Flame Retardant System Research Articles

An Investigation towards Coupling Molecular Dynamics with Computational Fluid Dynamics for Modelling Polymer Pyrolysis

Building polymers implemented into building panels and exterior façades have been determined as the major contributor to severe fire incidents, including the 2017 Grenfell Tower fire incident. To gain a deeper understanding of the pyrolysis process of these polymer composites, this work proposes a multi-scale modelling framework comprising of applying the kinetics parameters and detailed pyrolysis gas volatiles (parent combustion fuel and key precursor species) extracted from Molecular Dynamics models to a macro-scale Computational Fluid Dynamics fire model. The modelling framework was tested for pure and flame-retardant polyethylene systems. Based on the modelling results, the chemical distribution of the fully decomposed chemical compounds was realised for the selected polymers. Subsequently, the identified gas volatiles from solid to gas phases were applied as the parent fuel in the detailed chemical kinetics combustion model for enhanced predictions of toxic gas, charring, and smoke particulate predictions. The results demonstrate the potential application of the developed model in the simulation of different polymer materials without substantial prior knowledge of the thermal degradation properties from costly experiments.

Flame Retardant Properties and Mechanical Properties of Polypropylene with Halogen and Halogen-Free Flame Retardant System

In this study, to improve the flame retardancy properties of polypropylene, DBDPE/Sb2O3 and DBDPE/HBCD/Sb2O3 flame retardant systems were used for flame retardant PP, and a halogen-free flame retardant PP material was prepared using the one-component intumescent flame retardant PNP1D. Tensile tests, impact tests, ultimate oxygen index, UL94V-0 vertical combustion, thermogravimetric analysis, rheological analysis and scanning electron microscopy were used to study the flame retardant properties and mechanical properties of the flame retardant PP. The test results show that both the ultimate oxygen index of DBDPE/Sb2O3 compounded flame retardant PP and the ultimate oxygen index of PNP1D flame retardant PP are nearly double that of pure PP, passing the UL-94V-0 flame retardant standard. The thermal decomposition temperature range of DBDPE/Sb2O3 compounded system and the thermal decomposition temperature range of PNP1D flame retardant PP both completely cover the thermal decomposition temperature range of both the DBDPE/Sb2O3 compound system and PNP1D flame retardant PP completely covered the thermal decomposition temperature range of pure PP. The tensile and impact strength of the DBDPE/Sb2O3 flame retardant system with 10% SK-80 is 50% higher than that of the DBDPE/Sb2O3 flame retardant system without SK-80. The modified PP with 25% PNP1D is nearly 1 time higher than pure PP in terms of carbon formation and has an ideal flame retardant effect.

Effect of MMT on Flame Retardancy of PLA/IFR/LDH Composites

Nano filler synergistic intumescent flame retardant (IFR) system is an effective way to improve the flame retardant properties of polymer. In this study, the effects of montmorillonite (MMT) on the flame retardant properties of polylactic acid/layered double hydroxides (PLA/LDH) and PLA/IFR/LDH were investigated. The results show that both LDH and LDH/IFR can reduce the peak heat release rate (HRR) of PLA and prolong the combustion time of PLA; When a proportionate MMT is introduced into PLA/LDH and PLA/IFR/LDH systems, respectively, MMT will not only affect the degradation process of PLA composites during combustion, but also the PLA composites can form a more stable carbon layer during combustion, which could decrease the peak HRR and prolong combustion time of PLA composite. Furthermore, when 0.5 wt% MMT is incorporated, the peak HRR of LDH/ IFR/LDH composite is reduced by 16.17% and the combustion time is prolonged by about 70 s. This study can provide an opportunity to further optimize the properties of intumescent flame retardant polymer.

