Preparation of Intumescent Fire Protective Coating for Fire Rated Timber Door

Reduction of polystyrene/polyurethane plastic wastes from the environment into binders for water-resistant emulsion paints

Waste management is fundamental to resource and environmental sustainability. Expanded polystyrene (EPS) and polyurethane (PU) waste plastics were recycled and applied as binder in emulsion paint formulation. The recycled polystyrene (rPS) and polyurethane (rPU) were blended into composite resins, where toluene was used as the solvent. The blends of rPS and rPU were optimized, while some physicochemical properties of the composite blends (rPS/PU) were evaluated. The results showed that the incorporation of rPU into rPS increased the viscosity (1818 mPa-3924 mPa), rate of gelation (dry-to-touch time: 15 min-0.25 min), moisture content (2.7%-8.1%), moisture uptake (3.2%-5.0%), solid content (48%-53.4%) and density (0.82 g/cm3 to 1.050.82 g/cm3) of the rPS/PU composite resins. Characterization was carried out using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and atomic force microscopy (AFM). The results summarily showed that there are interactions among the rPS and rPU molecules in the composite, where complimentary structural and morphological characteristics were also achieved. The composite resin also exhibited superior bond strength (0.5-4.24 Mpa) on wood, cast mortar, ceramic, and steel surfaces due to its stronger intra- and inter-surface interactions compared to the neat rPS resin. The composite resin was used as a binder in the formulation of emulsion paint. The paint exhibited stronger resistance to water, among other superior properties, when compared to the paints formulated using neat rPS and conventional polyvinyl acetate (PVA) resins. The reduction of plastic waste in this study holds potential for the production of highly water-resistant emulsion paint for outdoor and indoor applications.

Sustainable management of hazardous asbestos-containing materials: Containment, stabilization and inertization

Asbestos is a group of six major silicate minerals that belong to the serpentine and amphibole families, and include chrysotile, amosite, crocidolite, anthophyllite, tremolite and actinolite. Weathering and human disturbance of asbestos-containing materials (ACMs) can lead to the emission of asbestos dust, and the inhalation of respirable asbestos fibrous dust can lead to 'mesothelioma' cancer and other diseases, including the progressive lung disease called 'asbestosis'. There is a considerable legacy of in-situ ACMs in the built environment, and it is not practically or economically possible to safely remove ACMs from the built environment. The aim of the review is to examine the three approaches used for the sustainable management of hazardous ACMs in the built environment: containment, stabilization, and inertization or destruction. Most of the asbestos remaining in the built environment can be contained in a physically secured form so that it does not present a significant health risk of emitting toxic airborne fibres. In settings where safe removal is not practically feasible, stabilization and encapsulation can provide a promising solution, especially in areas where ACMs are exposed to weathering or disturbance. Complete destruction and inertization of asbestos can be achieved by thermal decomposition using plasma and microwave radiation. Bioremediation and chemical treatment (e.g., ultrasound with oxalic acid) have been found to be effective in the inertization of ACMs. Technologies that achieve complete destruction of ACMs are found to be attractive because the treated products can be recycled or safely disposed of in landfills.

Environmentally Friendly Hybrid Organic-Inorganic Halogen-Free Coatings for Wood Fire-Retardant Applications

Wood and wood-based products are extensively used in the building sector due to their interesting combination of properties. Fire safety and fire spread, however, are of utmost concern for the protection of buildings. Therefore, in timber structures, wood must be treated with fire-retardant materials in order to improve its reaction to fire. This article highlights the flame retardancy of novel hybrid organic-inorganic halogen-free coatings applied on plywood substrates. For this purpose, either a huntite-rich mineral (H5) or its modified nano-Mg (OH)₂ type form (H5-m), acting as an inorganic (nano) filler, was functionalized with reactive oligomers (ROs) and incorporated into a waterborne polymeric matrix. A water-soluble polymer (P (SSNa-co-GMAx)), combining its hydrophilic nature with functional epoxide groups, was used as the reactive oligomer in order to enhance the compatibility between the filler and the matrix. Among various coating compositions, the system composed of 13% polymeric matrix, 73% H5 and 14% ROs, which provided the best coating quality and flame retardancy, was selected for the coating of plywood on a larger scale in one or two layers. The results indicated that the novel plywood coating systems with the addition of ecological coating formulations (WF-13, WF-14 and WF-15), prepared at two layers, reached Euroclass B according to EN13501-1, which is the best possible for fire systems applied to wood.

