Conventional Flame Retardants Research Articles

Effect of flame retardants and 1% stabiliser on thermal decomposition and physics properties of thermoplastic polymer due to TGA and DTA tests

This work introduces seven various polymer samples blended in a twin-screw extruder with flame retardants (FR), and an additive, which is a 1% Stabiliser, to investigate thermoplastic polymer melting, thermal decomposition, and melting moderates. The reduction method is used to analyze its melting points, physics and chemical properties, and thermal decomposition. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) tests are known as thermal analysis tests. It was established that halogenated flame retardants have little effect on reducing the rate of gas escape from polymer melt which affects the viscosity, as it was found. Thus, the APP and FR245 in Polymer help in some polymer leftovers. All samples were treated with flame retardants and no clay, melted completely, at the end of the test some samples did change. All these results investigated by (the XRD) test either, Scanning Electron Microscopic (SEM) or Digital images have been used also applied Limiting oxygen index (LOI) test, in the previous work for the same samples of polymers to verify the results and record a more precise outcome to draw the relationship between melting and dripping behavior via the following studies due to the furnace test which is modulated and calibrated. As a result, the addition of clay together with conventional flame retardants enhances the overall thermal stability forming the polymer. The compatibles help in improving the dispersion of the clay in polymer and reduce the rate of gas escape from polymer melt affecting the viscosity.

Dynamically bonded cellulose nanocrystal hydrogels: Structure, rheology and fire prevention performance

Flame retardant composite hydrogels offer many advantages over conventional flame retardants, such as high water-retention capacity, enhanced fire resistance, and mechanical tunability. Herein, we developed flame-retardant dynamic covalent hydrogels using wood-derived cellulose nanocrystals (CNCs) crosslinked with boronate ester bonds, addressing environmental and health issues associated with the presence of non-biodegradable synthetic polymer and/or inorganic nanoparticle components in the existing systems. Our rheological investigation shows a liquid-to-soft-solid transition of CNC dispersions with tunable network elasticity ranging between ≈ 0.2 kPa to 3.5 kPa and an immediate self-healing ability. Coating pine wood with these hydrogels delayed ignition by about 30 s compared to native wood, and achieved a remarkable limiting oxygen index of 64.5 %. Also, the increased borax content of the gels was found to decrease and delay the first peak of the heat release rate up to 40 s, causing an increase in the fire retardancy index by 277 %. We correlate the microstructure and rheological behavior with the fire prevention mechanisms for the rational design of sustainable fire-retardant materials, and the results showcased a circular use of plant-based dynamic gels to prevent wood fires, even after drying- a feature lacking in conventional hydrogels.

Evaluation of Three Common Green Building Materials Using ELECTRE Method

This research paper examines various options for replacing halogenated flame retardants with non-halogenated green construction material choices. Cellulosic construction materials like bamboo do not form compounds with conventional flame retardants. Due to a number of circumstances, including the minimal effectiveness of the flame-retardant activity, they may thus be an unnecessary component of the substrate and simply peel off. Utilizing an additive that comes into direct contact with at least one component of the "green building material" will provide long-lasting flame retardancy since the flame retardant will become a structurally integral element of the substrate. The response mechanisms of various treatment approaches are also discussed in this research to ensure that non-halogenated flame retardants effectively protect sustainable building materials like wood and bamboo. This paper demonstrates how various ELECTRE approaches may be used to choose effective tactics that take into account both technical and human behavioral barriers using a typical case study inside an organization. The impact of impedance from each system subsystem is investigated to assure the dependability of the selected method. When employee participation is a deciding element in the multidimensional strategic planning problem, a comparison of a range of compensated and non-compensatory models reveals that the models may produce less. Resistance strategies; However, ELECTRE shows very reasonable sensitivity. The alternatives are Gladstone, Port Augusta, Collie and Tarong. the evaluation parameters are Construction cost, Procurement cost, Waste reduction, GHG emissions, Cement replacement and Self-consolidating. The Final Result of Net superior value and rank the Gladstone is in fourth rank, The Port Augusta is in second rank, The Collie is in third rank, The Tarong is in first rank of the Net Inferior Value and Rank the Tarong is in fourth rank, The Gladstone is in first rank, The Port Augusta is in Second rank, The Collie is in third rank.

