How to improve the flame retardancy of lyocell fibers has become an important issue in textile industry. Herein, lyocell fibers were firstly undergone etherification reaction between sodium ...chloroacetate and the hydroxyl groups of lyocell fibers to obtain carboxymethylated lyocell fibers (CM-lyocell), then the sodium ions of CM-lyocell were replaced by aluminum ions, and the flame retardant lyocell fibers (FR-lyocell) were prepared. Compared with lyocell fibers, the degradation temperature of FR-lyocell decreased by about 80 °C, and the char residue in nitrogen increased from 15.1 to 31.8 wt% at 800 °C. Importantly, the limiting oxygen index (LOI) value of FR-lyocell fabric was increased from 17.2 to 26.4%. Besides, the peak of heat release rate (PHRR) and total heat release (THR) of FR-lyocell had 77.4% and 76.3% reduction, respectively. The FR-lyocell can generate a highly graphitized char layer and release more water at high temperatures, which are beneficial to improving the flame retardancy of lyocell fibers. Moreover, the tensile test showed that the tensile strength of FR-lyocell decreased from 3.95 to 3.08 cN/dtex with a 22% reduction, showing good strength retention.
Graphic abstract
Ammonium salt of diethylene triamine penta methylene phosphonic acid (ADTPMPA), a novel flame retardant, was synthesized and grafted on the lyocell fabric to obtain a kind of flame retardant lyocell ...fabric (FR-lyocell). Then FR-lyocell was coated by Ag nanoparticles (Ag NPs) to fabricate flame retardant and antibacterial lyocell fabric (FR-Ag-lyocell). The elemental composition, surface morphology, combustion behavior and antibacterial activity of the lyocell fabric before and after modification were investigated. The flame retardant and antibacterial mechanism of FR-Ag-lyocell fabric was also analyzed. The limiting oxygen index (LOI) values of FR-Ag-lyocell fabric before and after 20 laundering cycles (LCs) reached 44.8% and 31.3%, respectively. The treated lyocell fabric possessed lower peak of heat release rate (pHRR) and total heat release (THR) values compared with control lyocell fabric. The FR-Ag-lyocell fabric exhibited excellent antimicrobial ability against Staphylococcus aureus (
S. aureus
) and Escherichia coli (
E. coli
), even after 10 LCs. These results indicated that FR-Ag-lyocell fabric had durable flame retardant and antibacterial properties.
Graphic abstract
Polyester/cotton (PET/CO) fabrics usually burn more violently than single-component fabric due to significant differences of two components as well as “wick effect” during combustion process. Hence, ...it is very challenging to impart PET/CO fabrics excellent flame retardancy. In this work, a new monomer (ethoxy piperazine (phenyl) phosphoryl ethyl methacrylate, EPPEM) containing multiple unsaturated double bonds was synthesized. As EPPEM contained varied synergistic flame retardant components of phosphorus, nitrogen, and benzene ring, it was expected to form a dense cross-linked network structure on the surface of the fabrics by UV curing to prepare PET/CO fabrics with good flame retardancy and washing resistance. The limiting oxygen index (LOI) value of treated PET/CO fabrics increased up to 27.2% from 17.8% of control sample, which still reached 26.6% after 25 laundering cycles, indicating excellent flame retardancy and water-laundering resistance. Raman spectroscopy, thermogravimetric analysis coupled with Fourier transform infrared analysis and thermogravimetric mass spectrometry indicated that EPPEM promoted the production of more non-combustible compounds during pyrolysis process, such as H
2
O and CO
2
. Furthermore, EPPEM decomposed to produce acidic substances which promoted dehydration and coke formation of PET/CO fabrics, thereby preventing exchange of heat and combustible gas. On the basis of the results, a two-phase flame-retardant mechanism of EPPEM/UV-curable system for PET/CO fabrics was proposed.