Flame Retardant Coatings: Additives, Binders, and Fillers

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

Intumescent Silicate Coatings with the Addition of Alkali-Activated Materials

Fireproof inorganic coatings based on sodium silicate solution with intumescent additions were prepared and tested to assess their ability to limit the negative effect of a fire. The intumescent materials were obtained by the alkali activation of waste glass powder (obtained by the grinding of recycled soda-lime culet) and slag (waste resulting from the metallurgical industry). The replacement of talc (used as filler in paint formulation) with the intumescent materials obtained by the alkaline activation of waste glass powder (WGP), determined an increase in the intumescence coefficient (up to 65%) and decreased the activation temperature of this process. To evaluate these coatings’ abilities to prevent or delay the temperature increase in metal structures, the paints were applied on steel plates and tested in direct contact with the flame of a butane burner for 60 min. The coatings prevented the increase in the steel substrate temperature over one considered critical (500°C) for steel mechanical properties; the combination of two coatings, with different intumescence activation temperatures, correlated with the increase in the coating’s thickness, sensibly reduced the rate of temperature increase (up to 75%) in the steel substrate.

A Dual Active-Passive Coating with Intumescent and Fire-Retardant Properties Based on High Molecular Weight Tannins

In this study, the tannins extracted from the Pinus radiata bark were used to develop an active–passive dual paint scheme with intumescent (IN) and fire-resistant (FR) behaviors. The properties of the coating were observed to depend on the concentration of high-molecular-weight tannins (H-MWT) incorporated into the formulation. At high concentrations (13% w/w), the coating exhibits fire-retardant properties due to the generation of a carbonaceous layer; however, at low concentrations (2.5% w/w), it generates an intumescent effect due to the formation of a carbonaceous foam layer. The dual IN–FR scheme was evaluated against fire by flame advance tests, carbonization index, mass loss, and intumescent effect, and was also compared to a commercial coating. The dual scheme presented good mechanical properties with a pull-off adhesion value of 0.76 MPa and an abrasion index of 54.7% at 1000 cycles, when using a coating with a high solid content (>60%) and the same thickness as those of the commercial coatings. The results of the fire resistance test indicate that the dual scheme generates a protective effect for wood and metal, with an excellent performance that is comparable to that of a commercial intumescent coating.

Effect of the B:Zn:H2O Molar Ratio on the Properties of Poly(Vinyl Acetate) and Zinc Borate-Based Intumescent Coating Materials Exposed to a Quasi-Real Cellulosic Fire

In order to investigate an influence of the B:Zn:H₂O molar ratio on the fire protection efficiency of poly(vinyl acetate)-based thermoplastic intumescent coating materials (ICs), systems containing ammonium polyphosphate, melamine, pentaerythritol and different types of zinc borates (ZBs) were tested in a vertical position in quasi-real fire conditions. 3ZnO·2B₂O₃·6H₂O (ZB6), 2ZnO·3B₂O₃·3.5H₂O (ZB3.5) or 3ZnO·2B₂O₃ (ZB0) were added in amounts of 1–10 wt. parts/100 wt. parts of the other coating components mixture. Char formation processes and thermal insulation features were investigated using an open-flame furnace heated according to the cellulosic fire curve. Thermogravimetric features (DTG), chemical structures (FTIR) and mechanical strength of the ICs and the chars were analyzed as well. It was revealed that the type and dose of the ZBs significantly affect thermal insulation time (TIT) (up to 450 °C of a steel substrate) and sagging (SI) of the fire-heated coatings as well as the compressive strength of the created chars. The highest TIT value (+89%) was noted for the sample with 2.5 wt. parts of ZB3.5 while the lowest SI (−65%) was observed for the coatings containing 10 wt. parts of the hydrated borates (i.e., ZB3.5 or ZB6). The best mechanical strength was registered for the sample filled with the anhydrous modifier (3 wt. parts of ZB0). The presented results show that the ICs with the proper ZBs can be used for effective fire protection of vertically positioned steel elements.

Enhanced Resistance to Fire of the Bark-Based Panels Bonded with Clay

The aim of this study was to investigate the flammability of ecologically friendly, 100% natural larch and poplar bark-based panels bonded with clay. The clay acted as a fire retardant, and it improved the fire resistance of the boards by 12–15% for the surface and 27–39% for the edge of the testing specimens. The thermal conductivity was also analyzed. Although the panels had a density ranging from 600 to 900 kg/m3, thermal conductivity for the panel with a density of 600 kg/m3 was excellent, and it was comparable to lightweight insulation panels with much lower densities. Besides that, the advantage of the bark clay boards, as an insulation material, is mostly in an accumulative capacity similar to wood cement boards, and it can significantly improve the climatic stability of indoor spaces that have low ventilation rates. Bark boards with clay, similar to wood cement composites (wood wool cement composites and wood particle cement composites), have low mechanical properties and elasticity. Therefore, there their use is limited to non-structural paneling applications. These ecologically friendly, 100% natural and recyclable composites can be mostly used with respect to their thermal insulation, acoustics and fire resistance properties.