High-efficiency durable flame retardant with ammonium phosphate ester and phosphine oxide groups for cotton cellulose biomacromolecule

Construction of sustainable and highly efficient fire-protective nanocoatings based on polydopamine and phosphorylated cellulose for flexible polyurethane foam

Layer-by-layer (LBL) self-assembly is an effective strategy for constructing fire-resistant coatings on flexible polyurethane foam (FPUF), while the efficiency of fire-resistant coatings remains limited. Therefore, this study proposes an in situ flame retardancy modification combined with LBL self-assembly technology to enhance the efficiency of flame retardant coatings for FPUF. Initially, polydopamine (PDA) and polyethyleneimine (PEI) were employed to modify the FPUF skeleton, thereby augmenting the adhesion on the surface of the skeleton network. Then, the self-assembly of MXene and phosphorylated cellulose nanofibers (PCNFs) via the LBL technique on the foam skeleton network formed a novel, sustainable, and efficient flame retardant system. The final fire-protective coatings comprising PDA/PEI and MXenes/PCNF effectively prevented the collapse of the foam structure and suppressed the melt dripping of the FPUF during combustion. The peak heat release rate, the peak CO production rate and peak CO2 production rate were reduced by 68.6 %, 61.1 %, and 68.4 % only by applying a 10-bilayer coating. In addition, the smoke release rate and total smoke production were reduced by 83.3 % and 57.7 %, respectively. This work offers a surface modification approach for constructing highly efficient flame retardant coatings for flammable polymeric materials.

Synthesis of a novel Si-N-S flame retardant and its application on cotton cellulose biomacromolecule

A novel flame retardant containing Si, N, and S elements, ((2-(triethoxysilyl)ethyl)thio)ethan-1-amine hydrochloride (TETEA), was synthesized via a click reaction and characterized using nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FTIR). Subsequently, the flame-retardant cotton fabric was fabricated by sol-gel method. The results indicated that TETEA was successfully loaded on cotton fabric and formed a uniform protective layer on the surface of cotton fabric, exhibiting excellent flame retardancy. The flame-retardant cotton fabric achieved limiting oxygen index (LOI) of 28.3 % and passed vertical combustion test without after-flame or afterglow time at TETEA concentration of 500 g/L. Thermogravimetric analysis revealed that the residual carbon content of the flame-retardant cotton fabric was much higher than that of the control under air and N2 conditions. Besides, the flame-retardant cotton fabric was not ignited in cone calorimeter test with an external heat flux of 35 kW/m2. The peak heat release rate and the total heat release decreased from 133.4 kW/m2 to 25.8 kW/m2 and from 26.46 MJ/m2 to 17.96 MJ/m2, respectively. This phosphorus-free flame retardant offers a simplified synthesis process without adverse environmental impacts, opening up a new avenue for the development environmentally friendly flame retardants compared to traditional alternatives.

Facile Fabrication of Highly Efficient Chitosan-Based Multifunctional Coating for Cotton Fabrics with Excellent Flame-Retardant and Antibacterial Properties

Interest in the development of eco-friendly, sustainable, and convenient bio-based coatings to enhance flame retardancy and antibacterial properties in cotton fabrics is growing. In this work, chitosan was protonated at its amino groups using a method with a high atom economy using an equimolar amount of amino trimethylene phosphonic acid (ATMP), resulting in the fabrication of a single-component chitosan-based multifunctional coating (ATMP-CS), thereby avoiding any additional neutralization or purification steps. Cotton fabrics coated with various loads of ATMP-CS were prepared through a padding-drying-curing process. The morphology, thermal stability, mechanical properties, antibacterial properties, flame-retardant behavior, and flame-retardant mechanism of these fabrics were investigated. The coating exhibited excellent film-forming properties, and it imparted a uniform protective layer onto the surfaces of the cotton fabrics. When the load capacity reached 11.5%, the coated fabrics achieved a limiting oxygen index of 29.7% and successfully passed the VFT test. Moreover, the ATMP-CS coating demonstrated antibacterial rates against Escherichia coli and Staphylococcus aureus reaching 95.1% and 99.9%, respectively. This work presents a straightforward and gentle approach to fabricating colorless, environmentally friendly, and highly efficient fabric coatings that have potential applications in promoting the use of bio-based materials.

