Flame resistant cotton fabrics prepared by radiation-initiated polymerization with vinyl phosphonate oligomer and N-methylolacrylamide

Radiation-initiated polymerization of vinyl phosphonate oligomer (molecular weight 500–1000) and N-methylolacrylamide from aqueous solutions was investigated with cotton printcloth, flanelette, and sateen fabrics and with cotton (50%)–polyester (50%) flannelette fabrics. Determinations were made of the effects of radiation dosage, mole ratio of vinyl phosphonate in the oligomer to N-methylolacrylamide in aqueous solution, concentration of reactants, wet pickup of solutions on fabrics, and irradiation of both dry and wet fabrics on efficiency of conversion of oligomer and monomer in solution to polymer add-on. The effects of vinyl phosphonate oligomer and N-methylolacrylamide radiation-initiated polymerization on some of the textile properties of cotton printcloth and on flame resistances of cotton and cotton–polyester fabrics were evaluated. The breaking strength of modified cotton printcloth was about the same as that of unmodified fabric; however, the tearing strength and flex abrasion resistance of modified fabric were reduced. The textile hand of the modified printcloth fabrics that had flame resistance indicated: interaction between cellulose and vinyl phosphonate oligomer–poly(N-methylolacrylamide) and uniform deposition in the fibrous cross section (transmission electron microscopy); surface areas of heavy deposits of oligomer–polymer (scanning electron microscopy); and phosphorus located throughout the fibrous cross section (energy dispersive x-ray analysis). Polymerization of vinyl phosphonate oligomer and N-methylolacrylamide was radiation initiated with cotton–polyester fabric; however, this modified fabric did not have flame-resistant properties.     

Combination of a hydroxy‐functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: Part I. The chemical reactions

Multifunctional carboxylic acids, such as 1,2,3,4‐butanetetracarboxylic acid (BTCA), have been used as crosslinking agents for cotton cellulose to produce wrinkle‐resistant cotton fabrics and garments. Polycarboxylic acids were used to bond hydroxy‐functional organophosphorus oligomer to cotton, thus imparting durable flame retarding properties to the cotton fabric. This research investigated the chemical reactions between the hydroxy‐functional organophosphorus compound and BTCA on cotton. BTCA crosslinks cotton cellulose through the formation of a 5‐membered cyclic anhydride intermediate and esterification of the anhydride with cellulose. In the presence of the organophosphorus compound, BTCA reacts with both the organophosphorus compound and cellulose, thus functioning as a binder between cotton cellulose and the organophosphorus compound and making the flame retarding system durable to laundering. The cotton fabric treated by the combination of the organophosphorus compound and BTCA demonstrated lower wrinkle resistance and less tensile strength loss than that treated by BTCA alone. The phosphorus retention on the cotton fabric after one home laundering cycle was approximately 70%. Copyright © 2003 John Wiley & Sons, Ltd.     

Some physical properties of films made from cellulose dissolved in solutions of nitrogen dioxide in dimethylformamide

Water-soluble films of cellulose nitrate-nitrite were prepared by dissolving bleached sulfite pulp in a solution of nitrogen dioxide in dimethylformamide (DMF) at room temperature and heating the solution at 70°C for about 3 hr. Their water sorption, fine structure, and electrical properties were measured and compared with those of three other films—one water soluble (poly(vinyl alcohol)) and two water insoluble (cellophane and a film prepared from a cellulose solution in the nitrogen dioxide–DMF mixture and cast immediately after the cellulose had dissolved at room temperature). A comparison between the properties of water-soluble films and the poly(vinyl alcohol) film showed that the former had higher crystallinity, lower moisture absorption in the 0–80% relative humidity region, lower permittivity and a.c. conductance, and higher d.c. resistance. The DMF-cast water-insoluble film adsorbed less moisture than the cellophane film.     

