Flame Retardancy Of Composites Research Articles

Preparation and properties investigation of flame‐retardant rigid polyurethane foam composites based on alkylphosphate oligomer

AbstractIn this work, FR‐PNX, an alkylphosphate oligomer was introduced into rigid polyurethane foam (RPUF) to fabricate FR‐PNX/RPUF composites. The flame retardancy, thermal stability, and combustion properties of composites were investigated by limiting oxygen index (LOI), thermogravimetric (TG), microcalorimetry (MCC), scanning electron microscopy (SEM), et al. The flame retardancy tests demonstrated that the incorporation of 50 phr of FR‐PNX yielded composites that the highest LOI of 23.6 vol% and achieved a V‐0 rating in the UL‐94 test. TG results indicated that FR‐PNX promoted the decomposition of FR‐RPUF in the process, but enhanced the high‐temperature stability of the composites. MCC analyses revealed that the addition of FR‐PNX suppressed the heat release during combustion, and FR‐PNX50/RPUF exhibited the lowest total heat release of 17.3 MJ/m2, a 35% reduction compared to the pure sample. Moreover, the peak heat release rate was decreased to 83.1 W/g, representing a 46.9% reduction compared to pure RPUF. SEM and Raman analyses of the char residue demonstrated that the incorporation of FR‐PNX facilitated the formation of a dense and continuous char layer in the FR‐RPUF, with increased graphitization degree of the char layer, thereby enhancing the composite's fire resistance through the development of a more stable fire barrier.

Core-shell flame retardant/APP-PEI@MXene@ZIF-67: A nanomaterials self-assembly strategy towards reducing fire hazard of thermoplastic polyurethane

Ammonium polyphosphate (APP) is the most commercially valuable phosphorus-based flame retardant, but poor interaction with the polymer interface limits the flame-retardant efficiency. In this work, a new type of multi-layered nanomaterial coating APP (APP-PEI@MXene@ZIF-67) was prepared and introduced into thermoplastic polyurethane (TPU) polymers by a simple and green assembly strategy. The effects of different loading shells of modified APP on the flame retardancy of TPU composites were investigated, as well as their gas/condensed phase thermal degradation products and their flame-retardant mechanisms. The results showed that APP-PEI@MXene@ZIF-67 was more favorable for catalytic char formation than APP, and the residual char formed by its composites was denser and more continuous. Compared with the pure TPU, the pHRR, THR, pSPR, and TSP of TPU/APP-PEI@MXene@ZIF-67–2BL composites were decreased by 72.75 %, 87.25 %, 59.58 %, and 85.97 %, respectively, which significantly reduced the heat and smoke release during the combustion process. The gas-phase and condensed-phase flame retardant mechanisms synergized to construct a possible approach to address the fire risk and heat/smoke hazards of TPUs and promote the extensive application of TPU polymers.

Synergistic flame retardancy of aluminum diethylphosphinate and piperazine pyrophosphate/β‐cyclodextrin in polylactic acid

AbstractPolylactic acid has good biodegradability and processability, but its flammability and serious droplet characteristics limit its development and application. Therefore, developing safer flame‐retardant PLA materials is crucial. This research develops a novel flame‐retardant polylactic acid (PLA) material blend, utilizing aluminum diethylphosphinate (AlPi), piperazine pyrophosphate (PAPP), and β‐cyclodextrin. Optimal synergy occurs at a 5:1 PAPP/β‐CD mass ratio with 4 wt.% AlPi. This combination significantly reduces the heat release peak from 294.89 to 144.21 kW·m−2 and generates non‐combustible residues. The sample forms a stable, uniform carbon layer during combustion due to hydrogen bond crosslinking and Lewis acid–base reactions. The activation energy (Eα) is raised from 264.99 to 281.08 kJ·mol−1 between 312 and 402°C. Thus, an AlPi‐PAPP‐β‐CD based P‐C‐N composite flame retardant is investigated, offering a promising research direction for developing fire‐safe polylactic acid materials. This research may yield valuable insights for diverse applications.

