Search

Unsaturated polyester resins (UPR) are broadly applied in chemical, construction, transportation and electrical fields, etc. However, UPR materials are extremely flammable. Through radiation, conduction and convection, the released heat brings serious thermal hazards to surrounding life and the environment. Meanwhile, the combustion of UPR also releases a vast of toxic pyrolysis gases and smoke, causing extremely serious non-thermal hazards, endangering life and health, reducing fire visibility and hindering escape and rescue efforts. Therefore, the flame retardant modification of UPR materials is an inevitable measure to reduce its flammability and broaden its application breadth. In this review, the flammability of UPR materials is firstly analyzed from the perspective of their compositions and structures. Meanwhile, based on the differences in preparation methods of flame retardant UPR (FR-UPR) in literature research, it is divided into additive flame retardant, intrinsic flame retardant and interfacial flame retardant methods. The relationship between the highly efficient flame retardant structures and the properties, and the gaseous-phase flame retardant and condensed-phase mechanisms in FR-UPR composites are analyzed. Compared with traditional additive flame retardants, polymeric flame retardants, nanosheet flame retardants and intrinsic flame retardant method are important directions for the future development of FR-UPR composites. In addition, the interfacial flame retardant method can effectively improve the interfacial adhesion and flame retardant properties of fiber-reinforced UPR composites, and also has application prospects. This review analyzes the current challenges faced by FR-UPR, and looks forward to its possible future development directions to guide the preparation and application of high-performance FR-UPR. [ABSTRACT FROM AUTHOR]

Abstract: The main aim of this work was to investigate the flame retarded efficiency of melamine phosphate (MP), melamine phosphite (MPi) and melamine hypophosphite (MHP) on poly(butylene succinate) (PBS) composites. The flame retardant, thermal degradation and combustion properties of PBS composites were characterized by limiting oxygen index (LOI) test, vertical burning (UL-94) test, thermogravimetric analysis (TGA) and cone calorimeter (Cone), respectively. The LOI results showed that the LOI values followed the sequence of PBS/MP < PBS/MHP < PBS/MPi at the same additive loadings. TGA results indicated that the initial decomposition temperature of PBS composites decreased with the decrease of phosphorus valence state and the incorporation of all three compounds could promote the char formation. Adding these three compounds into PBS matrix can decrease the peak heat release rate (PHRR) obviously from cone calorimeter results. Scanning electron microscopy (SEM) was employed to characterize the morphology and structure of the char residues. The flame-retardant mechanism in gaseous phase and condensed phase were investigated by thermogravimetric analysis/infrared spectrometry (TG-IR) and in situ Fourier transform infrared spectroscopy (in situ FTIR), respectively, and the possible flame-retardant mechanism was proposed. [Copyright &y& Elsevier]

Highlights: [•] The star-shaped phosphorus-containing flame retardant was synthesized. [•] TRIPOD-DOPO can impart excellent flame retardant properties to UPR. [•] TRIPOD-DOPO acted in the gas and condensed phase at the same time. [ABSTRACT FROM AUTHOR]

A novelreactive phosphorus-containing acrylate (ODOPB-AC) was successfullysynthesized and characterized, and the flame retardant unsaturatedpolyester resins (FR-UPR) with various amounts of ODOPB-AC were prepared.The thermal decomposition and flame retardant properties of sampleswere investigated by thermogravimetric analysis (TGA), limiting oxygenindex (LOI), and microscale combustion calorimetry (MCC). As the ODOPB-ACcontent increased, the LOI value of FR-UPR was increased, while thevalue of peak heat release rate (PHRR) and total heat release (THR)were reduced. The evolved gas analysis and condensed thermo-oxidativedegradation process of UPR and FR-UPR were monitored by thermogravimetricanalysis/infrared spectrometry (TG-IR) and real-time infrared spectrometry(RT-IR), providing insight into the thermal degradation mechanism.ODOPB-AC acted in the gas phase through flame inhibition and in thecondensed phase through charring. Moreover, scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy (XPS) were used to explorethe morphology and chemical components of the char. [ABSTRACT FROM AUTHOR]

A novel natural carbon agent-based flame retardant urea salt of chitosan phosphate (UPCS) has been prepared with chitosan, phosphorus pentoxide, and urea. It was characterized by C NMR, P NMR, Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy. Its influence on thermal properties and flammability performance of polyvinyl alcohol was investigated through thermogravimetric analysis, microscale combustion calorimetry experiment, and real time FTIR. The surface morphology of the residual char was investigated with the scanning electron microscope measurement. The results revealed that UPCS accelerated the dehydration action as well as the formation of char. Furthermore, flammability performance of polyvinyl alcohol was improved by the presence of UPCS. [ABSTRACT FROM AUTHOR]

A novel natural material-based flame retardant melamine chitosan phosphate (MPCS) has been prepared. Its impact on thermal properties and flammability performance of polyvinyl alcohol (PVA) was analyzed. Thermogravimetric analysis data exhibited that MPCS enhanced the thermal stability of materials at high temperature. The results of thermogravimetric analysis/infrared spectrometry (TGA-IR) showed that MPCS decreased the yield of flammable volatilized products greatly. Microscale combustion calorimetry (MCC) data showed that peak heat release rate (PHRR), total heat release (THR) and heat release capacity (HRC) all reduced, which indicated that MPCS improved the flame retardancy of materials. [ABSTRACT FROM AUTHOR]

Abstract: Ethylene-vinyl acetate copolymer (EVA) flame retarded by a combination of intumescent flame retardants (IFR) and organically modified montmorillonite (OMMT) have been crosslinked by high-energy electron beam irradiation. The structure was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of electron beam irradiation on the thermal, mechanical and dynamic mechanical properties of the irradiated EVA nanocomposites were investigated. The XRD and TEM results demonstrated that the OMMT was well dispersed in the EVA nanocomposites. The LOI and UL-94 results showed that a synergistic effect on the flame retardancy of EVA nanocomposite existed between the IFR and OMMT. With the addition of 1wt% OMMT and 24wt% IFR, the LOI value of EVA/IFR/OMMT nanocomposite increased from 30.5 % to 33.5 %. The mechanical properties of the irradiated EVA nanocomposite were evidently improved at 160kGy dosage with the increase in the tensile strength to 18.5MPa. Thermal oxidative degradation of the flame-retardant EVA/IFR/OMMT nanocomposites was characterized by thermogravimetric analysis/infrared spectrometry (TG–IR) and real-time Fourier transformed infrared spectroscopy (RT-FTIR). [Copyright &y& Elsevier]

Abstract: A novel phosphorus monomer, 2,2-dimethyl-1,3-propanediol acryloyloxyethyl phosphate (DPHA), has been synthesized through phosphorus oxychloride reacting with neopentyl glycol and 2-hydroxyethyl acrylate (HEA). Its structure was characterized by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectroscopy (1H NMR) and 31P nuclear magnetic resonance spectroscopy (31P NMR). A series of UV-curable resins were manufactured by blending DPHA with triglycidyl isocyanurate acrylate (TGICA) at different weight ratio. The fire performance was examined by Microscale Combustion Calorimetry (MCC). The results obtained from MCC indicated that the addition of DPHA to TGICA decreased the peak heat release rate (PHRR), heat release capacity (HRC) and total heat of combustion (THC). The char residues of the composites were observed by scanning electron microscopy (SEM). The thermal decomposition behavior of DPHA/TGICA composites was characterized by using thermogravimetric analysis/infrared spectrometry (TGA-IR). The test results indicated that when the weight ratio of DPHA: TGICA=1/1, the onset temperature of the composite was highest and the largest char residue at 700°C was observed. The change of chemical structure during the thermal degradation process was monitored by real-time FTIR analysis. TGA-IR results indicated that the evolved products were CO, CO2, water, NH3, carbonyl, phosphorus oxides and aromatic compounds according to the temperature of onset formation. [Copyright &y& Elsevier]