A molecularly engineered fully bio-derived phosphorylated furan-based flame retardant for biomass-based fabrics

With the increasing awareness of environmental protection, the demand for eco-friendly bio-derived flame-retardant for textiles has received increasing attention. In this work, a fully bio-derived phosphorylated furan-based flame retardant (FAP) was synthesized by the Schiff reaction of furan-based compounds (furfural and furfurylamine). To evaluate the application scope and flame retardant efficiency of FAP, cotton fabrics and PLA nonwovens were selected as biomass-based representatives of natural fiber materials and synthetic fiber materials, respectively. Significantly, based on the composition of furan ring, phosphorus and nitrogen containing components of FAP, excellent charring and flame retardant properties of coated cotton fabrics and PLA nonwovens can be expected. TGA results showed that the residual char of C-FAP-3 and P-FAP-3 were 39.7% (increased by 267.6%) and 16.7% (increased by 215.1%), respectively, higher than those of control cotton (10.8%) and PLA nonwoven (5.3%). Cone test results exhibited that the peak heat release rate (PHRR) and total heat release (THR) values of C-FAP-3 were sharply decreased by 69.4% and 37.8%, respectively. P-FAP-3 also displayed a significant reduction in PHRR, implying high flame retardancy of C-FAP-3 and P-FAP-3. Notably, through the weight gains of FAP coating on cotton and PLA as well as the final LOI and VBT results of the flame retardant treated fabrics, it can be preliminarily inferred that control cotton fabrics are more likely to achieve better flame retardant effects than PLA. Additionally, the facile synthetic strategy of fully bio-derived flame retardants is expected to promote the development of green flame retardant strategies for high-performance textiles.

Facile fabrication of adenosine triphosphate/chitosan/polyethyleneimine coating for high flame-retardant lyocell fabrics with outstanding antibacteria

Addressing highly flammable and easily breeding bacteria property via environmentally friendly approach was critical for the large-scale application of lyocell fibers. Herein, a bio-based coating constructed by layer-by-layer deposition of adenosine triphosphate (ATP), chitosan (CS), and polyethyleneimine (PEI) was successfully fabricated to obtain excellent fire-resistant and antimicrobial lyocell fabrics (LBL/Lyocell). The resulted fabrics with add-on of 11.5 wt% achieved the limiting oxygen index (LOI) of 32.0 %. Meanwhile, compared with the pure lyocell fabrics, the peak of heat release rate (PHRR), total heat release (THR), and fire growth rate (FIGRA) of LBL/Lyocell fabrics decreased by 75.2 %, 61.0 % and 69.8 % in cone calorimetric test (CCT), respectively. By characterizing the gaseous products and solid residues, the presence of the ATP/CS/PEI coating could not only quickly form the dense expanded carbon layer by itself, but also promote the conversion of cellulose into thermal-stability residues, thus reducing the release of combustible substances during combustion and protecting the lyocell fabrics. In addition, LBL/Lyocell showed excellent antimicrobial properties with 99.99 % antibacterial rates against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This bio-based coating was a promising candidate for efficiently flame-retardant cellulose fibers with excellent antibacteria.

Evaluating the fire resistance and durability of cotton textiles treated with a phosphoramide phosphorus ester phosphate ammonium flame retardant

The phosphoramide phosphorus ester phosphate ammonium (PPEPA) flame retardant was synthesized by phosphorus oxychloride and ethanolamine, and its structure was characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). Cotton textiles treated with 20 wt% PPEPA (CT-PPEPA3) would have high durability and flame retardance. The limiting oxygen index (LOI) of CT-PPEPA3 was found to be 46.5 %, while after undergoing 50 laundering cycles (LCs) following the AATCC 61-2013 3 A standard, the LOI only decreased to 31.4 %. Scanning electron microscopy and X-ray diffraction analyses suggested the penetration of PPEPA molecules into the interior of cotton fibers, resulting in a minor alteration of the cellulose crystal structure. The excellent durability, FTIR, and energy-dispersive X-ray of CT-PPEPA3 provided evidence for the formation of -N-P(=O)-O-C- and -O-P(=O)-O-C- covalent bonds between the PPEPA molecules and cellulose. The -N-P(=O)-O-C- bond exhibited a p-π conjugation effect, leading to enhanced stability and improved durability of the flame-retardant cotton textiles. Vertical flame, thermogravimetric, and cone calorimetry tests demonstrated that the CT-PPEPA3 underwent condensed-phase and synergistic flame retardation. Additionally, these finished cotton textiles retained adequate breaking strength and softness, making them suitable for various applications. In conclusion, the incorporation of the -N-P(=O)-ONH4 group into the phosphorus ester phosphate ammonium flame retardant demonstrated effective enhancement of the fire resistance and durability of treated cotton textiles.

