Durable Flame Retardant Research Articles

Durable flame retardant and UV-resistant coating for Poly (ethylene terephthalate) fabric with recyclability and reusability

Poly (ethylene terephthalate) (PET)fabric is widely used in our lives due to its excellent mechanical strength, high elasticity, wrinkle resistance, and anti-abrasion. However, the inflammability and droplets produced during combustion restricted its application. Herein, a novel PET fabric with fire resistance, anti-dripping, and UV resistance is proposed to resolve this problem. Firstly, the finishing agent (AAD) was synthesized using adipoyl chloride, 9-anthracenemethanol, and diethyl(hydroxymethyl)phosphonate. Then AAD was introduced to the surface of PET fabric by dip-pad-cure process. The limiting oxygen index (LOI) value of AAD-treated PET enhanced to 23.8% from 19.3%. Besides, the fabric passed the vertical burning test (VBT) with no droplets generated. The fabric could still pass the VBT and maintain an LOI value of 23.3% after washing. Meanwhile, the AAD-treated PET fabric showed outstanding UV resistance with a high UPF value of 4318.27. The breaking force of AAD-treated PET was also improved. More importantly, the AAD coating could be easily removed from the fabric using dichloromethane and recycled using a rotary evaporator with a recovery rate of 98.6%. The recycled AAD could also recoated on the PET fabric to impart similar properties. This work proposed a novel strategy to prepare durable flame retardant and UV-resistant PET fabrics with recyclability.

Rigid polyurethane foam with durable hydrophobicity and flame retardancy endowed by novel functional surfactants

Traditional rigid polyurethane foam (RPUF) with flame retardancy might be easily damaged in some moist condition due to its hydrophobicity, which would lead to unsafety. Therefore, novel surfactants with both hydrophobic fluorinated group and flame-retardant phosphorus group were synthesized. With lower surface tension and more hydrogen bonds formed in polyurethane, the mixed surfactants, which were used in the preparation of RPUF, have not only obviously improved the size uniformity and integrity of cells but also enhanced its hydrophobicity, compressive strength and thermal insulating performance. Besides, effective ‘protection’ could be constructed on the surface of RPUF by prepared surfactants, when ammonium polyphosphate (APP) and expandable graphite (EG) were introduced to provide good flame retardancy. As a result, with just 2.8wt% content of those functional surfactants, hydrophobic and flame-retardant RPUF with water contact angle of 126 °, limiting oxygen index of 25%, compressive strength of 1.3MPa and thermal conductivity of 27mW/mK, were finally obtained, which is ahead of other flame-retardant RPUF reported before. It’s worth noting that, this hydrophobic and flame-retardant RPUF exhibits more stable and durable properties when soaking in HCl solution (2mol/L), NaOH solution (2mol/L), NaCl saturated solution and various solvents (THF and EtOH), or under strong fiction for 100 times and high and low temperature cycling test for 20 times. This would provide a novel and effective strategy to endow RPUF with enhanced and durable flame retardancy, hydrophobicity, compressive strength and thermal insulating performance even under extreme conditions.

Cotton fabric with durable flame retardancy, robust superhydrophobicity and reliable UV shielding

Cotton fabric with durable flame retardancy, robust superhydrophobicity and reliable UV shielding

Sustainable lignosulfonate-modified PA6.6 fabrics to improve durable flame retardancy, hydrophilicity and mechanical performance

