Comparison of different reactive organophosphorus flame retardant agents for cotton. Part II: Fabric flame resistant performance and physical properties

N-Methylol dimethylphosphonopropionamide (MDPA) is one of the most commonly used durable flame retardant agents for cotton. In our previous research, we developed a new flame retardant finishing system based on a hydroxy-functional organophosphorus oligomer (HFPO) and bonding agents, such as dimethyloldihydroxyethyleneurea (DMDHEU) and trimethylolmelamine (TMM). In this research, we compared the flame resistant performance as well as physical properties of the cotton fabric treated with these two flame retardant finishing systems. The cotton fabric treated with MDPA/TMM has a higher initial limiting oxygen index (LOI) than that of the fabric treated with HFPO/TMM due to higher nitrogen content in the system. The LOI of the cotton fabric treated with the HFPO and MDPA systems becomes identical when the treated fabric contains equal amount of phosphorus and nitrogen. The MDPA/TMM shows higher laundering durability on cotton than HFPO/TMM system. The fabric treated with HFPO/TMM and MDPA/TMM has low wrinkle resistance and low strength loss whereas the fabric stiffness significantly increases when the TMM concentration is increased.     

Formaldehyde-free flame retardant finishing of silk using a hydroxyl-functional organophosphorus oligomer

Flame retardancy is a desirable property for silk textiles, and it becomes necessity when silk textiles are for interior decorative use in building with public access. However, the flame retardant finishing technology available for silk has significant limitations. In this research, we studied the use of the combination of a hydroxyl-functional organophosphorus oligomer (HFPO) and 1,2,3,4-butanetetracarboxylic acid (BTCA) as a formaldehyde-free flame retardant finishing system for silk. When BTCA is applied to silk, most of BTCA reacts with the hydroxyl group on silk by single ester linkage. In the presence of HFPO, BTCA is able to bond HFPO onto silk by either a BTCA “bridge” between silk and HFPO or a BTCA-HFPO-BTCA cross-linkage between two silk protein molecules. We evaluated the flammability and physical properties of the silk fabric treated with HFPO and BTCA. The treated silk fabric demonstrated a high level of flame retardancy with modest loss in fabric tensile strength. The treated silk passed the vertical flammability test after 15 hand wash (HW) cycles. Increasing the HFPO concentration from 20% to 30% does not show significant improvement in the flame retardant performance of the treated silk. The thermal analysis data demonstrated that HFPO reduces silk's initial thermal decomposition temperature and promotes char formation.     

The bonding of a hydroxy-functional organophosphorus oligomer to nylon fabric using the formaldehyde derivatives of urea and melamine as the bonding agents

In this research, we studied the mechanism of bonding a hydroxy-functional organophosphorus oligomer (HFPO) to nylon 6.6 fabric using the formaldehyde derivatives of urea and melamine, including dimethyloldihydroxyethyleneurea (DMDHEU) and trimethylolmelamine (TMM), as the bonding agents. The nylon fabric treated with HFPO/DMDHEU or HFPO/TMM retained significant amount of phosphorus after multiple launderings. The laundering durability of the HFPO applied to nylon was probably attributed to the formation of a crosslinked polymeric network on the nylon fiber. The nylon fabric treated with HFPO/DMDHEU showed higher percent phosphorus retention than that treated with HFPO/TMM. The percent phosphorus retention of the treated nylon increased as the DMDHEU or TMM concentration was increased, and the nylon fabric's stiffness follows the same trend. The micro-scale combustion calorimetry and thermal analysis data indicate that the HFPO bound to nylon reduced peak heat release rate and heat release capacity of the nylon fabric, decreased decomposition temperature and promoted the char formation of the treated fabric. The nylon/cotton blend military fabric treated with HFPO/DMDHEO or HFPO/TMM demonstrated flame retardant performance after 10 laundering cycles.     

