Flame Retardant Filler Research Articles

Thermal Degradation Characteristics of Styrene-Butadiene-Styrene Copolymer Asphalt Binder Filled with an Inorganic Flame-Retarding Agent.

Asphalt binder is a complex mixture of dark brown polymers composed of hydrocarbons with generally poor fire resistance. To improve its flame retardancy when used in tunnel asphalt pavements, a new inorganic flame-retardant filler (FR) containing magnesium hydroxide, aluminum hydroxide, inorganic phosphate, and melamine salt was explored. Thereafter, limiting oxygen index (LOI) and smoke suppression tests for the flame-retarded asphalt binder (FRA) mastics mixed with FR and styrene-butadiene-styrene (SBS) copolymer asphalt binder were conducted. Thermogravimetric (TG) and differential scanning calorimetry (DSC) curves for the FRA were correspondingly generated. Based on the TG data, the reaction function g(α), apparent activation energy Ea, and pre-exponential factor A were quantitatively evaluated using kinetic analysis. In addition, a Fourier transform infrared spectrometry (FTIR) test was utilized to assess the effects of the presence of FR on the chemical composition of the asphalt binder. Dynamic shear rheometer (DSR) tests were also performed to evaluate the rheological behavior of FRA. Results show that the presence of the FR significantly reduced the LOI and improved the smoke suppression during combustion of the asphalt binder mastics. The presence of FR was found to increase the Ea and the complexity of the combustion reaction, thereby improving the flame retardancy of the asphalt binder. FTIR analysis indicated that the presence of FR did not induce any strong chemical reactions to significantly impact or alter the functional groups of the asphalt binder. Furthermore, it was also observed that the rutting parameter and critical failure temperature of FRA increased with the addition of FR due to the stiffening effect of the solid FR particles.

Interfacial gluing strategy derived closely-coupled ternary LDH@P-RGO nanohybrid towards constructing fire-safe epoxy resin

Inherently high fire hazard has been the disreputable and nerve-wracking issue of epoxy resin (EP), challenging its extended applications. Hence, we have adopted the interfacial gluing strategy to acquire closely-coupled ternary LDH@P-RGO nanohybrid as flame retardant filler. When loading 2.0 wt% LDH@P-RGO, peak heat release rate and total heat release are impaired by 36.5% and 38.4%, whilst total smoke production is lowered by 30.3%. Of note, total CO production is reduced by 37.6%. Moreover, the limited oxygen index is elevated from 22.6% to 29.1%. Flame retardation comparison with previous works also highlights the superiority of LDH@P-RGO towards impairing the fire hazard of EP. Strong evidences for the weakened emissions of toxic CO, NO and HCN gasses are also provided. Satisfactorily, the promotions in flexural strength and modulus are observable. This work can provide enlightenments for constructing closely-coupled nanohybrid via interfacial gluing strategy, mining its potencies in polymer-matrix composite aera.

Phosphorated cellulose as a cellulose-based filler for developing continuous fire resistant lyocell fibers

Developing a sustainable fire resistant regenerated cellulose fiber for realizing large scale industrial production is an urgent research topic. In this work, a cellulose-based flame retardant filler, phosphorylated microcrystalline cellulose, was successfully synthesized. The acquired phosphorylated cellulose (P-Cell) as a modified bio-based flame retardant was cost-effective and compatible with cellulose spinning dope. The preparation process of fire resistant fiber was the same as the lyocell fibers on a factory scale pilot production. The lyocell fibers loaded with 20 wt% P-Cell exhibited favorable thermal stability and fire retardancy. The char residue amount of fire resistant lyocell fibers remarkably increased by 118% at 700 °C compared with the pure lyocell fibers. As micro combustion calorimetry estimated, the total heat release and peak heat release rate of modified fibers significantly decreased by 87.6% and 82.4%, respectively compared with those of pure lyocell fibers. The flame retardant mechanism was ascribed to the formation of phosphorus-containing oxides and char layer in the condensed phase and the generation of incombustible compounds in the gaseous phase.

Flame Retardant Nano-Structured Fillers from Huntite/Hydromagnesite Minerals.

