO‐PEI‐CO2s). On the one hand, these CO2 adducts can disperse into PU foaming mixture to release CO2 as a climate‐friendly blowing agent. The resultant PUFs possess a density about 56 kg m−3 and a compressive strength over 200 kPa, suitable for some industrial applications. On the other hand, the DOPO grafting endows the PUFs with moderate flame retardancy, increasing the PUFs' limiting oxygen index value from 19.7 to 25 vol%, and decreasing the horizontal burning speed from about 360 mm min−1 down to 130 mm min−1. This study for the first time provides a type of polyurethane (PU) raw material that can serve as both blowing agents and flame retardants.

Revisiting flexible polyurethane foam flammability in furniture and bedding in the United States

SummaryThe flammability of flexible polyurethane foam has been well studied to date, via smoldering and flaming ignition. Its contribution to fire loss in the United States has also been well documented, as the flammability of this material will contribute to large fire events when not protected from ignition and heat sources. Despite this known fire risk, fire protection approaches for polyurethane foam are being questioned in regards to fire protection performance, as well as proven and hypothesized concerns over health impacts before and after fire events. The flammability of flexible polyurethane foam in furniture and bedding is a clear and present danger that must be addressed, and this article discusses the current available technologies for fire protection, with pros and cons of these approaches. Known physical and chemical behavior of these foams in fires is discussed, as well as how this behavior contributes to large fire events. Finally, issues that still need further research and information to definitively address the polyurethane foam flammability in the United States is discussed.

A Novel Rigid PU Foam Based on Modified Used Palm Oil as Sound Absorbing Material

Novel bio-polyol was successfully synthesized from used palm oil (UPO) and was further tested for preparing rigid polyurethane (PU) foams. In this work, the modified used palm oil (MUPO) was synthesized in a single step process, by epoxidation together with ring opening reactions. The reagent ratios and reaction time for MUPO synthesis were also studied. The chemical structure of MUPO was confirmed by 1H-NMR spectroscopy and FTIR. The hydroxyl value of MUPO increased with reaction time and depended also on reagent ratio. The GPC trace of MUPO showed a bimodal distribution and the molecular weight slightly decreased with OH value. New rigid PU foams were prepared from MUPO. The foam cell size and compressive strength at 10% strain increased with OH value. All the rigid PU foams had excellent sound absorption coefficients. The lowest OH value (OHV = 100 mg KOH/g) provided sound absorption from 2200 Hz. In addition, the flammability of PU foams was improved by adding 30% wt of triphosphate (TPP) as flame retardant. The investigations showed that a bio-polyol based on UPO was suitable for preparing rigid PU foams that could serve as alternative sound absorbing materials.

Recycling of waste melamine formaldehyde foam as flame-retardant filler for polyurethane foam

In the present research, the waste leftovers of a thermoset polymer foam with intrinsic flame resistance, melamine formaldehyde foam (MF), were pulverized to fine powder and added into polyurethane foam (PUF) as a flame-retardant filler. A series of characterizations were employed to investigate the obtained MF powder and the properties of the new flame retardant PUF. It was revealed that the pulverization process could produce fine MF powder. Moreover, it showed that the incorporation of MF powder could greatly decrease the heat release rate (HRR) and flammability of PUF without obvious impairment of mechanical property. Combined with a small amount of guanidine phosphate (GP), it could achieve quick self-extinguishment of the modified PUF. The process for recycling waste MF is easy and cheap, indicating an eco-friendly way for waste MF recycling, as well as a successful preparation of a low-cost and halogen-free flame retardant PUF.

Highly flame retardant and bio‐based rigid polyurethane foams derived from orange peel oil

Limonene dimercaptan (LDM), an orange peel oil‐based derivative, and glycerol‐1‐allyl ether (GAE) were used to synthesize bio‐based polyol (LDM‐GAE) using one step photochemical thiol‐ene reaction. The synthesized polyol was used to prepare flame retardant polyurethane foams using dimethyl methyl phosphonate (DMMP) as an additive flame retardant (AFR) and a new bromine containing reactive flame retardant (RFR) derived from 2,4,6‐tribromophenol. Both flame retardants lead to rigid polyurethane foams with excellent physical‐mechanical properties with a short self‐extinguishing time (7.5 and 12.8 sec for DMMP and bromine‐based foams, respectively) and with low weight loss after burning. The reactive bromine polyol lead to rigid polyurethanes with better physical‐mechanical properties than those of foams based on AFR with phosphorous, but the flame retardant properties of foams prepared using AFR are superior to the foams prepared using bromine polyol (RFR). Low addition of DMMP is sufficient to reduce the flammability of polyurethane foam without compromising its physical‐mechanical properties. These flame retardant rigid polyurethane foams based on limonene dimercaptan can be used in all applications of rigid polyurethane foams especially where flammability is an issue such as for insulation of buildings. POLYM. ENG. SCI., 58:2078–2087, 2018. © 2018 Society of Plastics Engineers