Эффективность комбинации огнезащитных вспучивающихся покрытий для стальных конструкций

Introduction. Steel constructions are one of the most widely used and rational types of constructions for buildings and structures of various functional purposes. As advantages in comparison with constructions made of other materials, their high load-bearing capacity, industriality, ease of installation are noted. One of the disadvantages is low fire resistance. A common way to increase the fire resistance of metal structures is considered to be the use of fire protection products, the experience of which has been developed for many decades. However, as practice and the results of fire tests show, it is quite difficult to obtain a stable and reliable result using such fire-retardant systems. Goals and objectives. Analysis of work on the creation of effective flame retardant technologies. Development of formulations of thin-layer bulging coatings, taking into account their use as protective layers of combined flame retardant systems. Evaluation of the characteristics of the resulting foam layers of the developed coatings. Conducting a comparative analysis of the effectiveness of combined technologies of intumescent fire protection. Methods. The research was based on experiments conducted in a firing furnace, with the possibility of isothermal or dynamic radiation heating of the surface of a steel sample up to 1000 °С. The installation makes it possible to study the properties and structure of the expanded layer of flame-retardant coatings and their thermal insulation ability under unilateral thermal exposure. Thermoelectric converters were used to measure the temperature on the unheated surface of the sample. Results and discussion. The conducted analysis of the works testifies to numerous studies in this direction. The development of intumescent systems is of great interest. In the course of the research, the authors have developed various formulations of thin-layer flame retardant coatings, as well as their combinations based on innovative chemical technologies for steel constructions, taking into account the availability and manufacturability of the raw materials used. The results of studies on the evaluation of the thermal insulation ability of the developed foam systems have shown that the fire-retardant effect due to the combination of various swelling coatings can be increased by 30 % or more. Conclusion. A new scientific direction has been formed related to the creation of combinations of bulging flame-retardant coatings for various construction structures. The establishment of various options for the combination of the use of fire-resistant coatings opens up wide opportunities for the creation of effective protection of various building materials and structures from the effects of fire. Keywords: combined fire protection, intumescent coatings, swelling, foam, thermal insulation ability, steel constructions.

A flame retardant containing biomass-based polydopamine for high-performance rigid polyurethane foam

An inorganic/polymer flame retardant system constructed from biomass can improve the comprehensive properties of rigid polyurethane foam.

An Eco-Friendly, Bio-Inspired and Synergistic Flame Retardant System with Outstanding Water Tolerance and Ultra-Low Addition for Silicone Rubber

An Eco-Friendly, Bio-Inspired and Synergistic Flame Retardant System with Outstanding Water Tolerance and Ultra-Low Addition for Silicone Rubber

Influence of the Process of Synthesis of Zeolites from Volcanic Ash in Its Synergistic Action as a Flame-Retardant for Polypropylene Composites

In this research, the influence of natural zeolites obtained from the volcanic ash of the Ubinas volcano has been studied as synergistic agents in a flame-retardant system (composed of ammonium polyphosphate, pentaerythritol, and polypropylene). Four zeolites were synthesized from volcanic ash, including those that had been calcined and those that had not. These were then placed in an alkaline solution at three synthesis temperatures. Zeolites were characterized through X-ray diffraction, specific surface area by nitrogen adsorption analysis (Brunauer–Emmett–Teller) and scanning electron microscopy. Polypropylene matrix composites were prepared with ammonium polyphosphate, pentaerythritol and zeolites at 1, 5 and 9%. Its thermal stability and fire resistance were evaluated by thermogravimetric analysis, limiting oxygen index, vertical burning test and cone calorimeter and its morphological structure by scanning electron microscopy. It was determined that the synthesis temperature and the use of calcined and without calcined volcanic ash have an influence on the characteristics of the zeolites and on its synergistic action.

Effect of amino acid‐triazine copolymer on intumescent flame retardant ethylene‐vinyl acetate

AbstractAmino acid‐triazine copolymer (CC‐Lys) was prepared by using lysine (Lys) and cyanuric chloride (CC). The structure and performance of CC‐Lys were tested by using Fourier transform infrared spectroscopy and thermogravimetric analysis. The CC‐Lys, ammonium polyphosphate (APP) and organic montmorillonite (OMMT), were applied in ethylene‐vinyl acetate (EVA) to improve its flame retardancy. The results showed that 20 wt% APP/CC‐Lys/OMMT makes EVA achieve the UL‐94 V0 rating. The reactions among APP/CC‐Lys/OMMT release some incombustible gases and promote the formation of a porous char layer with good barrier performance during combustion. Moreover, the quality of the char layer is improved. In addition, the peak of heat release rate of EVA composite is reduced by 87% and time to ignition is delayed. This work provides a good flame retardant system for EVA.