Innovative multifunctional fire retardance of poly(butylene adipate-co-butylene terephthalate)-based bio-composite formulation

Poly(butylene adipate-co-butylene terephthalate) (PBAT), a biodegradable aromatic-aliphatic copolyester, has been widely applied in various fields, but it shows the flammability, resulting in serious fire risk. The flame retardancy of some PBAT/polymer blend systems have been studied, but that of neat PBAT was seldom reported. In particular, the research and development of the bio-based green flame retardant agent is highly desired. In this work, fully bio-derived modified chitosan particles (C-CS), were synthesized and used to prepare a novel PBAT-based multifunctional flame-retardant composite. The PBAT/3%C-CS composite (PC3) exhibited an excellent anti-dripping and self-extinguishing performance and achieved the highest fire safety rating (V-0). Peak of heat release rate and total heat release reduced by 39.8 % and 14.9 %, respectively. The char residue yield of the PC3 increased by 211.6 % in the PC3, compared with that of neat PBAT. Both condensed- and gas-phase played dual roles on increasing the flame-retardant performance of the PC3. The PC3 showed a relatively compact and continuous char layer which acted as a physical barrier to suppress the heat exchange and O2 entry (into the matrix) in the combustion process. Meanwhile, the concentration of O2 and H·/HO· free radicals were diluted by a small portion of non-flammable gas products in the pyrolysis process. Also, the PC3 presented elevated crystallizability and anti-bacterial effect, and reduced UV-transmittance characteristic.

Phosphononitrile based bismaleimide electronic packaging substrate with both fire safety and dielectric properties: Assisting 5G communication

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 (Dk) 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.

Recent Progress in Two-Dimensional Nanomaterials for Flame Retardance and Fire-Warning Applications.

Graphene-like 2D nanomaterials, such as graphene, MXene, molybdenum disulfide, and boron nitride, present a promising avenue for eco-friendly flame retardants. Their inherent characteristics, including metal-like conductivity, high specific surface area, electron transport capacity, and solution processability, make them highly suitable for applications in both structural fire protection and fire alarm systems. This review offers an up-to-date exploration of advancements in flame retardant composites, utilizing pristine graphene-like nanosheets, versatile graphene-like nanosheets with multiple functions, and collaborative systems based on these nanomaterials. Moreover, graphene-like 2D nanomaterials exhibit considerable potential in the development of early fire alarm systems, enabling timely warnings. This review provides an overview of flame-retarding and fire-warning mechanisms, diverse multifunctional nanocomposites, and the evolving trends in the development of fire alarm systems anchored in graphene-like 2D nanomaterials and their derivatives. Ultimately, the existing challenges and prospective directions for the utilization of graphene-like 2D nanomaterials in flame retardant and fire-warning applications are put forward.

Non-combustible polymer composites with extremely high filler loading via polytetrafluoroethylene fibrillation

The incorporation of halogen-free flame retardants (FRs) into polymer matrices is a cost-effective and eco-friendly method for suppressing flames and smoke and enhancing fire safety. In energy applications, a high FR loading (e.g., >80 wt%) is often necessary owing to the excessive heat and toxic gases generated by the devices and components. However, achieving this in conventional polymer composites is significantly impeded by poor processability stemming from increased melt viscosity. This study proposes a new approach to fabricate highly loaded flame-retardant composites with an extremely high FR content of 95 wt% via fibrillation of thermally stable polytetrafluoroethylene (PTFE), which holds two different types of FRs, magnesium hydroxide (MH) and expandable graphite (EG). The hybrid composites exhibit excellent flame retardancy owing to the synergistic effects of the distinct mechanisms of the two fillers, securing a top V-0 rating in the UL-94 vertical burning test and a limiting oxygen index (LOI) exceeding 95 %. Importantly, their total heat release (THR) from the cone calorimeter test is less than 1 MJ/m2, an anomalously low value that meets the criteria for non-combustible materials (THR <8 MJ/m2). Alongside their non-combustible attributes, the composites also have high thermal conductivity, reaching up to 1.60 W/m·K, due to the presence of thermally conductive EGs. We believe that these composites and their fabrication methodology can offer new insights into the design of flame-retardant composites, which are likely to be applicable in practical applications involving severe fire hazards, such as batteries, electronics, and electric vehicles.

