Flame Retardancy Of Nanocomposites Research Articles

Synthesis and characterization of novel organoclay-epoxy based flame retardant nanocomposites

Synthesis and characterization of novel organoclay-epoxy based flame retardant nanocomposites

Robust, biodegradable and flame-retardant nanocomposite films based on TEMPO-oxidized cellulose nanofibers and hydroxyapatite nanowires

Flammability is a fatal drawback for sustainable packaging materials made from cellulose and its derivatives. Incorporating inorganic nanomaterials is a viable approach to improve the fire-resistant property. However, due to the aggregation of inorganic fillers and weak interactions between components, incorporating inorganic nanomaterials always had an adverse impact on the mechanical properties and optical transparency of cellulose-based nanocomposites. Herein, we presented a robust, biodegradable, and flame-retardant nanocomposite film composed of TEMPO-oxidized cellulose nanofibers (TOCNFs) and inorganic hydroxyapatite nanowires (HNWs). Both TOCNFs and HNWs possessed one-dimensional microstructure and could form unique organic-inorganic networks microstructure. The organic-inorganic networks interact through physical intertwinement and multiple chemical bonds, endowing nanocomposite film with outstanding mechanical properties. This nanocomposite film showed a tensile strength of 223.68 MPa and Young's modulus of 9.18 GPa, which were superior to most reported cellulose-based nanocomposite. Furthermore, this nanocomposite film demonstrated exceptional thermal stability and flame-retardant feature attributed to the inorganic framework formed by HNWs. This nanocomposite film also possessed a high optical transmittance even when HNWs content reached 30 % and could be decomposed quickly in soil. By employing organic-inorganic interpenetrating network structure design and multiple bonding interaction, cellulose-based nanocomposites can overcome inherent limitations and attain desirable comprehensive properties.

Fabrication of inorganic coatings incorporated with phosphorus-nitrogen-functionalized graphene oxide nanosheets to improve waterborne polyurethanes fire retardancy

A new inorganic flame retardant P/N-GO was prepared by chemically modifying graphene oxide (GO) with phosphorus trichloride (POCl3) and 4,4-diamino-diphenylmethane (DDM). The P/N-GO was covalently grafted into a phosphorus-containing aqueous polyurethane (PWPU) system to prepare a flame-retardant nanocomposite (P/N-GO/PWPU). Due to the uniform distribution of P/N-GO in the polymer matrix, a strong interfacial adhesion can be formed and the mechanical properties of the WPU can be significantly improved. The mechanical strength of the composites increased from 4.56 MPa to 9.16 MPa. The LOI value of WPU increased from 25.5% to 30.5%, indicating that its flame-retardant properties were improved and met the standards for flame-retardant materials. At the same time, the peak heat release rate (PHRR) was reduced from 184.374 kW/m2 to 116.730 kW/m2, which showed good flame retardant properties of P/N-GO/PWPU and was favourable for expanding the application scope and safe use of WPU.

Superior flame retardancy and smoke suppression of epoxy resins with zinc ferrite@polyphosphazene nanocomposites

To impart epoxy resin (EP) with excellent flame retardancy and smoke suppression, we prepared a novel inorgianic-organic nanocomposite flame retardant, zinc [email protected] ([email protected]). The inorganic zinc ferrite plays a role in catalytic carbonization, improving char yields. The organic polyphosphazene helps zinc ferrite improve its compatibility and flame retardancy. Through synergistic effects, [email protected] exhibited excellent flame-retardant and smoke-suppression properties in the EP matrix. Compared to neat EP, the limiting oxygen index of the epoxy with 5 phr [email protected] increased from 24.6% to 32.1% and reached UL94 V-0 rating; the peak heat release rate, peak smoke production rate, and carbon monoxide production of EP composites also decreased by 37%, 50%, and 39%, respectively. Condensed and gas phase analysis indicated that [email protected] helps epoxy generate more dense, stable, rigid residues and less pyrolysis volatile products, improving flame retardancy compared to ZF and PZS alone. Besides, the storage modulus of the composite was increased.

A Brief Review on Selected Applications of Hybrid Materials Based on Functionalized Cage-like Silsesquioxanes.

