Flammability is one of the main drawbacks affecting polymer matrix composites (PMCs), limiting metal replacement in several applications. Phosphorus compounds demonstrated a great ability in ...contrasting fire spreading. Here, phosphorylated poly(vinyl alcohol) (PPVA) has been synthesized and used as an intumescent flame inhibitor coating for carbon fiber reinforced polymer (CFRP) laminates. The synthesized PPVAs, with a phosphorylation degree up to 7.5 %wt, were investigated by spectroscopic (NMR and IR) and thermal (TGA and DSC) analyses. Moreover, thermal degradation kinetics was also rationalized by applying differential and integrals methods: the phosphorus catalytic effect combined with radicals-coupling behaviour deriving from the phosphorus species developed during the combustion has been highlighted, confirming the inhibitor role of PPVAs. Cone-calorimeter tests, simulating a small-scale fire scenario, were carried out on poly(vinyl alcohol)-coated and PPVA-coated materials prepared by solvent casting. Results highlight the anti-flame properties of PPVAs, especially as effective flame inhibitors: up to −58 % in the time of flame (TOF). Instead, poly(vinyl alcohol) coatings lead to an overall worsening of the material fire behaviour, highlighting the crucial role of phosphorous to reduce flammability. Such promising results pave the way for the use of PPVA coatings to reduce the fire risk of flammable composites making them safer.
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•Linear PVA-PPVA copolymers were synthesized with a high degree of phosphorylation.•Phosphorous role during combustion was determined by thermo-kinetic modelling.•Cone-calorimeter tests highlighted the flame-inhibitor ability of PPVA.•PPVA-coated composite laminates show a halved time of flame (TOF).•Aesthetics of coated CFRPs is maintained, and the total thickness is not affected.
Interface adhesion is a key factor to systematically understand heat transfer process from intumescent coating to underlying steel substrate. In this paper, epoxy intumescent coating EP/IFR/HBPSi was ...prepared by adding ammonium polyphosphate (APP), melamine (MEL) and a new organosilicone flame retardant phenyl silicone resin (HBPSi) to epoxy resin (EP). The temperature function was obtained by fitting the interval distance between the intumescent coating and the steel substrate measured from 23 °C to 715 °C with muffle furnace, which showed that the interface adhesion was greatly affected by the heating conditions. At the same time, the effects of incident heat flux, chemical formulation, thicknesses of epoxy intumescent coating, the composition, thickness and surface roughness of steel substrate on interface adhesion were investigated by SEM, energy spectrum analyzer, and temperature distribution measurement and so on. The results indicate that all of these factors have influence on interface adhesion. This work helps to further understand thermal protection mechanism of the intumescent coating for steel structure buildings.
In order to find a fully natural substitute of pentaerythritol (PER), which is the basic carbon source in thermal swelling systems, a powder of cocoa shells (CS) was tested in intumescent coatings ...based on poly(vinyl acetate) (ICs). Generally, CS are the main waste by-products of cocoa production, and their utilization is limited. The coating materials were mainly compounded using melamine (a blowing agent), ammonium polyphosphate (a dehydrating agent), and the same doses of PER, CS or their mixtures (PER/CS). They were primarily investigated using a gas flame-heated furnace (according to a cellulosic fire curve), TGA, and DSC techniques. The CS addition markedly affected charring processes of ICs during the fire test and improved intumescence effectiveness and thermal insulation time parameters (from 15.9 to 23.6 a.u. and from 28.2 to 30.9 min, respectively). Moreover, the natural additive increased compression strength of charred ICs on a steel substrate (from 1.48 to 1.88 kPa). The best performance properties were noted for IC with the PER/CS mixture containing 10 wt% of the organic component – in this case all the tested features were improved.
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•Intumescent coatings with a cocoa shells powder (CS)•CS reduces pentaerythritol content in the coatings.•CS improves thermal protective properties of the coatings.•CS improves compression resistance of charred coatings.
The design of environment‐friendly fireproof rigid polyurethane foams (RPUFs) that completely prevent ignition or the spread of fires is important for energy conservation and emission reductions. In ...this paper, an intumescent flame‐retardant coating was prepared and coated onto the surface of a RPUF to improve its flame retardancy. Vertical combustion experiments (UL‐94) showed that, compared with the pure RPUF, a RPUF coated with the expansion coating successfully self‐extinguished without a droplet formed after ignitor removal. Thermogravimetric analyses showed that the expanded coating effectively increased the rate of carbon residue formation. Cone calorimetry showed that when the pigment‐to‐binder ratio was 3.5:1, with 5% modified montmorillonite, 6% aluminum hydroxide, and 4% titanium dioxide, the intumescent coating effectively reduced the heat release rate and total heat release of the RPUF. Remarkably, the smoke release rate and total exhaust gas volume showed that the expanded coating provided obviously enhanced smoke suppression. Therefore, the flame retardancy and toxic smoke suppression provided by the RPUF thermal insulation material is essential and very useful for healthy development of human society and the environment.