Creating durable flame retardancy, enhanced mechanical performance, and hydrophilic polyamide 6.6 (PA6.6) textiles via cost-effectiveness from sustainable renewable sources is a considerable challenge. This study introduces a pretreatment process involving the application of sodium lignosulfonate (LS) to the surface of PA6.6 fabrics, thereby enhancing their hydrophilic and flame-retardant properties. Subsequently, a layer-by-layer (LbL) nanocoating treatment is employed, utilizing renewable polyelectrolytes—chitosan (CS), LS, and poly (sodium phosphate) (PSP)—to create 8-bilayer (BL) and 4-quarda layer (QL) structures that further improve the hydrophilicity and durable flame resistance of PA6.6 fabrics. The combined LS-modified and LbL coatings notably increased the limiting oxygen index (LOI) values from 19.5 % to 22.5 %, eliminated melt dripping, and secured a V-1 rating in the vertical burning (UL-94) tests. Moreover, the treated fabrics exhibited a 43 % reduction in the peak heat release rate (PHRR) and a lower fire growth rate (FGR) of 0.84 W/g·s, with a significant increase in char yield% in both air and nitrogen (N2) atmospheres. A cross-linked network structure is responsible for the superior hydrophilicity, enhanced tensile strength, and fabric softening properties. The self-crosslinking of sulfur-containing radicals with amide units ensures an anti-dripping performance that can withstand up to 30 home laundering cycles, demonstrating remarkable washing durability. However, a convincing approach has been developed for sustainable and high-performance materials for the textile industry, and a simple LbL technique using renewable polyelectrolytes that have traditionally been utilized in water treatment and food processing has been developed.

Construction and application of B/P/N durable flame retardant crosslinking system on cotton fabric

The inherent flammability of cotton fabrics necessitates the implementation of flame retardancy to prevent fires. In this study, a B/P/N cross-linking flame retardant system was developed using phosphoric acid, boric acid, and glycerol. The cross-linking system was ammoniated and catalyzed by urea and dicyandiamide to enhance water solubility and fiber bonding strength. Following treatment, the limiting oxygen index of the cotton fabric increased from 18.0 % to 40.5 %, while the damage length in vertical flammability testing decreased from 30.0 cm to 4.8 cm. Thermogravimetric testing revealed an increase in residual char content at 750 °C in a nitrogen atmosphere from 9.7 % to 31.9 %, proving improved thermal stability. Furthermore, the maximum heat release rate and total heat release of the treated samples decreased by 86.7 % and 36.5 %, respectively, compared with pure cotton fabrics. Finally, possible flame retardant mechanisms were inferred from XPS and TG-IR data, demonstrating efficacy in both solid phase and gas phase.

Fully biobased approach for sustainable flame retardancy, antibacterial and anti-UV modification of silk fabric

The versatile modification of silk fabric using a fully biobased approach is intriguing. In this study, phytic acid and vanillin, which are plant extracts, were utilized to synthesize reactive vanillin phytate ester for modifying silk fabric to achieve durable flame retardancy, antibacterial and anti-UV performance. The multifunctional properties, thermal resistance, smoke and heat suppression capacity, flame-retardant durability and mechanism of modified silk fabrics were investigated. The vanillin phytate ester imparted high antimicrobial and UV resistance to silk fabric, achieving a 97 % inhibition rate against Escherichia coli and reaching an “excellent” level of UV protection. The modified silk fabric also possessed the self-extinguishing capacity, with a limiting oxygen index value as high as 33.5 %. There was also a significant reduction of 71.7 % in peak heat release and 40 % in smoke release compared with those of the original silk. After undergoing 20 washing cycles, the modified silk fabrics also self-extinguished and passed the vertical burning test, and such good washing resistance was achieved by the Schiff base cross-linking of vanillin phytate ester on the silk fabric. An intumescent flame-retardant mechanism was also identified by char residue analyses, which was driven by the synergistic charring action of phosphate groups and aromatic structures.

A high-efficiency and durable flame retardant for cotton fabrics: Ammonium ethyl acryloylphosphoramidate

The ammonium ethyl acryloylphosphoramidate (AEA) was synthesized by acrylamide, ethanolamine, and phosphorus oxychloride; the nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) were applied to analyze the structure of AEA molecule. Using the dip-cure process to treat raw cotton (RC) with AEA flame retardant, the finished fabric had excellent flame retardancy. The cone calorimeter, thermogravimetric, FTIR, and vertical flame tests illustrated finished fabrics underwent synergistic and condensed-phase flame retardation. The finished fabric also had excellent durability, and the higher the sealing degree of phosphorus atoms, the higher the durability. The limiting oxygen index (LOI) of RC-AEA3-20 (raw cotton finished with 20 wt% AEA3) reached 45.4 %. However, the LOI only dropped to 34.9 % after 50 laundering cycles under the AATCC 61–2013 3 A standard. The excellent durability and FTIR analyses of finished fabrics suggested that the –N–P(=O)–O–C– covalent bond was formed between flame retardant and cellulose. This covalent bond exhibited a p–π conjugation effect, enhancing the stability of –N–P(=O)–O–C– bond, improving the durability of finished fabrics. In conclusion, adding reactive groups into flame retardants, like CH2=CH– and –N–P(=O)–O−NH4+, could increase the durability of finished cotton fabrics.