Effect of addition of aluminum phosphinate as fire retardant in a PBT vitrimer

This work investigates the effect of flame-retardant additives on the thermo-mechanical and dynamic properties of poly(butylene terephthalate) (PBT) vitrimers. The vitrimers were synthesized and compounded in a single step by reactive extrusion from commercially available PBT, an epoxy resin, a zinc-based transesterification catalyst, and aluminum phosphinate (AlPi) as a conventional flame retardant additive. We demonstrated that the presence of AlPi in relatively large amount (20 wt.-%) is compatible with the formation of the vitrimer network and does even play the role of a transesterification (co)catalyst accelerating the exchange reactions and improving the processability of the vitrimer. UL-94 flammability tests also confirm the effective role of AlPi as flame retardant in vitrimer.

Flame retardant textile finishing: thermal analysis and dermal security

Many flame retardants (FRs) are brominated, and many of them are considered toxic, persistent and/or bio accumulative. A switch to non-halogenated alternatives for textile finishing is considered beneficial, but there is little knowledge about their environmental impact, their health risks during the production process and those in their final use. A conventional and an alternative FR (based on dialkyl phosphono carboxylic acid amine and ammonium sulfamate; urea and organophosphonate PO(OH)2-R-PO(OH)2, respectively) were applied to cotton fabrics that could be in touch with the skin in their final use. Burning and thermal behaviors and dermal toxicity when exposed to skin rubbing are evaluated. Fabrics treated show that both FR products act as FRs. The increase in the thermal stability of the tissue that causes an increase in the decomposition temperature is a relevant effect associated with the application of the conventional FR in the tissue, while the most important effect of the alternative FR lies in the increase of the residue at 600°C, associated with the generation of fewer volatiles, which has an impact on the intensity of combustion. The study of the dermal toxic potential of FR-treated cotton bed sheets showed that the two tested products do not penetrate into the skin when applied under the conditions used and were safe when in contact with the skin. Moreover, the alternative FR seems to be safer when in contact with the skin considering also its higher concentration in the textile.

Eco-Friendly One-Pot Supramolecular-Assembly of P-N Flame Retardant for Fire-Safe Epoxy Resin.

Flame retardant treatment of epoxy resins (EP)to reduce their flammability for extending their range of applications attracts considerable attention. However, the synthesis process of conventional flame retardants is complicated and involves organic hazardous solvents. Meanwhile, how to ensure both the flame-retardant and mechanical properties is a long-standing and actual difficult problem. In this work, a supramolecular flame retardant (named ATPFR) is facilely created by one-pot reaction, using cheap and accessible raw materials in an ecologically benign aqueous solvent. ATPFR is applied to improve the fire safety of EP. With only 5wt% ATPFR addition, EP can reach the limiting oxygen index of 28.5% and the UL-94V-0 rating with a significant "blow-out effect." The cone calorimetry test reveals that the EP thermoset with 5wt% ATPFR has a 75.8% reduction in the peak heat release rate (p-HRR) and a 67.3% reduction in the peak smoke production rate (p-SPR), respectively, compared with the pure EP. Additionally, EP composites with the small amount of ATPFR exhibit a slight decrease and maintain good mechanical properties. Therefore, the facile synthesis and application of this supramolecular flame retardant provide a reliable way for the construction of polymer materials with environment-friendly and effective flame-retardant system.

