Magnesium Hydroxide Flame Retardant Research Articles

Synthesis of magnesium hydroxide flame retardant based on microcrystalline magnesite and its application in epoxy resin

Abstract A nanoscale hexagonal flake magnesium hydroxide (MH) flame retardant was prepared by a hydrothermal method using Tibetan microcrystalline magnesite as the raw material. The synthesized samples were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FSEM), thermogravimetric analysis-differential scanning calorimetry (TG-DSC), and laser particle size analysis. When subjected to hydrothermal treatment at 180 °C for a duration of 8 h in a solution containing 6 mol l−1 NaOH, and with the incorporation of 4 wt% of the surfactant polyethylene glycol 2000 (PEG2000), hexagonal flake MH, possessing an average particle size of 378.3 nm, was successfully synthesized. The study conducted an examination of the thermal, mechanical, and flame-retardant properties of both EP and EP/MH composites. The results revealed that the incorporation of 9 wt% MH led to a notable reduction in the peak heat release rate, total smoke production, and mass loss rate of the EP/MH composites by 36%, 14.5%, and 33.3% respectively, as compared to the pure EP. Remarkably, the tensile and flexural strength of the composite exhibited minimal impact.

Porous carbon network-based composite phase change materials with heat storage capacity and thermal management functions

Porous carbon network-based phase change composites have been widely used in energy storage and thermal management related fields. At present, the demand of energy crisis for photothermal energy storage and the prevention and management of thermal abuse of electronic equipment constantly promote the development of carbon-based composite phase change materials (PCMs). Therefore, a series of new composite materials filled with PCMs and polyethylene glycol (PEG) and added with flame-retardant magnesium hydroxide were developed, which makes the composites show certain flame-retardant ability in high-temperature environments. The results show that the thermal conductivity increases from 0.25 to 0.94 W/m·K, and the latent heat of phase change remains at 142.7 J/g. In addition, due to the capillary effect caused by the synergistic effect of multi-pore carbon (MPC) structure and cellulose macromolecular chain, the composite material has good shape stability, which effectively prevents the leakage behavior of PCMs during solid-liquid phase change. Moreover, the absorbance of the composite material can reach 1.28 L/(g cm) in the ultraviolet–visible light range of 200 nm–800 nm, and its photothermal conversion efficiency can reach 90.8 %. Therefore, this material has a broad application prospect in the thermal management of electronic equipment and photothermal energy storage devices.

Vulcanization kinetics and mechanical properties of filled ethylene-vinyl acetate copolymer rubber composites

Abstract The vulcanization reaction of ethylene vinyl acetate copolymer (EVM) rubber is fast, resulting in poor processing safety. EVM is often filled with flame-retardant fillers as insulating or sheathing material for wires and cables. Herein, the effects of flame-retardant magnesium hydroxide (Mg(OH)2), aluminum hydroxide (Al(OH)3) and of the traditional reinforcing fillers carbon black (CB) and silicon dioxide (SiO2) on the vulcanization kinetics of EVM were investigated. The vulcanization characteristics showed that the scorch time (T 10) of the unfilled EVM (KB), SiO2/EVM, Mg(OH)2/EVM, and Al(OH)3/EVM composites was about 1.75 min. T 10 of the CB/EVM composite was 2.22 min. Compared with KB, the activation energy (E a ) increased by about 15 kJ/mol for CB/EVM composites and by about 5 kJ/mol for SiO2/EVM, Mg(OH)2/EVM and Al(OH)3/EVM composites. The results indicate that CB delays the vulcanization time of EVM rubber, slows down the rate of vulcanization reaction and improves the safety of vulcanization. The addition of SiO2, Mg(OH)2 and Al(OH)3 has little effect on the vulcanization reaction. The mechanical properties show that CB/EVM is more uniformly vulcanized and has the best mechanical properties with a tensile strength of 17.61 MPa and elongation at break of 404.58 %. Mg(OH)2/EVM and Al(OH)3/EVM samples have prominent vulcanization non-uniformity resulting in poor mechanical properties.