Flame‐retardant finishing of cotton fleece fabric: part I. The use of a hydroxy‐functional organophosphorus oligomer and dimethyloldihydroxylethyleneurea

Cotton fleece has become a popular fashion in recent years. However, most of the 100% cotton fleece fabric is not able to meet the federal flammability standard (‘16 CFR Part 1610: Standard for the Flammability of Clothing Textiles’) without chemical treatment. In this research, we investigated the use of the combination of a hydroxy‐functional organophosphorus oligomer (HFPO) as the flame‐retarding agent and dimethyloldihydroxylethyleneurea (DMDHEU) as the binder to reduce the flammability of cotton fleece. We found that HFPO is effective in reducing the flammability of the cotton fleece whereas DMDHEU enhances the effectiveness of HFPO due to phosphorus–nitrogen synergism. The flammability as well as other properties of the treated cotton fleece is affected by both the concentration of HFPO and that of DMDHEU. The cotton fleece treated with HFPO/DMDHEU passes the federal flammability standard and shows high strength retention with little change in fabric whiteness and hand. We also found that the flame‐retardant finishing system is durable to multiple home launderings. The combination of HFPO and DMDHEU has the potential to become a practical flame‐retardant finishing system to reduce the flammability of cotton fleeces. Copyright © 2006 John Wiley & Sons, Ltd.     

涤纶织物浸轧用阻燃剂环状磷酸酯的合成

以亚磷酸三乙酯、三羟甲基丙烷和甲基磷酸二甲酯为原料合成了环状磷酸酯,可作为涤纶织物浸轧用的环保型耐久阻燃剂。利用正交实验讨论了反应过程中各因素对结果的影响。结果表明:亚磷酸三乙酯:三羟甲基丙烷:甲基磷酸二甲酯的摩尔比为1.05:1:1.2,自制复合有机酸为酯交换反应催化剂,质量分数为0.1%,反应温度85℃,反应时间3 h,自制复合有机碱为加成反应的催化剂,质量分数为1.0%,反应温度200℃,反应时间8 h,酯交换反应收率95.0%,加成反应收率90.0%。合成的阻燃剂具有良好的阻燃性能和耐洗性能,用量超过100 g/L时,处理的织物经50次水洗可达GB/T5455—1997 B1级。     

The effect of laundering variables on the flame retardancy of cotton fabrics

Some durable flame retardant finishes for cotton fabrics can become ineffective if improper laundering procedures are used. For example, one flame resistant fabric will lose a significant amount of its flame resistance after 5, 10 or 20 soap launderings (yet show no reduction in phosphorus content) while another fabric treated with a different formulation will remain flame resistant. Synthetic detergents, rather than soap chips, and soft water have been recommended for some tetrakis (hydroxymethyl) phosphorium chloride-based flame retardant fabrics to prevent a “lime soap” deposit which impairs performance. The effect of these laundering variables has been studied in relation to a variety of different types of durable flame resistant fabrics. One of eight papers to be published from the Symposium “Surface Active Agents in the Textile Industry,” presented at the AOCS Meeting, New Orleans, April 1970. So. Utiliz. Res. Dev. Div., ARS, USDA.     

Phosphorylation of cellulose with phosphorous acid and thermal degradation of the product

The reaction of cellulose with phosphorous acid in molten urea afforded a white, water-soluble product. The product was a monoester of phosphorous acid, and all the phosphorus residues were in phosphonic form, i.e., cellulose phosphonate. Quantitative addition of acrylonitrile to the P? H bonds in cellulose phosphonate occurred in the presence of sodium ethoxide. By alkali hydrolysis of the adduct, a polyelectrolyte having two different ionization groups, P? OH and COOH, could be prepared. Thermal degradation of three cellulose phosphonates, ammonium cellulose phosphonate (I), ammonium cellulose 2-cyanoethlyphosphonate (II), and ammonium cellulose 2-carboxyethylphosphonate (III), was examined. All three samples decomposed at a temperature around 270°C, but their thermal behaviors were different. Replacement of hydrogen in the phosphonic residue by 2-cyanoethyl and 2-carboxyethyl groups retarded dehydration of cellulose. Sample I had a satisfactory flame retardance; samples II and III were not flame resistant. Reduction of flame retardance may be due to the electron-withdrawing effect of the cyano and carboxyl groups.     

Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe²⁺] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ? acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe²⁺ redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003     

Durable flame resistance via reaction of cotton cellulose bearing aromatic amino groups with tetrakis(hydroxymethyl)phosphonium chloride

Chemically modified cotton fabric samples having different amounts of aromatic amino groups were prepared. These modified samples were reacted with tetrakis(hydroxymethyl)phosphonium chloride (THPC) under a variety of conditions using the pad-dry–thermofixation technique. The extent of the reaction (expressed as %P) was dependent of the degree of chemical modification of cotton, temperature and time of heating, and pH of the treating bath as well as incorporation of Lyofix CHN (N-methylol finishing agent), MgCl₂·6H₂O (catalyst), and urea at various concentrations. THPC did react with the modified cotton having a nitrogen content over a range of 0.4%–1.3% even in the absence of catalyst at a temperature as low as 30°C for 10 min to impart durable flame resistance to cotton. Increasing the temperature up to 80°C enhanced considerably the extent of reaction; he latter remained practically constant upon further increase in temperature. The reaction was favored in acidic media (pH 4–6), whereas alkaline media (pH 9–11) inhibited it. Incorporation of Lyofix CHN (9%), MgCl₂6H₂O (1%), and urea (5%) along with THPC (25%) in the treating bath required a curing temperature of 120°C and a curing time of 5 min to achieve a fabric containing as much as 2.7% phosphorus with excellent durable flame resistance. A tentative mechanism of the reaction between THPC and the modified cotton was also elicited.     

Electrospinning of polyacrylonitrile solutions containing diluted sodiumthiocyanate

The effect of NaSCN salt on the spinnability of polyacrylonitrile (PAN) solutions, its resulting morphology, mechanical property, and the flame resistance of the resulting electrospun nanofibers were studied. The intent was to develop a method to produce nanosized carbon fiber precursors with good properties. Electrospun PAN nanofibers from 9.7–9.9 wt% PAN/sodiumthiocyanate (NaSCN) (aq)/Dimethylformamide (DMF) solutions with 1.0–2.9 wt% NaSCN (aq), and 10–15 wt% PAN/DMF solutions without salt exhibited good spinnability and morphology with no beading in the range of applied voltage (18–20 kV) and take‐up velocity (9.8–12.3 m/s). The relatively high take‐up velocity produced good yarn alignment. The diameter distributions of the PAN nanofibers containing the NaSCN salt were narrower than those of the PAN/DMF nanofibers without the salt. It was determined that the maximum content of salt for production of electrospun PAN nanofibers with good morphology was below 3.8 wt% (40 wt% based on PAN). The salt concentration can positively influence on the narrow diameter distributions of the resulting electrospun fibers. Also, it could be confirmed that the salt effect on mechanical property and flame resistance of electrospun PAN nanofibers. In particular, the elongation of the PAN nanofiber with 2.9 wt% NaSCN (aq) was significantly increased as much as 186% compared with that of 10 wt% PAN nanofiber without the salt. The flame resistance and mechanical properties of the stabilized PAN nanofibers with NaSCN (aq) increased after oxidization process. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

Reaction of hexamethylphosphorous triamide with cotton cellulose

The reactivity of hexamethylphosphorus triamide, (P[N? (CH₃)₂]₃) (HPT), with cotton cellulose was examined under various conditions. HPT was found to react readily with the cellulose to produce a cellulose phosphite and/or phosphate ester having approximately one acidic hydrogen atom per phosphorus atom. The reaction of HPT with cotton cellulose was efficiently catalyzed by dimethylamine hydrochloride (1%). The phosphorus content imparted by the catalyzed reaction on cotton fabrics was approximately twice that imparted by the uncatalyzed reaction. Flame resistance of the treated fabrics ranged from fair to excellent. The treated fabrics also exhibited ion exchange properties and some crosslinking.     

