Preparation of a halogen-free P/N/Si flame retardant monomer with reactive siloxy groups and its application in cotton fabrics

A novel halogen-free phosphorus-nitrogen-silicon flame retardant monomer with reactive siloxy groups,N-(diphenylphosphino)-1,1-diphenyl-N-(3-(triethoxysilyl)propyl) phosphinamine (DPTA) has been synthesized and was applied to the fire-resistant finishing of cotton fabrics.The molecular structure of DPTA has been well characterized by elemental analysis,FTIR,1H NMR,and 31p NMR spectroscopies.The chemically-grafted cotton fabrics,which were treated with 25 wt％ DPTA,were obtained and confirmed by attenuated total reflectance Fourier infrared spectroscopy (ATR-FTIR).The flame retardancy and thermal property of the treated samples were investigated by limited oxygen index (LOI),vertical flammability test (VFT),thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC).It is noted that in vertical flammability test,the treated samples extinguished immediately upon removing the ignition source,whereas the untreated one was completely burned out.Furthermore,TGA and MCC tests revealed that the treated samples produced a high char formation and a low heated release during combustion.The surface morphology of the untreated and treated samples and the char residues after LOI tests were observed by scanning electron microscopy (SEM).Therefore,all the results showed that the treated cotton fabrics with 25 wt％ DPTA apparently improved the fireresistant and thermal performances.     

Electron spectroscopy for chemical analyses (ESCA)—A tool for studying treated textiles

Electron spectroscopy for chemical analysis (ESCA) has been successfully used to determine the location of flame-retardant polymers or reagents and crosslinking and oil/water-repellent reagents in relation to fiber surfaces of chemically modified cotton fabrics and cotton/polyester blends. Changes in intensity of characteristic ESCA element signals were followed as the particle size of the treated fabric varied. Dimethyloldihydroxyethyleneurea (DMDHEU) and the flame-retardant polymer formed from tetrakis(hydroxymethyl)phosphonium chloride (Thpc) and urea penetrate and are homogeneously deposited throughout cotton fabrics. The oil/water-repellent finish, FC-218, and the flame retardants from the THPOH/NH₃ reaction and tris(dibromopropyl) phosphate are deposited on the surfaces of both cotton and polyester fibers.     

Synthesis of a graft-functionalized flame retardant based on DOPO and its application on the surface of terylene/cotton fabrics

Terylene/cotton (TC) fabrics are widely used in the textile industry because of their superior softness and durability. In addition, its high combustibility leads to a great safety hazard, and the droplet phenomenon during combustion is particularly serious. 9-oxa-10-phospha-9,10-dihydrophenanthrene 10-oxide (DOPO) and its derivatives are frequently used as eco-friendly flame retardants in large quantities in substrates. It would be difficult to apply to the surface of the fabric, and the addition of large amounts would lead to a decrease in the mechanical properties. Therefore, it is necessary to design a strategy for graft-functionalized flame retardants that can be applied to surfaces. Here, this study reported a washing-fastness flame-retardant coating (DOPO-p) synthesized from DOPO and p-hydroxybenzaldehyde (p-HBA), coatings with a low weight growth and high flame-retardant efficiency are prepared by the strategy of dissolving with organic solvents. Water and dry-cleaning tests showed excellent washing fastness of TC fabrics. In the limiting oxygen index (LOI) test, the finished fabric achieved a LOI value of 22.9%. In the cone calorimetry test, the peak of heat release rate of the finished fabric is decreased by 27% and CO₂ release is reduced by 29% when the coating weight growth was only 3.3 wt%.     

A novel cyclic copolymer containing Si/P/N used as flame retardant and water repellent agent on cotton fabrics

A novel cyclic-shaped multifunctional copolymer named poly[tetra(tetramethylcyclosiloxyl-piperazin)-phosphinic acid methyl ether] (PNCTSi) was successfully synthesized. Its flame-retardant and hydrophobicity properties on cotton fabrics were investigated. The limited oxygen index (LOI) value of treated cotton fabrics with PNCTSi was up to 29.8%. By vertical burning test, it was found that the treated cotton fabrics have no after-flame and no after-glow. Apparently, more amounts of char were generated and hazardous volatiles distinctly reduce after combustion by thermogravimetric analysis. Besides, Treated cotton fabrics with PNCTSi can give a hydrophobic property, which reach a contact angle of 150°. The surface morphology of treated cotton fabric before and after combustion was analyzed by scanning electron microscopy, after burned, the surface morphology of cotton fiber exhibited more smooth and expanded feature. After washing the cotton fabric for 20 times, the LOI remains at above of 26.0%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47280.     