Modification of Glass/Polyester Laminates with Flame Retardants.

This paper presents a review of flame retardants used for glass/polyester laminates. It concerns flame retardants withdrawn from use such as compounds containing halogen atoms and flame retardants currently used in the industry, such as inorganic hydroxides, phosphorus and nitrogen-containing compounds, antimony, and boron compounds, as well as tin–zinc compounds. Attention is also drawn to the use of nanoclays and the production of nanocomposites, intumescent flame retardant systems, and mats, as well as polyhedral oligomeric silsesquioxanes. The paper discusses the action mechanism of particular flame retardants and presents their advantages and disadvantages.

Bio-Based Flame-Retardant Coatings Based on the Synergistic Combination of Tannic Acid and Phytic Acid for Nylon-Cotton Blends.

Natural and synthetic polymeric fibers are used extensively in making fabrics for a variety of civilian and military applications. Due to the durability and comfort, nyco, a 50-50% blend of nylon 66 and cotton, is used as the material of choice in many applications including military uniforms. This fabric is flammable due to the presence of cotton and nylon but has good mechanical properties and is comfortable to wear. Here, we report a novel surface functionalization method that utilizes a synergistic combination of bio-based materials, tannic acid (TA) and phytic acid (PA), to impart flame-retardant (FR) properties to the nyco fabric. TA and PA were sequentially attached to nylon and cotton fibers through hydrogen bonding interactions and phosphorylation, respectively. The surface functionalization of the treated fabrics was confirmed using Fourier-transform infrared spectroscopy. Thermogravimetric analysis, microscale combustion calorimetry, cone calorimetry, and vertical flame testing were employed to study the effect of the functionalization on the thermal stability and flammability of the nyco fabric. Though reasonable durable functionalization is observed from elemental analysis, it is not enough to impart wash-durable FR treatment. These results indicate that flame retardancy is enabled through the enhanced char formation provided by the combination of TA and PA. The TA-PA system applied to nyco shows great promise as a bio-based FR system. This study for the first time also provides evidence for the selectivity of TA in imparting FR characteristics for nylon and PA in imparting FR properties for cotton. The combination of TA and PA provides promising FR characteristics to nyco.

Preparation of Mn2+ Doped Piperazine Phosphate as a Char-Forming Agent for Improving the Fire Safety of Polypropylene/Ammonium Polyphosphate Composites.

A piperazine phosphate doped with Mn2+ (HP-Mn), as a new char-forming agent for intumescent flame retardant systems (IFR), was designed and synthesized using 1-hydroxy ethylidene-1,1-diphosphonic acid, piperazine, and manganese acetate tetrahydrate as raw materials. The effect of HP-Mn and ammonium polyphosphate (APP) on the fire safety and thermal stability of polypropylene (PP) was investigated. The results showed that the combined incorporation of 25 wt.% APP/HP-Mn at a ratio of 1:1 endowed the flame retardant PP (PP6) composite with the limiting oxygen index (LOI) of 30.7% and UL-94 V-0 rating. In comparison with the pure PP, the peak heat release rate (PHRR), the total heat release (THR), and the smoke production rate (PSPR) of the PP6 were reduced by 74%, 30%, and 70%, respectively. SEM and Raman analysis of the char residues demonstrated that the Mn2+ displayed a catalytic cross-linking charring ability to form a continuous and compact carbon layer with a high degree of graphitization, which can effectively improve the flame retardancy of PP/APP composites. A possible flame-retardant mechanism was proposed to reveal the synergistic effect between APP and HP-Mn.