Abstract: A functional polyhedral oligomeric silsesquioxane (NPOSS) with two epoxy ring groups was synthesized via the reaction between trisilanolisobutyl-POSS and triglycidyl isocyanurate, and then a halogen-free epoxy composite containing silicon/nitrogen was prepared. The results of microscale combustion calorimeter indicate that the presence of NPOSS (10% weight ratio) in epoxy resin (EP) can decrease its peak heat release rate by about 30%. The thermal oxidation and degradation behaviors of EP and EP/NPOSS composites were characterized by DSC, TG, FTIR-TG and dynamic FTIR. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the char residues of composites. The thermal degradation and flame retardant mechanism has been evaluated. NPOSS can retard the movement and scission of polymeric chains of EP and form a stable charred layer in the condensed phase to prevent the underlying materials from further combustion. [Copyright &y& Elsevier]

[Display omitted] • A core-shell structured piperazine pyrophosphate microcapsules (MT@PAPP) is constructed. • The MT@PAPP enhances the compatibility and mechanical property of TPE/MT@PAPP composites. • Compared with pure TPE, the PHRR and PSPR of TPE/MT@PAPP were reduced by 78.5% and 60.0%, respectively. In this study, core-shell structured piperazine pyrophosphate (PAPP) is designed to enhance the fire safety and mechanical property of styrenic thermoplastic elastomer (TPE) composites. The PAPP is microencapsulated with carbon nanotube modified melamine-formaldehyde resin to prepare core-shell structured flame retardants (MT@PAPP). Due to the excellent compatibility between the MT@PAPP and TPE matrix, the mechanical property of TPE/MT@PAPP is improved. Compared with TPE, the peak heat release rate and peak smoke production rate of TPE/MT@PAPP are decreased by 78.5% and 60.0%, respectively. Thus, the core-shell structured piperazine pyrophosphate microcapsule strategy provides an excellent approach to obtain high-performance TPE composites. [ABSTRACT FROM AUTHOR]

The fire hazard assessment of polymers and the effect of flame retardants constitutes the foundation for preventing and managing fire risks to public safety. This study addresses key challenges by considering intrinsic hazards, indicator volatility and correlations, while overcoming subjectivity in weight assignment and the neglect of flame-retardant treatments. Firstly, we initiate two novel steps of Pearson correlation analysis and predefined comparative scales for indicators, which enhance the objectivity, scalability and repeatability of analytic network process (ANP) weights. Secondly, we utilize the CRITIC method to incorporate indicator volatility and correlations, surpassing the limitations of separate calculations and subsequent combinations. The newly developed pure sample normalization method enhances the interpretability and scientific validity of CRITIC weights. Combining the ANP and CRITIC weights using Nash equilibrium theory, the results rectify the underestimated T -5% from 0.72% to 3.64%, reducing the overestimated PCO 2 , PSP and TSP from 11.98%, 9.62% and 9.59–7.25%, 9.12% and 5.69%, respectively. Finally, the fire hazards value effectively captures the increased fire hazards resulting from specific degraded indicators following flame retardant treatments. The research findings provide a fresh perspective for the safe design of flame-retardant polymers and fire hazard assessment, offering valuable insights for fire risk prevention and management. [ABSTRACT FROM AUTHOR]

A novel phosphorus/nitrogen-containing hyperbranched polymer (PN-HBP) was synthesized via esterification reaction of 2-carboxyethyl (phenyl) phosphinic acid (CEPPA) and tris (2-hydrooxyethyl) isocyanurate (THEIC). PN-HBP was characterized by Fourier transform infrared (FTIR) spectrometry and 1 H nuclear magnetic resonance ( 1 H NMR) spectrometry. Its initial decomposition temperature (T −5wt% ) is around 300 °C as the thermogravimetric analysis (TGA) showed. The flame-retardant polypropylene (PP) composites were prepared with the combination of PN-HBP and ammonium polyphosphate (APP) via melt blending. A higher limiting oxygen index (LOI) and a V-0 rating in the UL-94 vertical burning test were realized, indicating an apparent synergistic effect. The peak heat release rates (PHRR) of composites were reduced significantly compared with that of PP. The structure of the char residue was tested by Raman spectroscopy, indicating that the combination of PN-HBP and APP can prompt the formation of graphitized carbon layers and therefore improves the flame-retardancy of the PP composite. [ABSTRACT FROM AUTHOR]

Magnesium hydroxystannate [MgSn(OH)6, MgHS] was successfully prepared by a facile coprecipitation method. Then, MgHS was used to intumescent flame-retardant polypropylene systems. Thermogravimetry analysis results indicated that the introduction of MgHS can improve the thermal stability of the intumescent flame-retardant polypropylene system. Limiting oxygen index and UL-94 vertical burning test data show that the addition of MgHS can significantly improve the flame retardancy of intumescent flame-retardant polypropylene system. From the cone calorimetry results, it can be observed that the peak heat release rate is decreased in comparison with intumescent flame-retardant polypropylene. Moreover, the addition of MgHS significantly reduced the gaseous products, especially carbon monoxide. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-8@Ti 3 C 2 T x was synthesised and applied to prepare flame-retardant flexible polyurethane foam composites. • Flame-retardant flexible polyurethane foam composites displayed excellent heat and toxic gases suppression performance. • Flame-retardant flexible polyurethane foam composites showed notable mechanical properties during compression and tensile tests. • The flame-retardant mechanism of ZIF-8@Ti 3 C 2 T x was systematically explored through gas and condensed products. Flexible polyurethane foam (FPUF) is the most used polyurethane, but the highly flammable characteristic limits its widespread usage. In this work, ZIF-8@Ti 3 C 2 T x was synthesized to reduce the heat and toxic gases of FPUF. Flame-retardant FPUF was characterized by cone calorimeter (Cone), thermogravimetric analysis/fourier-transform infrared spectroscopy (TG-FTIR), tensile and compression tests. Compared with pure FPUF, these results showed that the peak of heat release rate (PHRR), total heat release (THR), CO and HCN of FPUF6 decreased by 46%, 69%, 27% and 43.5%, respectively. Moreover, the tensile and compression strength of FPUF6 demonstrated a 52% and 130% increment, respectively. The superior dual metal catalytical charring-forming effect and physical barrier effect of ZIF-8@Ti 3 C 2 T x were achieved. In summary, a simple and reliable strategy for preparing flame-retardant FPUF with reinforced mechanical and fire safety properties was provided. [ABSTRACT FROM AUTHOR]