In the current study, we propose a simple hydrothermal pathway to synthesize nano-structured Mg(OH)2 after application of thermal decomposition followed by hydration of commercial minerals based on hydromagnesite and huntite. The synthesis of nano-materials is performed without the use of any catalyst. The effect of decomposition temperature on the hydrothermal synthesis of Mg(OH)2 is extensively studied. It is shown that the morphology of resulting structures consists typically of particles ~200 nm in diameter and ~10 nm in thickness. Study of the structure at the molecular level designates the composition and supports the nano-sized characteristics of the produced materials. The associated thermal properties combined with the corresponding optical properties suggest that the material may be used as a flame retardant filler with enhanced transparency. In this concept, the flame retardancy of composite coatings containing the produced nano-sized Mg(OH)2 was examined in terms of limiting oxygen index (LOI), i.e., the minimum concentration of oxygen that just supports flaming combustion.

Preparation of Ni-Fe layered double hydroxides and its application in thermoplastic polyurethane with flame retardancy and smoke suppression

Aluminum hypophosphite (AHP), as an effective phosphorus-based flame retardant used in thermoplastic polyurethane (TPU), released a large amount of smoke and toxic gasses during combustion. In this work, a flame retardant filler, Ni-Fe layered double hydroxides (NiFe-LDHs), was synthesized and applied in TPU together with AHP. The limiting oxygen index (LOI) of the TPU/6AHP/1NiFe-LDH composite reached 30.7% with a V-0 rating in the UL-94 test. Compared with neat TPU, the peak heat release rate (pHRR) and total heat release (THR) values of TPU/6AHP/1NiFe-LDH sample were reduced by 67.9% and 40.8%, respectively. Moreover, both the smoke production and CO/CO2 yield were also decreased sharply. It was proposed that NiFe-LDH provided the effect of catalyzing char formation, and the obtained dense char layer was able to block both heat and smoke release. In addition, the addition of NiFe-LDH had little effect on the mechanical properties of TPU, and the tensile strength and elongation at break only decreased by 6.0% and 6.9%, respectively. This work provides a new strategy for fillers and flame retardants to improve the flame retardant properties and smoke suppression of TPU.

Rigid polyurethane foam composites based on iron tailing: Thermal stability, flame retardancy and fire toxicity

In order to explore the potential utilization value of iron tailings, the typical solid waste-iron tailings was introduced into rigid polyurethane foam (RPUF) as a flame retardant filler in this paper. The flame retardant performance, combustion performance, gas-phase products and char residue’s related properties of RPUF/ITS composites were systematically investigated by limiting oxygen index, thermogravimetric (TG), cone calorimetry (CCT) and thermogravimetric-infrared spectrometry (TG-FTIR). The results showed that ITS improved the overall thermal stability of the composites, and the T-5%, T-50%, Tmax1, Tmax2 and char residue rates were all higher than those of the pure samples. The CCT indicated that ITS had a certain effect on smoke suppression and heat release reduction. The peak heat release rate of RPUF-6 was reduced by 22.75% compared with that of the pure sample, and the total smoke release of RPUF-2 was reduced by 25.36%. Smoke factor (SF), fire growth rate index and fire performance index indicated that ITS reduced the fire risk of RPUF/ITS composites. TG-FTIR showed that ITS inhibited the decomposition of RPUF/ITS composites, and the release intensity of hydrocarbons, CO2, isocyanate compound, CO, aromatic compounds and esters decreased significantly. TG, MCC, scanning electron microscope and Raman implied that ITS promoted the formation of a dense char layer in RPUF and improved the heat resistance of the char layer.

Flame retardancy efficacy of phytic acid: An overview

AbstractThe article reviews the different methods of which, phytic acid (PA) can be employed as a flame retardant (FR) filler for different polymeric materials. The methods are critically discussed, based on the available literature and patents. Depending on the method used and the addition of FRs into a PA flame retarded system, different flame retarding modes of action and fire resistance performances are attained. The mechanism of action for PA‐based system remains similar to those observed in other phosphorus‐based FRs, namely, condensed and gas‐phase mechanisms.

