Showing papers on "Fire retardant published in 2016"

Fabrication of Green Lignin-based Flame Retardants for Enhancing the Thermal and Fire Retardancy Properties of Polypropylene/Wood Composites

Abstract: Despite growing extensive applications, until now the poor thermal stability and flame retardancy properties of wood–plastic composites (WPC) remain effectively unsolved. Meanwhile, industrial lignin has emerged as a potential component for polymer composites due to many advantages including abundance, rich reactive functional groups, high carbon content and tailored capability for chemical transformations. Herein, we have fabricated one biobased flame retardant based on industrial lignin chemically grafted with phosphorus, nitrogen and copper elements, as the functional additive for the WPC. Compared with unmodified lignin (O-lignin), functionalized lignin (F-lignin) is more effective to improve the thermal stability and flame retardancy of WPC because of presence of the flame retardancy elements (P and N) and the catalytic effect of Cu2+ on the char-formation. The presence of F-lignin not only reduces the heat release rate, total heat release and slows down the combustion process but also decreases tota...

A review of application of ammonium polyphosphate as intumescent flame retardant in thermoplastic composites

Abstract: The application of ammonium polyphosphate (APP) in different types of commodity thermoplastic composites (polyethylene, polypropylene (PP), polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(ethylene terephthalate) (PET)) have been discussed in terms of mechanical properties, morphologies and thermal properties. In addition, engineering thermoplastics such as acrylonitrile-butadiene-styrene (ABS), polyamides and poly(vinyl alcohol) (PVOH) and their composites added with APP and other additives were analyzed as well. It was suggested that improvement of mechanical properties and morphologies of the thermoplastic composites could be made possible with appropriate amount of APP and other additives such as montmorillonite (MMT), pentaerythritol (PER) and different types of layered double hydroxide (LDH). Furthermore, thermal properties such as limiting oxygen index (LOI) values together with cone calorimetry and thermogravimetric analysis (TGA) performance could be enhanced through optimum combination of APP, PER and melamine which functions as intumescent flame retardant (IFR).

Synthesis of a Novel P/N/S-Containing Flame Retardant and Its Application in Epoxy Resin: Thermal Property, Flame Retardance, and Pyrolysis Behavior

Abstract: The combination of DOPO and 2-aminobenzothiazole (ABZ) was designed to develop P/N/S-containing flame retardant DOPO-ABZ, and its chemical structure was confirmed by HRMS, FTIR, and 1H and 31P NMR. The reduced thermal stability of EP/DOPO-ABZ formulations was found through DSC and TGA, as compared to that of EP. Fire properties were evaluated by LOI, UL-94, and cone calorimeter tests, respectively. The results indicated that DOPO-ABZ imparted flame retardance to EP, and that EP/7.5 wt % DOPO-ABZ passed the V-0 rating, and acquired a LOI value of 33.5%; moreover, when the loading of DOPO-ABZ increased to 10 wt %, it could further suppress the heat release and smoke release of the curved epoxy resin. Finally, the flame-retardant mechanism was studied by TG-FTIR and py-GC/MS, disclosing that DOPO-ABZ exerted predominant gaseous-phase activity of fire inhibition via generating phosphorus-containing free radicals and nitrogen/sulfur-containing volatiles.

Graphene-based flame retardants: a review

Abstract: Graphene and its derivatives are potential flame retardant materials with good flame retardant performance; in particular, graphene as an adjuvant in combination with inorganic nanomaterials may be a promising candidate of flame retardant. This review describes the flame retardant mechanism, the development trend, and the classification of graphene-based flame retardants. It points out that graphene has attracted intensive interests in the fields of electronics, energy, and information, due to its excellent properties such as high thermal conductivity, good electron transport ability, and large specific surface area. In the meantime, graphene can change the pyrolysis as well as the thermal conductivity, heat absorption, viscosity and dripping of polymer during the combustion process. In other words, graphene can improve the thermal stability of polymer and delay its ignition, and it can also inhibit fire from spreading and reduce heat release rate.

