Superior Mechanical Behavior and Flame Retardancy FRP via a Distribution Controllable 1D/2D Hybrid Nanoclay Synergistic Toughening Strategy

The incorporation of commercial flame retardants into fiber-reinforced polymer(FRP)composites has been proposed as a potential solution to improve the latter’s poor flame resistance.However,this approach often poses a challenge,as it can adversely affect the mechanical properties of the FRP.Thus,balancing the need for improved flame resistance with the preservation of mechanical integrity remains a complex issue in FRP research.Addressing this critical concern,this study introduces a novel additive system featuring a combination of one-dimensional(1D)hollow tubular structured halloysite nanotubes(HNTs)and two-dimensional(2D)polygonal flake-shaped nano kaolinite(NKN).By employing a 1D/2D hybrid kaolinite nanoclay system,this research aims to simultaneously improve the flame retardancy and mechanical properties.This innovative approach offers several advantages.During combustion and pyrolysis processes,the 1D/2D hybrid kaolinite nanoclay system proves effective in reducing heat release and volatile leaching.Furthermore,the system facilitates the formation of reinforcing skeletons through a crosslinking mechanism during pyrolysis,resulting in the development of a compact char layer.This char layer acts as a protective barrier,enhancing the material’s resistance to heat and flames.In terms of mechanical properties,the multilayered polygonal flake-shaped 2D NKN plays a crucial role by impeding the formation of cracks that typically arise from vulnerable areas,such as adhesive phase particles.Simultaneously,the 1D HNT bridges these cracks within the matrix,ensuring the structural integrity of the composite material.In an optimal scenario,the homogeneously distributed 1D/2D hybrid kaolinite nanoclays exhibit remarkable results,with a 51.0%improvement in mode II fracture toughness(GIIC),indicating increased resistance to crack propagation.In addition,there is a 34.5%reduction in total heat release,signifying improved flame retardancy.This study represents a significant step forward in the field of composite materials.The innovative use of hybrid low-dimensional nanomaterials offers a promising avenue for the development of multifunctional composites.By carefully designing and incorporating these nanoclays,researchers can potentially create a new generation of FRP composites that excel in both flame resistance and mechanical strength.

Characterization of Flame Retardancy and Oil-Water Separation Capacity of Superhydrophobic Silylated Melamine Sponges

A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.

Determination of Physical, Mechanical and Fire Retardancy Properties of Innovative Particleboard Made from Corn Stalk (Zea mays L.) Particles

The demand for particleboard is increasing along with economic and population growth.However,two major barriers to the manufacture of particleboard are a shortage of raw materials(woodchips)and the emission of formaldehyde from conventional adhesives.Agricultural by-products such as corn stalks contain an abundance of renewable lignocellulosic fiber.This study evaluates the effect of citric acid as a natural adhesive and fire retardant addition on the physical,mechanical,and fire retardancy properties of particleboards fabricated from corn stalks.A cost-effective and inorganic salt,calcium carbonate,was tested to enhance the fire retardancy.Ammonium dihydrogen phosphate was also considered as a comparative control.Particleboards with the addition of calcium carbonate was pretreated with sodium chloride.The particleboards were pressed for 10 min at 200℃.Japanese Industrial Standard JIS A 5908:2022 was used as the benchmark for the physical and mechanical tests.Fire retardancy was dynamically tested by simulating a Bushfire Attack Level of 19 kW/m^(2).The particleboard with 25 wt%citric acid had superior mechanical properties and complied with the JIS A 5908 standard for Type 13 base particleboard.Particleboard with the addition of calcium carbonate(5%and 10%)showed significantly delayed pyrolysis time.

Comparative study on the flame retardancy of CO_(2) and N_(2) during coal adiabatic oxidation process

To test the effectiveness of N_(2) and CO_(2) in preventing coal from spontaneously combusting,researchers used an adiabatic oxidation apparatus to conduct an experiment with different temperature starting points.Non-adsorbed helium(He)was used as a reference gas,and coal and oxygen concentration temperature variations were analyzed after inerting.The results showed that He had the best cooling effect,N_(2) was second,and CO_(2) was the worst.At 70℃and 110℃,the impact of different gases on reducing oxygen concentration and the cooling effect was the same.However,at the starting temperature of 150℃,CO_(2) was less effective in lowering oxygen concentration at the later stage than He and N_(2).N_(2) and CO_(2) can prolong the flame retardation time of inert gas and reduce oxygen displacement with an initial temperature increase.When the starting temperature is the same,N_(2) injection cools coal samples and replaces oxygen more effectively than CO_(2) injection.The flame retardancy of inert gas is the combined result of the cooling effect of inert gas and the replacement of oxygen.These findings are essential for using inert flame retardant technology in the goaf.