Rapid developments in materials engineering are accompanied by the equally rapid development of new technologies, which are now increasingly used in various branches of our life. The current research trend concerns the development of methods for obtaining new materials engineering systems and searching for relationships between the structure and physicochemical properties. A recent increase in the demand for well-defined and thermally stable systems has highlighted the importance of polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane (DDSQ) architectures. This short review focuses on these two groups of silsesquioxane-based materials and their selected applications. This fascinating field of hybrid species has attracted considerable attention due to their daily applications with unique capabilities and their great potential, among others, in biomaterials as components of hydrogel networks, components in biofabrication techniques, and promising building blocks of DDSQ-based biohybrids. Moreover, they constitute attractive systems applied in materials engineering, including flame retardant nanocomposites and components of the heterogeneous Ziegler-Natta-type catalytic system.

Flame Retardant Nanocomposites of Polystyrene-Modified Sepiolite Clay

Flame retardancy is the property that is highly demanded when it comes to deal with plastics in different industries. In this research general purpose polystyrene (GPPS) and modified sepiolite clay are melt blended together to fabricate flame retardant nanocomposites. Structural analysis were performed with the help of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. Morphological analysis of the fabricated nanocomposites were carried out using scanning electron microscope (SEM). As a result of better clay dispersion in polymer matrix and intermolecular interactions, mechanical properties are also improved. The standard procedure (ASTM D4986-20) was followed for observing the flame retardancy of the fabricated nanocomposites. Tangible decrease is noted upto 48% in burning rate of the optimum sample which reflects improvement in flame retardancy.

Effect of surfactant modified nano-composite flame retardant on the combustion and viscosity-temperature properties of asphalt binder and mixture

To improve the compatibility and storage stability of Nano-composite flame retardant (NCFR) in asphalt, the surface of NCFR was modified by organic coating using four kinds of surfactants. First, the effect of surfactants on the surface activity of NCFR was evaluated. Then, the mechanism of surface enhancement modification of NCFR by surfactants was analyzed. Finally, the effects of surfactant-modified NCFR on the combustion characteristics and viscosity-temperature characteristics of asphalt were investigated. The results showed that the surfactants were coated on the surface of NCFR particles through intermolecular forces and chemical bonds. The surfactant coating modification of NCFR can improve the compatibility and storage stability of NCFR with asphalt. The surfactant further improves the asphalt fire safety by improving the NCFR dispersion, and the surfactant also effectively reduces the mixing temperature of flame retardant asphalt mixture. Surface modification of NCFR using surfactants is a multifunctional method of powder modification.

Simultaneous exfoliation and functionalization of black phosphorus by sucrose-assisted ball milling with NMP intercalating and preparation of flame retardant polyvinyl alcohol film

Recently, layered black phosphorus (BP) has become a rising star in two-dimensional materials because of high thermal stability, excellent mechanical properties, and size effect. Layered BP can be used as an ideal filler for the preparation of polymer-based composites with high performance. Realizing the exfoliation and functionalization of BP has become the key to BP's application. Under the protection of N-methylpyrrolidone (NMP) and the assistance of sucrose, we completed the preparation and functionalization of layered BP by ball milling. Surface grafting of oxygen-containing functional groups can realize the uniform dispersion of BP in matrix and improve its stability in air. As expected, the nanocomposites prepared by adding sucrose grafted BP into polyvinyl alcohol (PVA) matrix have significantly improved flame retardancy and mechanical strength. When the addition amount of BP-sucrose(N) was 5 wt%, compared with pure PVA, the decrease of the peak heat release rate (PHRR) and total heat release (THR) reached 52.5% and 32.8%, and the tensile strength increased by 131.2%. Moreover, the addition of NMP can avoid the excessive destruction of the two-dimensional crystal structure of BP, which can also improve the performance of nanocomposites. Due to the encapsulation effect of sucrose, the nanocomposites have excellent air stability. The Ag1/Ag2 value only decreases from 0.52 to 0.49 even after three months of exposure to environmental conditions, which proves that the degree of oxidation is low. This work has provided an efficient way to exfoliate and functionalize BP simultaneously, and expanded the application of BP in flame retardant nanocomposites.