Nanocoating of starch and clay that reduces the flammability of polyurethane foam

In an effort to reduce the flammability of flexible polyurethane foam, a thin polyelectrolyte multilayer coating comprising cationic starch and montmorillonite (MMT) or vermiculite (VMT) clay was deposited through layer-by-layer (LbL) assembly. These nanocoatings were characterized with electron microscopy, direct flame exposure and cone calorimetry. All coatings are conformal and maintain the shape of the foam after exposure to an open flame. Cone calorimetry revealed that five bilayers (BLs) of starch/clay reduce the peak heat release rate of foam by 54%, while ten BL coatings reduce the total smoke release by 39 and 67% with MMT and VMT, respectively. These results demonstrate one of the most efficient and renewable nanocoatings prepared using LbL assembly for reducing the flammability of flexible polyurethane foam.

Thermal stability and flammability of polyurethane foams chemically reinforced with POSS

This work reports on the thermal stability and flammability of a novel class of rigid polyurethane foams chemically modified by functionalized 1,2-propanediolisobutyl POSS (PHI-POSS) as a pendant group and octa (3-hydroxy-3-methylbutyldimethylsiloxy) POSS (OCTA-POSS) as a chemical cross-link. The foamed hybrid materials were prepared in a three-step process using a sorbitol-based polyether polyol, polymeric 4,4′-diphenylmethane diisocyanate and dimethyl propane phosphonate as a flame retardant. The addition of the POSS modifier influences the PU cellular structure as evidenced by a change in anisotropy index of the cross section parallel to the growth direction. Based on thermogravimetric data and flammability results, one can suggest that there is char formation at the surface and the formed layer acts as an insulating barrier limiting heat and mass transfer with flame retardant and thus leading to decreased heat release rate, especially for systems containing OCTA-POSS.

Aluminum hydroxide multilayer assembly capable of extinguishing flame on polyurethane foam

Polyurethane foam found in household furnishings and bedding creates a severe fire hazard, resulting in loss of life and property each year. In an effort to reduce the flammability of polyurethane foam, a polyelectrolyte multilayer (PEM) coating, comprised of polyethylenimine and polyacrylic acid-stabilized aluminum hydroxide (ATH), was deposited onto foam using layer-by-layer (LbL) assembly. PEM coatings with and without incorporation of ATH were deposited and compared to assess the effectiveness of ATH on flame suppression. All recipes resulted in conformal coatings, maintaining the open cellular structure of the foam. Only three bilayers of PEI/PAA-ATH retained the shape of foam after exposure to a butane torch flame for 10 s. With six bilayers, the flame was extinguished, which prevented flashover. Cone calorimetry revealed that this 6 BL coated foam exhibited a 64 % reduction in peak heat release rate and a 44 % reduction in maximum average rate of heat emission. This work demonstrates an extraordinarily effective flame-retardant nanocoating that uses environmentally benign chemistry and relatively few deposition steps, prepared using LbL assembly.

Inorganic nanoparticle thin film that suppresses flammability of polyurethane with only a single electrostatically-assembled bilayer.

In an effort to reduce the flammability of polyurethane foam, a thin film of renewable inorganic nanoparticles (i.e., anionic vermiculite [VMT] and cationic boehmite [BMT]) was deposited on polyurethane foam via layer-by-layer (LbL) assembly. One, two, and three bilayers (BL) of BMT-VMT resulted in foam with retained shape after being exposed to a butane flame for 10 s, while uncoated foam was completely consumed. Cone calorimetry confirmed that the coated foam exhibited a 55% reduction in peak heat release rate with only a single bilayer deposited. Moreover, this protective nanocoating reduced total smoke release by 50% relative to untreated foam. This study revealed that 1 BL, adding just 4.5 wt % to PU foam, is an effective and conformal flame retardant coating. These results demonstrate one of the most efficient and renewable nanocoatings prepared using LbL assembly, taking this technology another step closer to commercial viability.

