Vertical Flame Spread Tests Research Articles

Thermal Stability and Fire Retardant Properties of Polyamide 11 Microcomposites Containing Different Lignins

This study investigates the influence of various lignins and their content on the thermal stability and fire retardancy of biobased polyamide 11 (PA). Microcomposites based on PA and containing 5, 10, 15, and 20 wt % different lignins were prepared with a twin-screw extruder. Morphological analysis showed good interfacial interaction and uniform distribution of lignin particles within the resulting microcomposites. Further, thermogravimetric analyses carried out in inert atmosphere indicated that, unlike kraft lignin, which is able to give rise to the formation of lower char residue (41–48 wt % at 600 °C), the sulfonated counterpart provides a higher thermal stability as well as a higher char residue (55–58 wt %). Furthermore, vertical flame spread tests clearly showed that 15 wt % is the optimum of kraft or sulfonated lignin loading to achieve improved flame retardant properties and a V1 rating. In addition, a cone calorimeter was exploited to study forced combustion behavior; in particular the microcomp...

Synergistic inhibitory action of P- and Si-containing precursors in sol–gel coatings on the thermal degradation of polyamide 6

In this study, a combination of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-modified vinyl trialkoxysilane (DOPO–VTS) and tetraethoxysilane (TEOS) was used as a sol-gel finishing for the preparation of polyamide 6 (PA6) fibres with increased thermo-oxidative stability, retarded combustion performance and anti-dripping properties. Both DOPO–VTS and TEOS alone or in mixture were applied to the PA6 fabric at three different concentrations using a pad–dry–cure method. The presence of the coating on the PA6 fabric was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. A thermal analyses of the coated samples revealed that the coatings affected PA6 decomposition at lower temperatures, favoured char formation and reduced the total heat release. Vertical flame spread test showed that, at higher precursor concentrations in the coating, the carbonized char completely stopped the melt dripping of the polymer. This phenomenon was attributed to the coating's reinforcement of the fibre structure, which reduced its dripping capacity. TEOS and DOPO–VTS clearly acted synergistically in the condensed phase.

How much the fabric grammage may affect cotton combustion?

The present article is addressed to investigating the effect of different fabric grammages (mass per area unit) on cotton combustion. To this aim, 100, 200 and 400 g/m2 cotton fabrics were tested when exposed to (1) two different heat fluxes (25 and 35 kW/m2) under a cone calorimeter, (2) a methane flame in horizontal or vertical flame spread tests or (3) a propane flame in Limiting Oxygen Index tests, and (4) when pyrolysed and further oxidised in pyrolysis-combustion flow calorimetry (PCFC). The collected results demonstrated a precise relationship between fabric grammage and cotton combustion behaviour. Indeed, when exposed to a 35-kW/m2 heat flux, the higher the fabric grammage, the higher the total heat release during combustion was; the opposite trend was observed when the same fabrics were pyrolysed and further oxidised in PCFC. This finding was ascribed to the different scenarios described by these instrumentations; indeed, the cone calorimeter was able to reproduce cotton combustion in a well-ventilated context in the presence of air (thus, oxygen), while PCFC only represented the combustion of pyrolysis products. However, both techniques indirectly evidenced a linear dependence of char formation as a function of fabric grammage: the higher the fabric grammage, the larger the amount of char formed was. The same trend was also observed during horizontal and vertical flame spread tests. In conclusion, the present article is intended to show how cotton combustion may be affected by fabric grammage as well as how such behaviour is influenced by the experimental conditions in which it is investigated.

Functionalization of cellulose fibres with DOPO-polysilsesquioxane flame retardant nanocoating

The preparation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-functionalised polysilsesquioxane (Si-DOPO)-coating was described and its flame retardant efficiency for cotton fabric was thoroughly investigated. The 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide–vinyltrimethoxysilane (DOPO–VTS) was synthesized and applied to cotton fabrics at different concentrations using a sol–gel process. The structure of the synthesized DOPO–VTS was characterized using Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The characteristics of the Si-DOPO coatings formed on the cotton fibres were investigated using X-ray photoelectron spectroscopy, time-of-flight-secondary ion mass spectrometry and scanning electron microscopy. The flame retardant properties of the Si-DOPO-coated cotton samples were evaluated by thermogravimetric analyses, vertical flame spread tests and cone calorimetry analyses. The Si-DOPO coating increased the thermo-oxidative stability of the cotton fibres by increasing the stability of the protective char and inhibited cellulose fibres degradation. The Si-DOPO coating did not decrease the time of flaming combustion but did completely stop the vigorous combustion of the fibres. The results also suggest that the flame retardation by the Si-DOPO coating is due to the quenching of active radicals from the decomposing cellulose and the cellulose phosphorylation by the DOPO component as well as the silicon oxide formation by the silsesquioxane component on the fibre surface. These findings indicate that the flame retardant efficiency of the Si-DOPO coating can be ascribed to the combined activity of phosphorus acting in both gas and condensed phases and silicon acting in the condensed phase.

