In situ growth of 0D silica nanospheres on 2D molybdenum disulfide nanosheets: Towards reducing fire hazards of epoxy resin

Enhancing the flame retardancy of polylactic acid nonwoven fabric through solvent-free transparent coating

Polylactic acid (PLA) nonwovens, recognized as eco-friendly substitutes for petroleum-based synthetic fibers, face a significant challenge due to their inherent flammability. This work addresses this concern by synthesizing a hyperbranched polyphosphoramide flame retardant (TPDT) through a one-step polycondensation process without using solvent and catalyst. TPDT is subsequently applied to PLA nonwovens using a dip-pad finishing technique. Notably, with a mere 7 wt% weight gain of TPDT, the PLA nonwovens exhibit a substantial increase in the limited oxygen index (LOI) value, reaching 32.3 %. Furthermore, the damaged area in the vertical burning test is reduced by approximately 69.2 %. In the cone calorimeter test, 17 wt% weight gain of TPDT results in a 51.4 % decrease in peak heat release rate and a 56.0 % reduction in total heat release compared to the control PLA. Additionally, char residue increases from 1.5 wt% to 31.1 wt% after combustion. The strong affinity between TPDT and PLA molecules persists even after repeated abrasion, ensuring sustained flame retardancy. Importantly, the introduction of TPDT also imparts increased softness to the PLA nonwovens. This work addresses this concern by synthesizing a hyperbranched polyphosphoramide flame retardant (TPDT) through a solvent-free, catalyst-free, and one-step polycondensation process.

Recent Progress on Multifunctional Thermally Conductive Epoxy Composite

In last years, the requirements for materials and devices have increased exponentially. Greater competitiveness; cost and weight reduction for structural materials; greater power density for electronic devices; higher design versatility; materials customizing and tailoring; lower energy consumption during the manufacturing, transport, and use; among others, are some of the most common market demands. A higher operational efficiency together with long service life claimed. Particularly, high thermally conductive in epoxy resins is an important requirement for numerous applications, including energy and electrical and electronic industry. Over time, these materials have evolved from traditional single-function to multifunctional materials to satisfy the increasing demands of applications. Considering the complex application contexts, this review aims to provide insight into the present state of the art and future challenges of thermally conductive epoxy composites with various functionalities. Firstly, the basic theory of thermally conductive epoxy composites is summarized. Secondly, the review provides a comprehensive description of five types of multifunctional thermally conductive epoxy composites, including their fabrication methods and specific behavior. Furthermore, the key technical problems are proposed, and the major challenges to developing multifunctional thermally conductive epoxy composites are presented. Ultimately, the purpose of this review is to provide guidance and inspiration for the development of multifunctional thermally conductive epoxy composites to meet the increasing demands of the next generation of materials.

Dual char-forming strategy driven MXene-based fire-proofing epoxy resin coupled with good toughness

It is challenging that the functionalized MXene-based nanofillers are designed to modify the inherent flammability and poor toughness of epoxy polymeric materials and further to facilitate the application of EP composites. Herein, silicon-reinforced Ti₃C₂T_x MXene-based nanoarchitectures (MXene@SiO₂) are synthesized by simple self-growth method, and its enhancement effects on epoxy resin (EP) are investigated. The as-prepared nanoarchitectures realize homogeneous dispersion in EP matrix, indicating well performance-enhancing potential. The incorporation of MXene@SiO₂ achieves improved thermal stability for EP composites with higher T_-5% and lower R_max values. Moreover, EP/2 wt% MXene@SiO₂ composites obtain a 30.2% and 34.0% reduction in peak heat release rate (PHRR) and peak smoke production rate (PSPR) compared to those of pure EP, respectively, also achieving a 52.5% fall in smoke factor (SF) values and increased yield and stability of chars. The dual char-forming effects of MXene@SiO₂ nanoarchitectures, including the catalytic charring of MXene and the migration of SiO₂ to induce charring, are accounted for the results, as well as lamellar barrier effects. Additionally, EP/MXene@SiO₂ composites achieve an enhanced storage modulus of 51.5%, along with improved tensile strength and elongation at break, compared to those of pure EP.