Tri-source integrated adenosine triphosphate loaded BN in synergy with Cu-MOF to improve the fire safety of epoxy resin

The volume expansion of the char layer during combustion can effectively isolate the external flame and heat. However, the contribution of conventional flame retardants to the volume increase is largely negligible. Adenosine triphosphate (ATP), as a bio-based macromolecule, contains both acidsource, carbon source and gas source groups in its structure, which determines the ability of these groups to synergistically promote the formation of swollen residual carbon at high temperatures, resulting in a good flame retardant effect. Here, a novel and highly efficient organic–inorganic composite flame retardant was achieved by coupling ATP with BN using polydopamine (PDA) as a medium and anchoring Cu-MOF nanoparticles uniformly on its surface. Among them, the high barrier of BN imparted the EP resin and residual carbon excellent heat shielding properties, the presence of ATP facilitated the formation of expanded carbon slag. Besides, the metal ions in Cu-MOF promote the conversion of more cracking products to residual carbon, while the microporous structure of MOF has an appreciable adsorption effect on the flue gas. The results showed that compared to EP, the THR and PHRR for BN/PATP@Cu-MOF/EP decreased by 32.0% and 41.3%, separately. Moreover, the PSRP, TSP, PCOPR and PCO2PR values of BN/PATP@Cu-MOF/EP were visibly lower than those of other specimens, decreasing to 0.226 m2/s, 20.43 m2/s, 0.081% and 0.73%, accordingly, justifying its most optimal fume suppression effect. According to the condensed phase and gas phase flame retardant principle, the synergism of BN, ATP and Cu-MOF leading to the construction of an expanded coal network having greater strength and barrier properties, which is the key to reduce heat release and smoke generation. This study opens the door to new swellable flame retardants and provides a new effective way for flame retardant modification of polymers.

Performance and Microstructure Characterizations of Halloysite Nanotubes Composite Flame Retardant–Modified Asphalt

To solve the problems of low flame retardant efficiency and weak low-temperature performance of asphalt modified by conventional flame retardants (CFR), in this study, halloysite nanotubes (HNTs) and CFR were used to prepare nanocomposite flame retardants (NCFR) to modify asphalt. A fluorescence microscope (FM), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) were used to characterize the microstructure of NCFR-modified asphalt. An oxygen index meter, Cleveland open cup, and cone calorimeter were used to test the flame retardant properties of the asphalt. A dynamic shear rheometer, bending beam rheometer, and force ductility tester were used to test the rheological properties of asphalt. At the same time, flame retardant–modified asphalt mixtures were prepared to verify the flame retardancy and road performance of the flame retardant–modified asphalt. The research results showed that the asphalt modified with 8% CFR and 1% HNTs (MA/CFR/1% HNTs) showed better dispersibility. The increase of limiting oxygen index and self-ignition temperature and the decrease of heat release rate and smoke production rate of MA/CFR/1% HNTs indicated that it has good flame retardancy. At 64°C, compared with modified asphalt (MA), the rutting factor of MA/CFR/1% HNTs increased by 88.17%, the creep recovery increased, and the irreversible creep decreased, indicating that its high-temperature performance improved significantly. At −18°C, compared with that of MA/CFR, the low-temperature creep stiffness of MA/CFR/1% HNTs decreased by 36 MPa and the creep rate of MA/CFR/1% HNTs increased by 0.034, indicating that only 1% HNTs can improve the effect of degraded CFR on the low-temperature performance of MA. Simultaneously, MA/CFR and MA/CFR/1% HNTs can improve the high-temperature performance and water stability of asphalt mixtures. Adding 1% HNTs to a MA/CFR-modified asphalt mixture can improve the low-temperature performance of the asphalt mixture to the level of the low-temperature performance of the modified asphalt mixture. In summary, the modification of asphalt with 1% HNTs and 8% CFR can effectively improve the flame retardant efficiency and significantly improve the road performance of asphalt.

Synthesis and characterization of Tb doped Ni–Zn nano ferrites as substrate material for dual band MIMO antenna