Highly Efficient Flame Retardant Polyurethane Foam with Alginate/Clay Aerogel Coating

Abstract: Highly efficient flame retardant polyurethane foams with alginate/clay aerogel coatings were fabricated using a freeze-drying method. The microstructure and the interaction of the samples were characterized with scanning electron and optical microscopy (SEM) and (OM). The results show that PU foam has a porous structure with pore sizes of several hundred microns, and that of aerogel ranges from 10 to 30 μm. The PU foam matrix and the aerogel coatings have strong interactions, due to the infusion of aerogel into the porous structure of the foam and the tension generated during the freeze-drying process. Both the PU foam and the aerogel exhibit good thermal stabilities, with onset decomposition temperatures above 240 °C. Combustion parameters, including LOI, TTI, HRR, TSR, FIGRA, CO, and CO2, all indicate significantly reduced fire risk. Total heat release of all but one of the samples was maintained, indicating that the flame retardant mechanism is to decrease flame spread rate by forming a heat, oxygen, a...

A Large-Area, Flexible, and Flame-Retardant Graphene Paper

Abstract: Similar to the paper-making process, the efficient flame retardant graphene paper is conveniently obtained by using graphene oxide (GO) and hexachlorocyclotriphosphazene (HCCP) aqueous pulp. The “paper pulp” can also conceivably be used as ink to make other hydrophilic films become flame retardant paper. Further, the as-prepared reduced GO-HCCP paper (RGO-HCCP paper), compared with GO-HCCP paper, can maintain its intact structure for a longer time in an ethanol flame. As a consequence of these preparation methods, the bearing temperature of the as-prepared graphene papers shows a significant increase.

Scalable Preparation of Multifunctional Fire-Retardant Ultralight Graphene Foams

Abstract: Traditional flame-retardant materials often show poor tolerance to oxidants, strong acidic/alkaline reagents, organic solvents, along with toxicity problems. Herein, highly fire-retardant ultralight graphene foam has been developed, which possesses not only ultralight and compressible characteristics but also efficient flame-retardant properties, outperforming those traditional polymer, metallic oxide, and metal hydroxide based flame retardant materials and their composites. The newly developed unconventional refractory materials are promising for specific applications as demonstrated by the observed high temperature resistant microwave absorption capability.

PLA with Intumescent System Containing Lignin and Ammonium Polyphosphate for Flame Retardant Textile

Abstract: Using bio-based polymers to replace of polymers from petrochemicals in the manufacture of textile fibers is a possible way to improve sustainable development for the textile industry. Polylactic acid (PLA) is one of the available bio-based polymers. One way to improve the fire behavior of this bio-based polymer is to add an intumescent formulation mainly composed of acid and carbon sources. In order to optimize the amount of bio-based product in the final material composition, lignin from wood waste was selected as the carbon source. Different formulations of and/or ammonium polyphosphate (AP) were prepared by melt extrusion and then hot-pressed into sheets. The thermal properties (thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC)) and fire properties (UL-94) were measured. The spinnability of the various composites was evaluated. The mechanical properties and physical aspect (microscopy) of PLA multifilaments with lignin (LK) were checked. A PLA multifilament with up to 10 wt % of intumescent formulation was processed, and the fire behavior of PLA fabrics with lignin/AP formulation was studied by cone calorimeter.

Effect of Fully Biobased Coatings Constructed via Layer-by-Layer Assembly of Chitosan and Lignosulfonate on the Thermal, Flame Retardant, and Mechanical Properties of Flexible Polyurethane Foam

Abstract: A fully biobased coating containing chitosan (CS) and lignosulfonate (LS) was facilely fabricated on the surface of flexible polyurethane foam (FPUF) using layer-by-layer assembly method. The CS/LS based coatings were successfully deposited on the substrate, as demonstrated by UV–vis absorption spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and scanning electron microscopy. Subsequently, the different bilayers of the coatings were applied to enhance the thermal stability, fire resistance, and mechanical properties of FPUFs. It was found that the thermal degradation of coated FPUF under nitrogen atmosphere was obviously retarded compared with the pure FPUF. Furthermore, an eight-bilayer CS/LS based coating significantly improved the fire resistance of FPUF, as evidenced by the remarkable reduction (42%) of peak heat release rate. Meanwhile, the mechanical property of coated FPUF was improved. After the FPUF was covered with the eight-bilayer coating, the tensile strength...