Effect of zinc oxide on flame retardant finishing of plasma pre-treated cotton fabric

An organic phosphorus compound (flame retardant agent, FR) in combination with a melamine resin (crosslinking agent, CL), phosphoric acid (catalyst, PA) and zinc oxide (co-catalyst, ZnO/nano-ZnO) imparted effective and durable flame retardant properties. Also, atmospheric pressure plasma jet was applied as pre-treatment to improve post-finishing (flame retardant finishing) on cotton fabrics. In the present paper, surface morphology, chemical structure analysis, combustibility and mechanical properties of plasma pre-treated cotton fabrics subjected to flame-retardant treatment were investigated. Surface morphology of treated cotton specimens showed roughened and wrinkled fabric surface with high deposition of the flame retardant finishing agent, which was caused by the plasma etching effect and attack of acidic FR. The FTIR-ATR spectra for the treated cotton specimens showed some new characteristic peaks in chemical structure, interpreted as carbonyl bands, OH stretching vibration, COO⁻ stretching vibration, CH₂ rocking band and CH₃ asymmetric and CH₂ symmetric stretching. Moreover, FR-CL-PA-treated specimens showed remarkable flame-retardant property, which was further improved by the plasma pre-treatment and ZnO/nano-ZnO co-catalyst. However, flame-retardant-treated cotton specimens had poor mechanical strength when compared with control sample, resulting from side effects of the crosslinking agent used, while plasma pre-treatment and ZnO/nano-ZnO co-catalyst may compensate for the reduction in tensile and tearing strength caused by flame-retardant agents.     

Environmentally-benign,water-based covalent polymer network for flame retardant cotton

Cellulose - Relatively simple flame retardant finishing technologies for cotton are greatly desired in a variety of fire-sensitive applications (e.g., transportation, workwear, etc.). Many current...     

Preparation and flame retardancy of reactive flame retardant for cotton fabric

Journal of Thermal Analysis and Calorimetry - Monochlorotriazine aminopropyl silanol phosphate (MCASP) was synthesized as a novel flame retardant agent for cotton fabric. It was characterized by...     

An amino trimethylene phosphonic acid-based chelated boric acid complex that works as a synergistic flame retardant for enhancing the flame retardancy of cotton fabrics

The chelating ligands of boric acid and amino trimethyl phosphonate prepared a novel flame retardant (BAP) for the cotton fabric. A stable chemical and coordination bond was formed on the surface of the cotton fibers by a simple three-curing finishing process to make the fabric exhibits excellent durable flame retardancy. Cotton fabrics' tensile strength and whiteness got substantially retained after BAP treatment. 90 g/L BAP-treated samples (3 curing times, 50 laundry cycles) showed good flame retardancy and durability, holding the largest limit oxygen index, 29.7%, and the shortest damage length, 61 mm. A condensed phase and gas phase synergistic flame retardant mechanism was concluded by thermogravimetric, cone calorimeter tests, and thermogravimetric infrared analysis.     

Permanent flame retardant finishing of textile materials by a photochemical immobilization of vinyl phosphonic acid

A new photochemical method for a permanent flame retardant finishing of textiles made of cotton (CO), polyamide (PA) and polyester (PET) is described. Using a mercury vapour UV lamp vinyl phosphonic acid (VPA) can be fixed durable to different fabrics made of CO, PA and PET in the presence of a cross-linking agent and a photo-initiator. After a home laundering cycle up to 50 wt% of the reaction mixture is retained on the fabrics and the absolute phosphorus content was found to be more than 2.0% in all investigated cases. The photochemically modified textiles showed high levels of flame retardant performance and passed a vertical flammability test for protective clothing.     

Intrinsically flame retardant epoxy resin - Fire performance and background - Part I

The flame retardant effect of newly synthesized phosphorus-containing reactive amine, which can be used both as crosslinking agent in epoxy resins and as a flame retardant, was investigated. The effect of montmorillonite and sepiolite additives on the fire induced degradation was compared to pristine epoxy resin. The effect of combining the organophosphorous amine with clay minerals was also studied. It could be concluded that the synthesized phosphorus-containing amine, TEDAP can substitute the traditional epoxy resin curing agents providing additionally excellent flame retardancy: the epoxy resins flame retarded this way reach 960 °C GWFI value, 33 LOI value and V-0 UL-94 rating - compared to the 550 °C GWFI value, 21 LOI value and “no rate” UL-94 classification of the reference epoxy resin. The peak of heat release was reduced to 1/10 compared to non-flame retarded resin, furthermore a shift in time was observed, which increases the time to escape in case of fire. The flame retardant performance can be further improved by incorporating clay additives: the LOI and the HRR results showed that the optimum of flame retardant effect of clay additives is around 1 mass% filler level in AH-16-TEDAP system. Applying a complex method for mechanical and structural characterization of the intumescent char it was determined that the flame retarded system forms significantly more and stronger char of better uniformity with smaller average bubble size. Incorporation of clay additives (owing to their bubble nucleating activity) results in further decrease in average bubble diameter.     