A study on the modification of polypropylene by a star-shaped intumescent flame retardant containing phosphorus and nitrogen

In this paper, a star-shaped char forming agent BTETP containing phosphorus and nitrogen is synthesized and characterized in the paper. It is compounded with ammonium polyphosphate (APP) to form an intumescent flame-retardant system. The stable star-shaped structure is constructed, and the insulating char layer is formed on the surface of the polymer matrix by the synergistic effect between phosphorus and nitrogen, thus, the high-performance flame retardant PP is obtained. Its flame retardancy and thermal stability are studied by limiting oxygen index (LOI), vertical combustion test (UL-94), cone calorimetry (CCT), and thermogravimetric analysis (TGA). With only a 20 wt% addition of BTETP/APP (1:2), the PP composite can reach the UL-94 v-0 level, while the peak heat release rate (PHRR), total heat release rate (THR), and average mass loss rate (AV-MLR) are significantly reduced compared with pure PP, showing higher fire safety. Moreover, the residue at 800 °C can reach as high as 9%, indicating that the loading of BTETP/APP is conducive to promoting carbonization of the degradation products of PP to generate more char. In addition, the synergistic effect and the flame retardant mechanism are studied and discussed. This study provides a program for the synthesis of flame retardants with a high-performance and effectively avoids the problem existing in traditional flame retarding approaches.

Effect of Functionality of Organophosphorus Flame Retardants on Flammability and Thermal Stability of DGEBA-Based Epoxy Resin Nanocomposites

Background: Epoxy resins have been extensively used in fire hazard environments, such as printed circuit boards, electrical isolation materials, adhesives, construction, and transportation due to their economically viable, simple processing. Therefore, the development of thermally stable and flame-retardant epoxy resin systems is essential. Objective: The aim of the present study was to study the effect of the functionality of organophosphorus flame retardants on DGEBA-based epoxy resin nanocomposites on thermal stability and flame retardancy. Method: DGEBA (diglycidyl ether of bisphenol-A)-based epoxy resin nanocomposites having 2.0 wt% phosphorus were prepared with organophosphorus flame retardants with different functionalities by using an in-situ polymerization method. The flame retardant compounds uni-functional 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and bi-functional 2-(6-oxid-6Hdibenz [c, e] [1, 2] oxaphosphorin 6-yl) 1, 4-benzenediol (DOPO-HQ) were prepared. The thermal behavior of composites was studied by TG and DTA techniques. The flammability behavior was investigated by UL-94 and limiting oxygen index (LOI) tests. Results: The XRD and TEM results showed the mixed dispersion of nanoclay platelets in an epoxy matrix. The thermal stability of the epoxy composite (EPDOPO-HQ) containing bi-functional DOPOHQ is increased by 16°C in comparison to the epoxy composite (EPDOPO) containing uni-functional DOPO. According to the TG analysis, the addition of nanoclay was observed to be more effective and synergistic with bi-functional DOPO-HQ as the EPDOPO-HQ/NC sample gains more resistance to degradation after around 450°C and also gave rise to a high char yield. Epoxy resin samples containing reactive flame retardants gave UL-94 V-0 rating, but further addition of 2.0 wt% nanoclay lowered the rating from V-0 to V-1. Conclusions: TG analysis of the epoxy composite samples showed that the addition of nanoclay were observed to be synergistic with bi-functional flame retardant (DOPO-HQ) as the EPDOPO-HQ/NC sample gained more resistance to degradation after around 450°C due to the formation of mixed intercalated and exfoliated structure. The EPDOPO-HQ sample gave a high char yield with increased onset degradation temperature, high thermal stability as well as high flame retardancy.

Influence of ingredients on the properties of the flame retardant compound based on polyethylene

In this paper, the effects of a flame retardant system combining ATH/MPP (aluminum hydroxide/melamine phosphate) and the other additives such as zinc stearate (ZnSt) on some properties of flame retardant PE compound based on LDPE were studied. The total flame retardant content was 35% by weight. Mechanical properties (tensile at break, elongation at break), thermal stability, and fire resistance were determined by the respective methods ASTM D638, thermogravimetric analysis (TGA), scanning electron microscope (SEM), and UL-94 test. The obtained results showed that using the combination of ATH/MPP has increased the fire resistance and thermal stability of the PE compound. The sample CT7 (15%ATH/20%MPP/2%ZnSt) achieved the best fire resistance. The mechanical properties increased slightly when increasing the content of MPP and reached the maximum for samples containing only MPP. The SEM micrographs showed that the addition of zinc stearate improved the dispersion of ATH and MPP in the PE matrix. The effect of flame retardant additives and zinc stearate on the melt index value of the PE compound was also surveyed.