Hydrothermal Synthesis of Nickel Hydroxide Nanostructures and Flame Retardant Poly Vinyl Alcohol and Cellulose Acetate Nanocomposites

Abstract: Nickel hydroxide nanostructures were synthesized by a hydrothermal reaction. The effect of different precursors and surfactants on the morphology of nickel hydroxide nanostructures was investigated. Nanostructures were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. The influence of Ni(OH)2 nanostructures on the thermal stability and flame retardancy of the poly vinyl alcohol and cellulose acetate matrix was studied using UL-94 analysis. The enhancement of thermal stability and flame retardancy of nanocomposites is due to the endothermic decomposition of Ni(OH)2 and release of water which dilutes combustible gases.

Synergistic flame retardancy effect of graphene nanosheets and traditional retardants on epoxy resin

Abstract: Novel non-toxic halogen-free flame retardants are replacing traditional flame retardants in polymer and polymer matrix composite structures. In this study, graphene nanosheet (GNS) is investigatedin combination with traditional layered double hydroxide (LDH), layered rare-earth hydroxide (LRH), and phosphorus-based flame retardant (DOPO) to enhance the flame retardancy of epoxy resin. A synergistic flame retardancy effect is achieved in GNS/LDH and GNS/DOPO systems where combined GNS and LDH increased the viscosity of the epoxy melt, and limited the flame propagation through inhibition of dripping. The limiting oxygen index of epoxy increased from 15.9 to 23.6 with addition of 0.5 wt. % each of GNS and LDH. With the addition of 2.5 wt. % of both GNS and LDH, the total heat release of epoxy resin also reduced from 33.4 MJ/m2 to 24.6 MJ/m2. The synergistic effect of GNS and DOPO adopted a different mechanism. The addition of 2.5 wt. % of GNS and DOPO reduced the peak heat release rate from 1194 kW/m2 to 396 kW/m2, and the total heat release rate from 72.5 MJ/m2 to 48.1 MJ/m2. The synergistic mechanisms of the flame retardants were closely analyzed and correlated with the flame retardant properties.

Layer-by-Layer Assembly of Multifunctional Flame Retardant Based on Brucite, 3-Aminopropyltriethoxysilane, and Alginate and Its Applications in Ethylene-Vinyl Acetate Resin.

Abstract: An efficient and multifunctional brucite/3-aminopropyltriethoxysilane (APTES)/nickel alginate/APTES (B/A/Nia/A) hybrid flame retardant was fabricated via the layer-by-layer assembly technique with brucite, silane coupling agents, nickel chloride, and sodium alginate. The morphology, chemical composition, and structure of the hybrid flame retardant were characterized. The results confirmed the multilayer structure and indicated that the assembled driving forces were electrostatic interactions, dehydration condensation, hydrogen bonds, and coordination bonds. When used in ethylene-vinyl acetate (EVA) resin, the multifunctional flame retardant had better performance than brucite in improving the flame retardancy, smoke suppression, and mechanical properties. With 130 phr loading, the multifunctional flame retardant achieved a limiting oxygen index value of 32.3% and a UL 94 V-0 rating, whereas the brucite achieved only 31.1% and a V-2 rating, respectively. The peak heat release rate and total heat released decreased by 41.5% and 8.9%, respectively. The multifunctional flame retardant had an excellent performance in reducing the smoke, CO, and CO2 production rates. These improvements could be attributed to the catalyzing carbonization of nickel compounds and the formation of more protective char layers. Moreover, the elongation at break increased by 97.5%, which benefited from the improved compatibility and the sacrificial bonds in the nickel alginate. The mechanism of flame retardant, smoke suppression, and toughening is proposed.