Due to the high polarizability of traditional flame retardants, it is difficult to meet the excellent dielectric properties and flame retardancy required for electronic packaging materials. Therefore, we have designed a novel linear polyphosphazene that can balance the dielectric properties and flame retardancy of bismaleimide (BMI) composites. Here, fluorinated aromatic ring structure with the large freedom volume is connected to the main chain of polydichlorophosphazene (PDCP) as a side group, resulting in multifunctional fluorinated linear polyphosphazene (PBTFP). Attributed to the excellent P/N/F combination flame retardant strategy, extremely low polarizability, and large molecular free volume, PBTFP simultaneously improves the dielectric properties and flame retardancy of the BMI composites, including UL-94 rating of V0, and a dielectric constant (D k) as low as 2.69. In addition, as an elastomer, PBTFP exhibits positive effects on improving the hydrophobicity and toughness of BMI. Therefore, through a simple affinity substitution reaction, we prepared a multifunctional fluorinated linear polyphosphazene modified BMI based electronic packaging substrate material that can be applied to 5G high-frequency communication. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual network interpenetration strategy significantly improves impact toughness. • Exceptional fire shielding performances, ∼32.8 % reduction in total heat release. • 48.4% decrease in total smoke production and LOI of 34.5% are achieved. • The optimized composite material has a dielectric constant as low as 2.67. The high-frequency transmission of 5th-Generation Mobile Communication Technology (5G) and more integrated mobile terminals pose a challenge to the safety and dielectric properties of existing electronic packaging materials. This work innovatively designs a linear polyphosphazene compound (PABN) with benzonitrile as the reactive side group. The prepared bismaleimide (BMI)/PABN is an excellent dielectric composite material, breaking the technical barrier of balancing fire safety and dielectric performance. With only 1 wt% PABN, the UL94 rating of BMI composite reaches V0, and the impact strength increases by 48.5 %, demonstrating excellent fire safety and toughness. Specifically, the dielectric constant (D k) of the composite containing 4 wt% PABN is as low as 2.67, far meeting the requirements of 5G. In addition, the glass transition temperature (Tg) of all BMI/PABN composites is around 290 °C, and the initial decomposition temperature exceeds 400 °C, indicating potential applications in the integration and miniaturization of microelectronic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cardanol was applied to capture excess carbon dioxide from industry. • The bio-based NIPUs were synthesized from cardanol and carbon dioxide. • The comprehensive improvement effect of +5 valence of P was better than that of +3. • The modification of the intrinsic structure achieved eminent adhesion performance. Under the background of fossil fuel depletion and global warming, the large amount of carbon dioxide (CO 2) produced by industrial production was a renewable, clean and natural C1 feedstock that was becoming an ideal feedstock to produce value-added chemicals. The synthesis of non-isocyanate polyurethanes (NIPU) from cyclic carbonates as intermediate products was a typical way to realize the efficient recycling of CO 2. To improve the low carbonization, flammability and poor mechanics of NIPU and expand its application scenarios, the NIPU was synthesized from biological cardanol and CO 2 by a relatively green synthesis route, and modified by flame retardants containing different valence phosphorus. Compared with ECH-CarCO 2 -HMDA, the char residue of PO-CarCO 2 -HMDA and PP-CarCO 2 -HMDA increased by 248.8 % and 172.7 % respectively under nitrogen atmosphere, and 345.7 % and 151.9 % respectively under air atmosphere. More importantly, the peaks of heat release rate of modified NIPUs were reduced by 30.0 % and 18.4 %, and their total heat release were decreased by 15.2 % and 10.4 %, respectively. After various characterization analysis, this was mainly due to the generation of heat-stable structure containing phosphorus and oxygen during the burning process. Simultaneously, the toughness of PO-CarCO 2 -HMDA and PP-CarCO 2 -HMDA increased by 261.0 % and 105.1 %. In addition, the synthetic NIPU as an adhesive in different materials was also explored, and the adhesion strength can reach 2.47 MPa. This study provided a new idea for preparing bio-based NIPU which was more widely used. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-microporous COF-N with flame retardant, dielectric and toughening properties. • Cleverly designed to balance flame retardancy and dielectric properties. • ∼37.9 % reduction in PHRR and ∼55.6 % decrease in TSP. • The optimized composite material has a dielectric constant as low as 2.76. Most common flame retardants have high polarizability, so introducing flame retardants with simple structures to simultaneously improve the flame retardancy and dielectric properties of bismaleimide resin is a technical challenge. This work utilized the unique microporous structure of covalent organic framework (COF) as a low dielectric factor combined with molecular design to synthesize phosphonitrile based COF-N with a pore size of approximately 1.8 nm. The dielectric constant (D k) of BMI composite containing 1 wt% COF-N (BMI/COF-N 1.0) is as low as 2.76, far exceeding the requirement of less than 3. Moreover, BMI/COF-N 1.0 achieved UL94 at V0 rating, with a 37.9 % reduction in total heat release (THR) and a 55.6 % reduction in total smoke production (TSP), demonstrating excellent fire safety. In addition, the glass transition temperature (Tg) exceeds 290 ℃, which is greater than the heat resistance required for lead-free reflow soldering at 260 ℃. Therefore, a simple method is provided to prepare high-performance BMI based electronic packaging substrates. [ABSTRACT FROM AUTHOR]

Constructing fire-protective coatings has been to be an effective strategy for reducing fire hazards of polymeric materials. However, it remains a huge challenge to fabricate high-performance flame retardant coatings with biodegradability, excellent mechanical and thermal properties, as well as strong adhesion. Herein, inspired by snails exhibiting strong adhesion to a variety of surfaces by interfacial hydrogen-bonding, a biomimetic, highly adhesive, supramolecular nano-coating consisting of a tannic acid (TA)-functionalized hexagonal boron nitride nanosheets (TA-BNNS), TA and polyvinyl alcohol (PVA) was prepared by using a hydrogen-bond self-assembly strategy of solvent volatilization regulation. TA-BNNS was prepared via an efficient and green ball milling exfoliation method under mild conditions. Dynamically regulating the hydrogen bonds between PVA and TA molecules through the volatilization of ethanol was to achieve physical cross-linking. Then such a nanocoating was applied for surface treatment of rigid polyurethane foam (RPUF), which exhibiting excellent flame retardant properties. Compared to pure RPUF, the peak heat release rate (PHRR) and peak smoke production rate (PSPR) of the TA/PVA@BNNS coated RPUF were reduced by ~52.4 % and ~53.4 %, respectively. Therefore, this work provides new approach to the design and manufacture of green, efficient and non-toxic flame retardant materials. [Display omitted] • One-step ball milling was used to exfoliate and functionalize h-BN into highly water-dispersible boron nitride nanosheets. • The physical cross-linked network, based on abundant hydrogen bonding, exhibits superior adhesion properties. • High fire safety and environmental safety are achieved at the same time. [ABSTRACT FROM AUTHOR]

A SiO 2 based polymeric composite coating is developed via a facile strategy to get fire resistance for wooden materials. The composite coatings exhibit strong interfacial adhesion to versatile flammable substrates. The coating-treated wood features well flame resistance, a high LOI of 48.0%, a desired V-0 rating during vertical burning, low heat release rate and long ignition time. [Display omitted] 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 SiO 2 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. [ABSTRACT FROM AUTHOR]

A novel phosphorus-containing hyperbranched macromonomer (PHM), successfully synthesized via Michael addition polymerization of tri(acryloyloxyethyl) phosphate (TAEP) with n-butylamine (BA), was blended with epoxy acrylate resin (EA) to prepare UV curable flame retardant coatings. The study of thermal degradation of these coatings revealed that PHM can catalyze the degradation of EA, contributing to the formation of thermally stable char layer. The residues of EA3 (which contains 45 wt.% PHM) at various temperatures were analyzed by X-ray photoelectron spectroscopy (XPS) and the results displayed that the formation of phosphorus-carbon structure can well protect the carbonaceous char from thermal-oxidative degradation at 800 °C. Besides, the investigation of the flammability illustrated that the addition of PHM increased the limiting oxygen index (LOI) value and reduced the peak heat rate release (HRR) and total heat release (THR). [ABSTRACT FROM AUTHOR]

