Flame Retardant Flexible Polyurethane Foam Research Articles

Synthesis of Phosphorus–Sulfur-Containing Polyols for Intrinsic Flame Retardant Flexible Polyurethane Foams with Enhanced Mechanical Properties

Synthesis of Phosphorus–Sulfur-Containing Polyols for Intrinsic Flame Retardant Flexible Polyurethane Foams with Enhanced Mechanical Properties

A Bio-Based Polyol with Synergetic Phosphorous and Nitrogenous Effect for Constructing Intrinsic Flame-Retardant Flexible Polyurethane Foam

A Bio-Based Polyol with Synergetic Phosphorous and Nitrogenous Effect for Constructing Intrinsic Flame-Retardant Flexible Polyurethane Foam

Green biobased P‐N coating: Towards waste‐minimization flame retardant flexible polyurethane foam

AbstractThe increasing consumption of flexible polyurethane foam (FPUF) has caused two significant threats: fire hazards and environmental pollution. More seriously, while waste FPUFs can cause pollution, using many flame retardants also results in significant environmental hazards. Here, the novel process to realize the full lifecycle sustainable utilization of flame retardant FPUF was proposed. First, the biobased P‐N coating (LFPN) was green synthesized by mechanochemistry, and the FPUF was finished by polyelectrolyte‐assisted deposition technology. The fire performance index of FPUF was improved by 110.6% after being treated via LFPN. Moreover, the compression resistance of FPUF was enhanced without affecting the resilience. In order to extend the service life for FPUF, FPUF@LFPN can be reused as a sewage treatment material to remove metal pollution from water. Ultimately, the FPUF@LFPN absorbed metals can be converted into high‐value products such as metal oxide/carbon composites through the metal catalytic pyrolysis technique. This process can effectively reduce the fire and environmental hazards caused by FPUF and may provide an innovative train of thought for the green and sustainable use of other porous polymer materials.

Green flame-retardant flexible polyurethane foam based on polyphenol-iron-phytic acid network to improve the fire safety

Flexible polyurethane foam (FPUF) is one of the most promising cushioning materials, but its high flammability limits its further application. Here, a flame retardant coating was constructed on the foam surface by dipping based on tea polyphenols (TP), phytic acid (PA) and Fe2(SO4)3·xH2O. The results reveal that the flame retardant coating can dramatically improve the fire safety of FPUF. FPUF/TP-Fe-3PA can pass the UL-94 V-0 rating and the limiting oxygen index reaches 26.2%. Meanwhile, the peak heat release rate and total smoke production of FPUF/TP-Fe-3PA are reduced by 67.7% and 66.7%, compared with those of pure FPUF. Moreover, the flame retardant coating can keep more isocyanates in the condensed phase during the thermal degradation process. The flame-retardant and smoke suppression mechanisms are proposed. What is more, the existence of the flame retardant coating has little effect on the resilience of FPUF. This work provides a simple, green and renewable flame retardant FPUF.

Construction of a core-shell structure compound: Ammonium polyphosphate wrapped by rare earth compound to achieve superior smoke and toxic gases suppression for flame retardant flexible polyurethane foam composites

To expand the application and the added value of rare earth compounds, it was utilized to enhance fire safety of flexible polyurethane foam (FPUF) in furniture field. La2Sn2O7 with pyrochlore structure was utilized to wrap ammonium polyphosphate (APP), forming a novel core-shell structure compound (LAPP) and used in FPUF. Compared to pure FPUF, the peak of heat release (PHRR) and peak of smoke production rate (PSPR) of FPUF composites were reduced by 37.5% and 33.3%, respectively. Moreover, the released toxic gases (such as, CO, CO2, NO and NO2) during combustion were dramatically decreased. This is due to the LAPP not only exerted the combustion catalysis toxic gases and smoke reduction effect, but also enhanced the char residue with high quality and quantity. Therefore, to make full use of China's rare earth resources, it provides a facile and effective strategy to fabricate polymer composites with high fire safety for the furniture field.