Use of synthetic wollastonite nanofibers in enhancing mechanical, thermal, and flammability properties of polyoxymethylene nanocomposites

AbstractThis study investigates the mechanical, thermal, and flammability properties of synthetic wollastonite nanofibers (SWN) reinforced polyoxymethylene (POM) nanocomposites. SWN has been added into the POM nanocomposites in the range of 0.5–3 phr via melt blending. The mechanical properties were investigated through tensile and impact tests with scanning electron microscopy and energy dispersive X‐ray analysis. The thermal characterization was performed by thermogravimetry analysis and differential scanning calorimetry. Flame retardancy of nanocomposites was studied through cone calorimetry analysis and limiting oxygen index test. The tensile strength of nanocomposites improved by 5.88% at 1 phr SWN content, whereas Young's modulus increased with increasing content. The thermal stability of nanocomposites was enhanced as indicated by the higher initial degradation temperature, which rose about 22°C at 1 phr SWN content. The POM/SWN nanocomposites exhibited better mechanical strength despite their lower crystallinity due to the substantial reinforcing effect of SWN. The flame retardancy of nanocomposites improved, as indicated by the reduction of peak heat release rate from the cone calorimetry test. This study shows that SWN has simultaneously enhanced the mechanical strength, thermal stability, and flame retardancy of POM nanocomposites and has the potential in automotive applications.

Fire-retarded nanocomposite aerogels for multifunctional applications: A review

As one of the lightest materials in the world, aerogels are widely adapted in heat insulation , electromagnetic interference shielding, oil-water separation, etc. Nevertheless, owing to their high flammability , the application scenarios of aerogels in extreme environments are severely limited. To reduce the intrinsic inflammable properties of aerogels, nanomaterials are commonly incorporated as additives to fabricate flame retardant nanocomposites, which creates a barrier effect and catalytic carbonization capacity. Nonetheless, up-to-date, the multifunctional development of these aerogels has been barely explored. Herein, we systematically summarized the recent progress on multifunctional nanocomposite aerogels based on various nanomaterials with different dimensions. The preparation approaches and performance evaluation of the most common types of aerogels were depicted in detail. Moreover, the investigation of multifunctional aerogels and their prospects were demonstrated, and in-depth discussed. This review work aims to deliver an insight towards further directions and developments of multi-functional flame-retardant aerogels for extended applications in extreme environments. • The recent progress on flame retardant nanocomposite aerogels was reviewed. • The preparation approaches of the nanocomposite aerogels were described. • The proprieties and application of the flame retardant aerogels were illustrated. • The prospects of the flame retardant nanocomposite aerogels were depicted.

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.

Research on Fabrication of Flame Retardant Nanocomposite Coating to Protect Steel Structures on Epikote 240 Epoxy Resin Base with the Synergy of MWCNTs and Fly Ash

The use of industrial wastes such as thermal power plant fly ash can reduce the environmental risk. The fly ash properties are useful and can contribute to organic coatings. This paper examines a new strategy for coatings that protect steel structures from the effects of fire while enhancing mechanical properties. The aim of this study was to show that the fly ash additive can be a partial replacement for other conventional additives while also having a flame retardant effect. To study the effectiveness of the use of fly ash additives, we have sought to combine them with nanoadditives. Specifically, we study the synergy of fly ash with multi-wall carbon nanotube additives to reinforce the coating on the system: epoxy Epikote 240/ammonium polyphosphate (APP)/pentaerythritol (PER), and melamine. Content of fly ash was studied: 10 wt.% with 0.5, 1, and 1.5 wt.% of multi-wall carbon nanotubes (MWCNTs). The results prove that the synergies between fly ash and multi-wall carbon nanotubes increase the fire resistance to increase the protection of steel structures of the building. When using 10 wt.% fly ash and 1 wt.% MWCNTS, the coating can be considered as a flame retardant material with UL 94V-0 fire resistance and the limiting oxygen index of 27.2%..

Progress in Biodegradable Flame Retardant Nano-Biocomposites.