Regulating the Localization of Intumescent Flame Retardant for Improving the Flame Retardancy of Ethylene-vinyl Acetate Copolymer Using Polyamide 6 as a Charring Agent

Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.

An Approach to the Flame Retardancy of EVA Copolymer by Plasma Treatmentc2

An attempt was made in the paper aiming at imparting flame retardancy to polymers by plasma grafting technique Based on EVA copolymers with different VA contents the author tried to use the Ar plasma followed by grafting with/without subsequent saponification and metal ion exchange expediting the charring of polymers upon heationg Characterization of the flammability of the plasma treated EVA copolymers grafted with acrylic monomers(MAA,AA and AAm)indicates that this approach turns out to be a promising way and worthy doing whatever in research and/or applications

Elastic Aerogels of Cellulose Nanofibers@Metal–Organic Frameworks for Thermal Insulation and Fire Retardancy

Metal–organic frameworks(MOFs)with high microporosity and relatively high thermal stability are potential thermal insulation and flame-retardant materials.However,the difficulties in processing and shaping MOFs have largely hampered their applications in these areas.This study outlines the fabrication of hybrid CNF@MOF aerogels by a stepwise assembly approach involving the coating and cross-linking of cellulose nanofibers(CNFs)with continuous nanolayers of MOFs.The cross-linking gives the aerogels high mechanical strength but superelasticity(80%maximum recoverable strain,high specific compression modulus of^200 MPa cm3 g−1,and specific stress of^100 MPa cm3 g−1).The resultant lightweight aerogels have a cellular network structure and hierarchical porosity,which render the aerogels with relatively low thermal conductivity of^40 mW m−1 K−1.The hydrophobic,thermally stable MOF nanolayers wrapped around the CNFs result in good moisture resistance and fire retardancy.This study demonstrates that MOFs can be used as efficient thermal insulation and flame-retardant materials.It presents a pathway for the design of thermally insulating,superelastic fire-retardant nanocomposites based on MOFs and nanocellulose.

THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during com...

AN EVA/UNMODIFIED NANO-MAGNESIUM HYDROXIDE/SILICONE RUBBER NANOCOMPOSITE WITH SYNERGISTIC FLAME RETARDANCY

A novel EVA/unmodified nano-magnesium hydroxide （NMH）/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber （CFR）. The flammability of the ternary composite was studied by cone calorimeter test （CCT）. Synergistic effect on flame retardancy was found between silicone rubber and NMH. EVA/CFR ternary nanocomposite showed the lowest peak heat release rate （PHRR） and mass loss rate （MLR） among the samples of virgin EVA, EVA composites. The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.

Flame Retardancy, Smoke Suppression Effect and Mechanism of Aryl Phosphates in Combination with Magnesium Hydroxide in Polyamide 6

The flammability, smoke emission behavior and mechanical properties of two oligomeric aryl phosphates [bisphenol A bis（diphenyl phosphate） （BDP） and resorcinol bis（diphenyl phosphate） （RDP）] combined with magnesium hydroxide （MH） in polyamide 6 （PA6） have been investigated. Combining 5 wt% BDP, 50 wt% MH imparts a limiting oxygen index （LOI） of 40.9% and UL94 V-0 rating to PA6, meanwhile the peak rate of smoke release （pRSR）, total release of smoke （TSR） and Izod notched impact strength are 41%, 33% and 233% relative to the corresponding value of 55 wt% MH without BDP, respectively. Dynamic mechanical analysis （DMA） indicates that the improvement of toughness attributes to the enhanced compatibility between MH and PA6 by adding BDP. Furthermore, based on the comprehensive analysis of thermogravimetry （TG）, cone calorimeter and SEM-EDX investigations, possible flame retardancy and smoke suppression mechanisms were revealed. Besides the fuel dilution and barrier effect of MH, the combination of MH and RDP shows an additional flame inhibition effect. The combination of MH and BDP results in a dominant condensed phase barrier effect which leads to obvious reduction on smoke emission and flammability.