A strategy toward improving flame retardancy and thermal oxidative stability of polyamide 6 based on cuprous diethylphosphinate

With the number of vehicles increases every year, the demand for flame retardant and thermal oxidative stabilized PA6 has also surged significantly. Therefore, it is crucial to improve the flame retardancy and thermal oxidative stability of PA6. In this regard, a novel dual-functional cuprous diethylphosphinate (CuDP) was successfully prepared through an ion exchange reaction and was used to prepare PA6 composites. The effects of CuDP on the flame retardancy and thermal oxidative stability of PA6 composites were studied in detail. In contrast with an LOI value of 22.6, pHRR of 911.3 kW m−2, and THR of 109.2 MJ m−2 for pure PA6, the addition of 15 wt% of CuDP upgrades the LOI value to 28.2 and reached UL-94 V-0 rating. Meanwhile, there was a 43.8 %, 22.3 % and 17.9 % decrease in pHRR, THR and av-CO2Y, respectively. In addition, the flame retardant mechanism of CuDP was explored in detail, where CuDP can encourage PA6 to form a protective char layer in the condense phase and quench free radicals in the gas phase. Moreover, the incorporation of CuDP helped maintain the mechanical properties of PA6 composites during accelerated thermal oxidative aging experiments. This work presents a new approach for enhancing the flame retardancy and thermal oxidative stability of PA6 composites, which paves the way for its broader application.

Enhancing the UV resistance and flame retardancy of epoxy resin composites with fluorescent carbon dots

AbstractCarbon dots (CDs) are a novel class of carbon material which have gained widespread usages owing to their exceptional optical properties, low toxicity, and high biocompatibility. The nitrogen‐doped carbon dots (N‐CDs) using a normal curing agent of 4,4′‐diaminodiphenylmethane as resource was expected to not only have good compatibility with epoxy resin (EP), but also bring luminescent property to EP composites. It was interesting that the N‐CDs‐EP composites with 12.5 wt% addition exhibited a limiting oxygen index value of 31.4% and reached UL‐94 V‐1 grade, indicating a good flame retardancy. Compared with pure EP, the incorporation of N‐CDs formed more residual char and had extra smoke suppression effect. Besides, the N‐CDs‐EP composites exhibited a low transmittance less than 10% for the light wavelength below 490 nm. The N‐CDs contributed to the light shielding capabilities of the N‐CDs‐EP composites, which could effectively shield purple, blue, and cyan light. Furthermore, the mechanical properties including bending strength and impact strength, the dielectric property, and hydrophobicity of N‐CDs‐EP composites were also improved. The simple but effective modification strategy might be expected to be applied in many polymer systems.

Synchronous modification of ZIF-67 with cyclomatrix polyphosphazene coating for efficient flame retardancy and mechanical reinforcement of epoxy resin