Study on the preparation and inhibition mechanism of intumescent nanogel for preventing the spontaneous combustion of coal

A green, halogen-free, efficient, stable, and low-cost intumescent nanogel (ING) was prepared by combining an inorganic nanoparticle flame-retardant system with a chemical intumescent flame-retardant system. Polyacrylamide (PAM) gel was prepared by solution polymerization, then the modified nano-silica (MNS) and intumescent flame retardant were added to the PAM gel successively to prepare the ING. The preparation mechanism was analyzed, and response surface analysis showed that the optimal addition ratio of acrylamide, MNS, and potassium persulfate was 10:0.4:0.07, and the optimal reaction temperature was 75 ℃. The modification of nano-silica and the surface morphology of the composite gel were observed by scanning electron microscopy. In the electron spin resonance experiment, the free radical concentration of 5.70131 × 1017/g of the ING inhibited coal was significantly lower than other coal samples. The content of aliphatic hydrocarbon, aromatic hydrocarbon, and the oxygen-containing functional group in the in situ diffuse reflection Fourier transform infrared spectroscopy experiments all indicated that the ING achieved an excellent inhibition effect. Finally, the inhibition mechanism of the ING was analyzed for its physical, chemical, and composite effects. The PAM gel, MNS, and the intumescent flame retardant system demonstrated a triple inhibition effect, which indicates that ING is an ideal material for preventing the spontaneous combustion of coal.

The Preparation and Characterization of Polylactic Acid Composites with Chitin-Based Intumescent Flame Retardants.

In this work, a novel intumescent flame retardant (IFR) system was fabricated by the introduction of chitin as a green charring agent, ammonium polyphosphate (APP) as the acid source, and melamine (MEL) as the gas source. The obtained chitin-based IFR was then incorporated into a polylactic acid (PLA) matrix using melt compounding. The fire resistance of PLA/chitin composites was investigated via the limiting oxygen index (LOI), UL-94 vertical burning, and cone calorimeter (CONE) tests. The results demonstrated that the combination of 10%APP, 5%chitin and 5%MEL could result in a 26.0% LOI, a V-0 rating after UL and a 51.2% reduction in the peak heat release rate during the CONE test. Based on the mechanism analysis from both the morphology and the chemical structure of the char, it was suggested that chitin was a promising candidate as a charring agent for chitin reacted with APP and MEL with the formation of an intumescent layer on the surface.

The effect of boric acid on flame retardancy of intumescent flame retardant polypropylene composites including nanoclay

In this study, different amounts of boric acid (BA, 1.25, 2.5, 3.75 and 5.0 wt%) were used to enhance the effectiveness of an intumescent flame retardant (IFR) system composed of ammonium polyphosphate (APP) and pentaerythritol (PER) in polypropylene (PP) including 2 wt% montmorillonite nanoclay (MMT). Meanwhile, metaboric acid and boron oxide which were generated by the decomposition of BA appeared in the melt compounding and the burning processes, respectively. Extensive experimental studies were performed to investigate the effects of BA/boron oxide and MMT combinations on the properties of PP/IFR. The fire resistances of the composites were studied by UL 94, limiting oxygen index (LOI) and cone calorimetry tests. The thermal properties were determined by using thermogravimetric analysis, differential scanning calorimetry and thermal conductivity measurements. In addition, the mechanical properties of the composites were examined. The experimental results revealed that although the additions of 1.25 and 2.5 wt% BA with 2 wt% MMT significantly enhanced thermal and flame resistances of PP composites, 3.75 and 5.0 wt% BA additions generated antagonistic effects and deteriorated the fire resistance of the composites. The sample including 2.5 wt% BA addition achieved the best flame retardancy. The LOI value was increased from 18 to 31% with UL 94 V-0 rating. In addition, the peak heat release rate was reduced from 668.6 to 150.0 kW/m2 and the total heat release value was decreased from 247.9 to 98.4 MJ/m2. In the meantime, the thermal conductivity was increased from 0.22 up to 0.28 W/mK. Furthermore, CO, CO2 and the smoke productions were significantly decreased with respect to PP. NO generation was decreased with BA replacements. At the same time, although there was a slight decrease in the tensile strength, the flexural strength significantly increased with BA and MMT additions.