Erratum: Synthesis and Characterization of Nano‐sized Zinc Oxide Coating on Cellulosic Fibers: Photoactivity and Flame‐ retardancy Study

We have investigated the effect of zinc oxide as a photocatalyst and durable flame-retardant on cellulosic fibers. Zinc oxide nanocrystals were successfully synthesized and deposited onto cellulosic fibers using sol-gel process at low temperature. The samples were characterized by means of several techniques such as scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogravimetric analysis. The photocatalytic activity was tested by measuring the photodegradation of methylene blue under UV-Vis illumination. Moreover, flame-retardancy was tested by vertical flame spread test. The optimum add-on value for donating flame-retardancy onto cellulosic fabric was obtained to be in the range of 15.24 to 23.20 g of the ZnO per 100 g of fabric. Thermogravimetric analysis of pure and flame-retarded samples were accomplished and discussed. The results obtained are in agreement with Wall effect theory and Coating theory. The originality of this work on introducing photoactive flame-retarded fibers is highly valuable for industrial implementation.

Synthesis and Characterization of Nano-sized Zinc Oxide Coating on Cellulosic Fibers: Photoactivity and Flame-retardancy Study

We have investigated the effect of zinc oxide as a photocatalyst and durable flame-retardant on cellulosic fibers. Zinc oxide nanocrystals were successfully synthesized and deposited onto cellulosic fibers using sol-gel process at low temperature. The samples were characterized by means of several techniques such as scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogravimetric analysis. The photocatalytic activity was tested by measuring the photodegradation of methylene blue under UV-Vis illumination. Moreover, flame-retardancy was tested by vertical flame spread test. The optimum add-on value for donating flame-retardancy onto cellulosic fabric was obtained to be in the range of 15.24 to 23.20 g of the ZnO per 100 g of fabric. Thermogravimetric analysis of pure and flame-retarded samples were accomplished and discussed. The results obtained are in agreement with Wall effect theory and Coating theory. The originality of this work on introducing photoactive flame-retarded fibers is highly valuable for industrial implementation.

TG studies of synergism between red phosphorus (RP)–calcium chloride used in flame-retardancy for a cotton fabric favorable to green chemistry

The combined effect between calcium chloride and red phosphorus (RP) on the flame-retardancy of a cotton fabric (woven construction massing 152 g/m2) has been studied in this work. The laundered bone-dried massed samples were impregnated with suitable concentrations of individual aqueous red phosphorus suspensions and/or calcium chloride solutions and some bunches were impregnated with appropriate admixed solutions of the both chemicals. An acceptable synergistic effect was then experienced by using an admixed bath containing 0.20 F red phosphorus and 0.20 M calcium chloride for impartation of flame-retardancy to a cotton fabric. By using a vertical flame spread test the optimum mass of the mixture needed to donate flame-retardancy was obtained to be about 5.88 g anhydrous additives per 100 g dry fabric. Thermogravimetry (TG/DTG) results concerning untreated and treated cotton fabrics at the optimum addition were obtained and their curves were compared and commented, fortifying the flame spread tests outcomes. It can be deduced that the applied treatment functioned as a catalyst at the combustion’s temperature of the polymeric substrate and, thermosensibilized the combustion process. This synergism is in favor of green chemistry as well as the economical and industrial view points.

Intumescent Biobased-Polylactide Films to Flame Retard Nonwovens

The work focuses on the development of a new process to flame retard nonwovens, using films based on renewable resources. Films consist in intumescent formulations of polylactic acid (PLA), ammonium polyphosphate (APP) blended with lignin or starch and are coated on hemp or wool nonwovens. The objective of this study was to investigate the fire retardant and mechanical properties of textiles protected by FR PLA films for potential use in building applications. Horizontal and vertical flame spread tests as well as cone calorimetry tests show that flammability properties of nonwovens are significantly improved. Better mechanical properties are also obtained with coated nonwovens.