Flame Retardant Effect of Intumescent Coating on Rigid Polyurethane foam.
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•Phytic acid and Thiourea are derived from plants or fungi metabolites.•Phytic acid and Thiourea both act as acid source and mutual synergists.•Intumescent flame retardant (IFR) ...coating displays outstanding anti-dripping and char forming ability on PA6 fabric.•IFR coating mainly works in condensed- and gas-phase.•IFR coating offers an effective and cleaner strategy to minimize fire hazards of PA6 textiles.
This study focused on the construction of an eco-friendly and intumescent flame retardant (FR) coating for polyamide 6 (PA6) fabric. The intumescent FR coating, consisting of phytic acid, pentaerythritol and thiourea, was deposited onto PA6 fabric through dip-coating technique. The FR performance, anti-dripping ability, thermal stability, combustion behavior and mechanical property of the coated PA6 fabrics were explored. The severe dripping of coated PA6 fabric was totally eliminated, achieving an excellent FR performance at a low P (2.2%) and S (3.4%) content. Correspondingly, the LOI increased to 28.8% versus 23.2% of pristine one, displaying good flame retardancy. The char residue analyses confirmed the intumescent FR behavior of coated PA6 fabrics. The intumescent char layer played a major role in isolating the exchange of combustibles, oxygen and heat, leading to the significant reduction in heat release performance. The results of cone calorimetry test showed that the peak heat release rate and average effective heat of combustion of coated PA6 fabric decreased by about 36.5% and 34.4%, respectively versus pristine one. Meanwhile, the sulfur-based gases captured free radicals to interrupt the continuous combustion, leading to the significantly improved flame retardancy. Furthermore, the FR coating exerted little influence on the mechanical performance of PA6 fabric.
Connections are of high significance in the stability and integrity of steel structures. Connections play a key role in structures exposed to fire because they are supposed to support the entire ...elements against a variety of loads. In steel beams, a connection is generally implemented to join (at least) two perpendicular members. A thorough understanding of the heat transfer in structural members is a prerequisite to a reliable design. In the case of R30 requirements, a large number of members can be left unprotected if they are hot-dip galvanised. If hot-dip galvanising of a structure is not sufficient to provide required fire resistance, one part of the structure could be hot-dip galvanised while another part to be protected with a reactive fire protection system. When connecting a protected beam to an unprotected hot-dip galvanised beam, information regarding the heat transfer between these beams is required.
Additional heating in a connection due to hot dip galvanisation needs to be taken into account when verifying the load-bearing capacity of the component protected by reactive fire protection according to EN 1993-1-2. This study investigates the effect of heat development and transfer in full-scale steel I-beams from a hot-dip galvanised secondary beam to an intumescent-coated main beam through various bolted connections such as fin plates, double angles, and stiffeners with lugs. Fire protection was applied to the main beams, while the secondary beams were hot-dip galvanised. A thorough experimental, numerical and theoretical study was implemented as presented in this paper, the results of which are deemed to provide significant input into improving safety, hence mitigating the risk of steel beams.
An emerging composite flame retardant has been prepared by sodium modification of natural mineral rectorite (REC), and waterborne intumescent fire retardant coating (IFR-Na-REC) containing ...sodium-modified rectorite (Na-REC) was successfully fabricated. The flame retardancy, morphology, structure, chemical composition and mechanical property of the intumescent coating were in detail investigated. The results showed that Na-REC could greatly promote the heat insulation effect of waterborne intumescent coatings. The temperature of the backside of steel plate for the IFR-Na-REC coating with 10% Na-REC was recorded to be 202 °C after 60 min of fire test, 24 °C lower than that of the control coating, and the flame retardant time reached up to 119 min. The enhanced fireproof performance could be attributed to the increased adhesion of the coating to the substrate and the formation of ceramic-like protective layer between rectorite and components in intumescent coating, which acted as a fire barrier to protect the internal matrix. Our work could offer a more benign approach to the general production of composite flame retardant coatings for fire protection.
Natural mineral rectorite (REC) was chemically modified to prepare waterborne intumescent coatings for enhancing thermal insulation and fire retardancy. Display omitted
•Rectorite (REC) was chemically modified to prepare composite flame retardant.•Modified REC hybridized copolymers to produce flame retardant coating.•Na-REC could greatly enhance the heat insulation effect of intumescent coatings.•Ceramic-like protective shield of REC and copolymer contributed to this enhancement.