The improvement of fire safety performance of flexible polyurethane foam by Highly-efficient P-N-S elemental hybrid synergistic flame retardant

Herein, three different phosphorus-containing compounds (methyl phosphoryl dichloride, phenyl phosphoryl dichloride and phenyl dichlorophosphate) were reacted with 2-aminobenzothiazole respectively, and a series of synergistic flame retardants with phosphorus, nitrogen and sulfur elements were synthesized, named MPBT, PPBT and POBT respectively. Then, they were added to prepare flame-retardant flexible polyurethane foam (FPUF). Through the analysis of thermal stability, pyrolysis, heat release and smoke release behavior, the influence of different phosphorus-containing structures on the flame-retardant performance of FPUF was studied, and their flame-retardant mechanism was explored in detail. Among them, MPBT had the highest flame retardant efficiency with the same addition amount (10 wt%). The limiting oxygen index (LOI) value of PU/10.0% MPBT reached 22.5 %, and it successfully passed the vertical burning test. Subsequently, the addition amount of MPBT was increased and the best comprehensive performance of flame-retardant FPUF was explored. The results showed that the LOI value of PU/15.0% MPBT was increased to 23.5%. As for PU/15.0% MPBT, the peak heat release rate (PHRR) was 453 KW/m2, which was reduced by 46.64 %; and the flame retardancy index (FRI) value was also increased to 6.88. At the same time, the mechanical properties of flame-retardant FPUF were studied. The tensile strength of PU/15.0% MPBT reached 170 KPa, and the permanent deformation of FPUF/10% MPBT was only 4 %, showing its excellent resilience. The above results show that this phosphorus-containing element hybrid synergistic flame retardant (MPBT) has a very good application prospect in the field of flame-retardant polymer materials.

Flame retardant flexible polyurethane foams based on phosphorous soybean-oil polyol and expandable graphite

A phosphorous soybean-oil–based polyol was derived via epoxidation and ring opening reaction as an alternative to petrochemical-based polyol for the synthesis of flexible polyurethane foams (FPUFs). 5-wt.% and 10-wt.% of expandable graphite (EG) were added to further improve flame retardancy. The mechanical properties (tensile strength and compression stress) of the foams were investigated. Thermogravimetric analysis (TGA) coupled with Fourier-transform infrared (FTIR) were conducted to evaluate the pyrolysis; limiting oxygen index (LOI), UL 94 and cone calorimeter were performed to analyze the fire performance of the foams; smoke density chamber was used to investigate the smoke released during burning. When 10-wt.% of EG was used, the flame retardancy of the foams was much enhanced due to the synergistic effect between phosphorus and EG. The char yield was three times higher (54-wt.%). The fire load MARHE approached 100 kWm−2, half of the value expected for a superposition. The combination of phosphorous polyols and EG is proposed as strategy for future flame retarded FPUFs.

Self-healing polyelectrolyte complex coating for flame retardant flexible polyurethane foam with enhanced mechanical property

A self-healing coating containing polyethyleneimine (PEI)/ammonium polyphosphate (APP) polyelectrolyte complex was successfully prepared, and then was deposited on flexible polyurethane foam (FPUF) in association with graphene oxide (GO) via a simple dip-nip process to improve the flame retardancy and mechanical property. The vertical burning test revealed that the FPUF coated with PEI/APP and GO extinguished immediately after removing the igniter. The cone calorimeter results demonstrated that the coating effectively reduced the peak heat release rate by 63.8%. The char analysis suggested that PEI/APP formed an intumescent char structure and released inert gases, whilst GO improved the compactness of the char layer. Furthermore, the compressive strength of the coated foam sample was increased by 175.0% compared to that of the control FPUF sample. The mechanical properties analysis and morphology observation proved that the PEI/APP-GO coating had self-healing ability. This unique intrinsic self-healing coating provides a new opportunity for imparting flame retardancy and excellent mechanical property to foam materials used in many commercial cases.