This paper summarizes the results obtained in the course of the development of a specific group of biocomposites with high functionality of flame retardancy, which are environmentally acceptable at the same time. Conventional biocomposites have to be altered through different modifications, to be able to respond to the stringent standards and environmental requests of the circular economy. The most commonly produced types of biocomposites are those composed of a biodegradable PLA matrix and plant bast fibres. Despite of numerous positive properties of natural fibres, flammability of plant fibres is one of the most pronounced drawbacks for their wider usage in biocomposites production. Most recent novelties regarding the flame retardancy of nanocomposites are presented, with the accent on the agents of nanosize (nanofillers), which have been chosen as they have low or non-toxic environmental impact, but still offer enhanced flame retardant (FR) properties. The importance of a nanofiller’s geometry and shape (e.g., nanodispersion of nanoclay) and increase in polymer viscosity, on flame retardancy has been stressed. Although metal oxydes are considered the most commonly used nanofillers there are numerous other possibilities presented within the paper. Combinations of clay based nanofillers with other nanosized or microsized FR agents can significantly improve the thermal stability and FR properties of nanocomposite materials. Further research is still needed on optimizing the parameters of FR compounds to meet numerous requirements, from the improvement of thermal and mechanical properties to the biodegradability of the composite products. Presented research initiatives provide genuine new opportunities for manufacturers, consumers and society as a whole to create a new class of bionanocomposite materials with added benefits of environmental improvement.

Thermal and Flame Retardant Properties of Phosphate-Functionalized Silica/Epoxy Nanocomposites.

We report a flame retardant epoxy nanocomposite reinforced with 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide (DOPO)-tethered SiO2 (DOPO-t-SiO2) hybrid nanoparticles (NPs). The DOPO-t-SiO2 NPs were successfully synthesized through surface treatment of SiO2 NPs with (3-glycidyloxypropyl)trimethoxysilane (GPTMS), followed by a click reaction between GPTMS on SiO2 and DOPO. The epoxy nanocomposites with DOPO-t-SiO2 NPs as multifunctional additive exhibited not only high flexural strength and fracture toughness but also excellent flame retardant properties and thermal stability, compared to those of pristine epoxy and epoxy nanocomposites with a single additive of SiO2 or DOPO, respectively. Our approach allows a facile, yet effective strategy to synthesize a functional hybrid additive for developing flame retardant nanocomposites.

Flame retarding and smoke suppressing mechanisms of nano composite flame retardants on bitumen and bituminous mixture

To understand flame retarding and smoke suppressing mechanisms of developed nanocomposite flame retardant (NCFR) on bitumen and bituminous mixture, thermogravimetry (TG) and cone calorimeter (CONE) tests were performed, and combustion parameters of TG and CONE tests were discussed. Results indicate that combustion behaviors of bitumen and bituminous mixture are efficiently inhibited by NCFR. More compact and stable char residue is formed on bituminous mixture. NCFR reduces the smoke release amount and mass loss rate in condensed and gas phases during bituminous mixture combustion, and plays the roles of flame retarding and smoke suppressing effects, improving fire safety of bituminous materials.

Novel Polysilicone Flame-Retardant Functionalized Carbon Nanotubes: Synthesis, Characterization and Flame Retardancy as Used in Epoxy-Based Composites

Carbon nanotubes (CNTs) were covalently functionalized by a four components polysilicone (PMDA) to obtain novel, flame-retardant, polysilicone-functionalized carbon nanotubes (CNTs-PMDA). The chemical structure and thermal stability of the CNTs-PMDA were characterized and measured. Then, epoxy resin (EP)/CNTs-PMDA and EP/CNTs nanocomposites were prepared by a solution method, and thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cone calorimetry were used to evaluate the thermal stability, dispersion state, and flame retardancy of the nanocomposites, respectively. The results showed that the thermal stability of the EP/CNTs-PMDA was better than that of the EP/CNTs, with a higher char yield, and the CNTs-PMDA were dispersed well in the EP matrix. Furthermore, the CNTs-PMDA could improve the flame retardancy of the EP nanocomposites with 2 wt% loading due to the synergistic flame-retardant effect between the PMDA and CNTs, having better flame retardancy than either one alone.

Preparation and Characterization of DOPO-Functionalized MWCNT and Its High Flame-Retardant Performance in Epoxy Nanocomposites.