Flame‐retardancy of a Cellulosic Fabric by the Application of Synergistic Effect between Ammonium Bromide and Antimony(III) Oxide

AbstractThe synergistic effect between ammonium bromide and antimony(III) oxide as a nondurable finish on the flammability of 100% woven plain cotton fabric (with a density of 144 g/m2, the number of yarns 21 per 10 mm), has been investigated in this study. The laundered totally‐dried, weighed specimens were impregnated with suitable concentration individual aqueous ammonium bromide and/or antimony(III) oxide suspension solutions and some sets were impregnated with appropriate admixed solutions of the both chemicals. A vertical flame spread test was then carried‐out to characterize the flammability of the samples. An acceptable synergistic effect was then experienced by using an admixed bath containing 0.1 molar ammonium bromide and 0.05 unit formal antimony trioxide solutions for impartation of flame‐retardancy to a cotton fabric. The optimum mass of the mixture required to impart flame‐retardancy was about 3.64 g of anhydrous additives per 100 g of fabric. The results obtained are in favor of Wall Effect Theory. Moreover synergistic effect indicating dehydration of the treated substrate by using this combination via thermogravimetry could be deduced.

Thermogravimetry Studies Concerning the Synergism of Antimony Trioxide-Tin(II)Chloride Dihydrate on the Flame-Retardancy of a Cotton Fabric

The synergistic effect between antimony trioxide and tin(II)chloride dihydrate on the flame-retardancy of a cotton fabric (woven construction massing 150 g/m2) was studied in this investigation. The laundered bone-dried massed specimens were impregnated with appropriate concentrations of individual aqueous antimony trioxide suspensions or tin(II)chloride dihydrate suspensions, and some bunches were impregnated with suitable admixed solutions of both chemicals. An acceptable synergistic effect was then experienced by using an admixed bath containing 0.06 formal antimony trioxide and 0.06 formal tin(II)chloride dihydrate suspensions for impartation of flame-retardancy to a cotton fabric. By using a vertical flame spread test the optimum mass of the mixture needed to impart flame-retardancy was obtained to be about 10.38 g anhydrous additives per 100 g fabric. Thermogravimetry (TG/DTG) outcomes of untreated and the supported cotton fabrics at the optimum addition were put in practice and their curves were compared and commented. The results comply with flame-retardancy theories.

TG of a cotton fabric impregnated by sodium borate decahydrate (Na2B4O7·10H2O) as a flame-retardant

The effect of sodium borate decahydrate as a nondurable treatment on the flammability of 100% cotton fabric (woven plain 150 g m−2) has been investigated in this paper. The laundered bone-dried massed samples were impregnated with suitable concentrations of sodium borate decahydrate. Each bunches of fabrics were dipped into individual aqueous solutions of the salt, followed by means of squeeze rolls and drying at 110°C. By using a ‘vertical flame spread test’ the optimum add-on values to impart flame-retardancy onto cotton fabric was determined to be as 4.24 g salt per 100 g fabric. The objective of this study is thermogravimetry (TG) investigation of pure cotton, treated one with the salt at its optimum efficiency. So that outcomes could be compared and commented, finally the results obtained are in favor of ‘Chemical action theory’, ‘Condensed phase retardation’, ‘Dust or wall effect theory’ and also ‘Gas dilution theory’.

A Thermogravimetric Study of Cotton Fabric Flame‐Retardancy by Means of Impregnation with Red Phosphorus

AbstractThe effect of red phosphorus was found to be effective for flame‐retardancy of a pure cotton fabric. The laundered bone‐dried weighed samples were impregnated with red phosphorus at suitable concentrations. Vertical flame spread test was accomplished. The optimum add‐on value to impart flame‐retardancy onto cotton fabric was determined around 3.95 g of red phosphorus per 100 g of fabric. TG/DTG curves of treated samples showed a well‐timed weight loss occurred with regard to untreated specimens. This illustrates the sufficiency of impregnation and support its catalytic action on flame‐retardancy, which is compliance with data obtained via flammability test. The results are in favor of "Chemical Action Theory", "Gas Theory" and "Condensed Phase Retardation".

XRD characterization of the ashes from a burned cellulosic fabric impregnated with magnesium bromide hexahydrate as flame-retardant

The effect of magnesium bromide hexahydrate [MgBr2·6H2O] as a nondurable finish on the flammability of 100% cotton fabric, (woven construction, massing 150 g m−2) has been investigated. The laundered bone-dried, massed fabrics were impregnated with various concentrations of the aqueous above-mentioned salt solutions by means of squeeze rolls and drying in an oven at 110°C for 30 min. The specimens were then cooled in a desiccator, re-massed with an analytical balance and kept under standard conditions before the fulfillment of the vertical flame spread test.