Exceptionally flame-retardant flexible polyurethane foam composites: synergistic effect of the silicone resin/graphene oxide coating

A facile strategy was developed to fabricate flexible polyurethane (PU) foam composites with exceptional flame retardancy. The approach involves the incorporation of graphene oxide (GO) into a silicone resin (SiR) solution, which is then deposited onto a PU foam surface via the dip-coating technique and cured. Fourier-transform infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy measurements demonstrated that the SiR and GO were successfully coated onto the PU skeleton and the intrinsic porous structure of the PU foam remained intact. The effects of SiR and GO on the mechanical and thermal stability and flame retardancy of PU composites were evaluated through compression tests, thermogravimetric analysis, vertical combustion tests, and the limiting oxygen index. The measurement results revealed that the composites (PU@SiR-GO) showed superior flame retardancy and thermal and mechanical stability compared to pristine PU or PU coated with SiR alone. The mechanical and thermal stability and the flame-retardant properties of the PU composites were enhanced significantly with increasing GO content. Based on the composition, microstructure, and surface morphology of PU@SiR-GO composites before and after combustion tests, a possible flameretardance mechanism is proposed. This work provides a simple and effective strategy for fabricating flame-retardant composites with improved mechanical performance.

Green flame-retardant flexible polyurethane foam based on cyclodextrin

Flexible polyurethane (PU) foam is one of the most versatile materials, which has a widely range of applications. However, flexible PU foam it is easily ignitable and highly flammable. This study developed a kind of post-modification method to prepare inherent FR PU foam, which use β-CD as chain extender and introduce FR additive through a facile esterification between phosphoric acid and β-CD moiety in PU foams. The morphology and elasticity of PU still maintained after the modification of PU. β-CDs, as a bio-resources, can not only act as polyol carbon sources to promote carbon formation, but also crosslinked with phosphate ester and PU matrix through P–O–C bonds to form compact carbon layer during the combustion. This dense carbon layer effectively isolates the heat source of the flame, resulting in great improvement of combustion resistance. The time to ignition for 15% CD-H3PO4-PUF foam reached 152 s, which was over 10 times longer than that of pure PU foams. And the foam immediately self-extinguished when the flame was removed. The THR of 15% CD-H3PO4-PUF foam decreased by 70.43% compared to that of neat PU foam. The significant delay of TTI and reduction of THR can reduce the hazards of flame spread greatly.

Novel MoS2-DOPO Hybrid for Effective Enhancements on Flame Retardancy and Smoke Suppression of Flexible Polyurethane Foams.

A novel MoS2–DOPO hybrid has been successfully synthesized through the grafting of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) on the surface of MoS2 nanosheets using allyl mercaptan as an intermediate. MoS2–DOPO was used as a flame retardant additive to prepare flame-retardant flexible polyurethane foam (FPUF). The influence of MoS2–DOPO on the mechanical, thermal stability, and flame retardancy properties of FPUF composites were systematically investigated. The incorporation of MoS2–DOPO could not deteriorate greatly the tensile strength and 50% compression set of FPUF composites, but effectively improves the char residue. The cone calorimeter and smoke density tests results revealed that the peak heat release rate, total heat release, and the maximum smoke density of the MoS2–DOPO/FPUF composite were reduced by 41.3, 27.7, and 40.5%, respectively, compared with those of pure FPUF. Furthermore, the char residue after cone calorimeter tests and pyrolysis gaseous products of the MoS2–DOPO/FPUF composite were analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and thermogravimetric analysis/infrared spectrometry. The results suggested that the MoS2–DOPO hybrid played a synergistic flame retardant effect of gas and condensed bi-phase action. In addition, a possible flame retardancy and smoke suppression mechanism of the MoS2–DOPO/FPUF composite were proposed. This study provides a facile and promising strategy for the fabrication of polymer materials with excellent flame retardancy and smoke suppression properties.

Effect of aluminum diethylphosphinate on the thermal stability and flame retardancy of flexible polyurethane foams

Flame retardant flexible polyurethane foam (FPUF) was prepared through a free-foaming method with aluminum diethylphosphinate (ADP) as additive. The influence of ADP on the morphology, thermal and flame retardant properties of the FPUF was investigated, and the flame retardant mechanism was further explored. TGA results indicated that the addition of ADP slightly affected the initial degradation temperature and the maximum degradation temperature. With the increase of the ADP loading, the char yield of the resultant FPUF gradually increased. When the ADP loading was 20%, the peak heat release rate and the total heat release of the resultant FPUF was reduced by 35% and 33%, respectively, compared to the unmodified FPUF. The addition of ADP improved the char formation of the FPUF, which could inhibit the transfer of oxygen and flammable gases between the flame and the underlying polymer and thus improve the fire retardancy.