A novel phosphorus- and nitrogen-containing flame retardant (APNTHE) was synthesized through the reaction of N,N,N′,N′-tetrakis (2-hydroxypropyl) ethylenediamine, phosphoric acid and urea. Then, the ...APNTHE solution with a concentration of 120 g/L was used for the preparation of flame retardant cotton (FR-cotton). The elemental compositions, surface morphology, thermal stability and combustion behavior of the cotton before and after modification were investigated. Thermogravimetric (TG) analysis showed that the char residue of the treated fabric at 800°C was as high as 35.09% under a nitrogen atmosphere. Flammability tests after different LCs indicated that FR-cotton had durable flame retardancy. Compared to the blank sample, the peak of heat release rate and total heat release of the FR-cotton decreased by 91.89% and 90.53%, respectively. The char residual and TG-Fourier transform infrared spectroscopy analysis illustrated that APNTHE played a flame retardant role both in the gas phase and the condensed phase. All the results demonstrated that APNTHE can be regarded as a prospective flame retardant for cotton.
In order to improve the flame retardancy of polyacrylonitrile (PAN) fabrics, glycidyl methacrylate (GMA) was first grafted onto the surface of PAN fabric (PAN-g-GMA) by means of UV-induced photo ...grafting polymerization process. Then, PAN-g-GMA was chemically grafted with chitosan to obtain a bigrafted PAN fabric (PAN-g-GMA-g-CS). Finally, the flame-retardant PAN fabric (FR-PAN) was prepared by phosphorylation. The structure and elemental analysis of the samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal degradation properties and combustion characteristics of the fabrics were accessed by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and cone calorimeter (CC). The results show that the onset thermal decomposition temperature of FR-PAN fabric is lower than that of the control sample due to the degradation of the grafting groups. The combustion test indicates that the FR-PAN fabric has an excellent flame-retardant property and the combustion rate is significantly reduced. In addition, the char residue of the burned FR-PAN fabric is over 97%, indicating excellent char-forming ability.
The recycling and reutilization of cotton waste are in line with the sustainable development of society. Therefore, in this work, an environmentally friendly cellulose phosphate ammonium salt was ...synthesized by phosphorylation of cotton waste. Then the cotton fabrics were modified with cellulose phosphate ammonium salt by using the dip–dry–cure technique to obtain flame-retardant cotton fabric. The surface morphology, characteristic functional groups, and elemental components were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the cellulose phosphate ammonium salt was immobilized onto the cotton fabric through a P–O–C chemical bond. Vertical combustion tests before and after washing showed that the treated cotton fabric had durable flame-retardant properties. Thermogravimetry demonstrated that the treated cotton fabric retained a large amount of residual char and the pyrolysis temperature was significantly earlier than that of the control sample. Compared with the blank sample, the peak of heat release rate and total heat release of the modified fabric was reduced by 90.8% and 84.1%, respectively. Thermogravimetric infrared of flame-retardant cotton fabric proved that cellulose phosphate ammonium salt acted both in the gas and condensed phase during the decomposition of the treated fabric.
A novel effective halogen-free flame retardant (FR) rich in phosphorus (P) and nitrogen (N) was synthesized via Mannich and esterification reaction of ethanolamine, glyoxal, phosphoric acid and urea, ...and used for the preparation of durable flame retardant lyocell fabric (FR-lyocell). Its chemical structure was characterized by Fourier transform infrared spectra,
1
H and
31
P nuclear magnetic resonance spectra. Inductively coupled plasma emission spectrometry and elemental analysis were conducted to test the phosphorous, carbon and nitrogen contents. The results confirmed that the FR was successfully synthesized and grafted on the lyocell fabric via firm P–O–C covalent bonds. The limiting oxygen index of the FR-lyocell treated with 30 wt% flame retardant finishing solution is 44.6%, demonstrating high efficiency flame retardancy. The thermo-gravimetric analysis indicated that FR-lyocell degraded preferentially than that of the control sample and the char residue was 38.8 wt% at 800 °C in N
2
atmosphere. In addition, the cone calorimeter test revealed that FR-lyocell could not be ignited and the peak of heat release rate was much lower than that of original specimen. Furthermore, the char residue of FR-lyocell is compact and the
I
D
/
I
G
value is 0.771, exhibiting a super degree of carbonization. Moreover, TG-IR result revealed that FR played dual flame-retardant effect in the gaseous and condensed phases. The flame retardant finishing has a negligible impact on the mechanical properties of the fibers. In summary, FR-lyocell exhibits excellent flame retardancy and superior char forming capability, which is suitable for the preparation of flame retardant lyocell fibers.