Recently, ferrite materials with outstanding characteristics, like reflection and absorption ability, lightweight, and thinness in size, are essential to resolve electromagnetic interference challenges. In the present work, Terbium doped Nickel-Zink nano-ferrite material with a composition of Ni0.5Zn0.5Tb0.02Fe1.98O4 was prepared and used as a substrate in a dual-band yagi-Uda-shaped 4×4 multi input multi output antenna. X-ray diffraction (XRD) measurements confirmed the cubic spinel ferrite sample. A vibrating sample magnetometer and Field Emission Scanning Electron Microscope analysis are also performed to evaluate its magnetic and morphological properties. Dielectric constant (εr) and permeability (μr) are determined using a vector network analyzer. The Multi Input Multi Output (MIMO) antenna operates in dual frequency bands of 3.5 and 5.8 GHz, which is suitable for fifth-generation smartphone applications. The performance of a yagi-Uda-shaped 4×4 MIMO antenna with terbium-doped Nickel-Zink ferrite used as a substrate is explored regarding return loss, radiation efficiency, bandwidth, gain, inter-terminal isolation, envelope correlation coefficient, and Channel Capacity Loss. It is found that the size of the MIMO antenna is reduced with improved bandwidth, isolation, and Channel Capacity Loss performance using a nano-ferrite substrate as compared to those conventional Flame retardant (FR4) substrates.

Fabrication of Phytic Acid/Urea Co-Modified Bamboo Biochar and Its Application as Green Flame Retardant for Polylactic Acid Resins.

It is of great significance to develop green, sustainable additives to improve the thermal stability and flame retardancy of biopolymers. In this work, a synergistic modification of P/N elements to bamboo biochar (mBC) was successfully achieved by grafting a reaction of phytic acid and urea with preoxidized bamboo biochar. Fourier transform infrared spectroscopy, X-ray diffraction, nuclear magnetic resonance and scanning electron microscope determinations of the mBC demonstrated a successive grafting of phytic acid and urea to the originally porous surface. The ground mBC was blended with polylactic acid (PLA) to prepare mBC/PLA composites by extrusion and hot pressing. Mechanical strength studies showed a compromise in rigidity, which might originate from the mBC overdose and its limited miscibility with the resin. The thermogravimetric results supported the fact that the enhancement of thermal stability and flame retardancy of the composites with the mBC dosage, which showed that the mBC dosage in the PLA composites was not only lower than that of the conventional flame retardants, but also outperformed the counterparts using BC modified by inorganic phosphoric acid and urea. The mBC was prone to accelerate the earlier decomposition of the composites (30 °C lower in decomposition) and generate a continuous, dense residual carbon layer, which provides an effective shield resisting the mass and heat transfer between the combustion area and the underlying composite matrix. Only 10 wt% of mBC dosage could achieve a V-0 rating (UL94) for the composite, with a higher limiting oxygen index up to 28.3% compared to 20.7% for that of the virgin PLA; the cone colorimetric results also suggested that the flame retardancy had been greatly improved for all composites. In this work, biobased P-/N-containing bamboo biochar would be expected as a nontoxic biochar-based flame retardant that serves as green filler in polymer composites.

A rational design of functionalized black phosphorus cooperates with piperazine pyrophosphate to significantly suppress the fire hazards of polypropylene

The flammability of polypropylene (PP) not only has negative effects on human health but also causes environmental pollution. Herein, from the molecular polarity point of view, rationally designed hyperbranched charring foaming agents (HCFA) modified black phosphorus nanosheets by in situ polymerization to solve the fire hazards of PP. Based on the UL-94 test V-0 rating, the conventional flame retardant of piperazine pyrophosphate (PAPP) is substituted partly by the BP@PPC. Surprisingly, compared with 27 wt% of PAPP/PP, composites consisting of only 2 wt% of BP@PPC and 20 wt% PAPP/PP also passes the V-0 rating. The results of the cone calorimeter test confirmed that adding BP@PPC decreases the total heat release (THR) and peak heat release (PHRR) by a large amount, which are decreased by 23.4%, 85.8% respectively compared with PP. Moreover, it is uncommon for the fire growth index of BP@PPC composites to be 66.7% lower than that of PAPP/PP composites. In addition, the incorporation of BP@PPC has almost no impact on the mechanical characteristics of PP composites. This study offers a reference for combining established flame retardants with novel compounds to modify the burning behaviors of PP.