硅-磷阻燃剂对涤纶织物的阻燃研究

采用极限氧指数法（LOI）、垂直燃烧法等手段研究甲基三甲氧基硅烷包覆聚磷酸铵的协同阻燃剂,与水性聚氨酯组成阻燃涂层剂,对涤纶织物的阻燃效果。结果表明：甲基三甲氧基硅烷和聚磷酸铵配比为2：1,阻燃剂与水性聚氨酯配比为1：2,阻燃剂质量浓度为160g／L,烘焙温度为180℃,烘焙时间为120s,阻燃涤纶织物的极限氧指数为44．3％,损毁长度为29mm,阴燃时间和续燃时间均为0,达到GB20286-2006标准中的阻燃1级。     

Developments in flame-retarding polyester/cotton blends

The burning behaviour of polyester/cotton blended fabrics is discussed and possible flame-retardant strategies outlined. Particular attention is paid to the effectiveness of phosphorous- and nitrogen-containing and antimony(III) oxide/halogen flame-retardant systems. Recent developments within the UK are discussed which suggest that phosphonium salt condensate finishes are effective on cotton-rich blends and that antimony-halogen systems may be used on all polyester/cotton blend compositions. Both types of flame retardant have acceptable durability to laundering.     

Highly flame-retarding cotton fabrics with a novel phosphorus/nitrogen intumescent flame retardant

A novel phosphorus/nitrogen intumescent flame retardant, namely 6-chloro-4-(diethylamino phosphorate phosphoryl chloride)-2-(sodium 4-aminobenzensulfonate)-1,3,5-triazine (APPCABT), has been synthesized and characterized by elemental analysis, FT-IR, ¹H-NMR and ³¹P{H}-NMR spectroscopies. To investigate the flame-retarding properties of the treated cotton fabrics, APPCABT was applied to the chemical treatment of the cotton fabrics surface. The flame-retarding performance of the treated samples with APPCABT was evaluated by limiting oxygen index (LOI). The thermal degradation behavior of the treated samples was studied using thermogravimetric analysis (TGA). The surface morphology of the treated samples was observed by scanning electron microscopy (SEM). These results show that APPCABT is both an intumescent flame retardant with high efficiency and an excellent char-forming agent for the flame-retarding treatment of cotton fabrics.     

Polyimide-coated fabrics with multifunctional properties: Flame retardant,UV protective,and water proof

Multifunctional technical textiles are of great interest both by industry and academia and these products are considered as high value-added products that contribute to the economies of countries. In this study, polyamic acid (PAA) was synthesized through polycondensation of pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) in dimethyl acetamide (DMAc) at low temperature. Then, PAA was coated onto woven cotton and polyester fabric by padding technique. Finally, polyimide (PI)-coated multifunctional cotton and polyester fabrics were obtained by an easy coating technique and low-temperature imidization. Thus, low cost, easily accessible and widely used cotton and polyester fabrics were converted to high-performance textile products, which are flame retardant, UV protective, acid resistant, and waterproof. The chemical, thermal, morphological, optical, mechanical, wettability, chemical resistance, and flame retardancy properties of developed fabrics were investigated. Optical results showed that both PI-coated cotton and polyester fabrics are UV-A protective compared to noncoated fabrics. Moreover, PI-coated samples have high contact angles which are 111.43° and 113.40° for PI-coated cotton (PI-c-C) and PI-coated polyester (PI-c-PET), respectively. Young's modulus of PI-c-PET fabrics increased four times more than noncoated polyester fabric. PI coating changed the burning behavior of both cotton and polyester fabrics in a positive way. All the test results showed that these developed multifunctional textile products might find an application in different industrial areas such as automotive, aerospace, protective clothing, and so on due to easy and inexpensive production techniques and also superior properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47616.     

