Preparation and performance of waterborne intumescent coatings with mechanical, thermal properties and optimization of flame retardant paints

Fire-resistive performance of intumescent flame-retardant coatings for steel

Epoxy was effectively resin infused with 15 %wt intumescing Alumina Trihydrate (ATH) flame retardant (FR) formulations into a 10 %wt palm EFB natural fiber (NF) mat. The effects of ATH and its intumescing blend with Zinc Borate (ZB) and Ammonium Polyphosphate (APP) on flammability, thermal and mechanical properties of the composites were investigated. Compared to neat NF filled epoxy composites, specimens loaded with intumescing blend of FR formulations demonstrated an improved thermal properties, showing greater mass residual which can be attributed to the formation of cross-linked network amongst the NF, FRs and epoxy matrix upon combustion at elevated temperature tested within a TGA instrument. Incorporation of fibers drastically enhanced the mass residue and lowered the heat release compare to the pure epoxy. Addition of the intumescing blend of FR formulations also drastically reduces the combustion heat release, total mass loss and zero drip flame in the NF composites. The optimum FRs formulation with 5 %wt ATH and 10 %wt APP exhibited self-extinguishing property, achieved lowest mass loss and no drip flame under Bunsen burner tests, signifying the synergistic effects between ATH and APP within the NF epoxy composites. APP reacts with the carbonaceous network of NF throughout the ignition period, such interaction formed a thick char layer acting as gas and thermal barrier against the fire mechanism. This reaction does not take place in NF composite specimens without APP. In terms of mechanical properties, NF composites loaded with FRs broadly showed poorer tensile strength, mainly due to the existence of FRs, which acted as a nucleating agent affected the physico-mechanical characteristics of the composites. Amongst the FR rich formulations, specimens with APP or ZB blends seem to possess a more superior tensile strength compared with the neat ATH filled formulation. In addition, composites loaded with FRs showed enhanced Young’s modulus relative to those without addition of FRs.

We, scientists from a variety of disciplines, declare the following: Parties to the Stockholm Convention have taken action on three brominated flame retardants that have been listed in the treaty for global elimination. These substances include components of commercial penta-bromodiphenyl ether and commercial octa-bromodiphenyl ether, along with hexabromobiphenyl. Another brominated flame retardant, hexabromocyclododecane, is under evaluation. Many commonly used brominated and chlorinated flame retardants can undergo long-range environmental transport. Many brominated and chlorinated flame retardants appear to be persistent and bioaccumulative, resulting in food chain contamination, including human milk. Many brominated and chlorinated flame retardants lack adequate toxicity information, but the available data raises concerns. Many different types of brominated and chlorinated flame retardants have been incorporated into products even though comprehensive toxicological information is lacking. Brominated and chlorinated flame retardants present in a variety of products are released to the indoor and outdoor environments. Near-end-of-life and end-of-life electrical and electronic products are a growing concern as a result of dumping in developing countries, which results in the illegal transboundary movement of their hazardous constituents. These include brominated and chlorinated flame retardants. There is a lack of capacity to handle electronic waste in an environ-mentally sound manner in almost all developing countries and countries with economies in transition, leading to the release of hazardous substances that cause harm to human health and the environment. These substances include brominated and chlorinated flame retardants. Brominated and chlorinated flame retardants can increase fire toxicity, but their overall benefit in improving fire safety has not been proven. When brominated and chlorinated flame retardants burn, highly toxic dioxins and furans are formed. Therefore, these data support the following: Brominated and chlorinated flame retardants as classes of substances are a concern for persistence, bioaccumulation, long-range transport, and toxicity. There is a need to improve the availability of and access to information on brominated and chlorinated flame retardants and other chemicals in products in the supply chain and throughout each product’s life cycle. Consumers can play a role in the adoption of alternatives to harmful flame retardants if they are made aware of the presence of the substances, for example, through product labeling. The process of identifying alternatives to flame retardants should include not only alternative chemicals but also innovative changes in the design of products, industrial processes, and other practices that do not require the use of any flame retardant. Efforts should be made to ensure that current and alternative chemical flame retardants do not have hazardous properties, such as mutagenicity and carcinogenicity, or adverse effects on the reproductive, developmental, endocrine, immune, or nervous systems. When seeking exemptions for certain applications of flame retardants, the party requesting the exemption should supply some information indicating why the exemption is technically or scien-tifically necessary and why potential alternatives are not technically or scientifically viable; a description of potential alternative processes, products, materials, or systems that eliminate the need for the chemical; and a list of sources researched. Wastes containing flame retardants with persistent organic pollutant (POP) characteristics, including products and articles, should be disposed of in such a way that the POP content is destroyed or irreversibly transformed so that they do not exhibit the charac-teristics of POPs. Flame retardants with POP characteristics should not be permitted to be subjected to disposal operations that may lead to recovery, recycling, reclamation, direct reuse, or alternative uses of the substances. Wastes containing flame retardants with POP properties should not be transported across international boundaries unless it is for disposal in such a way that the POP content is destroyed or irreversibly transformed. It is important to consider product stewardship and extended producer responsibility aspects in the life-cycle management of products containing flame retardants with POP properties, including electronic and electrical products.