Design of Nacre-Inspired 2D-MoS2 Nanosheets Assembled with Mesoporous Covalent Organic Frameworks (COFs) for Smart Coatings

High loading capacity and smart release of inhibitors are the first and foremost characteristics of nanocontainers, which play a pivotal role in metal active corrosion protection. The present work explores the development of novel protective nanocontainers based on recently emerged covalent organic frameworks (COFs). These highly porous frameworks with large surface area, outstanding thermomechanical properties, low density, and ease of functionalization are used as nanocontainers. On the other hand, molybdenum disulfide (MoS₂), a state-of-the-art 2D layered compound with a sheetlike structure, was utilized thanks to its excellent barrier properties. However, these lamellar structures suffer a high agglomeration tendency in polymeric matrices. Therefore, we developed a novel hybrid nanocontainer, inspired by natural nacre, by an in situ growth of COF on MoS₂ to improve the stability and provide a high inhibitor loading capacity. The porous and nitrogen-rich structure of COF made it a good carrier to adsorb europium cations as inorganic inhibitors and release them on demand by pH changes to suppress the electrochemical reactions. The as-synthesized nanoplatforms were used as pH-responsive fillers in the epoxy resin. The nanocomposite coatings showed almost 50 kΩ cm² total resistance and high impedance values (10¹¹ Ω cm²) even after 77 days of immersion. Moreover, salt spray analysis depicted the smallest amount of rust and corrosion product after 31 days in the filled nanocomposite coating. Cathodic delamination and pull-off outcomes denoted that the filled coatings with the as-synthesized nanofiller showed the smallest cathodic delamination radius (3.41 mm) and lowest adhesion loss (24%) compared to the neat epoxy (7.55 mm and 46.7%). As such, the highly porous modified MoS₂ nanosheets are considered promising alternatives in a wide range of applications with anticorrosion properties.

Flame-retardant activity of ternary integrated modified boron nitride nanosheets to epoxy resin

In order to improve the fire safety of epoxy resin, ZIF-8 nanoparticle in-situ decorated boron nitride nanosheet (BN-OH/ZIF-8) is fabricated via self-assembly method and then ternary integrated BN-OH/ZIF-8/PA hybrids are prepared through the chemical etching effect of phytic acid. FTIR, XRD, XPS, TEM and TGA measurements are used to characterize the structure and morphology of the nanohybrids. The researches show that BN-OH/ZIF-8/PA not only uniformly distributed in EP matrix, but also improve the thermal stability of EP. The peak heat release rate, peak smoke production rate, total smoke production values, the fire growth index and peak CO production rate obtained from cone test are significantly decreased, demonstrating the reduction of the fire hazards of EP composites containing BN-OH/ZIF-8/PA. The nano barrier effect and catalytic activity of BN-OH/ZIF-8/PA may be conducive to suppress the release of combustible volatile products and heat, facilitate the formation of graphitized carbon layer, and protect matrix from flame damage. The ternary integrated method developed in this study explores a new way to improve the flame retardant properties of EP, thereby promoting its application range.

DOPO/Silicon/CNT Nanohybrid Flame Retardants: Toward Improving the Fire Safety of Epoxy Resins

Novel DOPO/silicon/CNT nanohybrid flame retardants (FR-CNTs) were synthesized and FR-CNTs were introduced into epoxy resins through thermal curing process. The SEM and TEM results indicate that CNTs distribute uniformly in epoxy resins due to the good dispersion of CNTs in DOPO/silicon/CNT nanohybrid flame retardants. The thermal stability and flame-retardant properties of EP/FR-CNTs composites are improved, which is attributed to the good dispersion of DOPO/silicon/CNT nanohybrid. The cone calorimeter results demonstrate that FR-CNTs can reduce peak heat release and the release of toxic gas effectively compared with EP/CNTs and EP/CNT/FR composites. The char-residue analysis indicates that the improved flame-retardant properties are due to the char-reinforcing effects and the catalyzing charring effect of FR-CNTs, which provides enough time for flame retardants to trap radicals. Generally, the char layers, which act as insulating barrier, can reduce the releasing of flammable gases and protect the underlying epoxy resins from the heat source.