Cyclomatrix polyphosphazenes have attracted widespread attention in the field of polymer flame retardancy. Nevertheless, the optimal manifestation of their distinctive structural attributes and flame-retardant properties necessitates a judicious selection of condensation monomers and synergistic templates during the fabrication of polyphosphazene flame retardants. In our previous studies, it was discovered that when ZIF-67 is functionalized with polyphosphazene, the by-product HCl from phosphazene polycondensation causes etching on ZIF-67. Based on this “synchronous etching” effect, a series of hybrid materials comprising cyclomatrix polyphosphazene and ZIF-67, denoted as ZIF-67@PDS (PDS, poly-(cyclotriphosphazene-co-4,4’-diaminodiphenyl sulfone)), ZIF-67@PBS (PBS, poly-(cyclotriphosphazene-co-Bisphenol A)), and ZIF-67@PZS (PZS, poly-(cyclotriphosphazene-co-4,4’-sulfonyldiphenol)), was synthesized utilizing DDS (4,4’-diaminodiphenyl sulfone), BPA (Bisphenol A), and BPS (4,4’-sulfonyldiphenol) monomers as precursors, respectively. Upon the incorporation of 2.0 wt.% of ZIF-67@PDS, ZIF-67@PBS, and ZIF-67@PZS, the flame retardant and mechanical characteristics of EP composites exhibited marked enhancement. The unique structural characteristics of hybrid and the synergistic effects of Co-P-N contribute to the improvement of comprehensive properties. Compared with pure EP, EP/ZIF-67@PZS has the best enhancement effect, and its pHRR, THR, and TSP decreased by 34.0%, 30.0%, and 40.5%, respectively. In terms of mechanical strength, ZIF-67@PZS also increases the flexural strength of EP by 37.42%. Relying on the “synchronous etching” effect, this study explores and verifies the effective combination of ZIF-67 and different types of polyphosphazenes, and obtains a series of ZIF-67-derived cyclomatrix polyphosphazene hybrids with different morphologies and properties in one step. It provides a new idea and strategy for the simultaneous modification of polyphosphazene materials and the preparation of multifunctional flame retardants in the future.

The investigation of flame-retardant fiber mats for high performance composites: flame retardancy and structure performance

The flame-retardant performance of carbon fiber reinforced composites serves as a critical metric for structural stability. Nonetheless, the prevalent methodologies for improving the flame retardancy of composites struggle to reconcile the dual objectives of flame retardancy and mechanical robustness, due in part to the constraints imposed by the conventional additive-based approach on the material interface. This study introduced a novel method involving a glass fiber mat, which was augmented with a polyurethane-based treatment integrated with flame-retardant substances, in particular ammonium polyphosphate and nickel hydroxide. This fiber mat was strategically applied to the composite surface, conferring both flame retardancy and enhanced structural resilience. The structure performance and flame retardancy of composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and the cone calorimeter test. Experimental comparisons with nontreated controls indicated that the innovative composites exhibited a reduction in total heat release and total smoke production by 13.7% and 18.8%, respectively. Concurrently, a notable enhancement in mechanical properties was observed, with increases of 20.9% and 23.1% for tensile and flexural strength. This well-balanced performance is attributable to the structure design, with toughened glass fiber mats to protect the composite surfaces from structural failure, and flame-retardant agent composition for combustion resistance and smoke suppression. Consequently, the proposed integrative flame-retardant structural design, enriched with specific flame-retardant treatments, offers a promising avenue for fabricating high-performance composite materials with potential utility in the aviation and aerospace sectors.

Synergistic flame‐retardant effects between silane coupling agents modified expanded graphite and Pt catalyst in silicone rubber composites

AbstractIn this work, different kinds of silane coupling agents modified expanded graphite (MEG) fillers were successfully prepared and then incorporated into silicon rubber matrix to fabricate flame‐retardant composite materials (SR/MEG). The inserted MEG fillers with siloxane chains exhibited good compatibility with the silicon rubber matrix, which cannot only reduce the negative impact of adding fillers on mechanical properties but also endow the silicon rubber composites with ideal flame retardancy. Subsequently, platinum (Pt) catalyst was incorporated into the SR/MEG composites to prepare SR/MEG/Pt composites, and the synergistic effects of MEG and Pt catalyst on the thermal stability, flame retardancy, and combustion behavior of silicon rubber composites were systematically investigated. The target SR/MEG/Pt composite with appropriate addition of MEG and Pt catalyst can obtain relatively high char residue of 41.9% and limiting oxygen index value of 29.6%, as well as achieve V‐0 rating in the vertical combustion test, owing to the formation of expanded and dense silicon–carbon protective layer under the catalysis of Pt catalyst. Moreover, the cone calorimeter test results showed that the peak of heat release rate and total heat release of SR/MEG composites were further reduced after the addition of an appropriate amount of Pt catalyst, manifesting the good synergistic effect of MEG and Pt catalyst on the flame retardancy performance of silicon rubber. The method proposed herein may provide a promising way for fabricating high‐performance flame‐retardant silicone rubber materials.