The aim of this research project was to investigate the effects of hybrid flame-retardant fillers on the fire protection and mechanical properties of solvent-borne intumescent coatings. Formulations of intumescent coatings with different combinations of flame-retardant fillers were developed and investigated through Bunsen burner test, adhesion strength test and Scanning Electron Microscopy (SEM). It was found that the formulation of intumescent coating was optimized with four combinations of flame-retardant fillers in proper compositions and had improved the fire protection performance and mechanical properties of the coating. In overall, filler compositions of coating sample D (1 wt.% nano CES/ 2 wt.% expandable graphite/ 1 wt.% zinc borate/ 4 wt.% calcium silicate) had contributed to positive fire protection performance (equilibrium temperature of 190 °C) and adhesion strength (2.62 MPa). Significantly, the incorporation of an appropriate combination of hybrid nano CES bio-filler, expandable graphite, zinc borate and calcium silicate had led to a better fire protection performance and mechanical properties of the solvent-borne intumescent coating.

This paper presents an investigation on solvent-borne intumescent flame-retardant coatings that can provide good bonding strength, water resistance and fire protection to the steel substrate. The fire protection performance and characterisations of the coatings were investigated by using the Bunsen burner test, thermogravimetry analysis, field emission scanning electron microscope, static immersion test and Instron Micro Tester. It was found that the fire protection and foam structure of the coating significantly improved by adding the combination of Mg(OH)2 and TiO2 flame-retardant fillers to the flame-retardant additives and acrylic binder. The formation of uniform foam structure and reaction of the coating which decompose into voluminous and multi-cellular char layers with thermal insulation properties contribute an important fire protection to the steel substrate from reaching its critical temperature. However, the combination of [Al(OH)3 and Mg(OH)2] flame-retardant fillers to the flame-retardant additives and epoxy binder led to maximum adhesion strength. The improvement in the bonding properties of the coating to the metal surface was attributed to the effective [Mg(OH)2 and TiO2] fillers/epoxy binder interface adhesion. Hence, the findings of this study reveal that the selection of appropriate combination of binders and flame-retardant fillers strongly influenced the fire protection, water resistance and mechanical properties of intumescent coatings.