Toughed interface of Mg(OH)2/polymer composites with improved mechanical performance via intramolecular “bridge”

Most commercialized polymers are flammable, which hinders their practical applications. The commonly employed flame retardant magnesium hydroxide (MDH) additives with high loading concentration will deteriorate the composite mechanical properties. Therefore, achieving flame retardant polymer composites without compromising their mechanical strength becomes imperative. Here, we employed a titanate coupling agent (TC) to modify the MDH surface, successfully achieving a 56.8 % enhancement of mechanical strength and improved flame retardancy in TC-MDH@ethylene-vinyl acetate (EVA) composites, compared to pristine MDH/EVA samples. Moreover, molecular dynamic simulation was performed to unravel that TC could function as intramolecular “bridge” to increase the binding energy via hydrogen bonds, which leads to toughed interface of MDH and polymers, as well as better compatibility and homogeneous dispersion between MDH and EVA. Such strategy could be employed to enhance both mechanical strength and flame retardancy of polymer composites.

Preparation and Sound Insulation Performance of Polystyrene Building Flame Retardant and Thermal Insulation Building Materials.

In this study, magnesium hydroxide (MH) was modified by sodium dodecylbenzene sulfonate (SDBS) to prepare modified magnesium hydroxide (MMH) flame retardant, which was mixed with polystyrene (PS) to obtain flame retardant PS composite plate. The micromorphology, mechanical properties, thermal stability, and flame retardancy of flame retardant PS composite plate were analyzed. The experimental results show that MMH is well dispersed in PS matrix, PS-MMH-3 has the best tensile strength and elongation at break, the limit oxygen index (LOI) is 44.3% higher than that of pure PS, and the combustion rate is slow, indicating that PS-MMH-3 has good flame retardant properties.

PP‐GF‐EPP sandwich structures as housing materials for rechargeable energy storage system of electric vehicles: Investigations into flame retardancy

AbstractThe growing importance of electric mobility has led to an increased demand for safety technologies in the automotive sector, such as the flame retardancy of materials used for electric vehicles. The fire protection of a fully equipped rechargeable energy storage system (REESS), including battery, housing, control electronics, etc., against a fuel fire must be tested according to UNECE Regulation No. 100 Annex 8E ‐ Fire Resistance (UNECE‐R100‐8E). To pass this fire retardancy requirement, the flame retardancy of the housing materials is of great importance. In this study, the flame retardancy of glass‐fiber‐reinforced polypropylene (PP‐GF) tape laminates containing the flame retardant magnesium hydroxide and different GF amounts, as well as sandwich structures of these PP‐GF tape laminates with a polypropylene bead foam (EPP) core, are investigated by a limiting oxygen index test, a UL94 test and a cone calorimeter test. Furthermore, a newly developed approach of a bench‐scale fuel fire test which simulates the fire treatment of the UNECE‐R100‐8E on component level is used.

Flammability, morphological and mechanical properties of sugar palm fiber/polyester yarn-reinforced epoxy hybrid biocomposites with magnesium hydroxide flame retardant filler

This paper aims to study the surface morphology, flammability and tensile properties of sugar palm fiber (SPF) hybrid with polyester (PET) yarn-reinforced epoxy composite with the addition of magnesium hydroxide (Mg(OH)2) as a flame retardant. The composites were prepared by hybridized epoxy and Mg(OH)2/PET with different amounts of SPF contents (0%, 20%, 35% and 50%) using the cold press method. Then these composites were tested by horizontal burning analysis, tensile strength testing and scanning electron microscopy (SEM) analysis. The specimen with 35% SPF (Epoxy/PET/SPF-35) with the incorporation of Mg(OH)2 as a flame retardant showed the lowest burning rate of 13.25 mm/min. The flame took a longer time to propagate along with the Epoxy/PET/SPF-35 specimen and at the same time producing char. Epoxy/PET/SPF-35 also had the highest tensile strength of 9.69 MPa. Tensile properties of the SPF hybrid with PET yarn (SPF/PET)-reinforced epoxy composite was decreased at 50% SPF content due to the lack of interfacial bonding between the fibers and matrix. Surface morphology analysis through SEM showed uniform distribution of the SPF and matrix with less adhesion, which increased the flammability and reduced the tensile properties of the hybrid polymeric composites. These composites have potential to be utilized in various applications, such as automotive components, building materials and in the aerospace industry.