Facilely produced highly adhered, low thermal conductivity and non-combustible coatings for fire safety

Fire resistant coatings have been proven as an efficient way to improve fire safety in three aspects: reducing the Heat Release Rate (HRR), delaying the ignition time and preventing heat transfer. Herein, a SiO₂ based polymeric composite coating with a lower thermal conductivity and brilliant fire resistance was developed. Isocyanate and sodium silicate could form the final Si-O-Si network structure by polymerization. Compared to the wood without coating, the coated wood shows a significantly increase in limit oxygen index (LOI), has reached 48.0 vol% in the test. As for the cone calorimetry test, coated wood shows a 55.3% decrease in the first peak Heat Release Rate (pHRR) and the Total Heat Release (THR) obtains fire-resistant standard. After exposed to butane flame for 30 mins, the coated wood could still maintain its structural integrity with only 180℃ on the non-exposed side. The commercial standard test of the coating was also investigated. To better understand what role does the polyurea play in the system, a theoretical calculation was done during the research to discuss the interaction between the silica and polyurea. As a fast brush-formed coating, it exhibits a great potential in the field of fire-resistant materials, and may broaden the application prospects of wood.

Functionalization of PET with Phosphazene Grafted Graphene Oxide for Synthesis, Flammability, and Mechanism

Significant improvement in the fire resistance of polyethylene terephthalate (PET) while ensuring its mechanical properties is a tremendous challenge. A novel flame retardant (GO-HCCP, graphene oxide-hexachlorocyclotriphosphazene) was synthesized by nucleophilic substitution of the graphene oxide (GO) and hexachlorocyclotriphosphazene (HCCP) and then applied in PET by an in situ polymerization technique. The scanning electron microscope (SEM) showed a better dispersion of GO-HCCP than GO in the PET matrix. The char yield at 700 °C increased by 32.5% with the addition of GO-HCCP. Moreover, the peak heat release rate (pHRR), peak smoke produce rate (pSPR)and carbon monoxide production (COP)values significantly decreased by 26.0%, 16.7% and 37.5%, respectively, which indicates the outstanding fire and smoke suppression of GO-HCCP. In addition, the composites exhibited higher elastic modulus and tensile strength without compromising the toughness of PET matrix. These significantly reduced fire hazards properties are mainly attributed to the catalytic carbonation of HCCP and the barrier effect of GO. Thus, PET composites with good flame-retardant and mechanical properties were prepared, which provides a new strategy for further flame retardant PET preparation.

Self-intumescent polyelectrolyte for flame retardant poly (lactic acid) nonwovens

The demand for eco-friendly poly (lactic acid) (PLA) nonwovens grows at a high rate in the past several decades, however, only a little attention has been received for flame retardant PLA nonwoven fabrics. In this work, a novel halogen-free self-intumescent polyelectrolyte tris (hydroxymethyl)-aminomethane polyphosphate (APTris) was synthesized by reacting ammonium polyphosphate with tris (hydroxymethyl) aminomethane, and was then used to improve the fire resistance of PLA nonwovens via a dip-nip process. The flammability characterization indicated the limiting oxygen index value was increased to 30.0% from 18.3%, and the damaged area in the vertical burning test was reduced by about 87.0% by the presence of APTris. The cone calorimeter test results revealed that the peak heat release rate and total heat release of the treated sample were decreased by 41.0% and 28.2% respectively compared with that of the control PLA nonwoven sample. The char residue was increased to 12.3 from 1.7 wt % at 800 °C. It is suggested that the dense char barrier formed at the presence of APTris prevents heat, smoke, and gas transfer, and hence enhance thermal dilatability and flame retardancy of PLA nonwovens. This simple sustainable halogen-free treatment has great potential to produce cleaner commercialized flame-retardant PLA nonwovens.