The high fire safety of polymer nanocomposites is being pursued by research institutions around the world. In addition to intrinsic flame retardancy strategy, the additive-type flame retardants have attracted increasing attention due to low commercial cost and easy fabrication craft. However, traditional additive-type flame retardants usually need high addition amount to achieve a desirable effect, which causes many side-effects on the overall performance of polymer materials, such as deteriorated mechanical property and processability. At present, two-dimensional (2D) nanomaterials have also been applied to reduce the fire hazards of polymer (nano)composites with the coupling of barrier function and catalysis as well as carbonization effect. Even though most research work mainly focus on graphene-based flame retardants, more emerging two-dimensional nanomaterials are taking away research attention, due to their complementary and unique properties, mainly including hexagonal boron nitride (h-BN), molybdenum disulfide (MoS2), metal organic frameworks (MOF), carbon nitride (CN), titanium carbide (MXene) and black phosphorene (BP). In this review, except for graphene, the flame retardant mechanism involving different layered nanomaterials are also reviewed. Meanwhile, the functionalization method and flame retardancy effect of different layered nanomaterials are emphatically discussed for offering an effective reference to solve the fire hazards of polymer materials. Moreover, this work objectively evaluates the practical significance of polymer/layered nanomaterials composites for industrial application. [ABSTRACT FROM AUTHOR]

Abstract: Flame retardant poly(butylene succinate) (PBS) composites were prepared by melt blending PBS with melamine phosphate (MP), using graphene or polyhedral oligomeric silsesquioxanes (POSS) as synergists. The comparative study on the effect of POSS and graphene on the mechanical, thermal properties and flammability of flame retardant PBS was investigated. The addition of POSS or graphene further improved the LOI values of the flame retardant PBS, and V0 rating was obtained for the formulation containing 18 wt% MP and 2 wt% graphene. The incorporation of POSS and graphene reduced the crystallization of PBS, but improved the tensile strength. The presence of graphene exhibited superior thermal-oxidative resistance of the char layer compared to POSS, which effectively retarded the mass and heat transfer between the flame and the burning substrate, thus the heat release rate and total heat release of the flame retardant PBS composites containing graphene was significantly reduced during combustion. [Copyright &y& Elsevier]

Abstract: This work mainly deals with a novel flame retardant system for glass-fiber reinforced poly(1,4-butylene terephthalate) (GRPBT) composites using trivalent rare earth hypophosphite (REHP) and melamine cyanurate (MC) through melt blending method. Firstly, two types of REHP, lanthanum hypophosphite and cerium hypophosphite, were synthesized and characterized. Thermal gravimetric analysis (TGA) was employed to investigate the thermal decomposition behavior of REHP and flame retardant treated GRPBT composites. Thermal combustion properties were measured using microscale combustion calorimeter. Fire performance was evaluated by limiting oxygen index, Underwriters Laboratories 94 and cone calorimeter. The results showed that the flammability of GRPBT is significantly reduced by the incorporation of the flame retardant mixture. Mechanism analysis revealed that the addition of MC reduces the condensed phase effect of REHP, but improves the flame inhibition in gas phase. [Copyright &y& Elsevier]

Abstract: A series of flame-retardant epoxy resins (EP) with different content of poly(DOPO substituted dihydroxyl phenyl pentaerythritol diphosphonate) (PFR) were prepared. The PFR was synthesized via the polycondensation between 10-(2,5-dihydroxyl phenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-BQ) and pentaerythritol diphosphonate dichloride (SPDPC). The structure of PFR was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR). The flame retardancy and the thermal stability of the EP/PFR hybrids were investigated by limiting oxygen index (LOI) test and thermogravimetric analysis (TGA) in air. The results showed that the incorporation of PFR into EP can improve the thermal stability dramatically. The mechanical results demonstrated that PFR enhanced failure strain slightly accompanied by a decrease in tensile strength. The thermal oxidative degradation mechanisms of the EP/PFR hybrids were investigated by real time Fourier transform infrared spectra (RTFTIR) and direct pyrolysis/mass (DP-MS) analysis. X-ray photoelectron spectroscopy (XPS) was used to explore chemical components of the residual char of EP and EP/PFR hybrid. DP-MS analysis showed that the degradation process of EP/PFR hybrid was divided into two characteristic temperature regions, attributed to the decomposition of phosphate and aromatic structure. [Copyright &y& Elsevier]

Abstract: A monomer, acryloxyethyl phenoxy phosphorodiethyl amidate (AEPPA), was synthesized and characterized using Fourier transform infrared (FTIR), 1H nuclear magnetic resonance spectroscopy (1H NMR) and 31P NMR. The copolymer with various amounts of styrene (St) was obtained by the free radical bulk polymerization between AEPPA and St, and characterized using 1H NMR. The thermal properties of the copolymers were investigated with thermogravimetric analysis (TGA) in air and nitrogen atmosphere, and differential scanning calorimetry (DSC). The TGA results in air indicated the copolymers with AEPPA show higher thermal stability than those without AEPPA. However, the TGA results in nitrogen showed that the decomposition temperature decreased and the char residue increased with the increase of AEPPA. The glass transition temperature (T g) of the copolymers from DSC indicated that a inverse proportion was observed between T g and the amount of AEPPA incorporated. The flammability of the copolymers was evaluated by microscale combustion calorimeter (MCC). The MCC results showed that AEPPA can decrease the peak heat release rate (PHRR) and the heat release capacity (HRC), and the sample CP10 shows the lowest PHRR and HRC. [Copyright &y& Elsevier]

Abstract: A novel phosphorus monomer (BDEEP) has been synthesized by allowing phosphorus oxychloride to react with 2-hydroxyethyl acrylate (HEA) and 1,4-Butane diol. Its structure was characterized by Fourier transformed infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The UV-curing behavior was investigated by FTIR. The combustibility was examined by microscale combustion colorimeter (MCC). The heat release rate (HRR) and heat release capacity (HRC) are 42.1w/g and 44.0J/gK, respectively. The thermal degradation was characterized using thermogravimetric analysis/infrared spectrometry (TG-IR). The curve of TGA indicates that there are three characteristic degradation temperature stages for the cured film, which was further characterized by real time Fourier transform infrared (RTFTIR) measurement. It is proposed that the flame retardant action results from decomposition of phosphate to form poly(phosphoric acid), which catalyses the breakage of bonds adjacent to carbonyl groups to form the char, preventing the sample from burning further. The volatilized products formed on thermal degradation of BDEEP indicated that the volatilized products are CO, CO2, water, alkane, carbonyl, phosphorus compounds and aromatic compounds according to the temperature of onset formation. [Copyright &y& Elsevier]

Abstract: The catalyzing carbonization function of alpha-zirconium phosphate (α-Zr(HPO4)2·H2O, α-ZrP) based on an intumescent fire retardant (IFR) polypropylene (PP) system is reported. The IFR system consists of ammonium polyphosphate and pentaerythritol. The morphology of the PP/organophilic ZrP nanocomposites is characterized by X-ray diffraction and high resolution transmission electron microscopy (HRTEM). The results indicate that an intercalated structure is formed. Thermogravimetric analysis, limiting oxygen index (LOI) and UL-94 are used to characterize the thermal stability and the flame retardant properties. It is found that there is a transformation of the char microstructure and an increment of LOI value in the PP systems with the OZrP, and the UL-94 level is improved, from failure, to a V-0 rating. The synergistic effect improves the flame retardant properties of PP remarkably. The morphology and structure (HRTEM and selected area electron diffraction) of the char residue also indicate the presence of graphite sheets. A possible mechanism for catalyzing carbonization is discussed. [Copyright &y& Elsevier]