Mechanical, viscoelastic, and flammability properties of polymer composites reinforced with novel Sirisha bark filler

Today is the era of advanced materials to resolve the issue due to ecological hazards. Research is being carried out to find the alternative of the existing materials with a low cost and eco-friendly nature. Polypropylene (PP) is one of the major commodity thermoplastics having wide applications worldwide. The neat PP is extremely sensitive to flame and therefore it is a challenging task for the researchers to reduce the flame sensitivity of PP composites for safe applications. Though the artificial flame retardant filler reduces the flame propagation, these are hazardous, costly, not environment friendly and, they reduce the mechanical strength of the polymer composites upon higher percentage loading. To overcome this difficulty, in this work, the novel natural Sirisha bark filler was reinforced to the coir fiber/PP hybrid composites to enhance the flame retardant and mechanical properties. The time to ignite (TTI) of the hybrid composites increased due to bark filler reinforcement in the composites and the flame spread reduced to zero. The impact strength of hybrid composites was found to be increased due to the strong interfacial adhesion of the bark filler with the PP matrix. The scanning electron microscope (SEM) micrographs revealed the well-defined grain boundaries of hybrid composites. The carbonaceous char coating over the surface of the hybrid composite was observed from the char morphology that acts as a hindrance to flame. The viscoelastic properties such as storage modulus, loss modulus, and loss tangent of the hybrid composites were studied by using dynamic mechanical analysis (DMA).

The synergism effect of montmorillonite on the intumescent flame retardant thermoplastic polyurethane composites prepared by selective laser sintering

AbstractSelective Laser Sintering (SLS) is a powder‐based 3D printing technology. It offers a new means of fabricating complex modules with special properties, such as mechanical, flame retardant, electrical and thermal properties. In this paper, the effect of an intumescent flame retardant (IFR) and montmorillonite (MMT) on the fire resistance of thermoplastic polyurethane (TPU) was investigated. TPU composites powders were prepared by mixing with a two‐step method and can be effectively applied to SLS. Morphology characters exhibited that the fillers disperse well in the TPU powder. The structure analysis and hydrophilia analysis of sodium montmorillonite (Na‐MMT) and organically modified montmorillonite (OMMT) demonstrates the different compatibility in TPU, which reflects diverse flame retardant behavior. With 22% IFR and 3% OMMT fillers, the LOI of TPU composites increased from 17.2% to 28% and subsequently a UL‐94 V‐0 ranking was obtained. In the CCT results, the formula of 22% IFR and 3% OMMT showed the lowest heat release and smoke production. The study also explored the effects of flame retardant fillers on the thermal stability of TPU composites and melting and crystallization behaviors in SLS processing. In addition, the char residues after heating were analyzed via scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and laser Raman spectroscopy. The results demonstrate that the composites have favorable flame retardant properties, thermal stability, char forming performance, and SLS process properties. The TPU composites prepared via SLS in this study demonstrated extensive potential in fire protection materials.

Innovative design of environmentally friendly silicon-based polyphosphazene-functionalized hydroxyapatite nanowires: An efficient enhancement strategy for the fire safety and mechanical properties of unsaturated polyester

Non-toxic, low-smoke, high-efficiency and environmentally friendly flame retardants have become a hot issue at present. Here, polyphosphazene crosslinked by hexachlorocyclotriphosphazene (HCCP), 3-aminopropyltriethoxysilane (APTES), and dopamine (DA) was used to modify hydroxyapatite nanowires (HAPNW), obtaining a new environmentally friendly nanohybrids (f-HAPNW). Immediately afterwards, f-HAPNW was incorporated in unsaturated polyester (UPR) matrix in the presence of a nanowire structure with a high aspect ratio, accompanied by excellent interfacial compatibility. The incorporation of a small amount of f-HAPNW achieved an overall improvement in the fire safety and mechanical properties of UPR nanocomposites, including 23% decrease in total heat release rate (THR), 25.7% and 29.5% reduction in total smoke production (TSP) and the peak of CO production rate (PCOP) when the content was 2.0 wt%; 80.1% and 11.9% simultaneous increase in tensile strength and fracture elongation, and 61.2% increase in impact strength when the content was 0.5 wt%. Compared with similar previous research, the introduction of bio-based materials and environmentally friendly flame retardants in the design achieved significant flame-retardant filler efficiency, while considering the issues of reducing smoke release and environmental pollution. In general, this work innovatively prepared an environmentally-friendly hierarchical f-HAPNW structure, and achieved a comprehensive improvement in the performance of UPR nanocomposites, providing a reference idea for the design of high-performance UPR nanocomposites.