Thermal properties and combustion behavior of POSS‐ and bohemite‐finished cotton fabrics

A finishing process with polyhedral oligomeric silsesquioxane (POSS) and bohemite nanoparticles has been exploited for enhancing the thermal stability and flame retardancy of cotton fabrics. The thermal behavior of flame retardant treated cellulosic fabric has been studied by thermogravimetric analyses (TGAs). It has been found that such nanoparticles favor the carbonization of the cellulose and slow down the kinetics of thermo‐oxidation in air. At the same time, the finished fabrics have turned out to be more efficient with respect to neat cotton as far as the flame retardancy is concerned, pointing out an increase of the time to ignition (TTI) and a decrease of the heat release rate (HRR). Furthermore, a comparison between the fire performances of the nanoparticles under study and a commercial phosphorus‐based flame retardant has been investigated. The morphology and elemental composition present in the treated fabrics have been also investigated using scanning electron microscopy (SEM) coupled to the energy dispersive spectroscopy (EDS), and the results have been compared with the untreated fabric. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Flame-resistant polyester/cotton fabrics

New experimental results are reported for the modification of 50/50 polyester/cotton blend fabrics made from bromine-free and bromine-containing polyester with a reactive flame retardant compound of high phosphorus content. Reaction of the cotton in the blend with methyl-phosphonic diamide yields modified fabrics in which flame resistance is attained without impairment of fabric hand. The level of flame resistance depends on the amount of insolubilized phosphorus in the treated fabric, but the hand is essentially unchanged even for fabrics of high phosphorus content which pass the vertical test of DOC-FF-3-71. The results of this work provide a basis for improved definitions of future approaches to the development of flame resistant polyester/cotton blend fabrics.     

DTA and TGA studies of flame-resistant fabrics

Preliminary thermal studies were made of cotton fabrics which had been made flame resistant by chemical modification or by blending with a flame-resistant modified acrylic fiber. DTA and TGA thermograms were made in both nitrogen and oxygen atmospheres. Differences were found in the thermograms of the untreated controls, depending upon amount of purification. Fabrics treated with the flame-retardant formulations had lower decomposition temperatures and higher percent residue. Decomposition in oxygen was more complete and proceeded at a lower temperature. Infrared spectra of selected samples, which had been partially or completely charred, were examined. These data are related to theories about the degradation of flame-resistant cotton fabrics.     

Thermal analyses of flame-retardant twills containing cotton,polyester and wool

Medium weight twill fabrics constructed from cotton and cotton blended with polyester and/or wool were analyzed under nitrogen by three thermoanalytical techniques. Fabrics were tested both before and after treatment with [tetrakis(hydroxymethyl)phosphonium] sulfate (THPS), urea, and trimethylolmelamine. The presence of all fibers was distinguishable in differential scanning calorimetric analysis (DSC) of untreated fabrics; the relative positions of the endothermic, decomposition peak temperatures were only slightly changed. After flame-retardant (FR) treatment, the blended cotton and wool fibers were altered. Both fibers decomposed as exotherms during DSC analysis. These data supported earlier microscopical, X-ray evidence that wool fibers were actually reacting with the FR treatment. The two DSC peaks for polyester polymer melting and decomposing remained unaffected by either blending with other fibers or the presence of the FR finish on the fabric. There was excellent agreement between DSC peak temperatures and the temperature of maximum rate of weight loss obtained from thermogravimetric analysis (TGA). Blending cotton with either of these fibers increased the residue measured after TGA. The increased residue correlated with increased flame resistance as measured by the 45° angle, edge-ignition burning rate test.     

Novel multi-element DOPO derivative toward low-flammability epoxy resin

In order to obtain cured epoxy resin (EP) with satisfactory thermal stability and flame retardancy, a multi-element P/N/Si-containing flame retardant (DPAK) was synthesized by a facile way and was used as a reactive flame retardant to prepare flame-retardant EP. The flame-retardant efficiency of DPAK was subsequently evaluated by limiting oxygen index (LOI), UL-94, and cone calorimeter (CC) test. With a low incorporation amount of DPAK (4 wt%), the resultant EP achieve to UL-94 V-0 rating, and the corresponding LOI value reached to 30%, which was higher than that of EP containing DOPO (2.9 wt%). More importantly, the thermogravimetric analysis (TGA) revealed their higher thermal stability than those of EP containing DOPO. Furthermore, dynamic mechanical analysis (DMA) shown the maintained glass transition temperature of DPAK-EP. The increase of CO/CO₂ ratio in the CC test for the DPAK-EP samples proved the gas-phase activity of DPAK. Additionally, DPAK showed evidence of condensed phase activity by increasing char residue in TGA and CC test. The scanning electronic microscope together with the energy dispersive X-ray spectrometer (SEM–EDX) and X-ray photoelectron spectroscopy (XPS) exhibited that DPAK promoted the formation of compacted phosphorus-silicon char layer. Subsequently, TG-FTIR results indicated that DPAK-EP produced lesser combustible gases than neat sample did, improving flame-retardant properties of epoxy resin.     

