This review covers mainly intumescent coatings, with briefer discussions of non-intumescent organic fire-resistive coatings and cementitious inorganic coatings. Emphasis is placed on the more recent developments, and the more recent patent literature is surveyed. Modeling and optimizing are covered both from basic and applied aspects. The chemistry of the production of a foamed char barrier is discussed. Enhancing the performance by adjuvants and choice of binders is shown to be possible. The important interactions of ammonium polyphosphate with other components such as titanium dioxide are described. Testing is briefly discussed, as are some shortcomings of present-day coatings, such as limited water resistance, and some opportunities for improvement.

Fire-Protective and Flame-Retardant Coatings - A State-of-the-Art Review

Ceramifiable polyolefin materials have an excellent application prospect in high-temperature-resistant wires and cables because of their excellent fire safety performance via a ceramization process under fire conditions. During the ceramization process, the control of the crystalline phase plays a vital role in determining the final fire resistance and ceramifiable properties. In this work, ammonium polyphosphate/zinc borate (APP/ZB) was developed to achieve the highly efficient flame retardance and ceramization of the ethylene-vinyl acetate/mica powder/organo-modified montmorillonite (EVA/MP/OMMT) composite. In the combustion test, the EVA/MP/OMMT/APP/ZB system displayed obvious flame retardance feature, showing much lower total heat release and total smoke production than neat EVA. After treating at high temperatures, rigid ceramic products were formed for EVA/MP/OMMT/APP/ZB. The ceramic that was formed at 900 °C had a flexural strength of 10.3 MPa for EVA/MP/OMMT/APP/ZB containing 23 wt % of APP/ZB (9.9:13.1), increased by 2475.0, 635.7, and 586.7% compared to the corresponding values of EVA/MP/OMMT, EVA/MP/OMMT/ZB, and EVA/MP/OMMT/APP. For the latter two systems, the content of ZB or APP was 23 wt %. APP/ZB showed a remarkable fluxing effect on the ceramization of the MP-based EVA composite. The fluxing mechanism of APP/ZB was revealed by different measurements. Both APP and ZB led to the formation of a glass melt containing α-Zn3(PO4)2 and orthophosphate by increasing the temperature. Successively, the melt crystalline structure cohered the OMMT and MP together, accompanied by the gradual disappearance of the mica phase and the generation of eutectic phenomenon. Finally, a ceramic with high flexural strength was formed, leading to the improved flame retardance and ceramifiable properties of EVA-based composites.

Simultaneously Improved Flame Retardance and Ceramifiable Properties of Polymer-Based Composites via the Formed Crystalline Phase at High Temperature.

We performed a combined calorimetric and molecular modeling investigation of poly(vinyl acetate) (PVAc) on silica to characterize the intermolecular interactions and the behavior of the adsorbed polymer. From temperature-modulated differential scanning calorimetry experiments, different regions of thermal activity suggested a gradient of mobility in the adsorbed polymer. Polymer segments in more direct contact with silica (tightly bound) showed a significantly elevated and broadened glass transition relative to the bulk polymer, while polymer further away (loosely bound) showed only a slightly elevated transition relative to the bulk polymer. A thermal transition for PVAc at the air interface (more-mobile) was also observed and was at lower temperatures than the bulk polymer. Density profiles from molecular dynamics studies suggested a structure of the adsorbed polymer similar to that experimentally observed. These studies were consistent with the presence of a motional gradient in the polymer segments, a...

Structure of the Interfacial Region in Adsorbed Poly(vinyl acetate) on Silica

The ceramifying process and mechanical properties of silicone rubber/ ammonium polyphosphate/ aluminium hydroxide/ mica composites

Ceramifiable flame-retardant silicone rubber composites were prepared by silicone rubber (SR) as the base polymer, and ammonium polyphosphate, calcium carbonate, sericite mica, and glass frits were utilized as additives. The flammability and thermal stability properties of ceramifying silicone rubber composites were studied by the limiting oxygen index (LOI), microscale combustion calorimetry (MCC), and thermogravimetric analysis (TG). The ceramic residues formed at various temperatures were studied by mechanical testing, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results indicated that the ceramifying silicone rubber achieved a LOI value of 31.2% and the flexural strength of ceramic residues formed at 1000 °C was 19.7 MPa. Moreover, the MCC results demonstrated that the heat release rate and total release rate of the composites were reduced significantly compared to the corresponding value of neat SR. The TG showed that the residue of composites was approximately 61.5% at 700 °C, as significantly higher than that the residue of neat SR. The XRD results demonstrated that fluoroapatite and Ca2SiO4 crystals were produced in the ceramic residue at high temperatures. The SEM analysis depicted that the number of holes was reduced and a dense structure was formed as the sintering temperature increased, leading to the excellent mechanical properties of formed ceramics at high temperatures.

Preparation and properties of ceramifiable flame-retarded silicone rubber composites

Fire-retardant ceramifying poly(vinyl acetate) (PVAc) sealants have been prepared. The degradation of PVA was integrated with the action of the fire retardants to reduce flammable gases, produce carbonaceous char and convert the fillers into a self-supporting ceramic barrier. PVA is readily degraded by elimination of acetic acid, yielding a char that provides a transitory phase as the filler particles fuse into a ceramic mass. Acetic acid is eliminated at similar temperature to the release of water from magnesium hydroxide fire-retardant, thereby diluting flammable acetic acid. The residual oxide from the fire-retardant filler and structural filler are fused by a flux, zinc borate. The degradative and ceramifying processes were characterised using thermogravimetry, infrared spectroscopy, scanning electron microscopy and ceramic strength. Thermogravimetry of the composites was compared with additive mass loss curves calculated from the components. Deviations between the experimental and additive curves revealed interactions between the components in the composites. The modulus of the PVAc composites and the strength of their ceramic residues after combustion were determined.

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Z. Al-Hassany

Papers

Fire-retardant and fire-barrier poly(vinyl acetate) composites for sealant application