The Reuse of Municipal Solid Waste Fly Ash as Flame Retardant Filler: A Preliminary Study

The growing increase in the production of municipal solid waste incinerator (MSWI) ashes has led to the research of new possibilities to reuse these by-products. This work aims to use MSW fly ash (FA) as a flame retardant filler. The FA was stabilized according to a simple stabilization process involving the mixing of only different ashes: bottom ash (BA), flue gas desulphurization (FGD) residues and coal fly ash (CFA). Stabilized FA, calcite and commercial flame retardants were compared as additives in an epoxy resin or polypropylene (PP) matrix. The self-extinguish performance of fillers was evaluated by fire resistance tests: the vertical burning test (UL94-V) and glow wire test (GWT) at 750 °C and 850 °C. A life cycle assessment (LCA) evaluation was also performed to estimate the reduction in environmental impact related to the production of the flame retardant with stabilized FA. The results show that this new filler is a promising alternative to traditional flame retardant. The ignition time of composites with calcite was lower than the corresponding sample with FA. From an environmental point of view, the replacement of calcite in an epoxy resin matrix or commercial flame retardant in a PP matrix with stabilized FA allows for a reduction in the impact of about 24.1% and 49.5%, respectively.

Surface decoration of Halloysite nanotubes with POSS for fire-safe thermoplastic polyurethane nanocomposites

• POSS modified HNTs were synthesized successfully by using a silane agent as a chemical bridge. • The POSS in combination with HNTs endows TPU with excellent flame retardancy without scarifying the mechanical property. • The incorporation of 2 wt% HNTs-POSS into TPU could effectively reduce the peak of the peak of CO production rate and total smoke release during combustion. Halloysite nanotubes (HNTs) have been considered as a promising flame retardant fillers for polymers. In this work, the polyhedral oligomericsilsesquioxane (POSS) containing amino group was covalently grafted on the surface of HNTs with 3-(2,3-epoxypropoxy)propytrimethoxysilane as a chemical bridge. The POSS modified HNTs (HNTs-POSS) dispersed uniformly in the thermoplastic polyurethane (TPU) matrix and endowed TPU nanocomposites with enhanced tensile properties and fire safety. Cone calorimeter tests revealed that the introduction of 2 wt% HNTs-POSS to TPU matrix remarkably reduced the peak of heat release rate (PHRR) and total heat release (THR) by 60.0% and 18.3%, respectively. In addition, the peak CO production rate and total smoke release (TSR) could be significantly suppressed by the addition of HNTs-POSS. The well dispersed HNTs in combination with the ceramified silicon network from the thermal decomposition of POSS contributed to the formation of a continuous and compact char layer, exhibiting a tortuous effect by inhibiting heat diffusion and evaporation of volatile gaseous. In addition, the released crystal water from HNTs could dilute the combustible volatiles and then decline the combustion intensity. The tensile tests demonstrated that introduction of 2 wt% HNTs-POSS would enhance the maximum stress of TPU nanocomposite with a slight decrease of elongation at break. The combination of HNTs and POSS through the construction of effective interfacial interactions provides a feasible way to effectively enhance the fire safety of TPU nanocomposites without scarifying ductility.

B-N-P-linked covalent organic frameworks for efficient flame retarding and toxic smoke suppression of polyacrylonitrile composite fiber

• B-N-P-linked covalent organic framework (BNPC) is synthesized for the first time. • BNPC significantly flame-retardancy efficiency in polyacrylonitrile fiber. • BNPC provides a kinetic advantage for cyclization-crosslinking of PAN. • The mechanical properties of PAN@BNPC fiber is simultaneously enhanced. Covalent organic frameworks (COFs) recently exhibit great potential as flame-retardant additives for polymers, yet the limited choice of building blocks and skeletons have hampered the improvement of their flame-retardant efficiency. Herein, we develop a novel boron-nitrogen-phosphorus-linked COFs (BNPC) for the first time through a facile self-condensation reaction of hydroxyphenylboronic acid substituted hexachlorocyclotriphosphazene, which is employed as flame-retardant filler for polyacrylonitrile (PAN) fiber. As reflected by cone calorimeter test, by introducing 7 wt% BNPC into PAN fiber, the peak heat release rate (PHRR), total smoke production (TSP) and CO production of PAN@BNPC-7 fiber are significantly decreased by 72.6%, 67.2% and 76.3%, respectively. Simultaneously, the limiting oxygen index (LOI) value is improved from 17.5% to 27.8%. The detailed flame-retardant mechanism analyses demonstrate that the BNPC not only provides a kinetic advantage for initiating the cyclization of PAN chains via an ionic mechanism, which significantly reduces the chain scission/toxic gases (HCN, CO) emission and promote the intermolecular crosslinking of cyclized ladder-like structures, but also offers excellent cooperative catalytic effect to produce highly compact and crosslinked P-B-N-rich char layer barrier on fiber surface. Moreover, the resultant PAN@BNPC-7 composite fiber retains good spinnability and exhibits enhanced mechanical properties. This work offers a scalable strategy for designing COFs with multi-flame retardant elements, endowing its great application potential in functional polymer materials.