A P/N flame retardant for polyester-cotton fabrics: Flame retardancy, mechanical properties and antibacterial property

A phosphorus‑nitrogen synergistic flame retardant (named POI) was obtained by the chemical reaction between phenylphosphonic acid (PPOA) and polyethyleneimine (PEI), and used to give the flame retardancy of PTCO. The effects of PPOA and POI on various properties of PTCO were investigated. PPOA obviously improved the flame retardancy of PTCO/PPOA, while the breaking force of PTCO/PPOA was greatly reduced. However, the introduction of PEI made the surface of fabrics smoother. PTCO/POI had better flame retardancy than PTCO/PPOA did, and the limiting oxygen index value of PTCO/POI reached to 29.8 %. POI had a good effect on reducing the Rmax of both cotton and polyester components. The phosphoric acid groups in POI can promote the dehydration and carbonization reactions of PTCO, which protects the inner fabrics, and POI can release incombustible gases such as NH3 and N2 during burning, which can dilute the oxygen concentration. The flame-retardant mechanism of PTCO/POI was mainly the condensed phase. At the same time, there were no changes in whiteness and mechanical properties compared with those of PTCO, and it also had antibacterial property. This work provides a simple and effective method to prepare flame-retardant and antibacterial PTCO.

The fabrication of flame-retardant viscose fabrics with phytic acid-based flame retardants: Balancing efficient flame retardancy and tensile strength

Viscose fabrics have been widely used in various applications, but their potential fire hazard has been a concern. To address this issue, improving the flame retardancy of viscose fabrics has become a significant priority. Phytic acid (PA) and xylitol were used to create a novel flame retardant, PAXY. PAXY was finished on viscose fabrics by pad-dry-curing process, and the performance of coated viscose fabrics was investigated. The results showed that the limiting oxygen index value of PAXY13-100 (fabrics finished with a 100 g/L flame-retardant solution and the flame retardant synthesized by a 1: 3 M ratio of PA to xylitol) reached 32.8 % and the heat release rate value was decreased by 77 %. Based on the findings from the analysis of both the gas phase and condensed phase products, PAXY promoted the dehydration of viscose fabrics to produce a denser char layer, which inhibited the production of flammable gases. Surprisingly, the breaking force retention of PAXY13-100 reached 90 % in warp and 114 % in weft. Compared with that of 100 g/L PA-treated fabrics, the breaking force of PAXY13-100 increased by nearly 400 %. This work provides a new strategy for PA-based flame-retardant finishing with the synergy of flame retardancy and breaking force retention.

Phosphamide-Based Washing-Durable Flame Retardant for Cotton Fabrics

A formaldehyde-free reactive flame retardant, an ammonium salt of triethylenetetramine phosphoryl dimethyl ester phosphamide phosphoric acid (ATPEPDPA), was synthesized and characterized using nuclear magnetic resonance (NMR). Fourier transform infrared spectroscopy test (FT-IR), durability test and scanning electron microscopy (SEM) results suggested that ATPEPDPA was successfully grafted on cotton fabrics through a -N-P(=O)-O-C covalent bond. Moreover, the limiting oxygen index (LOI) value of 20 wt% ATPEPDPA-treated cotton was 44.6%, which met stringent washing standard after 50 laundering cycles (LCs). The high washing resistance of the ATPEPDPA-treated cotton was due to the p-π conjugation between the N atom and the P(=O) group in the flame-retardant molecule, which strengthened the stability of the -N-P(=O)-O-C bonds between ATPEPDPA and cellulose, and the -N-P(=O)-(O-CH3)2 groups in the ATPEPDPA. The cone calorimetric test showed that the treated cotton had excellent flame retardance. In addition, the TG and TG-IR tests suggested that ATPEPDPA performed a condensed flame retardance mechanism. Furthermore, the physical properties and hand feel of the treated cotton were well maintained. These results suggested that introducing -N-P(=O)-(O-CH3)2 and -N-P(=O)-(ONH4)2 groups into ATPEPDPA could significantly increase the fire resistance and durability of cotton fabrics.