Preparation of flame retardant and antibacterial polyacrylonitrile composites based on modified microcrystalline cellulose loaded silver nanoparticles

To improve the fire safety of polyacrylonitrile (PAN) and expand its application area, flame retardant and antibacterial PAN composite was prepared by a simple and environmentally friendly method. First, AgNO3 and NaBH4 solutions were added to the microcrystalline cellulose (MCC) aqueous suspension to prepare MCC loaded Ag nanoparticles (Ag NPs) (MCC/Ag) by in situ reduction. Then, MCC/Ag was mixed in PAN solution to prepare MCC/Ag/PAN composite, which was then phosphorylated by phytic acid (PA) to obtain flame retardant MCC/Ag/PAN composite (FR-MCC/Ag/PAN). FR-MCC/Ag/PAN could achieve self-extinguishing with limiting oxygen index (LOI) value of 36.8 %. The thermogravimetric results showed that phosphorus-containing acids accelerated the char-forming ability of FR-MCC/Ag/PAN, and the final char residue was up to 29.76 % in air atmosphere. Thermogravimetric coupled with Fourier transform infrared spectroscopy (TG-FTIR) and scanning electron microscope (SEM) showed that FR-MCC/Ag/PAN formed an expanded and dense char layer after combustion, suppressing the release of low molecular toxic gases. Moreover, FR-MCC/Ag/PAN showed favorable inhibition of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This work proposed a novel method for developing flame retardant and antibacterial PAN material, which broadened the application field of polyacrylonitrile.

Preparation and Modification of Flexible Polyurethane Foam for Effective Flame Resistance and Sound Absorption

Polyurethane foam as an important sound absorption material is limited by the poor flame resistances in building field, but the modifications of flame resistances tend to have adverse effects on the sound absorption performance. Herein, dibutyltin dilaurate and triethylenediamine are used simultaneously as catalysts, and four new types of flame retardant polyether polyols (FPMPO) are synthesized and combined with modified expanded graphite (PEG) to prepare the flame resistance flexible polyurethane foam (FFPUF) by one-step method. The results show that the combination of the two catalysts can control the cell structure of FFPUF availably for sound absorption. The FPMPO have little negative influence on the cell morphology and the sound absorption performance of FFPUF, but the increase of flame resistances is finite due to the limited amount of FPMPO. In order to improve the flame retardant properties further, the FPMPO and the PEG are combined in the modification. Benefitting by the effective control structure and the modification with composite flame retardant, the FFPUF shows excellent sound absorption and flame retardant properties. The LOI value of FFPUF is 33.4 and the vertical burning level reaches V-0, and the average sound absorption coefficient maintains 0.68 in the 800-6300 Hz range.

A tannic acid-based intumescent flame retardant for improving flame retardancy of epoxy composites

A biomass intumescent flame retardant (TA-g-DOPO) was fabricated from tannic acid (TA) and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) through the bridge of silane coupling agent (KH560), which showed a low degradation rate at Tmax of 2.71%/min and a high char yield of 55.8%. Then, various EP composites with 4–10% TA-g-DOPO were prepared. Due to the presence of flexible silane structures and rigid phosphaphenanthrene rings as well as the remained phenol groups (tending to form hydrogen bonds with epoxy matrix), EP composite with a high content of 10% TA-g-DOPO exhibited no deterioration on the tensile and impact properties as well as the glass transition temperature (Tg) when compared with pure EP. More importantly, it reached a high LOI value of 30.3% and passed a V-0 rating in the UL-94 burning test. Additionally, its peak heat release rate (PHRR), total heat release (THR) and average mass loss rate (av-MLR) decreased by 23.2%, 15.5% and 30.2% respectively. Analyses from the condensed char and pyrolysis gases indicated that the improved flame retardancy was mainly attributed to the cooperation of the free-radical quenching effect of P-containing radicals and phenoxy radicals working in stages (derived from DOPO and TA respectively) and the physical barrier effect caused by the highly graphited, intumescent and porous char layer (reinforced by P- and Si-containing cross-linked structures). This work provides a sustainable biomass flame retardant with good flame-retarding efficiency based on TA.