Engineering MXene surface with POSS for reducing fire hazards of polystyrene with enhanced thermal stability

High-performance MXene-based polymer nanocomposites are highly desirable for diverse industry applications due to their exceptional mechanical, thermal and other properties. Nevertheless, it remains an intractable challenge to create flame retardant polymer/MXene nanocomposites due to the difficulty to achieve uniform dispersion of MXenes. Here, we reported a facile strategy for the surface manipulation of two-dimensional titanium carbide nanosheets (Ti₃C₂T_x) with 3-aminopropylheptaisobutyl-polyhedral oligomeric silsesquioxane (AP-POSS) (POSS-Ti₃C₂T_x) through electrostatic interactions. The POSS-Ti₃C₂T_x is steadily dispersed in many polar solvents. Upon incorporated into polystyrene (PS), the combined effect of AP-POSS and MXene makes the resultant PS nanocomposites exhibit significantly improved thermal and thermoxidative stability, e.g. 22 °C and 39 °C increases in the temperature at 5 wt% mass loss under nitrogen and air, respectively. Meanwhile, a 39.1 % reduction in the peak heat release rate, a respective 54.4 % and 35.6 % reduction in the peak CO production rate and the peak CO₂ production rate was achieved, which are superior to those of its own and previous counterparts. This outstanding fire safety is attributed to the combination of adsorption, catalytic and barrier effects of POSS-Ti₃C₂T_x. Hence, as-designed functionalized MXenes can be effectively applied in PS to formulate multifunctional polymer nanocomposites attractive for wide potential applications.

CNT modified layered α-MnO2 hybrid flame retardants: preparation and their performance in the flame retardancy of epoxy resins

In this paper, CNT modified layered α-MnO₂ hybrid flame retardants (α-MnO₂–CNTs) were synthesized through one-pot preparation. The structure and composition of the α-MnO₂–CNTs hybrid flame retardants were investigated by X-ray diffraction, TEM and SEM. Subsequently, the α-MnO₂–CNTs hybrids were then incorporated into epoxy resin (EP) to improve the fire safety properties. Compared with pure EP and the composites with CNTs or α-MnO₂, EP/α-MnO₂–CNTs composites exhibited improved flame retardancy and smoke suppression properties. With the incorporation of only 2.0 wt% of α-MnO₂–CNTs hybrid flame retardants, the peak heat release rate and total heat release of the composites showed 34% and 10.7% reduction respectively. In addition, the volatile gases such as CO and CO₂ were reduced and the smoke generation was also effectively inhibited. The improved fire safety of the composites is generally due to the network structures and the synergistic effect of α-MnO₂ and CNTs, the catalyzing charring effect, smoke suppression and the physical barrier effect of α-MnO₂ nanosheets.

In this paper, CNT modified layered α-MnO₂ hybrid flame retardants (α-MnO₂–CNTs) were synthesized through one-pot preparation.

Edge-exposed MoS2 nanospheres assembled with SnS2 nanosheet to boost NO2 gas sensing at room temperature