Durable multifunctional cotton fabric with superior biocidal efficacy and flame retardancy based on an ammonium phosphate N-halamine

Multifunctional textiles have become the mainstreams along with development of textile industry and the increased need of public. But a facile fabrication method with well-balance of multiple functions is still a challenge. In this work, an ammonium salt of tris(methylphosphonate)aminomethane (TAMPU), which can directly react with cellulose molecules and transform to N-halamine antibacterial structure, was easily synthesized and used to achieve multifunctional cotton fabric. As a result, the modified cotton fabric of 15.8 % weight gain exhibited excellent fire resistance with LOI value of 33.8 % and self-extinguishing behavior. Due to the good char-forming capacity of TAMPU, strong heat suppression was achieved and the peak of heat release rate (PHRR) and total heat release (THR) were decreased by 87.6 % and 60.8 %, respectively. Besides, the modified samples presented outstanding bactericidal effects, and all of S. aureus and E. coli could be inactivated within 5 min without dissolution phenomenon. Furthermore, the TAMPU-modified cotton fabric owned good washing durability and LOI value was remained at 29.8 % after 50 washing cycles. This TAMPU multifunctional modification had slight influence on the mechanical property and air permeability of cotton fabric. Thus, this work provides a convenient and friendly way to fabricate multifunctional flame-retardant and antibacterial cotton fabric.

Research and Application of Biomass-Based Wood Flame Retardants: A Review

Wood is widely used as a construction material due to its many advantages, such as good mechanical properties, low production costs, and renewability. However, its flammability limits its use in construction. To solve the problem of wood flammability, the most common method to improve the fire safety of wood is to modify the wood by deep impregnation or surface coating with flame retardants. Therefore, many researchers have found that environmentally friendly and low-cost biomass materials can be used as a source of green flame retardants. Two aspects of biomass-based intumescent flame retardants are summarized in this paper. On the one hand, biomass is used as one of the three sources or as a flame-retardant synergist in combination with other flame retardants, which are called composite biomass intumescent flame retardants. On the other hand, biomass is used alone as a feedstock to produce all-biomass intumescent flame retardants. In addition, the potential of biomass-based materials as an environmentally friendly and low-cost FR source to produce high-performance biomass-based flame retardants with improved technology was also discussed in detail. The development of biomass-based intumescent flame retardants represents a viable and promising approach for the efficient and environmentally friendly production of biomass-based flame retardants.

Flame retardant cotton fabrics with anti-UV properties based on tea polyphenol-melamine-phenylphosphonic acid

A novel, high-efficiency, phosphorus-nitrogen flame retardant based on tea polyphenol-melamine-phenylphosphonic acid (named TP-MA-PPOA) for cotton fabrics was prepared successfully. TP-MA-PPOA coating gives the cotton fabrics flame retardancy and anti-UV properties. The results reveal that the TP-MA-PPOA coating enables cotton fabrics to self-extinguish, the damage length is only 7.4 cm in vertical flame test, and the limiting oxygen index increases to 28.7%. Meanwhile, Cotton/TP-MA-PPOA also performs well in cone calorimetry test, as evidenced by 88.5% reduction of peak heat release rate, and 92.9% decrease of the fire growth rate compared with that of cotton fabrics. And the risk of fire is sharply reduced. In addition, the ultraviolet protection factor value of Cotton/TP-MA-PPOA is 35.2. Encouragingly, the TP-MA-PPOA coating shows little deterioration in the handle of the cotton fabrics.

Phytic Acid-Iron/Laponite Coatings for Enhanced Flame Retardancy, Antidripping and Mechanical Properties of Flexible Polyurethane Foam

The use of flexible polyurethane foam (FPUF) is severely limited due to its flammability and dripping, which can easily cause major fire hazards. Therefore, choosing an appropriate flame retardant to solve this problem is an urgent need. A coating was prepared on the FPUF surface by dipping with phytic acid (PA), Fe2(SO4)3·xH2O, and laponite (LAP). The influence of PA-Fe/LAP coating on FPUF flame-retardant performance was explored by thermal stability, flame retardancy, combustion behavior, and smoke density analysis. FPUF/PA-Fe/LAP has a good performance in the small fire test, which can pass the UL-94 V-0 rating and the limiting oxygen index reaches 24.5%. Meanwhile, the peak heat release rate values and maximum smoke density of FPUF/PA-Fe/LAP are reduced by 38.7% and 38.5% compared with those of neat FPUF. After applying PA-Fe/LAP coating, the value of fire growth rate index decreases from 10.5 kW/(m2·s) to 5.1 kW/(m2·s), dramatically reducing the fire risk. Encouragingly, the effect of PA-Fe/LAP coating on cyclic compression and permanent deformation is small, which is close to that of neat FPUF. This work provides an effective strategy for making a flame-retardant FPUF with antidripping and keeping mechanical properties.