Organic-inorganic hybrid flame retardant technology integrates independent ingredients into a whole, thus showing advantage of simultaneous improvement in flame retardant, smoke suppressant and mechanical properties of polymers over traditional flame retardants. In this work, a novel organic-inorganic hybrid flame retardant denoted as IR-MOF-3-Mel was synthesized by covalent hybridization of isoreticular metal-organic framework-3 (IR-MOF-3) with melamine. A relatively low amount of IR-MOF-3-Mel nanoparticles dramatically decreased the fire risk of epoxy resin (EP). Specifically, the EP with only 2.0 wt% of IR-MOF-3-Mel achieved a limiting oxygen index (LOI) of 30.5% as well as a UL-94 V-0 classification, whereas its counterpart with 2.0 wt% of IR-MOF-3 showed a LOI of 25.0% and no classification in UL-94 test. Furthermore, the peak heat release rate, total heat release and smoke production rate of the EP with 2.0 wt% of IR-MOF-3-Mel was declined by 74.0%, 71.4% and 35.6%, respectively, compared to neat EP. Additionally, the glass transition temperature, the tensile strength, and the young's modulus were 11 °C, 38%, and 27% higher than those of neat EP, respectively. The flame retardant mechanism analysis clarified that IR-MOF-3-Mel contributed to formation of a char layer with a high level of thermal resistance and graphitization which accounted for significantly reduced fire risks. Image 1 • With only 1.5 wt% of IR-MOF-3-Mel, the EP composite achieved a UL-94 V-0 rating. • 2.0 wt% of IR-MOF-3-Mel leads to an unprecedented reduction in both PHRR (−74.0%) and THR (−71.4%) of epoxy composites. • IR-MOF-3-Mel hybrid also shows good smoke suppression effect. • 2.0 wt% of IR-MOF-3-Mel improves the tensile strength by 38% compared to neat EP. [ABSTRACT FROM AUTHOR]

• This paper summarizes the flame retardant applications of synthetic textiles. • The common drawbacks like melt-dripping and limited charring are addressed. • Surface modification is done in many cases to address these issues. • Recently, bio-based fire retardants are widely used compared to petro-based compounds. • Metal-oxide nanoparticles, inorganic and nano-carbon compounds are also considered. Synthetic textiles make a great contribution as the apparel, industrial and technical textile goods, though most of them are inherently flammable. Thus, the fire retardant treatment of synthetic textile materials always puts a huge significance to deal with; meanwhile the art of flame retardant application is taking a new shape globally considering the modification of the textile surfaces as well as the structure of applied flame retardant compounds. Thus, this review depicts the fire retardant treatment of some common synthetic textiles like polyamide 66 (PA66), polyamide 6 (PA6), polyethylene terephthalate (PET) and polyacrylonitrile (PAN) etc. focusing on the traditional approaches as well as the recent practices. In addition, this article aims to be established as a kind of general review that summarizes all relevant works carried out till the date with a view to realize the growing trend of this field in terms of applied compounds and application techniques and try to discover their impacts on anti-dripping, fire and thermal behaviors. In this review, it is seen that the very common drawbacks of most of the synthetic textiles are the melt-dripping and limited charring. Thus, to overcome these phenomena, in many instances, researchers adopt the surface modification technique prior to the final finishing in attaining the fire retardant behaviors. This kind of surface engineering usually using some epoxidized and acyrated aliphatic chains surely modifies the flame retardant and combustion behaviors where some improvements in the reduction of the peak heat release rate (pHRR) and a significant increase in char yield% are realized. In addition, this kind of modification also seems to be much effective in stopping the melt-dripping phenomenon of synthetic textiles. In parallel, it is noticed that the researchers also take initiative to modify the chemical structure of applied flame retardant compounds; especially they do incorporate several flame retardant elements like phosphorus (P), nitrogen (N), silicon (Si) and boron (B) etc. in a single structure to intensify the fire retardant efficacy of the same. For example, some of these compounds are effective both in the condensed and gas phase flame retardant mechanism or in some cases, some structures can enhance the limited charring of synthetic textile materials or can provide thermal stability of these char residues via providing a physical barrier effect due to their synergistic involvement in a typical flame retardant system and thus, an optimum level of flame retardancy are realized for the treated textiles. So, it is thus indispensable to realize the physio-chemical interactions between the polymeric structures (i.e., textiles) and the applied flame retardant compounds to design the future fire retardant treatment through selecting a right compound and an appropriate application method for a typical textile material. From this point of view, this review is a significant work to focus on some key flame retardant and combustion parameters like limiting oxygen index (LOI) values, vertical burning test (VBT) and peak heat release rate (pHRR) data along with an exploration of the flame retardant mechanism and durability issues of such applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A hierarchical MoS 2 @TiO 2 structure is firstly designed and synthesized. • The combination properties of BD with 2 wt% MoS 2 @TiO 2 loading is greatly enhanced. • The mechanism of MoS 2 @TiO 2 in enhancing combination properties of BD is proposed. Abstract Bismaleimide/diallyl bisphenol A (BD), a kind of allyl-modified bismaleimide (BMI) system, which is widely used in the fields of aviation, aerospace, machinery, and electronics. However, the further applications of BD are severely restricted by its high crosslink density, brittleness, and undesirable flammability. In order to overcome these drawbacks, a hierarchical MoS 2 @TiO 2 structure is designed and synthesized to improve the mechanical and fire safety of BD, which are well matched with the high curing temperature and application temperature of BD. Specifically, with a relatively low loading of 2 wt% MoS 2 @TiO 2 , then the peak heat release rate (pHRR) and total heat release (THR) of BD composites are 314.25 kW/m2 and 53.58 MJ/m2, respectively, which are decreased by 32.5% and 15.0% in comparison to those of the pristine BD. Meanwhile, the TSR and yields of poisonous gases, especially CO and nitric oxide of BD/MoS 2 @TiO 2 2.0 are greatly decreased which indicates that the fire safety is effectively enhanced. The impact strength of BD/MoS 2 @TiO 2 2.0 sample is increased to 12.44 kJ/m2, which corresponding to a 96.8% compared with that of pure BD, and its storage modulus is 44462 MPa, a little higher than that of pure BD. Furthermore, Tg of BD/MoS 2 @TiO 2 2.0 is increased to 326 °C with a lower cross-linking density while that of BD is 316 °C. Conclusively, this investigation demonstrates that the MoS 2 @TiO 2 is a significant nano-additive for developing high-performance BD resins with excellent fire safety and mechanical properties, which provides a novel strategy for designing advanced BD composite material. [ABSTRACT FROM AUTHOR]

Bio-based and phosphorus-free coating was fabricated by layer-by-layer assembly method to obtain the flame retardant cotton fabric. For the first time, the modified cotton fabrics were prepared by utilizing positively charged polyethylenimine and negatively charged alginate together with subsequent crosslinking of barium, nickel and cobalt ions. Scanning electron microscopy and energy-dispersive X-ray demonstrated that the metal ions crosslinked coating was successfully constructed on the substrate. The thermal stability and flame retardancy were investigated by thermogravimetric analysis (TGA) and horizontal flame tests. TGA results showed that the degradation of the coated cotton fabrics were retarded at high temperature and the char residue of the cotton fabrics were improved after covered with the barium, nickel and cobalt ions crosslinked coatings. Furthermore, the fire resistance of cotton-Ba sample was enhanced significantly compared with the untreated sample, as evidenced by the obvious reduction (28%) of flame spread rate and complete char residue. Finally, the washing durability of coating on the fabric was enhanced after metal ions crosslinked with alginate based coating. [ABSTRACT FROM AUTHOR]