Preparation and characterization of Ammonium Polyphosphate/Diatomite Composite flame-retardant fillers

Ammonium Polyphosphate (APP) has been known as an effective flame retardant, but its dispersion in some materials is very poor so it is necessary to incoporate APP with some suitable additives. This study refers to the preparation of APP/Diatomite (DIA) composite flame-retardant fillers. The materials were prepared by two methods: by adding diatomie powder to the mixture during the preparation of APP or by adding diatomite powder to the suspension of very fine solid APP particals in water. The samples were put into separate porcelain bowls and dried at 210°C for 3 hours. The structure and morphology of the material was identified using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. Thermogravimetric (TG) analysis was performed to evaluate the thermal degradation behaviors of the material.

Study of the influece of flame retardant additives on ultra-violet curing thermosetting composites

Fibre-reinforced polymer composites are materials capable of reducing weight while maintaining optimised properties in multiple applications. However, the use of composite materials is not suitable for all sectors, where the need for improved fire properties is highlighted. In the present study, a thermosetting matrix composed of UV-curable acrylic monomers and UV-transparent aluminium trihydrate (ATH) flame retardant fillers have been added to UV-transparent polyester resin for the manufacture of flame retardant composites. An in-depth study of the most suitable types of ATH-based flame retardant additives and possible synergistic combinations to improve the fire performance of the UV-curable composite has been carried out. Not only has the type of flame retardant been studied, but also the most suitable additive percentage to comply with railway sector regulations. The compatibility between the fillers and the matrix has been analysed by means of dielectric analysis, as well as the properties of the matrix and final composites against fire and mechanical properties.

The viscoelastic properties of a halogen-free polymer composition, for cable products

The viscoelastic properties of a halogen-free polymer composition for cable products have been investigated. The influence of temperature parameters, shear rate on the die-swell ratio of the polymer composition has been determined; the dependence of the melt density on a temperature was investigated. The polymer matrix is a mixture of polyolefins (linear low density polyethylene; polyolefin elastomer and maleic anhydride modified linear low density polyethylene) as a flame retardant filler for the polymer composition is trihydrate alumina. The content of flame retardant filler in the polymer composition is 60 %. The polymer composition was manufactured on the compounding line of X-Compound, Switzerland. The investigation of both melt density and die-swell ratio of the polymer composition has been conducted with help of capillary viscometer type IIRT-AM. To determine the density of the melt the ratio of capillary length to diameter L/D=8/2 was used. The results of the study of the dependence of the melt density of the polymer matrix from a temperature of 150–190 °C at different loads showed that this parameter decreases from 789 to 744 kg/m3 and for polymer composition from 1309 to 1268 kg/m3. The die-swell ratio in the case of an increase of the shear rate at temperatures of 150–190°C for the polymer matrix increases from 1,102 to 1,520, and for the polymer composition decreases from 1,056 to 1,018. The investigation results of the dependence of both die-swell ratio of the polymer matrix and the polymer composition on the ratio of the length of the forming tool to the diameter indicates that the die-swell ratio for the polymer matrix was reduced from 1,296 to 1,152, and for the polymer composition from 1,045 to 1,01. It was established that the viscoelastic properties of the halogen-free polymer composition are significantly influenced by: processing temperature, shear rate, melt density, the ratio of the length of the forming tool to the diameter. The research results give a possibility for a reasonable approach for the determination of technological parameters of an insulation, sheathing of power cables and optical cables of microtube construction. It will also allow to quickly adjust the geometrical parameters of the forming tool of cable heads.

Intumescent-Grafted Bamboo Charcoal: A Natural Nontoxic Fire-Retardant Filler for Polylactic Acid (PLA) Composites.