The goal of this study was to recycle acrylonitrile-butadiene-styrene (ABS) into wood plastic composites (WPCs). One major concern in this application is flammability. Thus, halogenated and non-halogenated flame retardants (FRs) were investigated. FRs were mixed with ABS using an internal mixer or an extruder, and samples were molded using a hot press or an injection molding machine. Mechanical properties were assessed by flexural tests, and flammability was measured by UL-94 type tests and limiting oxygen index. Thermogravimetric analysis (TGA) and FTIR were also performed in order to understand the decomposition behavior of ABS-based WPCs.;Mechanical results showed that adding wood flour and FRs to ABS increased its flexural modulus; however, the addition of FRs into ABS-based WPCs reduced the flexural strength. All FRs could help to reach V-0 rating on the UL-94 test, but use of ammonium polyphosphate (AP423) required the least amount (20wt%) of FR when the wood content was fixed at 30wt%. Also, synergism existed between halogenated and non-halogenated FRs.;From TGA curves, the shift of the first peak of Rmax (maximum weight change rate) of ABS-based WPCs to a lower temperature with addition of non-halogenated FRs indicated that a dehydration reaction took place between wood and FRs. This was further verified by FTIR study. Common fillers, such as talc or calcium carbonate, likely to be present in recycled ABS were found to negatively affect the fire retardancy of ABS-based WPCs. However, one could add a coupling agent to recover the fire performance.;It was found that the coupling agent, after decomposition, formed a cross-linked network with non-halogenated FRs. Polybutadiene (PB) could further improve the fire resistance of ABS-based WPCs; however, high loading levels led to a poor dispersion, resulting in negative effects. Further, the use of triphenyl phosphate (TPP) shows synergism with AP423 in fire retardancy, and it also enhances the color of ABS-based WPCs. Another way to get improved color is to use gentler extrusion processing. By comparing ABS-based WPCs to polyolefin-based WPCs at the same level of fire performance, it was found that ABS-based WPCs had better performance in mechanical properties, indicating that ABS-based WPCs could have wider applications than ever polyolefin-based WPCs.;By minimizing the amount of added wood, one can flame retard ABS. Here, a halogen-free flame retardant system was developed for ABS using cellulose as a charring material and APP as a catalyst. The use of these additives permits compounding and injection molding of ABS at

SummaryThe aim of this study is to improve the flame resistance and toughness of poly(lactic acid) (PLA) with the addition of low amount of flame retardant fillers and plasticizer simultaneously. Poly(ethylene glycol) (PEG) was used as plasticizer for PLA. Ammonium polyphosphate, boron phosphate, and tri‐phenyl phosphate (TPP) were used as flame retardant additives. Among these flame retardant additives, boron phosphate was synthesized from its raw materials by using microwave heating technique. Characterization of PLA/PEG‐based flame retardant composites was performed by conducting tensile, impact, differential scanning calorimeter, thermal gravimetric analysis, scanning electron microscope, limiting oxygen index, and UL‐94 vertical burning tests. Mechanical tests showed that the highest tensile strength, impact strength, and elongation at break values were obtained with the addition of ammonium polyphosphate and TPP into PLA/PEG matrix, respectively. Scanning electron microscopy analysis of the composites exhibited that the more homogeneous filler distribution in the matrix was observed for TPP containing composite. The best flame retardancy performance was also provided by TPP when compared with the other flame retardant additives in the plasticized PLA‐based composites.

The implementation of organic phase change materials (PCMs) in several applications such as heating and cooling or building comfort is an important target in thermal energy storage (TES). However, one of the major drawbacks of organic PCMs implementation is flammability. The addition of flame retardants to PCMs or shape-stabilized PCMs is one of the approaches to address this problem and improve their final deployment in the building material sector. In this study, the most common organic PCM, Paraffin RT-21, and fatty acids mixtures of capric acid (CA), myristic acid (MA), and palmitic acid (PA) in bulk, were tested to improve their fire reaction. Several flame retardants, such as ammonium phosphate, melamine phosphate, hydromagnesite, magnesium hydroxide, and aluminum hydroxide, were tested. The properties of the improved PCM with flame retardants were characterized by thermogravimetric analyses (TGA), the dripping test, and differential scanning calorimetry (DSC). The results for the dripping test show that fire retardancy was considerably enhanced by the addition of hydromagnesite (50 wt %) and magnesium hydroxide (50 wt %) in fatty acids mixtures. This will help the final implementation of these enhanced PCMs in building sector. The influence of the addition of flame retardants on the melting enthalpy and temperatures of PCMs has been evaluated.