In this work, functionalized multi-walled carbon nanotubes (MWCNT) were synthesized by the reaction between acylated MWCNT and 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB). The obtained MWCNT-ODOPB was well dispersed into epoxy resins together with aluminum diethylphosphinate (AlPi) to form flame-retardant nanocomposites. The epoxy resin nanocomposite with phosphorus content of 1.00 wt % met UL 94 V-0 rating, exhibited LOI value of 39.5, and had a higher Tg compared to neat epoxy resin, which indicates its excellent flame retardant performance. These experimental results indicated that MWCNT-ODOPB was a compatible and efficient flame retardant for epoxy resins. Moreover, cone calorimeter analysis showed that the peak heat release rate (pHRR), total heat release (THR) values, and CO2 production profiles of the composites decreased with an increase in the additional amount of phosphorus.

Bisphosphoric modified amino functional [xFe3O4–2xAl(OH)3]/waterborne polyurethane nanocomposite with superparamagnetism and flame retardancy

Based on the strong adsorption of the diphosphate group to Fe and Al ions, first, the Fe3O4 and Al (OH)3 nanoparticles were modified by alendronate sodium (ALN), and organic phosphorus coated nanoparticles (Fe3O4‐ALN and Al (OH)3‐ALN) with the active group ─NH2 were prepared. Novel [xFe3O4–2xAl(OH)3]/waterborne polyurethane nanocomposite with superparamagnetism and excellent flame retardancy were prepared by in situ polymerization. The experimental results showed that when the content of Fe3O4‐ALN increased, the Ms increased. And the saturation magnetization reached 14.35 emu/g when the Fe3O4‐ALN content was 10 wt%. The nanoparticle network formed by Fe3O4 and Al (OH)3 can prevent the melting deformation of waterborne polyurethane (WPU) composite film and reduce the burning area. And the dual physical protective layer formed by nanoparticle network and char layer can prevent the combustible gas contacting with oxygen and giving off combustion heat, which effectively reduced the heat and smoke gas release. When the content of xFe3O4–2xAl(OH)3 was 20 wt%, the oxygen index of the composite was 28.4%, and the flame retardancy of nanocomposite was classified as V‐0 rating in the UL‐94 test.

Flame retardant nanocomposites based on 2D layered nanomaterials: a review

Two-dimensional (2D) layered nanomaterials, including layered double hydroxides, graphene, montmorillonite, expandable graphite and molybdenum disulfide, as additives to prepare polymer-based flame retardant nanocomposites, have received much interest in the scientific community in recent years. Based on some unique properties of these layered nanomaterials, as well as different flame-retarding mechanisms, various multifunctional nanocomposites can be designed and fabricated. In this paper, first the flame-retarding mechanisms are discussed. Then, the recent progress in polymer-based flame retardant nanocomposites modified by various 2D layered nanomaterials, including the modification methods, are reviewed. The present status and prospective are also discussed.

Development of Flame-Retarded Nanocomposites from Recycled PET Bottles for the Electronics Industry.

Recycled polyethylene-terephthalate (rPET) nanocomposites of reduced flammability were prepared by combining aluminum-alkylphosphinate (AlPi) flame retardant (FR) and natural montmorillonite (MMT), in order to demonstrate that durable, technical products can be produced from recycled materials. During the development of the material, by varying the FR content, the ratio and the type of MMTs, rheological, morphological, mechanical and flammability properties of the nanocomposites were comprehensively investigated. Related to the differences between the dispersion and nucleation effect of MMT and organo-modified MMT (oMMT) in rPET matrix, analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Differential Scanning Calorimetry (DSC), mechanical properties of the nanocomposites changed differently. The flexural strength and modulus were increased more significantly by adding untreated MMT than by the oMMT, however the impact strength was decreased by both types of nanofillers. The use of different type of MMTs resulted in contradictory flammability test result; time-to-ignition (TTI) during cone calorimeter tests decreased when oMMT was added to the rPET, however MMT addition resulted in an increase of the TTI also when combined with 4% FR. The limiting oxygen index (LOI) of the oMMT containing composites decreased independently from the FR content, however, the MMT increased it noticeably. V0 classification according to the UL-94 standard was achieved with as low as 4% FR and 1% MMT content. The applicability of the upgraded recycled material was proved by a pilot experiment, where large-scale electronic parts were produced by injection molding and characterized with respect to the commercially available counterparts.