In this work, an alternative flame-retardant filler based on phosphate- and urea-grafted bamboo charcoal (BC-m) at 10–30 wt % addition was aimed at improving the flame retardancy of polylactic acid (PLA) composites. The filler caused only a small reduction in strength properties but a slight increase in the modulus of elasticity of PLA composites. BC-m significantly improved the flame-retardant performance compared with pure BC. The limiting oxygen index (LOI) was 28.0 vol % when 10 wt % of BC-m was added, and 32.1 vol % for 30 wt % addition, which was much greater than the value of 22.5 vol % for 30 wt % pure BC. Unlike pure BC, adding BC-m at 20 wt % or more gave a UL-94 vertical flame test rating of V-0 with significantly reduced melt dripping. The peak heat release rate (pHRR) and total heat release (THR) of BC-m/PLA composites decreased by more than 50% compared with pure PLA, and the values for 20% BC-m were significantly less than that for 25% BC addition. The grafted biochar-based system provides an effective flame retardancy effect by a condensed-phase protective barrier through the rapid formation of a dense, honeycomb-like cross-linked carbonized char layer. The results suggest a promising route to enhancing the flame-retardant properties of biodegradable polymer composites using nontoxic, more environmentally friendly grafted biochar.

Studies on the modification of fly ash structure with alkaline pre-treatment as a green composite flame retardant filler

A green composite made up of renewable and recyclable materials has become one of the advanced material’s attractive topics. The smooth fly ash surface used in the green composite for flame retardancy enhancement are hard to bind with hydrophobic polymer. Thus, the surface modification of this filler is needed to increase its surface roughness and pore size to be more compatible with its polymer matrix. In this research study, the alkaline pre-treatment of fly ash has been performed by using sodium hydroxide solution (NaOH) with various concentrations (5 w/w%, 10 w/w%, 15 w/w%, 20 w/w%). For pore size and morphological of the filler’s evaluation, few analyses such as Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), Barret-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) pore size and volume analysis were conducted. Treated fly ash with 20 w/w% sodium hydroxide concentration gives the better morphological structure in terms of pore diameter, volume, area and high composition of aluminium, silicon with lower calcium and sulphur contents compared to others. Hence, the potential of the physiochemical properties of the green composite produced by using this modified filler will be improved as the adhesiveness of the filler with its matrix increased.

Characteristics of powdered layer on silicone rubber surface

In recent years, varying degrees of surface pulverization had been found on composite insulators running for years in severe outdoor environment such as dry, high altitude, salt fog and intensive ultraviolet radiation. Research on the basic characteristics of powdered substance is essential to maintain a high reliability of the power grid. In this study, the characteristics of the powdered layer of the composite insulator sheds aged for more than 10 years under three different environmental stresses are analyzed. The results show that powdered substance of each composite insulator sample contains two parts: the organic silicon which is oxidative degradation product of the original material polydimethylsiloxane (PDMS), and the partially dehydrated and deteriorated flame retardant filler aluminum hydroxide (ATH). However, the thickness of the powdered layer, the particle size distribution of the powdered substance and the composition ratio between the two components are different. The average particle size of powdered substance is between 2–7 μm. The content of Al element is 31.8–34.5%, the content of Si element is 12.7–17.5%, and the mass fraction ratio of two types of powdered substance is about 1/2–1/3. The essence of pulverization is finally concluded that the composite insulator is severely oxidized and degraded under the effect of various aging factors. The organic component silicone rubber is decomposed to fragments, and the bonding between inorganic flame retardant filler and polymer become weak. They will be detached from the main body skeleton and lost partly, then build up at the surface, forming powdered layer.

Flame behaviour of magnesium and aluminium hydroxide-filled polymer composites used in power and telecom cables

ABSTRACT The effect of flame contact on Low Smoke Zero Halogen (LS0H) polyethylene-based model composite used for power cable has been investigated, focusing the attention on the fate of aluminium trihydroxide (ATH) and magnesium dihydroxide (MDH) utilized as flame retardant fillers. By using a flame reproducing the calorific value of EU CPR Regulation, during the contact with flame, the composite with magnesium hydroxide shows the formation of intermediate carbonate, which further decomposes giving the oxide. The same finding was observed in the blank test performed on pure MDH. This feature was not observed in ATH composite and pure one. The higher decomposition temperature of MDH, together with the formation of carbonate could play a key role in the higher efficiency of MDH compared to that of ATH. Moreover, we report that the stearic acid, present in the composite as compatibiliser and as processing aid, seems to migrate towards the external surfaces.