2D-nanostructures as flame retardant additives: Recent progress in hybrid polymeric coatings

Intumescent coatings are an effective method for fire protection of steel structures. The search for more environmental friendly intumescent coatings has led to the utilization of palm oil clinker (POC) as a bio-filler in solvent-borne intumescent coatings in order to improve fire protection performance, mechanical strength and water resistance of steel structures. In this research, POC and hybrid fillers are mixed with an acrylic binder and then blended with flame-retardant additives in order to produce intumescent coatings. The samples were tested using Bunsen burner test, thermogravimetry analysis, surface spread of flame test, field emission scanning electron microscopy, static immersion test, and adhesion strength test. It was found that the optimum composition of POC and hybrid fillers gives the best fire protection performance with the lowest equilibrium temperature (171.3°C), high thermal stability, good water resistance and excellent mechanical properties. The results of the surface spread of flame test show that Sample A3, A4, and A6 were classified as Class 1, which is the best classification. For Sample A6 (a hybrid formulation), the addition of aluminium hydroxide gives better water resistance with the lowest rate of weight change (<0.2%), while the addition of magnesium hydroxide enhances the bonding strength of the coating up to 125% compared with Sample A1 which only has a single filler POC. It can be concluded that the optimum composition of POC and hybrid fillers results in intumescent coating with the greatest fire protection performance.

This study reports the effects of triethyl phosphate (TEP), diphenyl cresyl phosphate (DPK), and the combined amount of aluminum hydroxide (ATH) with TEP at different weight ratios as flame retardant (FR) fillers on the physical, structural, mechanical, and flammable properties of unsaturated polyester resin (UPR). The synthesis of unsaturated polyester chains based on maleic anhydride (MA), phthalic anhydride (PA), propylene glycol (PG), ethylene glycol (EG), and diethylene glycol (DEG) was conducted in a prototype stainless steel reactor at 200 ± 5°C. Unsaturated polyester chains confirmed by nuclear magnetic resonance (1H‐NMR) were diluted with styrene monomer to create ready‐to‐apply UPR. Viscosity tests were carried out on the samples that were prepared by mixing FR fillers with UPR at different loading rates without adding accelerator and initiator. Reactivity tests of the cross‐linking initialized UPR suspensions unveiled that FR fillers prolonged the peak time and lowered the peak exotherm temperature. FR filler‐induced alterations in the chemical structure of the cured samples were then monitored using Fourier transform infrared spectroscopy (FTIR). Flexural, hardness, tensile, impact, and heat distortion temperature (HDT) tests were performed on the solid samples with and without the FR fillers. The limiting oxygen index (LOI) of the samples was also examined, and TEP was eventually found to work better than DPK for the corresponding samples involved. Therefore, the samples produced by blending UPR with TEP as well as with the combined amount of TEP and ATH at different weight ratios were characterized through vertical burning (UL‐94), cone calorimeter, and smoke density tests. As a result, it was revealed that TEP operates very well on the gas phase, despite being incompetent on the condensed phase during combustion, whereas ATH acts on both gas and condensed phases in an equal mean. Furthermore, thermal degradation behavior of the samples with and without the FR fillers and their exhaust gas products were investigated using a thermogravimetric analyzer (TGA) coupled with a Fourier transform infrared spectroscopy (TG‐FTIR). All the findings considering the presence of FR fillers were then evaluated and discussed in a brief manner to sort out the best combination of the additives for the UPR resin.