PROMOTION EFFECT OF MELAMINE ON FLAME RETARDANCY OF EPOXY RESINS CONTAINING CAGED BICYCLIC PHOSPHATE

Caged bicyclic phosphate （CBP） and its dimelamine salt （PDS） were synthesized and added to epoxy resins to obtain the flame retarded epoxy resin composites. The flammability of the composites was characterized by the limiting oxygen index （LOI） and cone calorimeter tests. The LOI values of flame retarded composites increase consistently with the increase of flame retardant amounts, and they are almost the same when the loading of CBP is the same as that of PDS, although the phosphorus content of PDS is much lower than that of CBP. The total heat release increases in the order of CBP30/ER 〈 PDS30/ER 〈 PDS15/ER 〈 CBPI5/ER, whereas that of specific extinction area is CBP15/ER 〉 CBP30/ER 〉 PDS30/ER ≌ PDS15/ER. PDS exhibits more effective inhibition of oxidation of combustible gases. In the tests of thermogravimetric analyses （TG） and Fourier transform infrared spectroscopy （FT-IR）, it is found that the degradation of the composites is influenced greatly by the addition of flame retardants. By scanning electron microscopy （SEM）, a thick and tight char-layer is observed for PDS30/ER, resulting from the interaction of nitrogen species with phosphorus species. Therefore, the combination of CBP with melamine in the flame retarded system can improve the flame retardancy greatly.

Influence of Beta-Cyclodextrin Functionalized Tin Phenylphosphonate on the Thermal Stability and Flame Retardancy of Epoxy Composites

To enhance the thermal stability and flame retardancy of epoxy resin(EP),beta-cyclodextrin(β-CD)is successfully introduced into the layered tin phenylphosphonate(SnPP),which is incorporated into EP matrix for preparing EP/β-CD@SnPP composites.The results indicate that the addition ofβ-CD@SnPP obviously improve the thermal stability and residual yield of EP composites at higher temperature.When the amount ofβ-CD@SnPP is only 4 wt%,EP/4β-CD@SnPP composites pass V-1 rating,and LOI value is up to 30.8%.Meanwhile,β-CD@SnPP effectively suppress the heat release and reduce the smoke production of EP/β-CD@SnPP composites in combustion,and the peak heat release rate(PHRR),total heat release(THR),smoke production rate(SPR)of EP/6β-CD@SnPP composites reduce by 28.4%,33.0%and 44.8%by comparison with those of pure EP.The good flame retardancy and smoke suppression are ascribed to the synergistic effect of excellent carbon-forming capability and fire retardancy ofβ-CD@SnPP.

Polyisocyanuratoesters:Renewable Linear Polyesters with High Flame Retardancy

Biobased urea nowadays attracts increasing attention as a biomass resource with giant potential,which benefits from the development of biobased ammonia and ecological sanitation system.Urea is an ideal feedstock for chemical industry and developing new urea-based polymer materials can take advantage of the urea resource.In this work,a class of renewable linear polyesters,namely polyisocyanuratoesters(PICEs)were synthesized from a urea-based monomer bis(2-carbomethoxyethyl)isocyanurate and biobased aliphatic diols.Compared with conventional aliphatic polyesters,PICEs containing isocyanurate rings in the polymer chain backbone exhibit outstanding flame retardancy that both PICE-4(the number‘4’refers to the number of methylene in diols,e.g.4 for butylene and 6 for hexylene)and PICE-6 have high limiting oxygen index values over 30%.In the UL 94 tests,PICE-6 reaches V-1 rating;while V-2 is found for PICE-10.All PICEs exhibit similar pyrolysis behavior that the temperatures of 5%weight loss are around 320°C.PICEs are found to have glass transition among 20°C-45°C.No crystallization behavior is observed without annealing except for PICE-10,which can crystallize even at room temperature.

Mechanical Properties and Fire Retardancy of Wood Flour/High-Density Polyethylene Composites Reinforced with Continuous Honeycomb-Like Nano-SiO_(2)Network and Fire Retardant

The mechanical properties of wood flour/high-density polyethylene composites(WPC)were improved by adding a small amount of nano-SiO_(2)to obtain a network-structured WPC with a continuous honeycomb-like nano-SiO_(2)network.The wood flour was modified with a fire retardant(a mixture of sodium octabonate and amidine urea phosphate)to improve its fire retardancy.The flexural properties,creep resistance,thermal expansion,and fire retardancy of the WPC were compared to a control(WPCCTRL)without nano-SiO_(2)or fire retardant.The flexural strength and modulus of the WPC containing only 0.55 wt.%nano-SiO_(2)were 6.6%and 9.1%higher than the control,respectively,while the creep strain and thermal expansion rate at 90°C were 33.8%and 13.6%lower,respectively.The cone calorimetry tests revealed that the nano-SiO_(2)network physically shielded the WPC,giving it lower heat release and smoke production rates.The thermal expansion was further decreased by incorporating fire retardants into the WPC,which showed the lowest total heat release and total smoke production and the highest mass retention.This study demonstrates a facile procedure for producing WPC with desired performances by forming a continuous honeycomb-like network by adding a small amount of nanoparticles.