In comparison with the thermal hazard of polymers, noxious smoke and gas produced by the combustion of polymers make the environment self-purification a huge challenge. As a new type of a highly effective flame retardant, black phosphorus (BP) can effectively decrease the thermal hazard of polymers, but its performances in smoke suppression and toxicity reduction are unsatisfactory. In this article, a method of covalently grafting diazotized BP with a ferrocene oligomer was applied to promote the smoke suppression and toxicity reduction efficiency of BP. In our work, the BP-NH nanomaterials with a mass of amino groups on the surface were acquired by diazotizing the BP. Then, the BP-Fe was obtained by covalently grafting the ferrocene chloride salt and nitrogen-containing heterocycles on the surface of BP. The smoke production rate (SPR) and total smoke production (TSP) values of the epoxy resin (EP) decreased by 49.8% and 52.5% with the addition of 2 wt% BP-Fe, respectively. In comparison with previous studies, this work was far more effective than the previous work in smoke suppression and flame retardant. The release of toxic gases (CO and HCN) and volatile organic compounds in the EP was also effectively inhibited at the same time. In addition, the storage modulus and tensile strength of nanocomposites increased by 35.1% and 27.2% with the addition of 1 wt% BP-Fe. This work also provides a new idea on how to simultaneously strengthen the toxic smoke suppression, mechanical properties, and flame retardant of polymer materials. [Display omitted] • Rich amino groups on black phosphorus by diazotization strategy. • Ferrocene derivatives are grafted onto black phosphorus by covalent reaction. • Smoke suppression of epoxy resin composites can be significantly improved. [ABSTRACT FROM AUTHOR]

Devoting to coping with safety risk spreading with polymers, this work achieves dramatic synergistic improvements in composite toughness, photothermal healing, and fire safety through a novel targeted modification strategy for black phosphorus (BP). In detail, we herein use the emerging 2D BP as a template for in-situ growth by covalent triazine framework (HBP-CTF). Incorporating gradient increased HBP-CTF (1, 2, 4 wt%) into polystyrene (PS), the elongation at break increased by 61.59%, 74.60% and 62.82% for composites, respectively. This is attributed to the synergistic effects of two components of HBP-CTF as stress conduction unit and interface and dispersion improver, respectively. Furthermore, PS/HBP-CTF composites achieve photothermal healing over 96% in strength and elongation at break induced by outstanding photothermal properties (linearly quantifiable, R2 > 0.997). Noted, PS/HBP-CTF 2.0 and PS/HBP-CTF 4.0 achieve record reductions of 61.77% and 69.85% in peak heat release rate, accompanied by dramatically reduced total heat release. Taking the pyrolysis of HBP-CTF as an index, this work proposes the idea of using P 4 as the key product to monitor and distribute gas phase effects for BP-based flame retardants. The hybridization of CTF to HBP promotes the slow and continuous release of P 4 in the gas phase, revealing the structure and composition of char that cross-linking P and N. This work provides strategies for synergistically overcoming composite brittleness, crack failure, and high flammability, paving the way for practical applications. [ABSTRACT FROM AUTHOR]

A novel carbon fiber/MXene coalition (CF-Ar-MXene) is synthesized via a bidirectional aryl diazonium chemistry method using p-phenylenediamine as a chemical bridge, which effectively combines the two materials with different dimensions and makes full use of the advantages of both. CF-Ar-MXene coalition materials achieve high surface roughness and rich oxygen-containing active groups due to the presence of MXene on the surface of CF, which leads to the favorable interfacial interaction and compatibility between CF-Ar-MXene and epoxy resin (EP) matrix. As expected, after the incorporation of CF-Ar-MXene coalition into EP matrix, the flame retardancy and mechanical properties of EP composites are significantly improved. For example, with the addition of 3 wt% CF-Ar-MXene coalition, the peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of EP composites decrease by 42.6%, 48.2% and 32.1%, respectively. Meanwhile, the TG-IR results indicate that the amount of combustible volatile products and toxic gases also significantly decrease. Notably, with 2 wt% loading of CF-Ar-MXene coalition in EP composites, the tensile strength and elongation at break increase by 49.9% and 40.5%, respectively. Therefore, the efficient cooperation between CF and MXene in CF-Ar-MXene coalition and excellent interface compatibility with EP matrix are the main reasons for the excellent flame retardancy and mechanical properties of EP/CF-Ar-MXene composites. [Display omitted] • CF-Ar-MXene coalitions were prepared by a bidirectional aryl diazonium chemistry method for the first time. • The method used in this experiment is efficient and eco-friendly compared with the traditional modification method for CF. • CF-Ar-MXene coalitions achieved high filler efficiency in reducing the fire hazards and smoke production of EP. • Mechanical properties of EP/CF-Ar-MXene composites were efficiency enhanced. [ABSTRACT FROM AUTHOR]

With the advent of the 5G era, preparing conductive polymers to accomplish electromagnetic interference (EMI) shielding, mechanical enhancement, and flame retardancy are of vital importance. Graphite felt (GF) acts as a three-dimensional structure and organophosphorus derivatives containing different valences work as a flame retardant to form a novel EP composite. With GF incorporated into EP, EMI shielding effectiveness (SE) achieves around 60 dB, and absorption is dominated in the X band (8.2–12.4 GHz). Meanwhile, GF could exert a fiber reinforcement effect to enhance the mechanical properties of EP composites, tensile strength and impact strength of EP/GF are increased by 19.1% and 64.2%, respectively. However, owing to the "wick effect" of GF, 20 wt% DOPO-PEPA is added to acquire flame-retardant EP composites. Herein, a potential strategy broadens applications of EP composites in the high-end field and is provided to prepare polymer composites. [Display omitted] • A cost-reasonable EP composites composed of 3D GF and two-valence phosphorous derivatives is successfully fabricated. • The EMI SE EP composites achieve around 60 dB in the X band. • The pHRR and THR of EP/GF/20FR are reduced by 53.4% and 35.3%, respectively. • EP composites exhibit potential promise for large-scale production and industrial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • BP-Ti 3 C 2 nanohybrids were obtained by two-electrode electrochemical exfoliation method. • The smoke release of WPU/BP nanocomposites during combustion was suppressed with the introduction of Ti 3 C 2. • The mechanical properties and fire safety of WPU were simultaneously improved. The low exfoliation yield and large solvents consumption have become the major issue that limits the commercial application of two-dimensional nanomaterials. Emerging as an effective and environmentally friendly approach, electrochemical exfoliation has been attached by extensive concern. Hence, a simple and environmentally friendly two-electrode electrochemical exfoliation method was put forward to prepare black phosphorus-MXene (BP-Ti 3 C 2) nanohybrids without consumption of any organic solvents. The integration of BP and Ti 3 C 2 also imparts higher fire safety and mechanical properties to waterborne polyurethane (WPU). With the incorporation of 2.0 wt% BP-Ti 3 C 2 , the peak heat release rate, total heat release, total smoke production and total CO 2 yield of WPU were decreased by 42.2%, 12.9%, 12.6% and 16.5%, respectively, exhibiting a great flame retardancy effect. The employment of electrochemical exfoliation method towards BP and Ti 3 C 2 nanosheets not only imparts higher fire safety to polymer composites, but also provides a referable environmentally friendly preparation for two-dimensional nanomaterials. [ABSTRACT FROM AUTHOR]