Tuning the Nanocellulose–Borate Interaction To Achieve Highly Flame Retardant Hybrid Materials

Abstract: Tuning the Nanocellulose-Borate Interaction To Achieve Highly Flame Retardant Hybrid Materials

Impact of halogen-free flame retardant with varied phosphorus chemical surrounding on the properties of diglycidyl ether of bisphenol-A type epoxy resin: synthesis, fire behaviour, flame-retardant mechanism and mechanical properties

Abstract: This work aimed to investigate the effect of two types of phosphorus-containing flame retardants (P-FRs) with different chemical surroundings (phenylphosphonate-based (PO–Ph) and phenylphosphoric-based (PO–OPh)) on the flame-retardant efficiency for diglycidyl ester of bisphenol-A type epoxy (EP) resin. The two series of P-FRs which were named as FPx and FPOx (x = 1, 2 and 3), respectively, showed reactivity with epoxy group that was examined by differential scanning calorimetry (DSC) and variable temperature FTIR spectroscopy (VT-FTIR). A comparative study between the FPx and FPOx (x = 1, 2 and 3) containing flame-retardant epoxy was carried out via investigating their flammability, thermal stability and mechanical properties. The most significant difference in flame retardancy between them was that FPx (x = 1, 2 and 3) endowed EP with a V-0 rating in UL 94 test at 5 wt% loading, while FPOx (x = 1, 2 and 3) showed no rating at such loading. Importantly, it is found that there was almost 10 times difference in the flame-retardant efficiency for EP between FPx and FPOx, though they had similar chemically molecular structures. Moreover, TGA-FTIR and TGA-MS coupling techniques (TGA, thermogravimetric analysis; MS, mass spectroscopy) were employed to study the thermal decomposition of FP1 and FPO1; the impacts of FP1 and FPO1 on the thermal decomposition of EP were studied by TGA-FTIR as well. Furthermore, an online temperature detection experiment was designed to collect the temperatures by thermocouples and infrared thermometers in the UL 94 test. Based on the above results, the flame-retardant mechanisms of FP1 and FPO1 in EP are discussed. In addition, the impact of P-FRs on mechanical properties of EP was studied by means of tensile test and dynamic mechanical analysis.

Ultra-Fast Layer-by-Layer Approach for Depositing Flame Retardant Coatings on Flexible PU Foams within Seconds.

Abstract: In this letter, we are presenting a novel approach for the deposition of layer-by-layer (LbL) coatings capable of conferring flame retardant properties to flexible polyurethane foams exploiting subsecond deposition times. The process yields nanoscale coatings able to reduce by 33% one of the main fire safety parameters, namely the heat release rate peak, with a total treatment time of only 2.5 s. This new approach turned out to be three to 4 orders of magnitude faster than conventional LbL treatments. Such results make it possible for the exploit of LbL as a competitive, efficient and ecofriendly technology at industrial scale.

Facile Synthesis of a Highly Efficient, Halogen-Free, and Intumescent Flame Retardant for Epoxy Resins: Thermal Properties, Combustion Behaviors, and Flame-Retardant Mechanisms

Abstract: A novel branched poly(phosphonamidate-phosphonate) (BPPAPO) oligomer was synthesized from the polycondensation of phenylphosphonic dichloride and trihydroxymethylphosphine oxide followed by end-capping with aniline in a one-pot synthesis. BPPAPO exhibited excellent flame-retardant efficiency in epoxy resins (EP). With only 5.0 wt % loading, the EP composite reached UL-94 V-0 rating with a limiting oxygen index (LOI) value of 35.5%. BPPAPO catalyzed the early degradation of EP and promoted the formation of more char residue. Glass transition temperatures were partially lowered. When 7.5 wt % BPPAPO was incorporated, the peak heat release rate and total heat release were decreased by 66.2% and 37.3%, respectively, with a delayed ignition and the formation of a highly intumescent char residue. Combination of gas-phase and condensed-phase flame-retardant mechanisms was verified.