Flame-resistant cotton textiles by a continuous photocuring process

A continuous process for the photoinitiated copolymerization of vinyl phosphonate oligomer (MW 0.5–1.0 kg) and N-methylolacrylamide from aqueous solutions with cotton printcloth and a sateen fabric was investigated. The free radical reactions, initiated on the cellulose molecules by exposure of the padded cotton fabric to UV radiation gave a flame-resistant (DOC FF 3-71 test) textile product. The effects of several variables on the efficiency of oligomer and monomer conversion to polymer add-on were determined, with maximum efficiencies being 75–85%. Variables were fabric speed through the reactor (0.006–0.039 m/sec), light transmission through Pyrex or quartz windows in the tunnel, four sets of interchangeable tri-power UV lamps having different spectral distributions and relative intensities, and heat buildup within the reactor. Selected samples of these modified cotton fabrics were evaluated for flame resistance, some textile properties, and elemental phosphorus and nitrogen analysis. Copolymer and phosphorus distribution within and between the cotton fibers were illustrated by transmission electron microscopy and by energy dispersive x-ray analysis.     

Synthesis of phosphorus-containing flame retardants and investigation of their flame retardant behavior in textile applications

Flame retardants are a growing area of research interest. Nonhalogenated, durable, and nonleachable flame retardants are one of the main strategies used in the research of flame retardant polymers. In this regard, the covalent attachment of phosphorus-containing flame retardants onto cotton fabric has been developed. Two types of reactive phosphorus-containing flame retardants (MKT-1 and MKT-2) have been synthesized and used as a surface coating for cotton fabric. MKT-1 possesses anhydride and acid functionalities that can react with the  OH functionalities in cellulose. In addition, MKT-2 has both acid and organosilicon groups that can also react with the hydroxy group present in cellulose. The structures of the reactive flame retardants (MKT-1 and MKT-2) were characterized using ¹³C and ³¹P nuclear magnetic resonance spectroscopy. Thermal properties of the coated and uncoated cotton fabrics were investigated using thermogravimetric analysis. Surface characterization was carried out using scanning electron microscopy and X-ray photoelectron spectroscopy. A standard test method used to evaluate the flammability of blankets (BS 5852) was also applied to characterize the fire retardant properties of the coated and uncoated cotton fabrics studied. Different loadings of MKT-1 and MKT-2 on the fabric (10, 20, and 30% by weight in dimethylformamide solution) were applied in the dip coating process. The cotton fabric coated with 30% MKT-2 does not burn after being subjected to a propane burner for 20 s and also produced the highest char yield (36%) at 500 °C. Inductively coupled plasma–optical emission spectrometry showed that MKT-1 contains 8.23 ± 0.33 P% whereas MKT-2 contains 3.88 ± 0.15 P%. Although MKT-1 possess a higher P content than MKT-2, the additive effect caused by the organosilicon and nitrogen groups present in MK-2 enhance its flame retardant properties. Furthermore, the covalently attached flame retardant materials are durable and do not hydrolyze during washing. The mechanical properties of coated fabrics were characterized by a tensile test and significant change in elongation at break was observed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47935.     