Halloysite-based inorganic-organic hybrid coatings for durable flame retardant, hydrophobic and antibacterial properties of cotton fabrics

Developing durable protective cotton fabrics (CF) against potential environmental dangers such as fire hazards and bacterial growth remains an imperative but tough challenge. In this study, flame retardant, antibacterial and hydrophobic CF were successfully prepared via two-step coating. The inner coating entailed polyelectrolyte complexes consisting of polyethyleneimine and ammonium polyphosphate with the goal of enhancing the flame retardancy of CF. Halloysite nanotubes (HNTs), a kind of tubular silicate mineral, were creatively modified and introduced to multifunctional coatings to improve flame retardant and antibacterial properties of CF. N-halamine modified HNTs (HNTs-EA-Cl) and polydimethylsiloxane were applied as the outer coating to endow CF with antibacterial and hydrophobic properties and further improve the flame retardancy of CF. After halloysite-based inorganic-organic hybrid coatings, the limiting oxygen index of the treated samples (PAHP-CF) was over 28 %, and the release of heat and smoke was significantly inhibited. PAHP-CF could inactivate 100 % E. coli and S. aureus within 2 h. More importantly, PAHP-CF showed excellent hydrophobicity with a water contact angle of 148° and exhibited great prevention of bacterial adhesion. PAHP-CF exhibited excellent washing durability undergoing 5 washing cycles. This study promotes the development of multifunctional coatings and offers a new way to manufacture multifunctional cotton fabrics.

Low temperature carbonization, smoke suppression and durable flame retardancy of cotton fabric spray-assisted coated by phosphorus nitrogen silicon composite system

To solve the problems of flammability, smoldering, smoking and flame retardant durability of cotton fabric, flame retardant fininshing was executed using spray assisted self-assembly method, and P/N/Si synergistic flame retardant system was constructed by polyethylene imine (PEI), phytic acid (PA) and 3-aminopropyltriethoxysilane (APTES). Cotton cellulose carbonized at low temperature prompting by PA catalytic effect, and this cooperated with PEI thermal decomposition to endow cotton fabric with flame retardancy and smoking suppression by reducing its pyrolysis rate at high temperature and lessening combustible products. Meanwhile APTES as silane coupling agent further improved its flame retardant durability and smoke suppression effect. The synchronous thermal analysis results indicate that cotton fabrics treated by PA/PEI/APTES composite system present significant low-temperature carbonization trend, and their initial decomposition temperatures advance by 46.5℃-75.9℃. Moreover, they form 4.6 %-44.9 % aromatic structure char through dehydration and carbonization reactions during the low-temperature carbonization process, improving their thermal stability at high temperature, and their after-flame and smoldering phenomena disappear. The damaged length of treated fabric with five layers reduces to 5.0 cm, its limiting oxygen index reaches 33.7 %, and it presents excellent flame retardant durability and smoke suppression effect. This low-temperature carbonization mechanism possesses importantly innovative significance for the flame retardant finishing of cotton fabric, and it not only more actively guides the selection of flame retardants to make them match with the material required, but provides a new thinking method for flame retardant material research in the future.

