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The combination of egg white proteins (W) and hypophosphorous acid (HA) was used for developing a flame retardant coating for cotton fabrics by adopting the layer-by-layer assembly technique. This has resulted in a novel phosphorous-nitrogen-based assembly due to strong electrostatic interactions between W and HA. Coated cotton fabrics were characterized by using a variety of microscopic, analytical and thermal/combustion tests. Flammability properties of the fabrics were evaluated as per widely recognized standards like BS EN ISO 15025:2016 for protective clothing and ASTM D6413 for flame resistance of textiles. Coated cotton fabric showed self-extinguishing property with significant but fragile residual char structure, whereas uncoated fabric completely burnt with a little ash as residue. Thermogravimetric analysis revealed that decomposition temperature of coated fabric was lowered compared to control fabric, but char residue increased at 800 °C. Forced combustion cone calorimeter tests on the coated and uncoated fabrics showed that peak heat release rate, total heat released, and average rate of heat emission values reduced by 80%, 38%, and 40%, respectively, for coated fabrics as compared to control fabric. Even the mass loss rate value of the coated fabric has reduced significantly (from 514 g/m2.s for the uncoated fabric to 2 g/m2.s for coated fabric). Wash durability of the coated fabrics, though showed a slight reduction in flame-retardant properties as a consequence of ~ 9.7 wt% coating loss during soaking, yet there was no after-glow. [ABSTRACT FROM AUTHOR]

Traditional intumescent coatings are widely used as passive fire‐protective coatings for steel structures as they are capable of expanding in the range of 20–50 times the original thickness thereby providing excellent insulation. However, the fragile nature of such residue and susceptibility to thermo‐oxidation given their carbonaceous nature are key problematic issues. The concept of in situ ceramization is explored in this work as a means to form inorganic cohesive char with improved rigidity and thermo‐oxidative stability. Coating samples were prepared by incorporating ammonium polyphosphate, talc, Mg(OH)2, and polydimethylsiloxane as additives into acrylic resin at different weight fractions. Thermal analysis and x‐ray diffraction have confirmed the reactions between the additives to form various crystalline magnesium phosphate phases, and to a small extent, silicon phosphate, thereby ensuring the thermo‐oxidative stability of the residue. This is reiterated by the fire performance tests (by exposing the coatings to a temperature profile in a furnace similar to ISO 834 fire curve). Despite the advantages of rigid char and its thermo‐oxidative stability as a result of formation of inorganic phosphates, the lack of swelling has resulted in relatively poor insulation capabilities of the char, and subsequently, compromised the fire protection times (that are in the range of 45–55 min). However, pyrolysis flow combustion calorimeter results of the coatings are promising and have shown a significant drop of up to 70% in the peak of heat release rate values as compared to neat resin. [ABSTRACT FROM AUTHOR]

Hybrid composites composed of bio-based thin-ply carbon fibre prepreg and flame-retardant mats (E20MI) have been produced to investigate the effects of laminate design on their fire protection performance and mechanical properties. These flame-retardant mats rely primarily on expandable graphite, mineral wool and glass fibre to generate a thermal barrier that releases incombustible gasses and protects the underlying material. A flame retardant (FR) mat is incorporated into the carbon fibre bio-based polymeric laminate and the relationship between the fire protection properties and mechanical properties is investigated. Hybrid composite laminates containing FR mats either at the exterior surfaces or embedded 2-plies deep have been tested by the limited oxygen index (LOI), vertical burning test and cone calorimetry. The addition of the surface or embedded E20MI flame retardant mats resulted in an improvement from a base line of 33.1% to 47.5% and 45.8%, respectively. All laminates passed the vertical burning test standard of FAR 25.853. Cone calorimeter data revealed an increase in the time to ignition (TTI) for the hybrid composites containing the FR mat, while the peak of heat release rate (PHRR) and total heat release (TTR) were greatly reduced. Furthermore, the maximum average rate of heat emission (MARHE) values indicated that both composites with flame retardant mats had achieved the requirements of EN 45545-2. However, the tensile strengths of laminates with surface or embedded flame-retardant mats were reduced from 1215.94 MPa to 885.92 MPa and 975.48 MPa, respectively. Similarly, the bending strength was reduced from 836.41 MPa to 767.03 MPa and 811.36 MPa, respectively. [ABSTRACT FROM AUTHOR]

Material-scale tests involving milligrams of samples are used to optimize fire-retardant coating formulations, but actual applications of these coatings require them to be assessed with structural-scale fire tests. This significant difference in the scale of testing (milligrams to kilograms of sample) raises many questions on the relations between the inherent flammability and thermal characteristics of the coating materials and their "performance" at the structural scale. Moreover, the expected "performance" requirements and the definition of "performance" varies at different scales. In this regard, the pathway is not established when designing and formulating fire-retardant coatings for structural steel sections or members. This manuscript explores the fundamental relationships across different scales of testing with the help of a fire-protective system based on acrylic resin with a typical combination of intumescent additives, viz. ammonium polyphosphate, pentaerythritol, and expandable graphite. One of the main outcomes of this work dictates that higher heat release rate values and larger amounts of material participating in the pyrolysis process per unit time will result in a rapid rise in steel substrate temperature. This information is very useful in the design and development of generic fire-retardant coatings. [ABSTRACT FROM AUTHOR]

Multifunctional cotton fabric was prepared through a two-step layer-by-layer spray coating method, where the first layer of the coating comprising chitosan and ammonium phytate provided fire retardancy, and the second one with PDMS-ZnO composite imparted hydrophobicity to the fabric. A molecular dynamics (MD) simulation study was carried out to calculate interfacial adhesion of different components of the coating, based on which the sequencing of the coating layers was determined and used to prepare coated samples. The coated fabric demonstrated a significant improvement in fire retardancy through an increase in LOI from 18 % in control to 30 %, a reduction in char length from 30 cm to 7 cm, and a decrease in peak and total heat release rate values by 75 % and 33 %, respectively. The hydrophobicity of coated fabric was tested via water drop test where coated sample maintained a contact angle of 148° for up to 120 s, while the control sample showed 0°. [ABSTRACT FROM AUTHOR]