Controlling polyurethane foam flammability and mechanical behaviour by tailoring the composition of clay-based multilayer nanocoatings

This study is a thorough evaluation of clay-based Layer-by-Layer (LbL) coatings intended to reduce the flammability of polymeric materials. Through a systematic variation of a baseline coating recipe, an ideal combination of the coating attributes that provides a rapidly developing coating with an optimum balance of flammability, mechanical, and physical attributes on a complex 3D porous substrate, polyurethane foam (PUF) was identified. Using a unique trilayer (TL) assembly approach, the coating growth was significantly accelerated by the polymer (poly(acrylic acid) (PAA)/branched polyethylenimine (BPEI)) concentration in the formulation. However, to significantly reduce flammability without compromising other performance attributes, the concentration of the nanoparticle fire retardant (nanoFR, clay) suspension was critical. This study has resulted in the most significant reduction in PUF flammability using LbL technology without compromising any of the mechanical or physical attributes of the PUF. More specifically, a reduction in the peak heat release rate (pHRR) and average heat release rate (aHRR) of 33% and 78%, respectively, has been achieved. This reduction in flammability is at least two times more effective than commercial fire retardants and other LbL FR coatings for PUF. The insights gained through this research are expected to accelerate the development of other LbL coatings regardless of the intended application.

Development of layer-by-layer assembled carbon nanofiber-filled coatings to reduce polyurethane foam flammability

Layer-by-layer (LbL) assemblies made with carbon nanofibers (CNFs) are shown to reduce the flammability of polyurethane foam. The 359 ± 36 nm thick four bilayer coating of polyethyleneimine/CNF (cationic layer) and poly(acrylic acid) (anionic layer) contains 51 ± 1 mass fraction % CNF. This coating completely covers the entire internal and external surfaces of the porous foam. Even though the microscopic CNF distribution was non-uniform, the macroscopic CNF network armor that was generated from this LbL process significantly reduced the flammability of the foam (e.g., 40% ± 3% reduction in peak heat release rate). Normalized by flame retardant concentration, the reduction in foam peak heat release due to these CNF coatings is 38% larger than CNF embedded in the foam and as high as 1138% greater than other commercial technologies used to reduce foam flammability.

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.

Flame spread of flexible polyurethane foam: comprehensive study

Polyurethane foams are widely used in many industrial applications: automotive, upholstered furniture and mattresses, insulating panels for building, etc. By its chemical nature, polyurethane is very flammable and the flammability of polyurethane foams is an important industry issue. Depending on the final application, many test methods are in place to characterise foam combustion and legislation exists to ensure that foams comply with specific standards. This paper deals with the fire properties of flexible polyurethane foams. It provides basic correlations between some existing fire test methods and the data recorded under cone calorimeter conditions. The long term target of such an investigation is to predict the burning behavior of foams under specific test conditions from the data of the cone calorimeter.

Thermal degradation of urethane modified polyisocyanurate foams based on aliphatic and aromatic polyester polyol

Combustion of polyurethane foams releases toxic gaseous products. Therefore, decreasing the flammability of polyurethane foams is of practical significance to public health and the environment. The reported study investigated the thermal stability of urethane modified polyisocyanurate foams based on the presence of aromatic, aliphatic polyester polyol and polyether polyol moieties. Thermogravimetric analysis and differential scanning calorimetry demonstrated that the foam containing the lowest isocyanate index (220) and the lowest molecular mass of polyether polyol (200) was the most flammable (35% of char residue). Furthermore, the foams which contained a high molecular mass of polyether polyol (2000) and high isocyanate index (460) experienced fire performance (45% of char residue) similar to those foams containing aliphatic and aromatic polyester polyol (41 and 44% of char residue respectively).

Effectiveness of derivatives of hypophosphorous acid as flame retardants for rigid polyurethane foams

Rigid polyurethane foams (PUF) have been modified with flame retardants (inorganic salts and phosphonous acids) formed from hypophosphorous acid. Certain physical and mechanical properties and flammability of PUF have been studied. These modifiers are compared with respect to their effectiveness as flame retardants for PUF both with one another and with trade materials Fyrol 6, Fyrol CEF and di-ammonium hydrogen phosphate. The effectiveness of flame retardants is also estimated mathematically according to the equation of Zabski-Jedlinski.

Enhanced flammability of polyurethane foam

Tests indicate that different brands of polyurethane foam will exhibit different burning characteristics when coated with a polystyrene sealer.