Self-assembled coatings with durable flame retardancy for EPS foam

Layer by layer (LBL) self-assembly coatings upon expandable polystyrene (EPS) surface play an important role in improving its flame retardancy. However, a large number of layers is needed to achieve a satisfied fire performance, and the coatings are difficult to adhere on the inert EPS surface, resulting in the poor durability. In this work, the surface of EPS was activated by ultraviolet ozone (UVO) with the appearance of oxygen contained groups, then a LBL coating with only two bilayers (branched polyethyleneimine (BPEI)-kaolinite (kaol)-BPEI-diethylene triamine penta (methylene phosphonic acid)) was covalently connected on the EPS surface. Compared with neat EPS, the obtained E-K5D30 sample increased the value of limiting oxygen index (LOI) from 18.8 % to 37.7 %, improved the ignition time from 59 s to 95 s, reduced the peak heat release rate (pHRR) value from 282.0 kW/m2 to 220.9 kW/m2, and enhanced the char residues from 6.3 % to 32.3 % after the combustion. Moreover, an ultraviolet (UV) curing layer with P/N elements was prepared upon E-K5D30 sample to maximize the flame retardant durability. A novel amino-intercalated kaol was used to play a smoke suppression role. The results showed that E-K*5D30-P8N3 sample further increased the LOI to 39.2 %. Even after 12 h washing, the E-K*5D30-P8N3 sample exhibited a slight LOI reduction to 37.8 %, and fire performance index (FPI) value of 0.405 m2·s/kW, showing the successful construction of coatings with good fire safety and flame retardant durability.

A bio-based durable reactive flame retardant for cotton fabric based on lentinan

Cotton fabric has extensive application due to its comfort and breathability. However, the inherent flammability limits its wide application. Durable polysaccharide-based flame retardants with a low impact on the softness of fabrics are rarely reported. In this work, a novel flame retardant ammonium phosphate of lentinan (APLNT) was synthesized and grafted on the surface of cotton fabric. The treated cotton fabric had a high limiting oxygen index (LOI) value of 43.3 % and passed the vertical burning test (VBT) with a 21.1 % weight gain of APLNT. Compared with control cotton, the peak heat release rate and total heat release values of Cotton-APLNT2 decreased by 92.8 % and 50.9 %, respectively. In addition, the cotton fabric still passed the VBT and kept an LOI value of 27.0 % even after 50 laundering cycles, indicating that the fabric can be used for daily needs. More importantly, the treated fabric remains soft. This research provided a new strategy for preparing bio-based durable flame retardant cotton fabrics.

Eco-friendly, efficient and durable flame retardant lyocell fabrics prepared via a feasible grafting of taurine

Inspired by alkaline oxidative degradation of cellulose, a novel eco-friendly scenario for preparation of flame retardant lyocell fabrics was developed by the chemical grafting of biomass taurine. FTIR and XPS results verified the establishment of a covalent bond between taurine and lyocell fabric. Thermogravimetric analysis and vertical combustion test proved the improved char-forming ability and flame resistance of the grafted fabric. The THR and pHRR of the finished fabric were successfully reduced by 67.3 % and 89.9 % respectively after modification. In addition, after 50 wash cycles, the LOI value of the grafted fabric was maintained at 29.5 %. The gas-phase and condensed-phase flame retardant mechanisms were proposed from the analyses of pyrolysis gaseous products and char residue of the modified fabrics. The modification process is simple to operate and provides a feasible green flame retardant strategy for flammable lyocell fabrics.

Construction of durable flame retardant, anti-dripping, and smoke-suppressing recycled polyester fabric

Recycled poly(ethylene terephthalate) (R-PET) fabrics offer a sustainable and eco-friendly alternative to virgin PET but exhibit high flammability and increased smoke emission. In this study, magnesium hydroxide nanoparticles (nano-Mg(OH)2) with the particle size of 53 nm were synthesized and combined with cyclic phosphate ester through high-temperature and high-pressure immersion technology. The organic‒inorganic flame retardant (FR) agents were expected to penetrate the R-PET fibers, thus achieving high washing durability for flame retardancy and smoke suppression. The surface structural performance of nano-Mg(OH)2 and the smoke and heat suppression capacity, FR performance, mechanism and laundering resistance of the modified R-PET samples were also explored. The organic‒inorganic FR system significantly improved the FR properties and anti-dripping ability of R-PET while significantly reducing smoke and heat generation. Moreover, the modified R-PET fabrics exhibited self-extinguishing ability even after 40 washes, indicating their high washing resistance. The organic‒inorganic FR system was effective in both gas and condensed phase, providing multilevel fire safety. This study provides efficient and durable FR-functionalized R-PET fabrics with low smoke suppression and high fire safety.