Graphic abstract
Lyocell fabrics are widely applied in textiles, however, its high flammability increases the risk of fire. Therefore, to resolve the issue, a novel biomass-based flame retardant with phosphorus and ...nitrogen elements was designed and synthesized by the reaction of arginine with phosphoric acid and urea. It was then grafted onto the lyocell fabric by a dip-dry-cure technique to prepare durable flame-retardant lyocell fabric (FR-lyocell). X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated that the flame retardant was successfully introduced into the lyocell sample. Thermogravimetric (TG) and Raman analyses confirmed that the modified lyocell fabric featured excellent thermal stability and significantly increased char residue. Vertical combustion results indicated that FR-lyocell before and after washing formed a complete and dense char layer. Thermogravimetric Fourier-transform infrared (TG-FTIR) analysis suggested that incombustible substances (such as H2O and CO2) were produced and played a significant fire retarding role in the gas phase. The cone calorimeter test corroborated that the peak of heat release rate (PHRR) and total heat release (THR) declined by 89.4% and 56.4%, respectively. These results indicated that the flame retardancy of the lyocell fabric was observably ameliorated.
A biomass vitamin B6-based flame retardant, ammonium salt of pyridoxine phosphoric ester acid (ASPPEA) was synthesized and used for modification of lyocell fibers. FTIR, XPS and EDX analyses ...indicated that lyocell fibers had been successfully grafted with ASPPEA. The ASPPEA improved the char-forming ability, as evidenced by the increase of the char residue (51 wt%) of ASPPEA-treated lyocell fibers. The limiting oxygen index (LOI) value of ASPPEA-treated lyocell fabrics increased up to 48.3%. After 450 min washing, the LOI value remained 30.8%, thus demonstrating the flame retardant durability. The total heat release of ASPPEA-treated lyocell fabrics decreased by 82.5%. During the pyrolysis, the ASPPEA decomposed to produce acidic substances which promoted the dehydration and char formation of lyocell fibers, thus blocked the exchange of heat and flammable gas. This research proposes a novel application of vitamin B6 to impart lyocell fibers with flame retardancy.
To improve the strength and maintain the inherent properties of flame-retardant polyacrylonitrile (FR-PAN) fiber, a commercialized hydrocarbon polymer, i.e., poly (vinyl alcohol) (PVA), used as an ...enhancement component, was blended with polyacrylonitrile (PAN) spinning dope to fabricate a PVA/PAN composite fiber through wet-spun technology. Then, cross-linked PVA/PAN composite fiber (C-PVA/PAN) was acquired via boric acid cross-linking. Finally, flame-retardant C-PVA/PAN fiber (FR-PVA/PAN) was prepared by phosphorylation. The structures of the samples were characterized by Fourier transform infrared analysis (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermogravimetric analysis (TGA) results reveal that the thermal stability of the composite fiber is lower than that of the pristine PAN fiber. However, the char residue of the composite fiber is higher than that of the control sample, wherein, FR-PVA/PAN has the highest char residue of 62.5 wt% at 800 °C. The results regarding the combustion properties of FR-PVA/PAN show that the fire hazard of FR-PVA/PAN is restrained greatly, indicating excellent flame-retardant performance. The corresponding flame-retardant mechanism of FR-PAV/PAN is investigated by Pyrolysis gas chromatography and mass spectrometry (Py-GC/MS) and thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR). The results indicate the gas-phase and condensed-phase flame-retardant mechanisms.
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