A novel hyperbranched charring foaming agent (HCFA), successfully prepared via an A 2 B 3 approach with about 97% yield, was combined with ammonium polyphosphate (APP) to flame-retard polypropylene (PP) at a 30 wt% loading. The results of thermogravimetric analyses of various PP samples in air and nitrogen showed that the HCFA/APP system could effectively improve the thermal and thermal-oxidative stabilities of the char residues. And PP3 with a 3/1 mass ratio of APP to HCFA left the highest amount of char residue at 800 °C. The studies of their flammability revealed that the addition of HCFA can make great contribution to the increase of the limiting oxygen index and the UL-94 V0 rating, and the decrease of the heat release rate (HRR) and fire growth index (FGI) of PP/APP/HCFA composites relative to PP with 30 wt% APP. The investigation of their water resistance demonstrated that the PP composites with a mass ratio of APP to HCFA being between 3:1 and 1:1 still obtained a UL-94 V-0 rating after 168 h soaking in hot water, due to the delayed migration of intumescent flame retardant from the complexation between hydrophilic APP and hydrophobic HCFA. Besides, their mechanical properties were also investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A placoid scale like biomimetic structure (PEPA-IPTS@Ti 3 C 2 T x) was synthesized. • The compatibility between PEPA-IPTS@Ti 3 C 2 T x and EP matrix was greatly enhanced. • The tensile strength and impact strength of EP nanocomposites increased by 30.1% and 43.5%, respectively. • The PHRR and THR of EP5 showed a 47.3% and 44.1% reduction, respectively. • EP nanocomposites acquired superior toxicity reduction and smoke suppression due to multi-element catalytic effect. In recent years, developing high performance thermosetting nanocomposites has attracted wide-ranging research attention. As a rising two-dimensional material, MXene still confront the intrinsic weakness for preparing epoxy resin with superior comprehensive performance. Inspired by the overlap architecture of placoid scale, an in-situ growth technique was applied to fabricate biomimetic-structural MXene derivative, which displayed significant increase in interfacial compatibility, mechanical property, and flame retardancy of epoxy resin (EP). In contrast to pure EP, the tensile strength and impact strength of EP nanocomposites increased by 30.1% and 43.5%, respectively. Furthermore, the fire hazard of EP nanocomposites was significantly reduced. With 5 wt% of PEPA-IPTS@Ti 3 C 2 T x incorporated into EP (EP5), the peak of total heat release (THR) and total smoke production (TSP) decreased by 44.1% and 26.8%, respectively. Therefore, biomimetic structure nanohybrid (PEPA-IPTS@Ti 3 C 2 T x) provides a facile and reliable strategy to prepare EP nanocomposites with excellent comprehensive performances. [ABSTRACT FROM AUTHOR]

The flame-retardant and anti-dripping properties of biodegradable polylactide (PLA) materials during the combustion process were improved using intumescent flame-retardant (IFR) and different synergists. Organophilic montmorillonite (OMT), zinc borate (ZB), fumed silica (FS), tetraethoxysilane (TEOS) and polytetrafluoroethylene (PTFE) were chosen as the anti-dripping synergists for IFR in flame-retardant PLA. The flammability properties and thermal stability of PLA composites were investigated with UL-94, limiting oxygen index (LOI), thermogravimetric analysis (TGA), melt flow index (MFI), etc. It is found that OMT and ZB are the best anti-dripping synergists for IFR PLA. The anti-dripping mechanisms of all the additives are discussed. [ABSTRACT FROM PUBLISHER]

Halogen-free flame retardant rigid polyurethane foams (RPUF) were synthesized by substituting a part of polyther polyol with polyol-modified lignin and filled with phenolic encapsulated ammonium polyphosphate (PFAPP). Lignin was chemically modified with flame retardant elements, phosphorous, via a three-step reaction. The foams maintained a regular cell structure and had even smaller average cell size than pure foam. The effects of lignin polyol and PFAPP on the apparent density, compressive strength were discussed. The thermal stability, flame retardant properties and mechanical properties of the foams are improved. Compared with pure foam (0.2 % char residue at 700 °C), modified foam with lignin and PFAPP exhibits much higher char formation (42.7 % char residue at 700 °C). The FR properties of these modified foams were evaluated by cone calorimeter and limiting oxygen index (LOI). The modified lignin in foam system further reduces the heat release rate and shows the combustion process. The addition of 15 % PFAPP and 10 % modified lignin into RPUF led to a considerable increase of the compressive strength with respect to the neat RPUF. [ABSTRACT FROM AUTHOR]

Highlights: [•] Oligomers with different chemical components in molecular chains were synthesized. [•] FP-3 containing three IFR components possessed high thermal stability. [•] FP-3 possessed lowest flammability. [•] FP-3 exhibited a synergistic interaction between gas and condensed phase. [Copyright &y& Elsevier]

[Display omitted] • The linear polyphosphazene and MoSe 2 hybrid (LPP-MoSe 2) was constructed. • EP/LPP-MoSe 2 exhibits low PHRR, THR, EHC, TSP, CO yield and CO 2 yield. • LPP-MoSe 2 shows synergistic flame retardant effect in gas-phase and condensed-phase. • LPP-MoSe 2 displays significant toughening and strengthening effect on EP. Epoxy resins (EP) are deemed as one kind of most commonly used thermosets, but immanently suffer from inflammability and brittleness. Herein, we report a newly designed hierarchical molybdenum diselenide (MoSe 2) nanotubes assembled from several-layered nanosheets, and then merged with linear polyphosphazene (LPP) for constructing LPP-MoSe 2 hybrids. LPP-MoSe 2 possesses great advantages in improving the properties of EP for their typical nanotube structure and the combination effect of transition metal, phosphorous and nitrogenous compounds. The developed EP/LPP-MoSe 2 composites present obvious reduction in flammability, obtaining a high LOI value of 29% and reaching V-0 rating in UL-94 test. They also exhibit obvious reduction in the heat hazards of EP, such as peak heat release rate (39.0%) and total heat release (24.8%), as well as the toxicity hazards including total smoke production (31.3%) and the yields of CO and CO 2. Gas-phase and condensed-phase mechanism are elucidated to explain the contribution of LPP-MoSe 2 to the fire retardation of EP. Moreover, the addition of LPP-MoSe 2 can also obviously enhance the mechanical properties of EP. The impact strength of EP is only 9 kJ/m2, while EP/LPP-MoSe 2 3.0 can reach up to 14.2 kJ/m2. Based on tensile test, the well-dispersed LPP-MoSe 2 also leads to significant elevation in tensile strength (74.6%) and elongation at break (100%) of EP. Our data demonstrate that LPP-MoSe 2 shows impressive performance in developing high-performance EP composites, thereby broadening the practical application of EP. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) have been widely used to improve fire safeties of polymers as burgeoning flame retardants. There is no report about the influence of MOFs' compositions on enhancing fire safety of polymers. This work synthesized 9 pristine MOFs, including 3 MOFs with 1,3,5-tricarboxylic acid as organic ligands, which were added into polystyrene and epoxy resin, respectively. To deeply investigate impacts of MOFs' components, heat release, smoke emission and CO production behaviors were detected during the combustion processes of polymer/MOFs. It is clear that cobalt-based MOFs had better flame-retardant performance than other MOFs with same organic ligands. While the influence of organic ligands is irregular, affected by corresponding metallic components. The type of polymers also affects flame-retardant performance of MOFs. This work systematically analyzed the influence of MOFs' components on performance of polymer composites, which provides guidelines and database for further application of MOFs as flame retardants. [Display omitted] • H 2 BTC, 2-MIM, and H 3 BTC based MOFs were prepared with different metal salts. • MOFs' impact on heat release, smoke/CO emission behaviors is detected and studied. • Studied the role of MOF's components in improving fire safety of polymers. • Co-MOFs have the best performance, while the role of organic ligands is irregular. [ABSTRACT FROM AUTHOR]