Enhancing Thermal Insulation of Poly(β-Hydroxybutyrate) Composites with Charring-Foaming Agent-Coated Date Palm Wood

Date palm fiber (DPF) holds great potential for composite materials, but its flammability limits its practical applications. In this study, DPF was modified using a pad-drying method to impregnate it with a 5 wt.% solution of ammonium dihydrogen phosphate (ADP). These treated fibers were then utilized to fabricate poly(β-hydroxybutyrate)- (PHB-) based composites. The resulting thermal insulators were comprehensively evaluated for their flammability, physical, mechanical, and thermophysical properties, as well as morphological and thermal stability characteristics. The findings revealed a significant reduction in flame spread and smoke suppression; however, the concentration used is not sufficient to achieve the desired rating grades. The thermal insulation capacity of the modified fiber composites was substantially enhanced, particularly with the 40% PHB/DPF-ADP composite displaying the lowest thermal conductivity at 0.0564 W/m.K. Moreover, the presence of gaps and voids at the interface led to a reduction in tensile strength to 4-7 MPa. Additionally, the modified fiber composites exhibited significantly reduced water absorption (~0.76%), attributed to the formation of a highly water-resistant substance containing a furan compound. This work provides a simple and effective approach for achieving durable flame retardancy and long-term thermal insulation performance, offering promising opportunities for the practical application of biobased PHB composites.

Preparation and characterization of durable flame retardant cotton fabrics using phosphorylation reaction of cellulose with ammonium etidronate

Preparation and characterization of durable flame retardant cotton fabrics using phosphorylation reaction of cellulose with ammonium etidronate

A novel phosphorus/nitrogen-containing polyacrylonitrile fiber with excellent flame retardancy and mechanical properties

To improve the flame retardancy, smoke suppression and mechanical properties of polyacrylonitrile (PAN) fiber, it was first modified with diethylenetriamine to prepare the aminated PAN fiber (A-PAN). Second, diethyl phosphite (DEP) was grafted onto the A-PAN to fabricate flame retardant PAN fiber (DEP-A-PAN). XPS and FTIR analysis confirmed that phosphorus and nitrogen elements were covalently bonded to the surface of PAN fiber. TGA revealed that the incorporation of DEP promoted char formation of PAN matrix and suppressed the thermal degradation. DEP-A-PAN exhibited a significantly reduced peak heat release rate (pHRR) compared to the control sample. Moreover, the limiting oxygen index (LOI) of DEP-A-PAN was up to 34.3 %, and remained at 26.6 % even after 50 laundering cycles (LCs), demonstrating excellent durable flame retardancy. Interestingly, DEP-A-PAN exhibited improved tensile strength of 2.97 cN/dtex. This work developed a simple and feasible method for preparing mechanical-enhanced flame retardant and smoke suppressive PAN fiber, which could be large-scale preparation.

Reasonable multi-functionality of cotton fabric with superior flame retardancy and antibacterial ability using ammonium diphosphate as cross-linker

Ammonium phosphates have been proven to be efficient and durable flame retardants for cellulose fabric. However, a facile process for their multifunctional flame-retardant modification has not yet been reported. In order to achieve this goal, we synthesized an ammonium diphosphate of ethylene glycol (AP) and used it as a crosslinker to fabricate flame-retardant and antibacterial cellulose fabric with a dihydroxyl N-halamine precursor (BD) via a one-pot process. The AP/BD modified fabric exhibited superior flame retardancy, with a LOI value of 32.9% and self-extinguishing behavior at only 11.0% weight gain. The heat release was significantly inhibited, with an 81% reduction in peak heat release rate (PHRR) and a 60% reduction in total heat release (THR). Furthermore, the modified fabric maintained its self-extinguishing properties even after undergoing 50 washing cycles, demonstrating excellent washing durability with a LOI value of 30.5%. In addition to its outstanding flame retardancy, the AP/BD modified fabric also displayed excellent biocidal efficacy due to the formation of N-Cl bonds through simple bleaching treatment. All inoculated bacteria were killed within just 5 min of contact without any noticeable dissolution occurring. Moreover, the oxidative chlorine that acted as an antibacterial factor could be recharged after long periods of storage and washing. Importantly, no significant changes in whiteness, air permeability or hand feeling were observed after the AP/BD modification process. Therefore, this work presents a common and facile approach for preparing highly-efficient flame-retardant cellulose fabrics with multifunctionality.