No one wants their bed, couch, chair, computer, or TV to catch on fire. “If an ordinary upholstered chair in your home gets ignited, it can essentially take your whole house down,” says Richard Gann, a senior research scientist at the U.S. National Institute of Standards and Technology’s (NIST) Building and Fire Research Laboratory. The most flammable part of a mattress or couch is its plastic polyurethane foam cushioning, he explains. Once a fire gets through a chair or mattress’s fabric covering and into this cushioning, it can start a catastrophic reaction that quickly leads to “flashover,” in which nearly everything combustible inside a room ignites simultaneously. Until very recently, brominated flame retardants, especially polybrominated diphenyl ethers (PBDEs), were one of the main materials used to reduce the speed with which the plastic components of consumer goods including beds, couches, chairs, and electronics could be consumed by fire. However, growing evidence shows that PBDE compounds are escaping from the products they protect and making their way into the products’ users. Moreover, the chemicals may disrupt human thyroid hormone functioning and cause other health effects, prompting many nations to ban or suspend their use in new consumer goods. [For more information on the health effects of PBDEs, see “Unwelcome Guest: PBDEs in Indoor Dust, p. A202 this issue.] Although bromine- and chlorine-containing flame retardants are still used in some products, the need for new alternatives is being driven by a confluence of policy, standards, and pressure from environmental groups. Europe banned the use of two formulations, PBDE pentaBDE and octaBDE, in 2004, the same year they were withdrawn from the North American market. A third compound, decaBDE, was banned 1 April 2008 by the European Court of Justice. Stateside, Maine has banned the use of decaBDE, the only PBDE still on the market in North America, in mattresses and residential upholstered furniture produced and sold in that state, and will extend the ban to electronics in 2010. Washington prohibits the use of decaBDE in mattresses and sets a process for a future ban in furniture and electronics if the state can identify a safer and feasible alternative that meets fire safety standards. Asian countries and other U.S. states have similar legislation in the works. “Instead of adding new fire retardant chemicals that ultimately may be shown to cause health problems, we should be asking whether we need to use these chemicals or if there are other ways to achieve equivalent fire safety,” contends Arlene Blum, a biophysical chemist and visiting scholar at the University of California, Berkeley. “So many of the chemicals we have banned in the past were flame retardants—think about asbestos, polychlorinated biphenyls, polybrominated biphenyls, tris(2,3-dibromopropyl) phosphate, PBDEs—[and] they all ended up in the environment and in people,” she points out. “We need to think carefully about adding these sorts of chemicals to consumer products before there is adequate health information.”

Polymeric materials are vital in modern life due to their versatility and cost-effectiveness. Thermosets are highly valued for their exceptional durability, chemical resistance, and mechanical strength. Despite these advantages, challenges such as enhancing fire safety and recyclability persist. Covalent Adaptable Networks (CANs) offer a promising solution, providing a sustainable platform for materials with self-healing and recyclable properties. This study addresses these challenges by developing innovative CANs through Aza-Michael addition and retro-addition chemistry. Amino-ester networks (AE) composed of m-Xylenediamine, and pentaerythritol triacrylate were manufactured while simultaneously incorporating phosphorus-based flame retardant (FR) additives synthesized in situ. A systematic characterization of physical, thermal, flame-retardant, and reprocessability properties was performed for the novel AE. Ten thermomechanical recycling cycles were performed for the AE to demonstrate the robustness of the new material, showing no degradation or changes in its physical, thermal, and flame-retardant properties. The chemistry involved in the recyclability was characterized via Raman Spectroscopy. The thermoset containing 0.7 wt% phosphorus (P) exhibits self-extinguishing behavior, achieving a V-0 rating. Compared to the material without flame retardant additives, the presence of the new in-situ FR (3.6 wt% P) allows for a significant reduction in total heat release (43%) and total smoke release (46%). The new FR molecule was also compared with a similar, previously reported molecule (EDA-bis-TEPT) and showed significantly better flame-retardant properties. Furthermore, the potential of these innovative thermosets was explored for applications such as fire-safe carbon fiber-reinforced composites, indicating a promising direction for developing sustainable and high-performance polymer materials.