A reactive phosphorus-containing polyol incorporated into flexible polyurethane foam: Self-extinguishing behavior and mechanism

A novel liquid phosphorus-containing polyol named as PDEO was prepared via reactions between ethylene glycol and phenylphosphonic dichloride. PDEO reacts with the -NCO-terminated prepolymers and forms urethane linkages in the chain extending reaction step, thus, it was used to prepare inherently flame-retardant flexible polyurethane foams (FPUFs). The structure and properties of flame-retardant FPUFs were characterized by scanning electron microscopy (SEM), tensile measurements, limiting oxygen index (LOI), vertical burning tests, cone calorimeter tests and thermogravimetric analysis (TGA). The vertical burning test demonstrated that fire extinguished instantly after the withdrawn of the pilot flame, while the PDEO loading was only 10 php. In addition, the persistent flame retardancy of PDEO in FPUFs was proved by thermal ageing test. The corresponding flame-retardant mechanism of PDEO-containing FPUFs was investigated by pyrolysis gas chromatography mass spectrometry (Py-GC/MS), X-ray photoelectron spectroscopy (XPS), SEM and FTIR, and the results indicated a gaseous phase dominated flame-retardant mechanism of PDEO.

Persistently flame-retardant flexible polyurethane foams by a novel phosphorus-containing polyol

To overcome the poor compatibility, easy migration of additive flame retardants, a novel polyester polyol (DMOP) was synthesized from dimethyl methylphosphonate and diethanol amine through transesterification and used in the foaming formula to prepare inherent flame-retardant flexible polyurethane foams (FPUFs). DMOP mainly play soft segments in the foams which increases the flexibility and elongation at break. With a low incorporation amount of 10 php (ca. 6.3 wt%), the resultant FPUF can pass vertical burning test. More importantly, accelerated ageing tests at 140 °C for 64 h indicate the persistent flame retardancy of DMOP for FPUF. The thermogravimetric analysis (TGA) results reveal their lower thermal stability than that of ordinary polyurethane. The corresponding flame-retardant mechanism of DMOP-containing FPUFs is investigated by Pyrolysis gas chromatography and mass spectrometry (Py-GC/MS) and FTIR, which indicates the phosphorus in DMOP mainly played their role in the vapor phase. This work thus offers a facile route for preparing FPUFs with persistent, efficient flame retardancy.

Flame retardant flexible polyurethane foams from novel DOPO-phosphonamidate additives

In this work we report synthesis and flame retardant application of novel 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based phosphonamidates. Two mono and one bis DOPO-phosphonamidates were synthesized and incorporated in polyether based polyurethane (PU) manufacturing process. For the comparison of fire performance of these DOPO-phosphonamidates, we have chosen commercially available flame retardants (TCPP, DOPO and Exolit® OP 560) commonly used in flexible PU foam manufacturing. UL94 HBF fire results of various PU foam formulations indicate that DOPO-phosphonamidates exhibit superior fire performance as compared to the commercial flame retardants. 6,6′-(ethane-1,2-diylbis-(azanediyl)-bis-(6H-dibenzo[c,e][1,2]-oxaphosphine-6-oxide (EDAB-DOPO))/foam formulations exhibit the best fire performance as compared to other DOPO-phosphonamidate/foam formulations. A concentration of only 5% EDAB-DOPO on wt. of polyol is needed to achieve a HF1 rating. Thermal decomposition studies of the DOPO-phosphonamidate/foam formulations indicate their limited condensed phase interaction. In TGA experiments, a very small residue (<5%) was observed at 800 °C for all PU formulations. Additionally EDAB-DOPO showed evidence of intermediate condensed phase interaction in the first stage of PU foam decomposition. Direct insertion probe (DIP) – MS studies indicate that mono DOPO-phosphonamidates volatilize primarily in the first stage of thermal decomposition of PU foams whereas the EDAB-DOPO, being thermally more stable is only detected in gas phase in the second stage. Like in case of TCPP/PU foam formulation, the increase in the CO/CO2 ratio in the cone calorimeter experiments for the DOPO-phosphonamidate/foam formulation further proves the gas phase activity (flame inhibition) of these DOPO-phosphonamidates. EDAB-DOPO being thermally more stable seems to offer more sustained gas phase activity during the entire burning stage of PU foams in cone calorimeter experiments. Higher thermal stability of EDAB-DOPO may explain its superior flame retardant efficacy among all the DOPO-phosphonamidates investigated in this study.