Bioinspired mono-component lignin endowing epoxy resin with simultaneously improving flame retardancy and mechanical properties

As an appropriate bio-based substance of flame retardant, lignin exhibits an increasing focus due to its environmental friendliness, high-efficiency charring, and renewable property. However, the conventional flame retardants containing lignin with high flame safety always confront with deterioration of mechanical properties of matrix. Here, a novel flame retardant (LMA) by assembling lignin with melamine and amino trimethyl phosphonic acid through electrostatic interaction was constructed. The LMA displayed excellent interfacial strength with epoxy resin resulting from the ring-opening reaction between rich hydroxyl group in LMA and epoxy resin (EP), thereby the tensile strength, impact strength and Young's modulus of EP-LMA7 increased by 17.9%, 53.7% and 25.7%, respectively. More importantly, EP-LMA7 passed the V-0 rating of UL-94 and the limiting oxygen index (LOI) value achieved 30.2%. Moreover, with respect to EP, the peak of heat release rate and the peak of smoke production rate of EP-LMA7 decreased by 72.3% and 77.5%, respectively. The detailed characterization illustrated that the excellent intumescent charring resulted in the satisfactory flame safety of EP. This work will further broaden the efficient utilization of lignin.

Effect of ammonium polyphosphate as synergist with nano silica dioxide on flammability of boron compound pretreated bamboo flour-HDPE composite

In this study, bamboo polymer composite (BPC) was prepared by blending of high-density polyethylene (HDPE) with boric acid - borax (Ba-Bx) pre-treated bamboo fibers as reinforcement material and by using maleic anhydride grafted polyethylene as coupling agent. BPCs were incorporated with conventional flame retardants (FRs) additives such as ammonium polyphosphate (APP) along with nano particles such as silicon dioxide (nano-SiO2) and flame performance was investigated using cone calorimeter and limiting oxygen index analysis (LOI). The thermal behaviour of BPC was investigated under nitrogen atmosphere using thermogravimetric analyser (TGA). The maximum improvement in flammability was achieved with flame additive i.e., Ba-Bx 5%/APP15%. LOI value was found to be highest at Ba-Bx 5%/APP 13%/nano-SiO2 2%. Mechanical properties of BPCs were analysed using flexural and tensile tests. While the flame and thermal properties of BPCs was improved significantly, the strength properties were marginally reduced due to application of FR additives. In general, APP as synergist with Ba-Bx improved thermal stability and flammability of BPCs.

Comparable Investigation of Phosphorus-Based Flame Retardant Electrolytes on LiFePO4 Cathodes

Improving the flame retardant and electrochemical properties of electrolytes is of great significance to enhance the safety of lithium-ion batteries (LIBs). In this work, the effect of cresyl diphenyl phosphate (CDP), dimethyl methyl phosphonate (DMMP), trimethyl phosphate (TMP) and triphenyl phosphate (TPP) as flame retardant additives in the standard electrolyte on the performance of LiFePO4/Li cell are comprehensively studied. The results show that when the mass fraction of flame retardant is less than 20%, the purpose of flame retardant can be achieved in the electrolyte. When the cells without and with 20 wt% of CDP, DMMP, TMP, and TPP additives are, respectively, their capacity retentions are 80, 46, 82, 84, and 57% after 100 cycles at 0.5C. According to characterization analysis, DMMP and TMP can facilitate the formation of stable interface films on cathode and subsequently improve the battery performance. Compared with expensive or complicated synthetic flame retardants, conventional flame retardants like CDP, DMMP, TMP, and TPP have great potential for application in electrolytes to improve the safety of LIBs. This work can provide useful scientific research and industry in the study of phosphorus-based flame retardant electrolytes.