Flame retardancy effect of surface-modified metal hydroxides on linear low density polyethylene

Metal hydroxides （MAH） consisting of magnesium hydroxide and aluminum hydroxide with a mass ratio of 1：2 were surface-modified by y-diethoxyphosphorous ester propyldiethoxymethylsilane, boric acid and diphenylsilanediol in xylene under dibutyl tin dilaurate catalyst at 140 ℃. Phosphorus, silicon and boron elements covalently bonded to metal hydroxide particles were detected by X-ray photoelectron spectroscopy. The degradation behavior of the surface-modified MAH was characterized by thermogravimetric analysis. The results show that linear low density polyethylene （LLDPE） composite, filled with 50% （mass fraction） of MAH modified by 5.0% （mass fraction） of modifiers, passes the V-0 rating of UL-94 test and shows the limited oxygen index of 34%, and its heat release rate and average effective heat combustion in a cone calorimeter measurement decrease obviously; The mechanical properties of MAH can be improved by surface-modification. The uniform dispersion of particles and strong interfacial bonding between particles and matrix are obtained.

SYNTHESIS OF DIALKYL TETRABROMOPHTHALATES BY PTC AND THEIR FLAME RETARDANCY

Eight dialkyl tetrabromophthalates (DATBPs) were synthesized by reacting tetrabromophthalic anhydride with excess alcohols which were used not only as a reactant but also as a solvent and using a quaternary ammonium salt as a phase transfer catalyst (PTC). The yields were found to be between 85-93%. Their structures were characterized by IR, NMR and elementary analysis. The flame retardant properties of the compounds were also studied.

Preparation and Flame Retardancy of Polyurethane/POSS Nanocomposites

Polyurethane/polyhedral oligomeric sisesquioxane （PU/POSS） nanocomposites were syn- thesized via polymerization utilizing the compatibility between POSS nanopartieles and 4J-diphenyl methylene diisocyanate. Scanning electron microscope images and Fourier transform infrared spectra revealed that POSS nanoparticles were dispersed in PU matrix. Thermal gravimetric analysis was employed to investigate the thermal decomposition be- havior of PU/POSS nanocomposites at elevated temperatures. Then fire performance was evaluated by limiting oxygen index, underwriters laboratories 94 testing and char residue morphology. These results showed that the addition of POSS promoted the formation of char residues which were covered on the surface of polymer composites, leading to the ira-provement of thermal stability and flame retardancy.

Development of Cockleshell-Derived CaCO₃for Flame Retardancy of Recycled PET/Recycled PP Blend

Recycled polyethylene terephthalate (RPET) and recycle polypropylene (RPP) blends filled with a renewable filler, i.e. cockleshell-derived CaCO3 (CS) were prepared as an environmental friendly thermoplastic composite. The effects of CS particle size and content on thermal stability, mechanical performance and flame retardant properties of the blends were investigated. Thermogravimetric analysis was performed to elucidate the thermal decomposition kinetics of the filled composites. The iso-conversion of the Flynn-Wall-Ozawa was developed by the second order polynomial function for thermal oxidative degradation of the blends while peak derivative temperature from the Kissinger method was able to verify the mechanism of degradation in these blends. The results indicated that both CS and commercial grade CaCO3 improved thermal stability and enhanced the stiffness as well as impact performance of the blends. However, this could only be achieved when high filler content was present in the RPET/RPP blends.

Synergistic effect of MXene on the flame retardancy and thermal degradation of intumescent flame retardant biodegradable poly(lactic acid)composites

The effect of Ti3C2 MXene nanosheets on the intumescent flame retardant(IFR)poly(lactic acid)(PLA)composites was investigated among a series of PLA/IFR/MXene,which were prepared by melt blending 0-2.0 wt%MXene,10.0 wt%-12.0 wt%IFR and PLA together.The results of limiting oxygen index(LOI)and vertical burning(UL-94)discover that the combination of 0.5 wt%MXene and 11.5 wt%IFR synergistically improves the fire safety of PLA to reach UL-94 V-0 rating with LOI value of 33.0%.The PLA/IFR/MXene composites perform an obvious reduction in peak of heat release rate(HRR)in cone calorimeter tests(CCTs).Furthermore,the carbon residues after CCTs were characterized by scanning electron microscope(SEM),laser Raman spectroscopy(LRS),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).It is demonstrated that both the titanium composition of the MXene structure and the characteristics of the two-dimensional material enhance the PLA/IFR/MXene composite materials’ability to produce a dense barrier layer to resist burnout during thermal degradation.

Non-covalently Functionalized Graphene Oxide-Based Coating to Enhance Thermal Stability and Flame Retardancy of PVA Film

The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.