A series of flame retarding biodegradable polylactic acid composites (FR-PLA) based on aluminum hypophosphite (AHP) and expanded graphite (EG) were prepared by the melt-compounding method. The effect of AHP and EG on the flame retardancy and thermal stability of PLA were investigated by thermogravimetric analysis (TGA), UL-94 vertical burning test, limiting oxygen index, microscale combustion calorimetry and cone calorimeter testing. The gas products of PLA and FR-PLA composites were investigated by TG-IR technology. TGA results showed that the FR-PLA composites presented higher char residue and reduced mass loss rate than neat PLA. Significant improvement of flame retardancy of PLA/AHP/EG composites indicated an excellent synergistic effect between AHP and EG. Cone calorimeter tests gave clear evidence that the combination of AHP and EG resulted in a significant reduction of the heat release rate (HRR) and total heat release (THR). TG-IR revealed that the combination of AHP and EG resulted in significant decrease of gas products. The char residue of FR-PLA composites were also investigated by scanning electron microscope, Fourier transform infrared spectra spectroscopy and X-ray photoelectron spectroscopy. Based on the analysis, possible flame retardant mechanism was discussed. [ABSTRACT FROM PUBLISHER]

Composites based on poly(vinyl alcohol) (PVA) and aluminumhypophosphite(AHP) are prepared by solvent blending. The thermal, mechanical, andcrystallinity properties of the composites are studied. AHP remarkablyimproves the char residue yield during the thermal degradation andcombustion of AHP/PVA composites. The flame retardancy of the compositesis obviously improved. The increased char which protects underlyingPVA from heat and oxygen is one of the key reasons for the improvedflame retardancy. The crystallinity of the composites is decreased.The glass transition temperature (Tg)and the storage modulus of the composites are increased. In the compositewith 15 wt % AHP, limiting oxygen index (LOI) reaches 28.0%, UL-94V-0 rating is obtained, Tgis increasedby 7 °C, and the storage modulus is increased by 17.2% in comparisonwith neat PVA. Moreover, AHP/PVA composites keep high transparenceand maintain most of the mechanical properties of PVA, which is advantageousfor the practical application of the composites. [ABSTRACT FROM AUTHOR]

Abstract: Silane precursor microencapsulated intumescent flame retardant (IFR) was prepared by sol–gel process and then modified with vinyltrimethoxysilane (A-171) with the goal of that the vinyl group functionalized silica microcapsule could be introduced into EVA matrix through crosslinking, which will enhance the compatibility and dispersion between EVA matrix and microencapsulated IFR. The effects of silane precursor microencapsulation technology on the mechanical, electrical, thermal, interfacial adhesion and flame retardant properties of intumescent flame-retardant EVA cable were investigated by mechanical test, resistance meter, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), limiting oxygen index (LOI) and UL-94 test. The Fourier transform infrared (FTIR) results indicated silane precursor microencapsulated IFR were successfully prepared, and the water contact angle (WCA) results indicated that silane precursor results in the transformation of hydrophilic to hydrophobic of IFR surface. The characterization for the various properties of EVA composites demonstrated that silane precursor microencapsulation technology enhanced the interfacial adhesion, mechanical, electrical, thermal stability and flame retardancy of EVA/MCAPP/MCPER system. Furthermore, the water resistance test results demonstrate that EVA/MCAPP/MCPER composites have good water durability. This investigation provides a formulation for the industrial application as insulated materials of EVA cable with excellent properties. [Copyright &y& Elsevier]

Abstract: A series of flame-retardant epoxy resins containing boron and silicon were obtained through a crosslinking reaction, using tris (2-hydroxypropyl) borate (THPB) together with octaaminophenyl POSS (OapPOSS) as the curing agents. The limiting oxygen index (LOI) reached 30.5% when the contents of boron and silicon in the cured system were 1.5% and 0.5%, respectively, indicating that THPB and OapPOSS exhibited good flame retardant effect on epoxy resins (EP). Microscale combustion calorimetry (MCC) results indicated that the peak heat release rate (PHRR) and total heat release (THR) of the cured systems were reduced by 69% and 46%, respectively, compared to those of pure EP. Moreover, the thermal degradation process and flame retardant mechanism of the composites were investigated by TGA, real time FTIR and TG-FTIR. The chemical components of the char residues were explored by XPS. [Copyright &y& Elsevier]

Abstract: Ethylene vinyl acetate copolymer (EVA) flame retarded by ammonium polyphosphate (APP) and pentaerythritol (PER) was cross-linked by electron beam irradiation. The effects of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of EVA composites were investigated. The volatilized products of EVA/APP/PER composites were characterized by thermogravimetric analysis/infrared spectrometry. As VA content increased, the volatilized products increased in the second decomposition step, but decreased in the third decomposition step. For all samples, the increase of irradiation dose could improve both the gel content and the Limit Oxygen Index (LOI, the minimum oxygen concentration by volume for maintaining the burning of a material) values of irradiated composites. The mechanical and thermal properties of the irradiated EVA composites were also evidently improved at appropriate irradiation dose as compared with those of unirradiated EVA composites, whereas these properties decrease at higher irradiation dose because of the electron beam irradiation-induced oxidative degradation or chain scission. [Copyright &y& Elsevier]

Similar to graphene, few-layer black phosphorus possesses many excellent properties such as good thermal stability, mechanical properties and unique characteristic dimension effects, which is considered as promising nanoadditives. But the low yield and inferior interfacial adhesion with polymer matrix are unavoidable obstruction to fabricate high performance nanocomposites. Herein, we report a facile and environmentally friendly approach to simultaneously exfoliate and modify black phosphorus (BP) by electrochemical cathodic exfoliation, where BP crystal acted as the cathode and ethylene imine polymer (PEI) acted as electrolyte and modifier. The positively charged PEI would uniformly anchor on the surface of the newly peeled-off BP nanosheets through electrostatic attraction effect, resulting in preventing the agglomeration of BP nanosheets and improve the compatibility between BP and waterborne polyurethane (WPU) matrix. Significantly, with the addition of 2.0 wt% PEI modified BP in WPU matrix, the fire safety of WPU composites was enhanced. The peak heat-release rate, total heat release, total smoke production and total CO yield are decreased by 34.3%, 21.2%, 22.3% and 50.2% compared to pure WPU, respectively. Also, the tensile strength of WPU composites was increased by 71% (from 21.9 to 31.0 MPa) at the cost of the breaking elongation slightly decreased by 5.6%. This work provides the possibility for the scalable preparation and a real application of BP in polymer nanocomposites. Image 1 • A facile and environmental route to simultaneously exfoliate and modify BP. • BP-PEI had good flame-retardant contributions in both gaseous and condensed phase. • Functionalized BP enhanced flame-retardant properties of WPU composite. [ABSTRACT FROM AUTHOR]