Correlation between limiting oxygen index and phosphorus/nitrogen content of cotton fabrics treated with a hydroxy‐functional organophosphorus flame‐retarding agent and dimethyloldihydroxyethyleneurea

The combination of a hydroxyl‐functional organophosphorus flame‐retarding agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame‐retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame‐retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame‐retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003     

Preparation and characterization of the halogen-free,smoke suppression,organic–inorganic hybrid flame-retardant expandable polystyrene materials

Expandable polystyrene (EPS) is a plastic widely used in the field of construction, but it is flammable. This work provided a novel strategy for flame-retardant modification of EPS. A kind of polyester polyol (JZP) with the high content of phosphorus and nitrogen was synthesized. Then, intrinsic flame-retardant polyurethane (PFWPU) with the high content of phosphorus and nitrogen was synthesized by JZP acted as soft segment chain extender. Finally, a high-efficiency flame-retardant expandable polystyrene thermal insulation material (AF-EPS) was prepared by the organic–inorganic hybrid flame-retardant synergistic action of PFWPU and ammonium polyphosphate. The effects of different contents of inorganic flame retardants on flame retardancy of materials were studied by limiting oxygen index (LOI), cone calorimetry, thermogravimetric analysis/infrared spectrometry , scanning electron microscopy, and so on. The test results showed that the carbon residue rate of the modified material increased from 0 to 28.5%, the LOI increased from 17 to 35.8%, and the vertical combustion test reached the highest grade V-0. In addition, the total smoke production of AF-EPS samples decreased from 2.33 m² to 0.57 m², the time to ignition was increased to 41 s, and the peak heat release rate and the total heat release were decreased by 90.2 and 62.7%, respectively.     

Aqua-mediated in situ synthesis of highly potent phosphorous functionalized flame retardant for cotton fabric

Flame retardancy in various materials is becoming an increasingly important performance feature. In the textile industries, fire-related problems have become an important concern over the decade. Herein, the polyvinyl alcohol (PVA) and graphene-supported material were functionalized with trimethyl phosphate (TMP) for the synthesis of flame retardant (FR) composite material [graphene polymer functionalized trimethyl phosphate (GPTMP)] in the aqueous medium, which improves the stability of cotton fabric against flame. Graphene and PVA fabricated with phosphorus functional groups make the fabric more comfortable against fire and help to avoid further spreading of fire. The composite-coated fabric sustains for a long time on continuous flame with maintaining its initial shape and size. The GPTMP-coated fabric shows flame retardancy for up to 540 s on constant flame exposure, whereas control samples such as PVA-, graphene oxide-, and TMP-coated fabrics resist for up to 15, 20, and 14 s, respectively. The limiting oxygen index (LOI) and vertical flammability test (VFT) for synthesized composites were performed to confirm and support the flame retardancy property of GPTMP. The GPTMP shows the 35% LOI value and forms the char length of 2.6 cm during VFT. This work provides a simple and eco-friendly method to obtain novel GPTMP, which has a high potential as a FR for different fabrics, including cotton.     

Verification Concerning the Relative Superiority of a Cellulosic Fabric with Regard to Polyester in Terms of Flammability

In order to prove the superiority of cotton fabric to polyester with regard to flammability, we have studied the effect of Graham's salt as a moderate and nondurable finish on the flammability of pure polyester and cotton fabric. The laundered bone-dried, weighed fabrics were impregnated with suitable concentration of aqueous Graham's salt solutions by means of squeeze rolls and drying at 110°C for 30 min. They were then cooled in a desiccator, reweighed with analytic precision, and kept under ordinary conditions before the accomplishment of the vertical flame test. The optimum add-on value to impart flame retardancy was about 43.65% for polyester fabric and 36.78% for cotton fabric. The results obtained comply with the Coating Theory. Moreover, the superiority of cotton fabric to polyester fabric in terms of combustibility has been deduced.     