Optimization of Flame Retardant Amount for Epoxy Anti-Sliding Surface Layer

To improve the flame retardant ability of anti-skid epoxy surface material in the tunnel, the paper conducted study on influence of inorganic flame retardant magnesium hydroxide (abbrev. MH), organic flame retardant decabromodiphenylethane (abbrev. DBDPE) and antimony trioxide (abbrev. AO) on the performance after they were applied in anti-skid epoxy surface material. The mechanical properties, rheological properties, combustion properties and thermal stability of epoxy surface with different flame retardants were tested. After optimizing the blending amount to determine the optimal proportion, flame retardant efficiency of those was evaluated. The analysis showed that organic flame retardant DBDPE and AO have a better performance at the same dosage. The oxygen index of DBDPE/AO epoxy cement increased much faster than MH with the amount of flame retardant. When content reached 16%, the oxygen index of the DBDPE/AO reached 31.8%, which meant that it was a flame retardant material and had little effect on other properties of the cement. It is not a good treatment to add too much flame retardant in the epoxy anti-sliding surface, otherwise the rheological properties and mechanical properties would be influenced largely. When the content of composite flame retardant DBDPE/AO got to 12%, each performance index would meet the design requirements. The excessive content of MH was unsuitable because it would greatly reduce the mechanical properties and the ease of construction of epoxy cement. Based on comprehensive performance analysis, 9% DBDPE/AO is recommended as the flame retardant for anti-skid epoxy surface.

Locally induced chemical conversion processes — A means to control tribological properties of polymer composites?

Thermoplastics are gaining traction as materials for tribological systems. However, varying load conditions and unintentional temperature excursions make the behavior unpredictable and raise the need for smart materials able to react to changes in the systems boundary conditions. Utilizing fillers with physical or chemical material transformations, e.g. flame-retardants, seems to be a promising approach. In the present study, a polyamide based compound reinforced with carbon fibers and filled with the flame-retardant magnesium hydroxide was investigated. Tribological tests were performed on a Pin-on-Disk tribometer under constant sliding speed and incrementally increasing contact pressure. Compared to an unfilled reference, a significant improvement of the tribological performance could be demonstrated. Local hot spots in the contact interface trigger the material transformation which actively prevents severe thermal damage.

Investigation on Smoke Suppression Mechanism of Hydrated Lime in Asphalt Combustion

In this study, cone calorimeter and thermogravimetric analyses were used to simulate the asphalt combustion process under the conditions of fire radiation and programmed temperature increase. The gaseous compositions and release rules were analyzed by infrared spectroscopy to investigate the influence of hydrated lime on the smoke suppression mechanism in the asphalt combustion process. The experimental results show that hydrated lime can promote the asphalt mastic surface to form a barrier layer during the combustion process. This barrier layer can reduce the burning intensity of asphalt. Although the compositions of gaseous products do not change much, the rates of CO production and smoke release are decreased. In addition, hydrated lime is alkaline and can thus neutralize acidic gases such as SO2 and reduce the toxicity of gaseous products. With the addition of 40 wt.% hydrated lime, the total smoke release and the CO release rate both decrease by more than 20% relative to the addition of the same amount of limestone fillers and decrease by more than 10% relative to the addition of the same amount of magnesium hydroxide flame retardant.

Flame retardant mechanism and surface modification of magnesium hydroxide flame retardant

At present, a polymer material, as a representative of the fine chemical industry rapid development, promote the additives research and development process. Magnesium hydroxide flame retardant agent has green environmental protection low cost advantages, received more and more attention. Many countries use magnesium hydroxide as a name retardant instead of halogenated name retardant. Magnesium hydroxide has low fire retardant efficiency, it can achieve flame-retardant effect under large filling volume and then seriously deteriorate mechanical and processing properties of materials. In order to improve mechanical property of materials, and we must modify the surface properties of magnesium hydroxide. There have been researches about magnesium hydroxide surface modification, which normally applied surfactants or coupling agents as surface modification instead of not macromolecular surface modifiers. Increasingly becoming the focus of flame retardants research at home and abroad, magnesium hydroxide as flame retardant additives is easy to reunite dispersion such poor compatibility. Therefore, it’s an important inquisitive task to improve the surface properties.

Mussel-Inspired General Interface Modification Method and Its Application in Polymer Reinforcement and as a Flame Retardant.