SnS₂ nanosheets (NSs) have become an ideal candidate for high performance gas sensors due to their unique sensing properties. However, the restacking and aggregation in the process of sensor manufacturing have great influence on the gas sensing performance. In this study, we synthesized a novel heterojunction of the flower-like porous SnS₂ NSs with edge exposed MoS₂ nanospheres via a facile hydrothermal method and sensitive response has achieved at room temperature (27℃). After functionalization, the SMS-Ⅱ showed excellent response (Ra/Rg = 25.9-100 ppm NO₂), which is 22.3 times higher than that of the pristine SnS₂ NSs. The sensor also has the characteristics of short response time of 2 s, excellent base line recovery (28.2 s), long-term stability and reliability within 16 weeks, good selectivity and low detection concentration of only 50 ppb. The p-n heterojunction formed between the edge-exposed spherical MoS₂ and the 3D flower-like SnS₂ NSs has a synergistic effect, providing a highly active sites for the adsorption of NO₂ gas, which greatly enhance the sensitivity of the sensor. Simple fabrication and excellent gas sensing performance of the SnS₂/MoS₂ heterostructure nanomaterials (NMs) will highly effective for commercial gas sensing application.

Mesoporous silica via self-assembly of nano zinc amino-tris-(methylenephosphonate) exhibiting reduced fire hazards and improved impact toughness in epoxy resin

Mesoporous silica@nano-zinc amino-tris-(methylenephosphonate) (m-SiO₂@Zn-AMP) spheres were synthesized via a self-assembly process to integrate the outstanding flame retardancy, thermal stability, and mechanical properties of these materials. The results indicated that nano Zn-AMP particles were successfully deposited on the surface of m-SiO₂ through electrostatic interactions. The prepared m-SiO₂@Zn-AMP was utilized to improve the flame retardancy, smoke suppression, and mechanical properties of epoxy resin (EP). The storage modulus, impact, and tensile strengths of the EP with 1% m-SiO₂@Zn-AMP (sample EP/1m-SiO₂@Zn-AMP) were increased by 29.9, 50.0, and 23.5 %, respectively, relative to the values for untreated EP. The presence of multiple flame retardant elements (i.e. Si, P, N, and Zn) in the mesoporous spheres led to the formation of high yields of compact char residues and the release of inert substance during combustion, for high flame retardancy and efficient smoke suppression in the condensed and gaseous phase. The EP/5m-SiO₂@Zn-AMP sample achieved a V0 rating in a vertical UL-94 test. Compared to untreated EP, the amount of total smoke released and the peak CO production rate of EP/5m-SiO₂@Zn-AMP were reduced by 53.1 and 61.5 %, respectively. Additionally, the total heat release and peak heat release rate of EP/5m-SiO₂@Zn-AMP were decreased by 45.2 and 57.8 %, respectively.

Recent Developments in the Flame-Retardant System of Epoxy Resin

With the increasing emphasis on environmental protection, the development of flame retardants for epoxy resin (EP) has tended to be non-toxic, efficient, multifunctional and systematic. Currently reported flame retardants have been capable of providing flame retardancy, heat resistance and thermal stability to EP. However, many aspects still need to be further improved. This paper reviews the development of EPs in halogen-free flame retardants, focusing on phosphorus flame retardants, carbon-based materials, silicon flame retardants, inorganic nanofillers, and metal-containing compounds. These flame retardants can be used on their own or in combination to achieve the desired results. The effects of these flame retardants on the thermal stability and flame retardancy of EPs were discussed. Despite the great progress on flame retardants for EP in recent years, further improvement of EP is needed to obtain numerous eco-friendly high-performance materials.

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

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

Facile synthesis of aluminum branched oligo(phenylphosphonate) submicro-particles with enhanced flame retardance and smoke toxicity suppression for epoxy resin composites