Synthesis of a novel synergistic flame retardant based on cyclopolysiloxane and its flame retardant coating on cotton fabric

A synergistic flame retardant (silicon, phosphorus and nitrogen) based on cyclic polysiloxane, ammonium salt of tetramethylcyclosiloxyl-piperazin-phosphinic acid (APCTSi) was successfully prepared and firmly bonded to cotton fabric through a chemical grafting method. The chemical structure of APCTSi was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H and ³¹P nuclear magnetic resonance (¹H NMR and ³¹P NMR). The scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) proved that APCTSi successfully adhered to the surface of cotton fabric and the elements on the surface of cotton fabric were evenly distributed. The flame retardant properties were characterized by limiting oxygen index (LOI), vertical burning test, thermogravimetric (TG) analysis and TG-FTIR. The limiting oxygen index (LOI) can reach 30.9% with a char length of 8.7 cm for the weight gain of APCTSi was 16.2%. The combustion behavior was characterized by cone calorimetry test. The peak heat release rate (pHRR) and total heat release (THR) values of treated cotton fabric decreased by 30% and 48% respectively compared to that of pure cotton fabric. All the results proved that the cotton fabric treated by APCTSi had the flame retardant effect of condensed phase (forming stable char layer) and gas phase (releasing nonflammable gases).

Graphic abstract

     

An improved method for the durability of the flame retardant PA66 fabric

This paper describes an attempt in order to improve the durability of the flame retardant polyamide 66 (PA66) fabric prepared by the reaction of surface photografting with acrylamide (AM) under UV irradiation. In this study, N,N′-methylene bisacrylamide (MBAAm) combined with acrylamide has been used as a photosensitive monomer during flame retardant finishing of the PA66 fabric sample. “Durable efficiency” has been introduced to evaluate the durability of AM/MBAAm-g-PA66 fabric after 50 times washing with the 0.5 % commercial grade detergent solution. The result indicates that durable efficiency reaches its maximal value of 94.5 % when the MBAAm concentration is 5.0 mass%. The effect of MBAAm on the flame retardancy, thermal stability and tensile properties of the treated PA66 fabric has been investigated, respectively. And an interesting phenomenon shows that although MBAAm could improve the thermal stability of the treated fabric significantly at high temperature, it could have a negative effect on the flame retardancy and tensile properties of the fabric sample when its concentration is high. Its possible mechanism has been discussed here.     

Bio-waste derived,phosphorus decorated composite for highly efficient flame retardant for cotton fabric

In this, an efficient flame retardant composite has been prepared using biowaste derived phosphorous groups decorated graphene supported nanomaterial. The eggshell was utilized as a source of calcium carbonate, which was converted to monocalcium phosphate (CP) by phosphoric acid treatment. As-prepared monocalcium phosphate was functionalized with graphene to prepare graphene functionalized monocalcium phosphate (GCP). The GCP-coated fabric didn't ignite during the flame test and sustained more than 600 s on continuous exposure to flame without changing its initial length and shape. Whereas, graphene oxide (GO), and CP coated cotton fabric burnt out very easily within a short time. The efficient flame retardant property of as synthesized GCP coated cotton fabric was confirmed with a high limiting oxygen index (34.1) and char length of 2.5 cm was generated from the VFT test. The synthesized GCP coated cotton fabric also confirmed efficient flame retardant properties. This facile method enables an easy process for mass production of cost-effective, bio-waste derived nanomaterial for a significantly highly efficient candidate for different applications in sustainable chemistry, including flame-retardant applications.

Graphical abstract

     

Synergism of polysiloxane and zinc borate flame retardant polycarbonate

Liquid polysiloxane (PSI) and zinc borate (ZB) were combined for the flame retardance of polycarbonate (PC). During polymer combustion, for the PC flame-retarded with PSI only, PSI can form char residue containing silica on the material surface. But the liquid silicone tends to drip with melting polymer and volatilize in high temperature, thus decreasing the charring performance. In the case of only ZB flame retardant involved, this inorganic flame retardant and possible some of its decomposition products (B₂O₃) more difficultly move to the surface and it appears that they do not effectively contribute to the char formation. Present study suggests that the existing synergism between PSI and ZB is the result of chemical reaction via forming cross-linking B–O–Si structure. As results, the loss of Si/silicone is reduced by eliminating the melt dripping. Meanwhile, boron species can be “dragged” by PSI (in the form of borosiloxane) to the surface of the char residue. Consequently, Si and B elements together contribute to the integrity of char residue layer with better quality, achieving obviously improved flame retardance compared with only PSI and only ZB flame retardant systems.     