Preparation and properties of multilayer core-shell structure ammonium polyphosphate synergistic with THEIC for flame retardant LDPE

In this paper, a new type of highly efficient intumescent flame-retardant low-density polyethylene composite was prepared using two key technologies, namely, microencapsulation encapsulation technology and novel carbon formation technology. Precisely, β-cyclodextrin encapsulated modified ammonium polyphosphate@melamine formaldehyde resin (β-CDMCAPP@MF) was prepared by using Si-IFR synergistic flame retardant effect combined with the gel-solution method, and then flame retardant low-density polyethylene (LDPE) was prepared by compounding with tris-(2-hydroxyethyl) isocyanate (THEIC). The results showed that β-CDMCAPP@MF was modified with MF, β-CD, and silica coating. This modification resulted in excellent hydrophobicity and good compatibility with LDPE. The addition of IFR containing β-CDMCAPP@MF significantly improved the flame retardancy of the LDPE composites. Specifically, when 30 wt% of β-CDMCAPP@MF was added, the ultimate oxygen index of the composites reached 24.7 %, and V-0 grade and the tensile strength went 11.41 MPa. Compared with IFR/LDPE with the same proportion of MF@MCAPP and β-CD@MCAPP, the ultimate oxygen indices were increased by 9.72 % and 12.15 %, respectively. The introduction of THEIC into the flame retardant system resulted in a LOI value of 36.5 % and an FRI value of 2.523, which is 32.33 % higher than that of the composites containing 30 wt% of the flame retardant system (without THEIC). Cone calorimetry test results showed that introducing β-CDMCAPP@MF and THEIC significantly improved the smoke emission.

Synergistic effects of organosilicon flame retardant and DOPO-based reactive compatibilizer for high performance PC/PBT composites

PC/PBT alloy is flammable resulting in fire safety hazards in practical applications and the existing flame retardants have a great influence on the mechanical properties, which limits its application range. Therefore, it is an urgent problem to improve the flame retardancy of PC/PBT alloy while taking its mechanical properties into account. Herein, a novel flame retardant and reactive compatibilizer was synthesized by grafting 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) onto ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA), named as DOPO-EG, to improve the flame retardancy and mechanical properties of PC/PBT alloy simultaneously. Additionally, based on the effective synergistic effect of enhancing the charring and flame retardancy between silicon and phosphorus, the organosilicon flame retardant (RMSi) is introduced and compounded with DOPO-EG to prepare excellent flame retardancy PC/PBT/DOPO-EG/RMSi composites. The results showed that the PC/PBT/DOPO-EG/RMSi composites with 10 wt% DOPO-EG and 8 wt% RMSi (CBE10P10Si8) reached UL-94 V-0 rating and the peak of heat release rate (PHRR) and total heat release rate (THR) of CBE10P10Si8 decreased by 42% and 16% respectively. This is due to the fact that DOPO is cracked into phosphorus radicals to capture and eliminate the active H and OH radicals, inhibiting the chain free radical reaction, and RMSi is enriched on the surface of CBE10P10Si8 to form an inorganic oxygen insulation protective layer during combustion. The impact strength of CBE10P10Si8 increased from 5.8 kJ/m2 to 11.9 kJ/m2. The improvement of impact strength is owing to the existence of DOPO-EG which promotes the formation of the interface layer between PC and PBT phases, resulting in the transfer of stress between the two phases. This work provides a new method for the preparation of PC/PBT alloy with excellent flame retardancy and mechanical properties, and also provides a certain reference value for the research of flame retardancy and toughening modification of polymer composites.