Grafting of acrylic monomers onto cotton fabric using an activated cellulose thiocarbonate–azobisisobutyronitrile redox system

The feasibility of a cellulose thiocarbonate–azobisisobutyronitrile (AIBN) initiation system to induce graft copolymerization of methyl methacrylate (MMA) and other acrylic monomers onto cotton fabric was investigated. Other acrylic monomers were acrylic acid, acrylonitrile, and methyl acrylate. The initiation system under investigation was highly activated in the presence of a metal‐ion reductant or a metal‐ion oxidant in the polymerization medium. A number of variables in the grafting reaction were studied, including AIBN concentration, pH of the polymerization medium, nature of substrate, monomer concentration, duration and temperature of polymerization, and composition of the solvent/water polymerization medium. The solvents used were methanol, isopropanol, 1,4‐dioxane, cyclohexane, benzene, dimethyl formamide, and dimethyl sulfoxide. There were optimal concentrations of AIBN (5 mmol/L), MMA (8%), Fe²⁺ (0.1 mmol/L), Mn²⁺ (8 mmol/L), and Fe³⁺ (2 mmol/L). A polymerization medium of pH 2 and temperature of 70°C constituted the optimal conditions for grafting. The methanol/water mixture constituted the most favorable reaction medium for grafting MMA onto cotton fabric by using the Fe²⁺–cellulose thiocarbonate–AIBN redox system. MMA was superior to other monomers for grafting. The unmodified cotton cellulose showed very little tendency to be grafted with MMA compared with the chemically modified cellulosic substrate. A tentative mechanism for the grafting reaction was proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1261–1274, 2004     

Some theoretical aspects of bromine-containing triazine flame retardants

We studied flame retardancy of cotton fabric treated with five diaminotriazines containing bromine—three compounds with the bromine on aliphatic groups and two with the bromine on phenyl groups. Flame retardancy, as measured by oxygen index and FF3-71 flammability standards, was better on the fabrics containing aliphatic bromine than on the fabrics containing aromatic bromine. Thermogravimetric analyses (TGA) and differential thermogravimetric analyses (DTG) were obtained on the fabrics, results of which supported the theory that HBr liberated during burning lowers the ignition temperature and decomposition point of the cellulose causing a reduction in flammable gases and an increase in residual char. Since C? H and C? Br bond strengths are stronger on aromatic groups than on aliphatic groups, our results agree with the theory that flame retardancy increases as the C? Br bond strength decreases. In other words, since bromine inhibits oxidation reactions in the gas phases, the heat evolved is expected to become less as the C? Br bond strength decreases.     

Modification of cellulosic fabrics to impart flame retardancy properties

Graft copolymerization of dimethylaminoethyl methacrylate (DMAEMA) onto cotton‐cellulose in the fabric form was carried out using a cellulose‐thiocarbonate‐ammonium persulphate redox initiation system. Effects of the concentration of the monomer, effect of liquor ratio, grafting time, and temperature were studied. The results point out the following important aspects of flame retardation of cellulose fabrics. (1) The graft polymerization of DMAEMA can improve the flame retardant properties of cellulose fabrics. (2) Tertiary amine grafted to cellulosic fabrics is suitable for nitrogen compounds that can effectively operate as synergists. The flame retardant properties of the poly‐DMAEMA‐ grafted‐phosphorylated cellulosic materials were found to be excellent even after 25 dry clean washings. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Flame retardant cotton

The water‐soluble organophosphorus compound, namely, hexahydroxymethylamidocyclotriphosphatriazatriene (HHMAPT) was synthesized by reacting phosphonitrile chloride with liquid ammonia followed by reaction with formaldehyde. It is rich in phosphorus and nitrogen and as a polyfunctional compound it can undergo several reactions with itself forming an in situ polymer or with cotton cellulose similar to conventional N‐methylol finishing agents. It was successfully used as a flame retarding agent in the absence and presence of etherified methylolated melamine (EMM). Investigations into the different factors that affect these reactions and the effect of these on the properties of the finished fabrics give rise to the following points; (1) P%, N% and crease recovery increase by increasing the curing time and temperature; (2) the most effective catalyst is NH₄Cl; P% and N% increase by increasing the concentration of NH₄Cl from 5 to 12.5 g/l (3) an increase in EMM and HHMAPT concentrations is accompanied by enhancement in P%, N% and crease recovery; (4) the fabric samples exhibit durable flame retardancy at temperatures higher than 120°C in the absence of EMM while in the presence of EMM, all samples exhibit durable flame retardancy properties, regardless of the temperature of curing; (5) the durable flame retardancy is achieved at concentrations higher than 60 g/l HHMAPT and 7.5 g/NH₄Cl. All samples exhibit loss in tensile properties but within an acceptable range (20%), crease recovery is improved in all samples. Copyright © 1999 John Wiley & Sons, Ltd.     