A facile surface phosphorylation grafting strategy to fabricate durable flame-retardant wool fabric

Inspired by the phosphorylation of amino acids, a facile surface grafting approach with dimethyl phosphate (DMP) was developed to endow durable flame retardancy to wool fabrics. The grafting behavior between DMP and wool fibers was investigated by ATR-FTIR analysis and XPS spectroscopy. After undergoing the grafting modification process, the flame-retardant ability of the grafted sample was clearly enhanced, with an increase in the limiting oxygen index (LOI) value from 23.8 % to 30.5 %. Even after 25 washing cycles, it still retained 27.0 %. Meanwhile, cone-calorimeter tests (CCT) demonstrated that the grafted wool fabric achieved a peak heat release rate that decreased by 28.1 % and total heat release decreased by 19.2 %. The grafted wool fabric also showed better thermal stability, with T50% increased from 370 °C to 397 °C (N2 atmosphere), 408 °C to 439 °C (air atmosphere). Char residues had a large increase, from 0.6 % to 21.8 % (air atmosphere), during a thermogravimetric (TG) test. Moreover, char residue analysis confirmed that the introduced phosphorylated structure could assist the wool fabrics to form intensive, expanded protective char residue after exposure to flame, protecting the matrix from decomposition. In this work, we provide a facile strategy for fabricating durable flame-retardant (FR) wool fabrics under a low temperature.

A cationic, durable, P/N-containing starch-based flame retardant for cotton fabrics

A cationic, durable flame retardant for cotton fabrics, 6-(2-(dimethoxy phosphoryl)-2-(trimethyl ammonium)) methoxy-2-methoxy-polysaccharide ammonium phosphate (DTPAP), was synthesized. Its structure was verified by NMR and FTIR spectroscopy. According to the FTIR spectra and X-ray photoelectron spectroscopy (XPS), DTPAP formed P(=O)-O-C bonds with cellulose molecules and firmly grafted to cotton fabrics, giving the fabric a high durability. DTPAP-25-treated fabrics passed the vertical flame test (VFT), and the limiting oxygen index (LOI) was 43.9 %. After 50 laundering cycles (LCs), the DTPAP-25-treated fabrics had an LOI of 29.9 %, passed the VFT, and retained their flame retardancy. EDS data showed that, compared with engrafted cationic ammonium phosphate flame retardants, the DTPAP-treated fabrics contained fewer metal ions. Cone calorimetry data showed that DTPAP-25-treated fabrics did not display concentrated heat release. The results suggested that DTPAP exhibited a condensed-phase flame retardant mechanism, and the introduction of cations into the ammonium phosphate flame retardant reduced ion exchange, which improved the durability.

Electrostatic self-assembly endows cellulose paper with durable efficient flame retardancy and mechanical performance improvement

Flameproof modification of paper can improve safety and application performance. However, traditional paper is prone to moisture absorption, resulting in significant reduction in flame retardant performance, even complete failure, greatly limiting the application environment. In order to achieve long-term flame retardant properties of paper, while avoiding the loss of physical properties caused by the introduction of flame retardants, in this work, a plant acid/phosphate and melamine formaldehyde coating (PyA/PA-MF) is prepared through electrostatic self-assembly for durable flame retardant performance of cellulose paper. Due to the electrostatic interaction, the paper surface become greatly rough with introduction of PyA/PA-MF, a uniform microsphere structure is formed on the surface of the paper cellulose, which effectively fix the phosphorus-containing groups. The oxygen index reaches 33 % and the carbon length was only 6.3 ± 0.2 cm, the pHRR and THR are decreased by 80 % and 73 %, respectively. After being immersed for 72 h, the oxygen index is still 31.4 % and carbon length is no more than 12 cm. mechanical property of modified paper is significant increased in the tensile strength (2.4 MPa) compared to the blank paper (1 MPa), as well as that the whiteness of the surface of the modified paper will not change. In summary, PyA/PA-MF endows paper long-term flame retardant performance while maintaining its basic performance.