The surface chemical modified aluminum hypophosphite (AHP) defined as MAHP was successful prepared through P–H bonds on AHP surface reacted with the aldehyde groups in hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene made in our lab. The wettability of the flame retardants was evaluated by water contact angle tests, and the water contact angle of the prepared MAHP dramatically increased from 0° for AHP to 145°, which indicated the surface modification made the superhydrophilic AHP into superior hydrophobic MAHP. The prepared MAHP and AHP, respectively, incorporated into polyamide 6 (PA6) matrix to prepare flame retardant PA6 composites and the fire retardancy and thermal degradation behavior of flame retardant PA6 composites were investigated by limiting oxygen index, vertical burning test (UL‐94), cone calorimeter, and thermogravimetric analysis tests. The morphologies and chemical compositions of the char residues for PA6 composites were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy, respectively. The water resistant properties of flame retardant PA6 composites were evaluated by putting the samples into distilled water at 70°C for 168 hr, and the mechanical properties for flame retardant PA6 composites were investigated by the tensile, flexural, and Izod impact strength tests. The results demonstrated that the PA6/MAHP composites successfully passed UL‐94 V‐0 flammability rating, and the limiting oxygen index value was 27.6% when the loading amount of MAHP was 21 wt%. However, there is no rating in vertical burning tests for PA6/AHP composite with the same amount of AHP, which indicated the surface modification of AHP enhanced the flame retardancy efficiency for PA6 composites. The morphological structures and analysis of X‐ray photoelectron spectroscopy of char residues revealed that the surface modification of AHP benefited to the formation of a sufficient, flame retardant elements rich, more compact and homogeneous char layer on the materials surface during combustion, which prevented the heat transmission and diffusion, limit the production of combustible gases, inhibit the emission of smoke and then led to the reduction of the heat release rate and smoke produce rate. The mechanical properties results revealed that the surface modification of AHP enhanced the mechanical properties, especially the Izod impact strength comparing with that of PA6/AHP composites with the same amount of flame retardant. After water resistance tests, the PA6/MAHP composites remained superior flame retardancy and presented continuous and compact char layer after cone calorimeter tests; however, the fire retardancy for PA6/AHP composite obviously decreased, and the char layer was discontinuous with big hole caused by the extraction of AHP by water during water resistance tests. Copyright © 2017 John Wiley &amp; Sons, Ltd.

The paper describes how to make PP homopolymer flame retardant through the use of halogenated and halogen-free additives. The paper attempts to capture the intricacies involved in compounding recipe development, physical and mechanical properties and performance aspects during injection moulding of the final article. In a nutshell, the paper describes the end user's experience of flame retardant additives in PP homopolymer from concept to product. The present work was directed towards compound development and the characterization of physical, mechanical, flammability performance and performance during the injection moulding of PP homopolymer. The application identified was injection mouldable battery boxes for applications in the telecom sector. PP compounds were prepared from halogen-based and halogen-free flame retardant (FR) additives, designed to meet V0 at 3.2 mm thickness as per the UL94 test protocol. Flame retardant polypropylene; (FR-PP) is used for “back-up” batteries. These are used in telecommunications and railway units and supply energy immediately in the case of an interruption of normal power supply. The batteries contain sulphuric acid as electrolyte. Experimental work was undertaken to develop FR-PP compounds and investigate the effect of FR additives on critical properties. The effect of FR-additives on the heat sealing properties of battery containers was also investigated. The results show that halogenated FR additives can contribute to the excellent acid resistance of PP. Use of non-halogenated FR additives in PP resulted in compounds having densities close to 1.0 g/cm3, at identical loadings to those used with halogenated FR additives. In comparison, FR-PP compounds based on halogenated FR additives gave densities close to 1.2 g/cm3. The data obtained from this investigation show that both types of FR/PP compounds are suitable for battery box applications made by injection moulding.