Intumescent coating was studied relative to the fire performance of nail-laminated timber. Three NLT specimens were coated with three different intumescent coating thicknesses (1, 2, and 3 mm) in ...even-numbered laminae and compared to uncoated NLT specimens. As a result of the coating, the internal temperature of the coated specimen increased more slowly than that of the uncoated specimen. The average charring rate of the intumescent coating specimen was reduced by 12.8% (1-mm thickness), 14.1% (2-mm thickness), and 15.4% (3-mm thickness) compared with the uncoated specimen. However, statistical analysis showed there was no significance between 1-, 2-, and 3-mm coating thicknesses. The combustion of wide surfaces of timber laminae between the plywood was delayed due to the coated plywood, and the timber laminae became a one-dimensional charring rate problem. Therefore, if even laminae are coated with an intumescent, then the NLT can be designed with a one-dimensional charring rate condition.
Intumescent fire-retardants (IFR) are widely applied in fire protection coatings of steel and wooden structures. The addition of inorganic fillers, such as layered ionic clays, can improve the ...fireproof performance of IFR coatings. However, a fundamental insight of how these filler materials synergistically interact with the IFR materials remains elusive. In this study, we address this fundamental knowledge gap by systematically investigating the synergy between the IFR fire protection coatings and the CaAlCO3-layer double hydroxide (LDH) or montmorillonite (MMT) fillers, which render substantially longer fire resistance (>20 min), reduced specific extinction area (by 54.7 and 44.1 m2 kg−2, respectively), and reduced heat release (by 0.9 and 0.7 MJ m−2, respectively). Combining experimental results and density functional theory calculations, we show for the first time that the superior fireproof performance of the MMT-IFR fire coating originates from the chemical modifications of the char layer by Si-doping. The chemical stabilisation of the silicon- and nitrogen-doped graphene (Si–N-G) structures improves the oxidation resistance of the char layer. Additionally, the formation of the Si–N-G structures with limited lattice deformation stabilised the porous morphology of the char layer, thereby promoting its heat-shielding performance.
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Abstract
Zum Erwärmungsverhalten von Anschlüssen ungeschützter feuerverzinkter Stahlkonstruktionen im Brandfall liegen bisher keine normativen Regelungen vor, sodass aktuell auf die in DIN EN ...1993‐1‐2 enthaltenen wenigen Angaben für nicht feuerverzinkte Stahlkonstruktionen zurückgegriffen wird. In der Norm fehlen außerdem Angaben, wie der thermische Einfluss eines ungeschützten Bauteils auf ein damit verbundenes geschütztes Bauteil zu berücksichtigen ist. Forschungsergebnisse zeigen, dass durch Feuerverzinken die Feuerwiderstandsdauer von Stahl verbessert werden kann. Für den Fall, dass eine Feuerverzinkung bei einem Teil der Konstruktion nicht ausreicht, um den erforderlichen Feuerwiderstand sicherzustellen, könnte ein Teil der Konstruktion feuerverzinkt und ein anderer Teil mit einem reaktiven Brandschutzsystem geschützt werden. Die zusätzliche Erwärmung in einem Anschlussdetail, die aus dem feuerverzinkten Bauteil resultiert, muss beim Tragfähigkeitsnachweis des mit einem reaktiven Brandschutzsystem geschützten Bauteils berücksichtigt werden. Der Einfluss auf das Erwärmungsverhalten von Anschlüssen zwischen feuerverzinkten Sekundärträgern und mit reaktiven Brandschutzsystemen geschützten Hauptträgern wird daher mithilfe von Brandversuchen an unterschiedlichen Anschlussdetails untersucht. Ziel dieser Untersuchung ist die Gewinnung von thermischen Daten im Anschlussbereich von Trägern mit I‐Profil, weshalb die Brandversuche ohne mechanische Belastung durchgeführt werden.
Translation abstract
Heating of the connection of a hot‐dip galvanized secondary beam to a primary beam with applied reactive fire protection system in case of fire – part 1: fire tests on different connection details
There are currently no normative regulations on the heating behavior of connections of unprotected hot‐dip galvanized steel constructions in the case of fire, so that the few specifications for non‐hot‐dip galvanized steel constructions contained in DIN EN 1993‐1‐2 are currently used. The standard also lacks information on how to take into account the thermal influence of an unprotected component on a protected component that is connected to it. Research results show that hot‐dip galvanizing can improve the fire resistance of steel. In the case, that hot‐dip galvanizing is not sufficient to ensure the required fire resistance for one part of the structure, one part of the structure could be hot‐dip galvanized and another part protected with an intumescent coating. The additional heating in a connection detail resulting from the hot‐dip galvanized component has to be taken into account for the ultimate limit state design of the component protected with a reactive fire protection system. The influence on the heating behavior of connections between hot‐dip galvanized secondary beams to main beams with fire protection is therefore investigated with the help of fire tests on different connection details. The aim of this investigation is to obtain thermal data in the connection area of beams with I‐profile, which is why the fire tests were carried out without mechanical load.