A novel and submicro-scale aluminum branched oligo(phenylphosphonate) (AHPP) has been successfully synthesized and embedded into a polymeric substrate to improve the fire safety of epoxy resin (EP). The chemical structures of intermediates and target products were characterized using the nuclear magnetic resonance spectroscopy, X-ray diffraction and Fourier transform infrared analysis. Morphology analysis confirmed that all of the as-synthesized AHPP submicro-particles are mutually well-separated. Combustion results demonstrated that the limiting oxygen index value is increased to 30.5% from 23.5% while the PHRR and THR are decreased by ca. 68.1% and 41.2%, respectively for the EP/AHPP-7.5 composite compared to the corresponding values for pure EP. In addition, the binary blends display the satisfying smoke toxicity suppression performance during combustion. The total smoke production and the total CO yield for EP/AHPP-7.5 are dramatically reduced by 62.0% and 32.3%, respectively, which may mainly be ascribed to the catalytic carbonization performance of the polymers and formation of Al₂O₃ layers on the surface of the char residues. As a result, the findings in this study enabled the submicro-scale phosphorus-containing flame retardant to be a potential candidate as an efficient additive for reducing smoke toxicity of polymer composites.

Facile synthesis of a novel transparent hyperbranched phosphorous/nitrogen-containing flame retardant and its application in reducing the fire hazard of epoxy resin

In this study, a novel hyperbranched phosphorus/nitrogen-containing flame retardant (HPNFR) was facilely synthesized via the transesterification reaction of dimethyl methylphosphonate and tris (2-hydroxyethyl) isocyanurate and characterized successfully by ¹H NMR and FTIR. The sample with 4 wt% HPNFR can achieve V-0 rating in UL-94 test and possess a LOI value as high as 34.5%. Conspicuous blowing-out effect was observed during the vertical burning test. TG results indicated that the presence of HPNFR significantly improved the thermal stability of EP thermosets. From cone test, THR, p-HRR, p-SPR and TSP values of HPNFR/EP composites were decreased in comparison to those of pure EP, revealing the reduced fire hazard of EP composites with HPNFR. SEM images of EP thermoset with 4 wt% of HPNFR after cone test exhibited compact and continuous char layers, while those of pure EP are fragmentary and broken. From TG-IR test, the yield of toxic CO and other pyrolysis products was significantly reduced, indicating a decrease in toxicity. Phosphorus-containing compounds were detected in gas phase, which verified the gaseous phase flame retardant effect of HPNFR. Besides, HPNFR would not significantly damage the transparence of EP thermosets, consequently reserved it's application value in some special fields.

Confined Dispersion of Zinc Hydroxystannate Nanoparticles into Layered Bimetallic Hydroxide Nanocapsules and Its Application in Flame-Retardant Epoxy Nanocomposites

In many fields, nanoparticles are frequently dispersed onto kinds of nanocarriers integrated into hybrid nanocomposites to acquire advanced performance. However, the nanoparticles usually tend to agglomerate on the surface, according to traditional synthetic methods. Besides, the exposed state of loaded nanoparticles and the weak adhesion with the supporters make them fall off during practical application, leading to "second agglomeration" of the nanoparticles and attenuated synergistic effects. In this work, we engineered layered bimetallic (Ni-Co) hydroxides (NCHs) into enclosed nanocages derived from metal organic frameworks (MOFs). Zinc hydroxystannate (ZHS) nanoparticles were selected to be confined dispersed within the hollow cavity of the three-dimensional nanocages. ZHS nanoparticles were tightly immobilized, monodispersing to form a novel multiyolk@shell nanostructure with NCH nanocages. To prove the effectiveness of this structural design, the as-synthesized hybrids ZHS@NCH were introduced into the epoxy matrix to inquiry its performance. Compared to neat ZHS, neat NCH, and physical mixture of ZHS and NCH, ZHS@NCH conferred better flame retardancy, thermal stability, and mechanical properties upon the epoxy nanocomposites. With the adding amount of 6 wt % ZHS@NCH, the UL-94 rating of the nanocomposite was V-0, and the peak of heat release rate value was reduced by 69.1%, while the mechanical properties were slightly influenced. The ingenious synthetic strategy gives insights into uniform distribution of nanoparticles within nanocapsules and enlightens the facile fabrication of multiyolk@shell nanomaterials.