Flame retardancy of unsaturated polyester composites with modified ammonium polyphosphate,montmorillonite, and zinc borate

Ammonium polyphosphate (APP) was modified using a new method, where the resulting modified APP (MAPP) was obtained by mixing APP with unsaturated polyester resin (UPR). MAPP was more effective in improving the flame retardancy of UPR than APP which was due to the improved dispersion of MAPP in UPR composite. Then, the UPR composites were prepared based on dimethyl methylphosphonate, MAPP, montmorillonite, and zinc borate. Finally, the flame-retardant and mechanical properties of the UPR composites were analyzed using the limited oxygen index (LOI), thermogravimetric analysis, UL-94 vertical burning test, scanning electron microscopy, cone calorimetry, mechanical tests, and viscosity measurements. The LOI and UL-94 tests showed that the flame-retardant properties clearly improved with the addition of fillers in the UPR composites compared to pristine UPR. The synergistic effect of Si- and P-containing flame retardants in this composite resulted in the LOI value increasing from 18.9 to 31.3% and achieved the UL-94 V-0 rating. Moreover, the heat release rate was lower than the pristine UPR. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47180.     

Effect of chicken‐feather protein‐based flame retardant on flame retarding performance of cotton fabric

A new kind of eco‐friendly chicken‐feather protein‐based phosphorus–nitrogen‐containing flame retardant was synthesized successfully with chicken‐feather protein, melamine, sodium pyrophosphate, and glyoxal. And its structure was characterized by Fourier transform infrared spectroscopy, and the thermogravimetry of the agent was analyzed. Then the flame retarding performances of the chicken‐feather protein‐based flame retardant and in combination with the borax and boric acid in application to a woven cotton fabric were investigated by the vertical flammability test and limited oxygen index test. In addition, the surface morphologies of the treated and untreated fabrics were conducted by the scanning electron micrographs (SEM), and the thermogravimetric analyses of the treated and untreated cotton were explored, and the surface morphologies of char areas of the treated and untreated fabrics after burnt were tested by the SEM. The results showed that the flame retardancy of the cotton fabric treated by the chicken‐feather protein‐based flame retardant in combination with borax and boric acid was improved further, and the combination of the chicken‐feather protein‐based flame retardant and borax and boric acid could facilitate to form a homogenous and compact intumescing char layer, and the combination of them plays a good synergistic effect in the improvement of the flame retardancy of the treated cotton fabric. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40584.     

Preparation of modified polyesters containing triphosphorous and their applications to PU flame-retardant coatings

Three phosphorous functional groups were introduced in one structural unit of polymer backbone to enhance the flame retardancy of PU coatings. In the first step, we synthesized tetramethylene bis(orthophosphate) (TBOP) that contained two phosphorus functional groups in one structural unit. In the next step, we synthesized modified polyesters (ATBTP-10,-20,-30) that contained triphosphorous groups by condensing polymerization of TBOP, 1,4-butanediol, trimethylolpropane, adipic acid, and phenylphosphonic acid (PPA). The amount of PPA in the ATBTPs was 10, 20, and 30 wt%. Then, flame-retardant PU coatings (AHFC−10,−20,−30) were prepared by curing ATBTPs with hexamethylene diisocyanate-biuret (curing agent) at room temperature. From the TGA analysis of diphosphorus-modified polyester (ATBT) and ATBTPs, the residues of ATBT, ATBTP-10, ATBTP-20, and ATBTP-30 were 24.6, 27.5, 29.2, and 31.9%, respectively. From this result, it was found that the residue increased in relation to the amount of PPA. Physical properties of the films of flame-retardant coatings were deteriorated with the addition of PPA (flame retarding component), however, all the films of flame-retardant coatings, except AHFC-30, met the required physical properties standard for coatings. Char lengths of the AHFCs measured by the 45° Meckel burner method were 2.9∼4.8 cm, and LOI values were 28∼31%, which indicates that the prepared AHFCs showed good flame retardancy.