Thermal and flame retardant properties of novel intumescent flame retardant polypropylene composites

Novel intumescent flame retardant polypropylene (PP) composites were prepared based on a char forming agent (CFA) and silica-gel microencapsulated ammonium polyphosphate (Si-MCAPP). The thermal and flame retardancy of flame retardant PP composites were investigated by limiting oxygen index, UL-94 test, cone calorimetry, thermogravimetric analysis, scanning electron micrograph, and water resistance test. The results of cone calorimetry show that the flame retardant properties of PP with 30 wt% novel intumescent flame retardants (CFA/Si-MCAPP = 1:3) improve greatly. The peak heat release rate and total heat release decrease, respectively, from 1,140.0 to 156.8 kW m^?2 and from 96.0 to 29.5 MJ m^?2. The PP composite with CFA/Si-MCAPP = 1:3 has the excellent water resistance, and it can still obtain a UL-94 V-0 rating after 168 h soaking in water.     

Thermal properties of flame retardant viscose fibers

This paper discusses the problem of the thermal properties of flame retarding additives based on phosphazene derivatives and of the commercial agents TomflamB, FlammexT23P and StockhausenW-20949, as well as of flame resistant viscose fibers containing the above agents. Results of this investigation showed the action of FlammexT23P, StockhausenW-20949 and phosphazene derivatives at lower temperature. TomflamB acted within a much wider range of temperatures. The flame retardant additives applied to viscose fibers change the thermal properties of the fiber material.     

Effects of common synergistic agents on intumescent flame retardant polypropylene with a novel charring agent

In this article, the laboratory-made poly (p-ethylene terephthalamide) (PETA) was used as a novel charring agent and it combined with ammonium polyphosphate (APP) to prepare the intumescent flame retardant (IFR). For improving the flame-retardant efficiency of IFRs on polypropylene (PP), several general synergistic agents, such as common zinc oxide (Com-ZnO), nanometer structural zinc oxide (Nano-ZnO), zeolite 4A, and aluminum hypophosphite(Al(H₂PO₂)₃), were added in composites of PP/IFR, and the synergistic effect was investigated by the limited oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TG), thermogravimetry-fourier transform infraredspectroscopy (TG-IR) test, and scanning electron microscopy (SEM). It indicated that the flame retardancy was significantly enhanced in terms of prompting the char formation of PETA and interaction between APP and synergistic agents. Overall, Al(H₂PO₂)₃ was the most effective synergistic agent among them. TG-IR analysis showed that the addition of Al(H₂PO₂)₃ could delay the release of NH₃, and make the release of NH₃ more smooth, which was useful to form a dense char. SEM presented that compact, continuous and good intumescent charring layers were observed in all PP/IFR systems with synergistic agent.     

Development of an environmentally friendly halogen‐free phosphorus–nitrogen bond flame retardant for cotton fabrics

A novel flame retardant diethyl 4‐methylpiperazin‐1‐ylphosphoramidate (CN‐3) containing phosphorous and nitrogen was prepared. Its chemical structure was confirmed by nuclear magnetic resonance (¹H‐, ¹³C‐, and ³¹P‐NMR), Fourier transform infrared spectroscopy, and elemental analysis. Print cloth and twill fabrics were treated with CN‐3 to achieve different levels of add‐on (7–22 wt% add‐ons for print cloth and 3–18 wt% add‐ons for twill). Thermogravimetric analysis, vertical flame test, and limiting oxygen index (LOI) were performed on the treated cotton fabrics and showed promising results. When the treated print cloth and twill fabric samples were tested using the vertical flame test (ASTM D6413‐08), we observed that the ignited fabrics self‐extinguished and left behind a streak of char. Treated higher add‐ons fabrics were neither consumed by flame nor produced glowing ambers upon self‐extinguishing. LOI (ASTM 2863–09) was used to determine the effectiveness of the flame retardant on the treated fabrics. LOI values increased from 18 vol% oxygen in nitrogen for untreated print cloth and twill fabrics to maximum of 28 and 31 wt% for the highest add‐ons of print cloth and twill, respectively. The results from cotton fabrics treated with CN‐3 demonstrated a higher LOI value as well as a higher char yield because of the effectiveness of phosphorus and nitrogen as a flame retardant for cotton fabrics. Furthermore, FT‐IR and SEM were used to characterize the chemical structure on the treated fabrics as well as the surface morphology of char areas of treated and untreated fabrics. Published 2012. This article is a US Government work and is in the public domain in the USA.     