Inspired by the remarkable adhesion of mussels, the mimicking of natural adhesive molecules has been widely used for surface modification. In the present study, an economical and easily available biomimic material named as tannic acid–Fe3+ (TA–Fe3+) was first directly used as a surface modifier, carbonization agent, smoke inhibitor, and flame-retardant synergist. Compared with the flame-retardant magnesium hydroxide (Mg(OH)2), TA–Fe3+-modified Mg(OH)2 endowed polyamide 6 (PA 6) with improved mechanical performance and flame-retardant properties. The flame-retardant and smoke-suppressant properties were tested by the limiting oxygen index and cone calorimeter tests. The flame-retardation mechanism was investigated by thermogravimetric analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The tensile strength could increase up to 90%, and the modified flame retardant was found to have higher UL-94 grade with the same dosage of flame-retardant additives. The peak heat release rate, total heat release, peak of smoke production rate, and total smoke production were significantly reduced. The synergistic effect between TA–Fe3+ and Mg(OH)2 was also discussed. This study provides new insights into the direct utilization of a biomimicking adhesive molecule, TA–Fe3+, to realize simultaneous composite reinforcement and flame-retardant property enhancement. Meanwhile, because of the extensive synergies of flame-retardant metal oxide with iron element and the universal growth characteristics of TA–Fe3+, it has potential applications in the preparation of various flame-retardant polymers.

Spray-Drying-Assisted Layer-by-Layer Assembly of Alginate, 3-Aminopropyltriethoxysilane, and Magnesium Hydroxide Flame Retardant and Its Catalytic Graphitization in Ethylene-Vinyl Acetate Resin.

Alginates (nickel alginate, NiA; copper alginate, CuA; zinc alginate, ZnA) and 3-aminopropyltriethoxysilane (APTES) were alternately deposited on a magnesium hydroxide (MH) surface by the spray-drying-assisted layer-by-layer assembly technique, fabricating some efficient and environmentally benign flame retardants (M-FR, including Ni-FR, Cu-FR, and Zn-FR). The morphology, chemical compositions, and structures of M-FR were investigated. With 50 wt % loading, compared with EVA28+MH, the peak heat release rate, smoke production rate, and CO production rate of EVA28+Ni-FR decreased by 50.78%, 61.76%, and 66.67%, respectively. The metals or metal oxide nanoparticles arising from alginates could catalyze the pyrolysis intermediates of EVA into graphene and amorphous carbon, which could bind the inorganic compounds (the decomposition products of MH and APTES) together and form some more protective barriers. For each M-FR, the flame retardant and smoke suppression efficiency were different, which were caused by the diverse carbonization and graphitization behaviors of three alginates. ZnA generated some ZnO aggregations and could not catalyze the graphitization of intermediates. For CuA, the catalytic graphitization was limited by the tightly binding graphene layer. As for NiA, the configuration of the Ni atom could not provide strong binding of Ni substrate and carbon. The liquid-like Ni nanoparticles could restructure and get out from firm graphene shells, so the catalytic graphitization of NiA was efficient and sustainable. This work displayed the catalytic graphitization mechanism of alginates while exploring a simple and novel strategy for fabricating efficient green flame retardants.

Influence of flame retardant magnesium hydroxide on the mechanical properties of high density polyethylene composites

The effects of incorporating magnesium hydroxide as a flame retardant on the mechanical properties of high density polyethylene which include tensile, flexural, compressive, shear and fracture toughness behaviours were investigated. The weight fraction of the filler material ranges from 10 to 50 wt %. The effects of filler weight percent and strain rate during tensile testing by means of a universal testing machine were both studied to identify the behaviour of the produced composites. It was observed that the flexural modulus and Young's modulus increased steadily while the tensile fracture strength and the tensile yield strength were inversely proportional to the weight fraction of magnesium hydroxide. The tensile yield strength showed a steady decrease with the loading of filler material until 10% then it showed a plateau until 50%. The tensile elongation at break decreased sharply between zero and 10% weight fraction, followed by a slight decrease until 50% weight fraction. The flexural strength peaked with the increase of magnesium hydroxide weight fraction. The strain rate showed a dramatic effect on the tensile properties of the samples. The compressive strength and shear strength of specimens were directly proportional to Mg(OH)2 until 40% and 30%, respectively. The novelty in optimizing between filler content and testing configurations reveal wide range of applications.

Date palm fibre filled recycled ternary polymer blend composites with enhanced flame retardancy

Flammability of recycled polypropylene (PP)/low density polyethylene (LDPE)/high density polyethylene (HDPE) ternary blends containing date palm fibres is investigated in this study. Melt blending is used for the composite preparation and the palm fibres induce good mechanical strength to the blend composites. The effect of flame retardant magnesium hydroxide, is studied through the limiting oxygen index analysis and cone calorimeter studies. Morphology of the palm fibres in presence of fire retardant reveals interesting facts of base hydrolysis. Since the polymers used are recycled ones and the fibres are obtained from the date palm leaves, the whole composite manufactured stands as low cost, less energy consuming and environmental friendly. Though the flame retardant reduced the mechanical properties, the palm fibres strengthened the whole composite thus helping to achieve the flame retardancy and mechanical properties simultaneously. Flame retardancy is correlated with the thermal degradation and thermal conductivity of the blend fibre composites as well.