Flame retardance and fume inhibition of bio-based composite flame retardant on bituminous combustion and its numerical models

To investigate the effects of sustainable bio-based composite flame retardant (BCFR) on flame retardance and fume suppression of bitumen and establish unified combustion models of bitumen and BCFR bitumen, the mass loss and fume release during bituminous and BCFR bituminous combustion processes were studied using thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) tests. Results show that when bitumen burns out, BCFR bitumen remains the residue rates of 33%, 28% and 21% at 5, 10 and 15 °C/min, respectively. BCFR dilutes active free radicals involved in combustion at early bituminous combustion stage, thus reducing the reaction rate, and then inhibits bituminous combustion by forming intumescent char layer, increasing the char yield of bitumen, strengthening the thermal stability of char produced from bituminous combustion. BCFR does not reduce the kinds of fume constituents released from bituminous combustion but inhibits the release of aldehydes and phenols mainly by suppressing the oxidation reaction at early bituminous combustion stage. BCFR can effectively suppress the fumes release amount during bituminous combustion at lower heating rates. The proportions of alkanes and ketones released at the second and third stages of BCFR bituminous combustion are larger than those of bituminous combustion by 9.27% and 5.8% at 15 °C/min, respectively. Although BCFR has limited inhibitory effects on fume release amount at a larger heating rate, it inhibits the volatilization and combustion of alkanes in bitumen. Meanwhile, the combustion models of bitumen and BCFR bitumen established can better reproduce TG test results. This study develops a cleaner and more efficient bio-based flame retardant, and provides a reliable bituminous combustion model for large-scale fire simulation.

Multiple synergistic effects of silicon-containing flame retardants and DOPO derivative enhance the flame retardancy of epoxy resin

ABSTRACT Presuming that the filler structure can regulate the flame retardancy of polymeric materials, this study investigates the flame-retardant properties of EP-containing phosphorus/silicon. Sepiolite (Sep) fibers and SiO2 nanoparticles are shown to synergistically enhance the flame retardancy of EP-based composites. The underlying retardant mechanisms of the synergistic effect are also discussed and the mechanical properties of EP-based composites are examined. Among the prepared composites, EP/DiDOPO/Sep5&SiO25 (DiDOPO = derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) achieved the maximum limiting oxygen index (29.4%) and a UL-94 V-0 rating. The EP/DiDOPO/Sep5&SiO25 composites also minimized the peak heat-release rate and total heat release and maximized the strength and modulus.

Preparation of flame retardant and antibacterial polyacrylonitrile based on Cu2+ chelated six-armed star-type flame retardant SCCP and chitosan

In this work, a six-armed star-type flame retardant (SCCP) contained phosphorus, nitrogen and sulfur contents was developed, which was then combined with chitosan (CS) to chelate Cu2+ (SCCP@CS-Cu) and blend with polyacrylonitrile (PAN) to produce flame retardant and antibacterial PAN composite (PAN/SCCP@CS-Cu). TG showed that the residual char of PAN/SCCP@CS-Cu in air and nitrogen atmosphere was as high as 16.41 % and 48.48 % at 800 °C, respectively, which were greater than that of PAN. The LOI value of PAN/SCCP@CS-Cu improved to 33.0 % and the peak heat release rate (PHRR) and total heat release (THR) of the composite were all greatly reduced. In addition, the total smoke production (TSP) of PAN/SCCP@CS-Cu decreased by 73.6 % compared to the control sample. Interestingly, the antibacterial properties of PAN/SCCP@CS-Cu against E. coli and S. aureus reached 98.45 % and 99.33 %. This work provides an insight into developing an environmentally friendly PAN composite with flame retardancy, smoke suppression and antibacterial properties, greatly expanding its application field.