（急）磷-氮阻燃剂的合成及整理棉织物性能

以亚磷酸二甲酯、丙烯酰胺和三聚氯氰为原料，合成了无甲醛磷-氮阻燃剂，并通过轧焙烘工艺对棉织物进行了阻燃整理。通过红外光谱对中间体和阻燃剂的结构进行了表征。通过红外光谱、电镜和EDS对整理织物的结构、表面形态和元素组成进行了表征，采用极限氧指数、垂直燃烧、锥形量热测试了整理织物的阻燃性能，采用热重测试了整理织物的热稳定性能。结果表明：阻燃剂成功整理到织物上，整理织物的最大热分解速率降低，残炭率提高。整理织物的极限氧指数由18%提高到31%，续燃时间，阴燃时间由9 s，25s均降到0 s，损毁长度由300 mm降低到74 mm。整理织物的最大热释放速率（PHRR）由203.5 kW?m-2降低到57.9 kW?m-2，总释放热（THR）由6.0 MJ?m-2,降低到2.7 MJ?m-2。     

Synthesis and application of a sulfur‐containing phosphoric amide flame retardant for nylon fabric

A sulfur‐containing flame retardant (SFR) was synthesized from polyphosphoric acid, epoxy chloropropane, and thiourea. Using a water‐soluble isocyanate‐terminated (WIT) cross‐linker, the flame retardant was applied as a flame‐retardant finishing on nylon fabric. WIT is a compound that not only cross‐links SFR and nylon cellulose but also contains no formaldehyde. Comparisons of the main performances of SFR with those of N‐methyloldimethylphosphonopropionamide (known as ‘Pyrovatex CP’) and a bicyclic phosphonite (known as ‘Antiblaze 19T’) indicate that the presence of sulfur in SFR plays a crucial role in decreasing the flammability of the nylon fabric. The limiting oxygen index value and damaged carbon length of the finished nylon fabric were 29.4% and 5.7 cm, respectively, when the concentrations of SFR and WIT were 200 and 40 g/L, respectively, and the baking temperature and time were 150 °C and 3 min, respectively. After 10 laundry cycles, the fabric still retains some flame retardancy. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal properties of tritylated and tosylated cellulose

Triphenylchloromethane and p-toluenesulfonyl chloride were reacted with chopped or powdered cellulose, with and without premercerization, to form trityl–cellulose ethers or tosyl–cellulose esters. Powdered and premercerized cellulose samples were more readily derivatized. Differential scanning calorimetric (DSC) and thermogravimetric (TG) analyses were performed in nitrogen on these derivatives. DSC and TG thermograms were affected by the particular derivative and the degree of substitution. The decomposition temperatures for both derivatives were lower than for the unmodified cellulose. Trityl cleavage may have been detected by DSC as a broad endothermic area showing no weight loss that preceded the major endothermic decomposition peak. Decomposition temperatures were lowered, but not sufficiently to prevent decomposition products from being combustible. No increase in residue was effected. Thermal decomposition of tosyl–cellulose was substantially different from that of the trityl derivative. As the degree of tosyl substitution increased, decomposition occurred at lower temperatures as an increasing exotherm. Tosyl derivatives all produced high residues. These changes in thermal characteristics were indicative of increased flame resistance. Oxygen index (OI) values relate to flame resistance and show that tritylation was detrimental to the cellulose and that tosylation imparted some degree of flame resistance.