Ammonium Chloride as a Flame Retardant in a Polyester Fabric and its Detection

The effect of ammonium chloride as a nondurable finish on the flammability of 100% polyester fabric has been investigated. The laundered, bone-dried, weighed fabrics were impregnated with a suitable concentration of aqueous ammonium chloride solution by means of squeeze rolls and drying at 110°C for 30 min. They were then cooled in a desiccator, re-weighed in an analytical balance and kept under ordinary conditions before the fulfillment of the vertical flame spread test. The optimum add-ons to impart flame retardancy were about 20.21–21.87 g anhydrous ammonium chloride per 100 g fabric. These results comply with the Free Radical Theory. Finally, the Mohr analytical test method was used to detect the salt content in finished fabrics.

A Combination of Red Phosphorus-Zinc Chloride for Flame-Retardancy of a Cotton Fabric

In this investigation, the combination of red phosphorus with zinc chloride was found to be effective for flame-retardancy of a pure cotton fabric. The fabrics were dipped in individual aqueous suspensions of red phosphorous and/or the zinc chloride; meanwhile, some sets were impregnated with appropriate admixed solutions of both chemicals. The vertical flame spread test was accomplished to characterize the flammability of the specimens. A suitable synergistic effect was then experienced by using an admixed bath containing 0.15 formal red phosphorous and 0.15 formal zinc chloride solutions to impart flame-retardancy to a cotton fabric. The optimum mass of the mixture required to donate flame-retardancy was about 5.6 g anhydrous additives per 100 g fabric. The results obtained are mainly in favor of Free Radical Theory.

Thermal decomposition pathway of a cellulosic fabric impregnated by magnesium chloride hexahydrate as a flame-retardant

We have investigated the effect of magnesium chloride hexahydrate [MgCl2·H2O] as a nondurable finish on the flammability of 100% woven cotton fabric, (plain construction, with a density of 144 g m−2, the number of yarns 21/10 mm). The laundered bone-dried, massed fabrics were impregnated with suitable concentrations of aqueous solution of the above-mentioned salt, by means of squeeze rolls. They were then dried horizontally in an oven at 110°C for 30 min. The optimum add-on value after the fulfillment of vertical flame spread test to donate flame-retardancy onto cotton fabric was obtained to be in the range of 6.73–8.30 g of the salt per 100 g fabric. Thermogravimetry (TG) of pure cotton, treated cotton and the salt was accomplished, and their TG curves were compared and commented. The results obtained are in favor of the ‘gas dilution theory’, chemical action theory and also in compliance with the ‘free radical theory’. The formation of sal ammoniac was proven by sprinkling concentrated ammonia upon the inflamed treated specimen.

The Effect of Antimony Trioxide-Zinc Chloride Binary Combination on Flame-Retardancy of a Cotton Fabric

The combination of antimony trioxide with zinc chloride was realized to be effective for flame-retardancy imparted to a cotton fabric. The fabrics were dipped into individual aqueous suspensions of antimony trioxide and/or the zinc chloride; meanwhile some sets were impregnated with appropriate admixed solutions of the both chemicals. Vertical flame spread test was then accomplished to characterize the flammability of the specimens. A suitable synergistic effect was then, experienced by using an admixed bath containing 0.1 formal antimony trioxide and 0.1 formal, zinc chloride suspension solutions for the impartation of flame-retardancy to a cotton fabric. The optimum mass of the mixture required to donate flame-retardancy was about 7.19 g anhydrous additives per 100g fabric. The results obtained are in favor of Chemical Action Theory, Gas Dilution Theory, and Condensed Phase Retardation.

Synergistic Effect of Red Phosphorus, Boric Acid on the Flame-Retardancy of a Cotton Fabric

The combination of red phosphorus with boric acid was found to be effective for flame-retardancy of a cotton fabric. The laundered bone-dried weighed samples were impregnated with suitable concentrations of individual red phosphorous and/or with boric acid The fabrics were dipped into individual aqueous suspensions of red phosphorous and/or the solutions of boric acid, and some sets were impregnated with appropriate admixed solutions of the both chemicals. A vertical flame spread test was then accomplished to characterize the flammability of the specimens. An acceptable synergistic effect was then experienced by applying an admixed bath containing 0.125 formal red phosphorous and 1 molar boric acid solutions for the impartation of flame-retardancy to a cotton fabric. The optimum weight of the mixture required to impart flame-retardancy was about 8.47g anhydrous additives per 1.00g fabric. The results obtained are in favor of Chemical Action Theory, Gas Dilution Theory, and Condensed Phase Retardation.