Flame retardant properties and mechanism of an efficient intumescent flame retardant PLA composites

The charring agent (CNCA‐DA) containing triazine and benzene rings was combined with ammonium polyphosphate (APP) to form intumescent flame retardant (IFR), and it was occupied to modify polylactide (PLA). The flame retardant properties and mechanism of flame retardant PLA composites were investigated by the limited oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis, microscale combustion calorimetry, scanning electron microscopy, laser Raman spectroscopy analysis and X‐ray photoelectron spectroscopy. The analysis from LOI and UL‐94 presented that the IFR was very effective in flame retardancy of PLA. When the weight ratio of APP to CNCA‐DA was 3:1, and the IFR loading was 30%, the IFR showed the best effect, and the LOI value reached 45.6%. It was found that when 20 wt% IFR was loaded, the flame retardancy of PLA/IFR still passed UL‐94 V‐0 rating, and its LOI value reached 32.8%. The microscale combustion calorimetry results showed that PLA/IFR had lower heat release rate, total heat release, and heat release capacity than other composites, and there was an obvious synergistic effect between APP and CNCA‐DA for PLA. IFR containing APP/CNCA‐DA had good thermal stability and char‐forming ability with the char residue 29.3% at 800°C under N₂ atmosphere. Scanning electron microscopy observation further indicated that IFR could promote forming continuous and compact intumescent char layer. The laser Raman spectroscopy analysis and X‐ray photoelectron spectroscopy analysis results indicated that an appropriate graphitization degree of the residue char was formed, and more O and N were remained to form more cross‐linking structure. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal and flame retardant properties of novel intumescent flame retardant low-density polyethylene (LDPE) composites

A char-forming agent (CFA) and silica-gel-microencapsulated ammonium polyphosphate (MCAPP) were selected to form novel intumescent flame retardant system (IFRs), and then the influence of this novel IFRs on the thermal and flame retardant properties of low-density polyethylene (LDPE) were studied. The results of cone calorimetry show that the flame retardant properties of LDPE with 30?wt% novel IFR (CFA/MCAPP?=?1:3) improve remarkably. The heat release rate peak, total heat release (THR) decreases, respectively, from 1479.6 to 273.5?kW?m^?2 and from 108.0 to 80.5?MJ?m^?2. The LDPE composite with CFA/MCAPP?=?1:3 has the excellent water resistance, and it can still obtain a UL-94?V-0 rating after treated with water at 70?°C for 168?h.     

Roles of organic intercalation agent with flame retardant groups in montmorillonite (MMT) in properties of polypropylene composites

Three kinds of organic intercalation agent containing flame retardant groups, melamine (MA), triphenylphonium (TPP) chloride, and tetradecyl trihexyl phosphonium (TTP) bromide were intercalated into montmorillonite (MMT) via cation exchange reactions. These modified MMTs are combined with intumescent systems and compounded with PP. The flame retardant and thermal properties of the PP composites are studied. The organic intercalation agents in the layers of MMT play important roles in the char formation and flame retardant properties of PP composites. MA shows a better performance in limiting oxygen index (LOI) value and TPP helps to increase UL‐94 properties, whereas TTP maintains or deteriorates the flame retardancy of polypropylene/intumescent flame retardant (IFR) composites. The LOI and UL‐94 properties increase firstly and then decrease as the content of MMT increases. The MA acts as a blowing agent and emits an inert gas to provide migration impetus, which results in a better intumescent structured and stronger char to endure heat erosion. Although TPP and TTP emit combustible gas that burn, especially for TTP as it has a more flammable aliphatic chain. The synergistic effect between MA‐MMT and IFR is better than that for TPP‐MMT and TTP‐MMT. Copyright © 2014 John Wiley & Sons, Ltd.