A Synergistic Flame Retardant System Based on Expandable Graphite, Aluminum (Diethyl-)Polyphospinate and Melamine Polyphosphate for Polyamide 6.

Expandable graphite (EG), aluminum (diethyl)polyphosphinate (AlPi) and melamine polyphophate (MPP) was used as flame retardant multi-material additive in a polyamide 6 (PA6) matrix. Flame inhabitation performances were conducted by cone calorimeter, LOI and UL-94 tests, synergisms identified analyzed by TGA-FTIR and TGA-GC/MS and effects found were comprehensively discussed. SEM images were used for char residue characterization. For PA6 containing 20 wt.% EG and 5 wt.% AlPi/MPP (3:2), a well working synergism in limiting oxygen indices could be identified exhibiting the highest oxygen index (OI) measured: 46%. The study shows that the synergism due to the partial substitution of EG by AlPi/MPP can be attributed to two effects: (1) When PA6/AlPi/MPP mixtures decompose predominantly CO2 evaporates in early decomposition stages. CO2 evaporations was found to be sensitive to the heating rate applied, whereas specifically high heating rates increased the CO2 yield measured. (2) Solid decomposition products of AlPi/MPP act as “glue” between expanded graphite and thus increase the mechanical residue stability.

Expanded Polystyrene Beads Coated with Intumescent Flame Retardant Material to Achieve Fire Safety Standards.

The compatibility and coating ratio between flame retardant materials and expanded polystyrene (EPS) foam is a major impediment to achieving satisfactory flame retardant performance. In this study, we prepared a water-based intumescent flame retardant system and methylene diphenyl diisocyanate (MDI)-coated expandable polystyrene microspheres by a simple coating approach. We investigated the compatibility, coating ratio, and fire performance of EPS- and MDI-coated EPS foam using a water-based intumescent flame retardant system. The microscopic study revealed that the water-based intumescent flame retardant materials were successfully incorporated with and without MDI-coated EPS microspheres. The cone calorimeter tests (CCTs) of the MDI-coated EPS containing water-based intumescent flame retardant materials exhibited better flame retardant performance with a lower total heat release (THR) 7.3 MJ/m2, peak heat release rate (PHRR) 57.6 kW/m2, fire growth rate (FIGRA) 2027.067 W/m2.s, and total smoke production (TSP) 0.133 m2. Our results demonstrated that the MDI-coated EPS containing water-based intumescent flame retardant materials achieved flame retarding properties as per fire safety standards.

Synergistic effect of layered double hydroxide and montmorillonite: Towards super-efficient fireproofing of leather

In this paper, high efficiency fire safety leather was obtained by synergistic flame retardant system of montmorillonite (Mt) and layered double hydroxide (LDH). Acetone organic modified MgAl LDH (O-LDH) and hexadecyl trimethyl ammonium chloride intercalation organic modified montmorillonite (O-Mt) was prepared. Organic modified layered materials O-LDH and O-Mt were introduced into modified zanthoxylum bungeanum seed oil (MZBMSO) to prepared MZBMSO/O-LDH and MZBMSO/O-Mt composites, respectively. Then they were treated leather together, and effectively improved the flame retardant performance. When the dosage ratio of MZBMSO/O-LDH to MZBMSO/O-Mt was 1:3, the results of vertical combustion showed that the leather would self-extinguish after the fire source was removed, and the limit oxygen index (LOI) could reach at 33.8%. The mechanism of flame retardation was discussed, it had a good protective effect on leather collagen fibers due to the synergistic effect of O-LDH and O-Mt. This work provided a novel synergistic flame retardant system strategy for the preparation of flame retardant leather, improving the safety and application range of leather products.