Novel flame retardant flexible polyurethane foam: plasma induced graft-polymerization of phosphonates

Flame retardancy of flexible polyurethane foams has become an issue due to very severe regulations.

Inherently Flame-Retardant Flexible Polyurethane Foam with Low Content of Phosphorus-Containing Cross-Linking Agent

A halogen-free phosphorus-containing triol named phosphoryltrimethanol (PTMA) was synthesized and used as a cross-linking agent and a reactive-type flame retardant to prepare inherently flame-retardant flexible polyurethane foam (FPUF). Incorporation of a low content (7.8 wt %) of PTMA into the polyurethane chains can increase the flame retardance of FPUF because of good char formation. The residual chars and evolved gases of PTMA-cross-linked FPUFs were analyzed by SEM, FTIR spectroscopy, inductively coupled plasma-atomic emission spectrometry (ICP-AES), energy-dispersive X-ray (EDX) spectroscopy, and thermogravimetric analysis (TGA) coupled with FTIR spectroscopy. The results indicated that more than 60% of the phosphorus in PTMA-cross-linked FPUF was decomposed into polyphosphoric acid or its derivatives and retained in the char residue. This shows that PTMA mainly played a role in the condensed phase of flame-retardant FPUF. Based on the results, a possible thermal degradation mechanism of PTMA-cross-...

Flame retardant and thermal decomposition properties of flexible polyurethane foams filled with several halogen-free flame retardants

Expandable graphite (EG), dimethyl methylphosphonate (DMMP), melamine (MEL), zinc borate (ZB), or magnesium hydroxide (MH) was separately added to polyurethane to form flame retardant flexible polyurethane foam (FPUF) in one-step. The cell morphologies of the FPUF composites before and after burning were observed by scanning electron microscopy (SEM), their flammability was evaluated by limiting oxygen index (LOI) tests, and their thermal stability and evolved gaseous products were examined by thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA-FTIR). The results indicated that all the five flame retardants could improve the flame retardant performance of FPUF on the basis of their own mechanism. DMMP possessed the highest flame retardant efficiency, and one of the important reasons was that it could promote the formation of char. EG could inhibit molten drop of FPUF during burning effectively. All the five flame retardants could decrease the maximum decomposition velocity mainly because of their heat absorption effect. ZB displayed an excellent inhibition ability for the release of the evolved gaseous products because of its adsorption effect. All the flame retardants except DMMP were capable to decrease the CO yield at the temperature (400°C) of maximum decomposition velocity for their respective mechanisms, but all of them were not able to inhibit CO generation at higher temperature (600°C). POLYM. ENG. SCI., 54:2497–2507, 2014. © 2013 Society of Plastics Engineers

Halogen-Free Flame-Retardant Flexible Polyurethane Foam with a Novel Nitrogen–Phosphorus Flame Retardant

A novel nitrogen–phosphorus flame retardant, 2-carboxyethyl(phenyl)phosphinic acid melamine salt (CMA), was synthesized by the reaction of 2-carboxyethyl(phenyl)phosphinic acid with melamine in aqueous solution, and it was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), inductively coupled plasma-atomic emission spectrometry (ICP-AES), elemental analysis, and thermogravimetric analysis (TGA). Halogen-free flame-retardant flexible polyurethane foams (FPUF) were prepared successfully by using CMA as a flame retardant. The effects of CMA content on the mechanical, thermal, and flame-retardant properties of FPUF were investigated by tensile test, TGA, limiting oxygen index (LOI), flame propagation test (Cal T.B. 117A-Part I standard), and cone calorimeter. The foam morphology of FPUF was studied via scanning electron microscopy (SEM). The results showed that CMA endowed FPUF with good flame-retardant properties. FPUF containing only 12 wt % CMA can pass Cal ...

Flame Retardant Flexible Polyurethane Foam By Post-Treatment with Alumina Trihydrate/ Latex Binder Dispersion Systems

Flame Retardant Flexible Polyurethane Foam By Post-Treatment with Alumina Trihydrate/ Latex Binder Dispersion Systems