Tensile and flexural properties of polypropylene composites filled with highly effective flame retardant magnesium hydroxide

The reinforcing effects of highly effective flame retardant magnesium hydroxide (FMX) content on the tensile and flexural properties of filled polypropylene (PP) composites were investigated within the FMX weight fraction range from 5 to 60 wt%. It was found that the Young's modulus and flexural modulus increased approximately linearly while the tensile yield strength and tensile fracture strength decreased slightly with increasing the FMX weight fraction. When the FMX weight fraction was lower than 20%, the tensile elongation at break decreased considerably, and then decreased slightly; the flexural strength increased when the FMX weight fraction was lower than 30%, and then decreased slightly. The tensile properties increased with increasing rate of tension. Moreover, the tensile yield strength of the composites was estimated using an equation proposed in previous work, and good agreement was shown between the predicted and the measured data.

Thermal analysis of kenaf fiber reinforced floreon biocomposites with magnesium hydroxide flame retardant filler

The Floreon (FLO) biopolymer is an advanced bioplastic materials, invented by The University of Sheffield and CPD Plc, in November 2013. Nine combinations of the kenaf fiber (KF) reinforced FLO with magnesium hydroxide (MH) flame retardant filler were fabricated and tested on Thermogravimetry Analysis, Differential Scanning Calorimetry, and Dynamic Mechanical Analysis (DMA). Scanning electron microscopy has been used to study the cross‐section of interface. The low thermal stability of natural fiber composite has found lower decomposition temperature but a higher residual mass. MH filler containing composite has higher residual mass at 600°C but it is not the best flame retardant for the FLO biopolymer composites as the pure FLO biopolymer has higher decomposition temperature than MH reaction temperature. Some synergistic effect located in char formation, Tg reduction and a lower tan δ peak shown in the three phase system (KF/FLO/MH). The MH filler has found more significant in enhancing mass residual. The Tg were show deterioration for all samples compared with the pure FLO biopolymer. The melting temperature has found no significant change either KF or MH or both of these were inserted. The values of coefficient, C recorded decreasing as increasing the fiber loading. This showing the fibers transfer the loading effectively. Close value of storage moduli found in DMA for all samples except sample 4. POLYM. COMPOS., 39:869–875, 2018. © 2016 Society of Plastics Engineers

High throughput preparation of magnesium hydroxide flame retardant via microreaction technology

Magnesium hydroxide flame retardant is prepared with narrow PSD on a pilot scale using microreaction technology.

Modification of Magnesium Hydroxide Flame Retardant Using Oleic Acid by Wet Method

The magnesium hydroxide (Mg(OH)2, MH) was modified using oleic acid (C17H33COOH, OA) by wet techonlogy. The modification effect of MH was evaluated by activation index and oil absorption rate. The optimum technological conditions were as follows: the concentration of magnesium hydroxide slurry was 35wt%, the oleic acid 2wt% ,temperature 70 °C, time 40 min and a stirring rate 2200 rpm. Additionally, the structure and morphology of the improved modified MH powders were characterized by SEM, XRD, FTIR, TGA-DSC. Compared with the unmodified MH, the modified MH had better dispersibility and hydrophobicity.

Preparation of magnesium hydroxide flame retardant from light calcined powder by ammonia circulation method

Lamellar magnesium hydroxide (MH) with a purity of 99.5% was synthesized using industry lightly calcined powder as raw material and ammonium salt solution as circulating mother liquid by ammonia circulation method. The structures and morphologies of MH were characterized by X-ray diffraction, scanning electron microscope, laser particle size analyzer and thermo gravimetric analysis. The experimental results showed that the hexagonal flake MH products were about 0.86μm in mean particle size (D50) and nanometers in thickness, and were loose enough for filtering. The BET surface area was about 8m2∙g−1, indicating that the products can be applied as additives of the macromolecule compounds. The diffraction intensity of the (001) direction was higher than that of the (101) direction and the decomposition temperature of products was about 400°C.