Synthesis of multifunctional flame retardant with toughening and transparency and its application in epoxy resin

The transparency and mechanical properties of EP are inevitable influenced by the addition of most conventional flame retardants. A multifunctional flame retardant, phosphorus-containing pyrazolyl derivative (DPAP) was prepared, which may provide exceptional flame retardancy, toughness, and transparency to EP materials. With only 10% DPAP added, the EP/DPAP composite can achieve a UL-94 V-0 rating and LOI of 35.2%. Compared to pure EP, the PHR and THR of EP/DPAP-10 (containing 10%wt DPAP) are dramatically reduced by 40.9% and 23.2%, respectively. Meanwhile, the elongation at break of the sample surprisingly increased by 30.2% and the transmittance only decreased from 82% to 72%. The combination of a large number of hydrogen bonds and low crosslink density enhances the toughness of EP/DPAP composites. Although the flame retardant function is added, the EP/DPAP composite still maintains a high transparency. The results show that the addition of flame retardant function has little effect on the transmittance of EP. All of these findings revealed that the EP/DPAP composite with exceptional overall performance has the potential to be used in a broader range of applications.

Development of Intumescent Flame Retardant for Polypropylene: Bio-epoxy Resin Microencapsulated Ammonium-polyphosphate

As polypropylene (PP) has no charring ability on its own due to the lack of hydroxyl functional groups, the flame retardant system needs the addition of carbonizing agent in a relatively great amount. Ammonium-polyphosphate (APP), a conventional flame retardant additive was modified by microencapsulation with a sorbitol-based bioepoxy resin shell to create an intumescent flame retardant system with enhanced charring ability for PP. The flame retardant efficiency of the microencapsulated additive, which contains all the components needed in an effective intumescent flame retardant system, was evaluated in PP matrix at different loadings.When compared to the physical mixture of the component, the microencapsuated form of APP (MCAPP) was found to have improved flame retardant efficiency in PP. The LOI values of the MCAPP containing PP samples increased by 8–11 V/V% besides achieved V-0 classification according to the UL94 test. During cone calorimeter tests, the burning intensity was reduced (peak of heat release rate decreased by 20–35% and shifted in time), increased amount of charred residue was obtained, and based on the calculated Flame Retardancy Index (FRI) “Excellent” fire performance was achieved when MCAPP was used. The improved flame retardant performance is attributed to the effective interaction between the APP core and the readily available carbonizing shell, which promoted the formation of increased amount of char accompanied with improved heat protecting and barrier efficiency.

Graphite flame retardant applied on polyester textiles: flammable, thermal and in vitro toxicological analysis

Expandable graphite was applied to an upholstery polyester textile material as an eco-friendly flame-retardant alternative to halogenated compounds. Fabrics treated with the flame retardant were evaluated by flammability tests. Besides, thermal analysis was carried out by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Moreover, a percutaneous absorption study was conducted to verify the safety in terms of dermal penetration of the flame-retardant treated upholstery fabric for human use. The upholstery fabric treated with expandable graphite successfully passed the flammability tests. Thermogravimetric analyses with TGA and DSC showed that the flame-retardant application slightly decreased the initial decomposition temperatures regardless of the atmosphere but increased the final residue at 600°C (35.7% in O2 and 44.5% in N2) compared to non-treated upholstered fabrics. Dermal permeation of expandable graphite applied on the polyester fabric showed no penetration after 24 h of fabric exposure time. This result demonstrated that graphite-treated polyester fabric is dermatologically and toxicologically safe for use in upholstery. Applied expandable graphite proved an efficient and safe flame-retardant alternative to conventional flame retardants for eco-friendly flame resistance applications in upholstery fabrics.

Construction of strong non‐covalent interactions for preparation of flame‐retarded acrylic pressure‐sensitive adhesives with improved shear and peel strengths

AbstractThe development of acrylic pressure‐sensitive adhesives (PSAs) with good flame retardancy is of great importance for the optoelectronic, automobile, and aircraft applications. However, a well‐known problem is that conventional flame retardants, while imparting good flame retardant properties to acrylic PSAs, compromise the cohesion and result in the unsatisfactory shear and peel strengths. In this work, flame‐retarded acrylic PSAs with improved shear and peel strengths were successfully prepared by constructing a tight non‐covalent crosslinking network that effectively counteract the negative effect of flame retardants on cohesion. In addition, the combination of dimethyl methylphosphonate (DMMP) and SiO2 increases the flame retardant effectiveness and reduces the overall required loading of flame retardants. As an example, when the amount of acrylic acid (AA) was 35 wt%, acrylic PSA containing 12.7 wt% DMMP and 2.5 wt% SiO2 particles showed well‐balanced adhesive properties and flame retardancy, with a shear strength of 3600 min and a peel strength of 15.0 N/25 mm, as well as a UL‐94 V‐0 rating. Meanwhile, it exhibited a high transmittance of above 90%. Furthermore, TG‐FTIR results confirmed that the flame‐retarded behaviors occurred in vapor phase.