Application of calcium montmorillonite on flame resistance, thermal stability and interfacial adhesion in polystyrene nanocomposites

To exploit the application of calcium montmorillonite (CaMt) and improve the flame resistance of polystyrene (PS), two kinds of long carbon chain quaternary ammonium bromides with different spatial effect (i.e., cetyltrimethyl ammonium bromide (CTAB) and didodecyl dimethyl ammonium bromide (DDAB)) were used to intercalate CaMt for yielding corresponding organic calcium montmorillonite (CaOMt). The PS nanocomposites containing CaOMt (PS/CaOMt) were prepared by melt blending method. The effects of CaOMt on flame resistance, thermal stability, tensile properties and interfacial adhesion of PS/CaOMt were investigated. The results showed that both CTAB and DDAB were intercalated into CaMt to get CaOMt with an exfoliated/intercalated structure, which could endue good interfacial adhesion and thermal stability for PS/CaOMt. All peak values of flame resistance parameters of PS/CaOMt decreased and corresponding combustion times were postponed obviously. Moreover, Young’s modulus of DDAB-intercalated PS/CaOMt was improved by 49.1% while its tensile strength kept at the same level as PS.

Improving the flame retardancy of ethylene vinyl acetate composites by incorporating layered double hydroxides based on Bayer red mud

Nowadays, reducing the hazards of bayer red mud (BRM) is an important research direction in the fields of environmental and safety. In this article, Mg/Al/Fe ternary layered double hydroxides (Mg/Al/Fe-LDHs) were synthesized successfully by a co-precipitation method based on introducing Mg2+ into the BRM suspension. The thermogravimetric analysis (TGA) results showed that the decomposition rate of LDHs is higher than that of BRM, which indicates that LDHs can absorb more heat than BRM during the decomposition process. Subsequently, BRM and LDHs were added into the ethylene vinyl acetate (EVA) to investigate its effects on reducing flammability of the composites. The cone calorimeter test (CCT) results demonstrated that 50 wt% LDH-B can make the peak value of HRR (PHRR) decrease from 1694.8 kW/m2 (EVA) to 199.2 kW/m2 (ELDH2). The smoke density test (SDT) results showed that the luminous flux of ELDH2 is nearly 95% at the end of test with a pilot flame, which is much higher than that of EVA and EBRM. The thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) results confirmed that LDHs can improve the thermal stability of composites and reduce the production of some toxic gases. Compared with BRM, the improved flame retardancy of Mg/Al/Fe-LDHs is ascribed to the introduction of Mg2+, which offering an enhanced catalytic carbonization capability, as well as the physical barrier effect of char residue layer catalyzed by the lamellar LDHs

Surface Manipulation of Thermal-Exfoliated Hexagonal Boron Nitride with Polyaniline for Improving Thermal Stability and Fire Safety Performance of Polymeric Materials

In this article, the polyaniline (PANI)/thermal-exfoliated hexagonal boron nitride (BNO) hierarchical structure (PANI-BNO) was constructed via in situ deposition to improve the dispersion and interfacial adhesion of boron nitride in multi-aromatic polystyrene (PS) and polar thermoplastic polyurethane (TPU). Because of the conjugated structure and polar groups in PANI, the uniform dispersion and strong interfacial adhesion between PANI-BNO and PS and TPU were achieved. Thermogravimetric analysis results showed that the incorporation of PANI-BNO enhanced the thermal stability of PS and TPU, i.e., the temperatures at both 5 and 50 wt % mass loss. In addition, PANI with high charring ability also acted as a critical component to generate a synergistic effect with BNO on reducing the fire hazards of PS and TPU. This well-designed structure led to a remarkable reduction of flammable decomposed products and CO and CO₂ yields. Meanwhile, a dramatic decrease in the real-time smoke density and total smoke production was observed for PS and TPU nanocomposites with 3 wt % PANI-BNO hybrids, respectively. The multiple synergistic effects (synergistic dispersion, char formation, and barrier effect) are believed to be the primary source for these enhanced properties of polymer nanocomposites.