Clays as Inhibitors of Polyurethane Foams' Flammability.

Polyurethanes are a very important group of polymers with an extensive range of applications in different branches of industry. In the form of foams, they are mainly used in bedding, furniture, building, construction, and automotive sectors. Due to human safety reasons, these applications require an appropriate level of flame retardance, often required by various law regulations. Nevertheless, without the proper modifications, polyurethane foams are easily ignitable, highly flammable, and generate an enormous amount of smoke during combustion. Therefore, proper modifications or additives should be introduced to reduce their flammability. Except for the most popular phosphorus-, halogen-, or nitrogen-containing flame retardants, promising results were noted for the application of clays. Due to their small particle size and flake-like shape, they induce a “labyrinth effect” inside the foam, resulting in the delay of decomposition onset, reduction of smoke generation, and inhibition of heat, gas, and mass transfer. Moreover, clays can be easily modified with different organic compounds or used along with conventional flame retardants. Such an approach may often result in the synergy effect, which provides the exceptional reduction of foams’ flammability. This paper summarizes the literature reports related to the applications of clays in the reduction of polyurethane foams’ flammability, either by their incorporation as a nanofiller or by preparation of coatings.

Multi-Objective Optimization and Performance Characterization of Asphalt Modified by Nanocomposite Flame-Retardant Based on Response Surface Methodology.

In order to improve the safety of the tunnel asphalt pavement in the event of a fire, and reduce the deterioration of the low temperature crack resistance of the asphalt by the flame retardant. The research uses aluminum hydroxide (ATH) as a smoke suppressant, diethyl aluminum hypophosphite (ADP) as a flame retardant, and halloysite nanotubes (HNTs) as a synergist to modified styrene-butadiene-styrene block copolymer (SBS) modified asphalt (MA). First, the content of ATH, ADP, and HNTs was used as the response variable. The physical properties (Penetration, Softening point, Ductility) and static flame retardant properties (Limiting oxygen index meter, Ignition point) of the asphalt modified by nanocomposite flame-retardant (HNTs-CFRMA) were the response variables. The response surface methodology was used to design the test, and regression models were established to analyze the influence of flame retardants on the performance of asphalt. Then, comprehensively considering the effects of physical properties and flame retardant properties, the normalized desirability function was used to perform a multi-objective optimization design on the components of the nanocomposite flame retardant modifier to obtain the best flame retardant formula. Finally, the rheological properties of MA, conventional flame-retardant modified asphalt (CFRMA), and HNTs-CFRMA were tested based on Dynamic shear rheometer, Multiple stress creep test, Force ductility tester, and Bending beam rheometer. The performance of flame-retardant and smoke suppression were tested by the Cone calorimeter tests. The result shows that ATH, ADP, and HNTs can enhance the high temperature performance of asphalt, reduce the penetration. The addition of HNTs can increase significantly the softening point and reduce the deteriorating effect of flame retardants on the low temperature performance of asphalt; the addition of ATH and HNTs can improve significantly the flame retardancy of asphalt. Based on the desirability function of power exponent, the formulation of the nanocomposite flame retardant with better physical properties and flame retardant properties is ATH:ADP:HNTs = 3:5:1, and the total content is 9 wt%. Nanocomposite flame retardants can improve obviously the high temperature rheological properties of asphalt. The rutting factor and the cracking factor of HNTs-CFRMA improve markedly, and the irrecoverable creep compliance is reduced, compared with MA and CFRMA. Nanocomposite flame retardant can make up for the deterioration of conventional flame retardants on asphalt’s low temperature performance. At the same time, it has better flame-retardant performance and smoke suppression performance.