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Heat release rate (a) and total heat released (b) as a function of temperature (measured with MCC) for coated and uncoated PA 6.6
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To overcome the flammability of polyamide, an intumescent ammonium polyphosphate (APP) and chitosan (CH) system, with and without thiourea (THU) and urea (U) dissolved into the chitosan solution, was deposited on an enzymatically modified textile via layer-by-layer (LbL) assembly. Fifteen bilayers (BL) of APP/CH:THU, or 15 BL APP/CH:U, deposited on...
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To explore how different reaction parameters affect the
major features of short-chain ammonium polyphosphate (APP)
fertilizers, a batch of manufacturing experiments were conducted
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urea and monoammonium phosphate (MAP)−urea]. The APP features
including polymerization degree, polymeri...
Citations
... Flame-retardants based on chemicals from the biomass, proteins [13], and plant and animal extracts [14][15][16], are part of the new generation of FRs whose abundance, eco-friendliness, and non-toxicity are of great importance in the replacement of the current problematic chemistries. They can be applied on the surface of synthetic textiles or incorporated into the fiber during its extrusion [17]. Unfortunately, many of these techniques can affect the chemical and physical properties of the treated fabric [18], so alternative treatments are still being sought. ...
... Additionally, MEL-based flame retardants are currently used primarily in intumescent coatings, flexible polyurethane foams, polyamides, and thermoplastic polyurethanes [169]. The market for MEL-based flame retardants is believed to expand in the near future due to continued research and application development work in the direction of polyolefins and thermoplastic polyesters [170,171]. ...
This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.
... 32 Proteins from natural sources like hydrophobins and caseins, 33 plant extracts, 34 whey proteins, 35 and so forth have also been examined as novel green components in intumescent FRs for cotton. Furthermore, low-molecular-weight additives like melamine, 36 urea, 37 thiourea, 38 and guanidine sulfamate 39 have also been explored as additives that improve the flame retardancy of intumescent systems. These additives help in creating a strong char and imparting flame retardancy with fewer deposited BLs. ...
... These additives help in creating a strong char and imparting flame retardancy with fewer deposited BLs. 29,38,40 Guanidine sulfamate improves the flame retardancy of polyester fabric, 40 while urea and thiourea improve the flame retardancy of polyamide fabric, as additives to the CH solution in CH/ammonium polyphosphate assemblies. 38 Monoammonium phosphate (MAP), an environmentally benign fertilizer used as a component of commercial powder extinguishers, 41 has shown potential as a FR chemical for textiles. ...
... 29,38,40 Guanidine sulfamate improves the flame retardancy of polyester fabric, 40 while urea and thiourea improve the flame retardancy of polyamide fabric, as additives to the CH solution in CH/ammonium polyphosphate assemblies. 38 Monoammonium phosphate (MAP), an environmentally benign fertilizer used as a component of commercial powder extinguishers, 41 has shown potential as a FR chemical for textiles. 42 Lignin (L) is another renewable chemical with high thermal stability and char-forming capability, which has the potential to be included in coatings. ...
Creating multifunctional textiles using chemicals from renewable sources is challenging. In an effort to develop a
sustainable and efficient multifunctional cotton treatment, a lignin-based multilayer nanocoating comprising magnesium
lignosulfonate, chitosan, and monoammonium phosphate (MAP) was deposited using layer-by-layer assembly. A five bilayer
coating adds 15.5 wt % to cotton and imparts fire extinguishing behavior and excellent UV and antimicrobial protection to the fabric.
Just a two bilayer coating imparts sufficient self-extinguishing behavior to pass the standard vertical flame test. The combined
influence of lignin as a char-forming and UV-protective macromolecule, chitosan as a char-forming biopolymer, and MAP acting as an antimicrobial agent (and a blowing agent and an acid source in an intumescent flame retardant system) results in a very powerful
multifunctional textile treatment with very few layers of deposition.
... On the other hand, Polyamide is a semi-crystalline thermoplastic biodegradable polymer that is used for several engineering applications. With all these interpretations, its heat distortion temperature is low, and it is a water absorber for the presence of amide functional groups in its molecular chain, which exacerbates its mechanical properties, tribological properties and dimensional stability severely [10,11]. So as to achieve to inhibit these shortages, chitosan nanoparticles, as a very well-known biocompatible and biodegradable material, has been blended with polyamide to obtain a polymer composite with distinguished properties [12,13]. ...
The principal intention of this work is to fabricate and characterize the polyamide/chitosan nanocomposite by a novel single solvent method through the electrospinning procedure. The thermal properties and morphology of prepared nanocomposite are studied by thermogravimetric analysis (TGA) and field-emission scanning electron microscopy (FE-SEM). TGA exposed that the primary decomposition temperature is reduced with rising of chitosan content in the nanocomposites and origin disintegration temperature for polyamide/chitosan nanocomposites is perceived to be in the range from 300 to 500 °C. Also, FE-SEM images demonstrated that the nanofibers of chitosan have good adhesion on the matrix and are well-oriented. Besides, the crystallinity and structural characteristics of the polyamide/chitosan nanocomposites are investigated by using X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR), respectively. The results of XRD proved that the successful blending of chitosan in polyamide is achieved via the electrospinning method. FT-IR results demonstrate that the nanofibers are consist of amine groups. Also, the electrical properties of the nanocomposite improved with the increasing content of chitosan and the conductivity of the polyamide/chitosan 5 wt% demonstrates the maximum current of 0.3 nA. Besides, the sheet resistance of the composite reduced 118–20 × 10⁹ Ω/□ with raising the chitosan volume from 0 to 5 wt%.
... The compounds used for FR LbL deposition of polyamide are similar to those applied to cotton and polyester. According to the literature, polyamide is mainly treated with cationic polymers, such as PAH, CH and PEI, as a primer layer or one of the polyelectrolyte pairs [125,[133][134][135][136]. As a pre-treatment, chemical grafting with PAA as well as enzymatic modification have been reported [137,138]. Apaydin et al. experimented with a 1 mg/mL cationic PAH solution and a 1 wt% anionic MMT suspension to deposit 5, 10 and 20 BLs on PA6. Cone calorimetry revealed that 20 BLs reduced the pHRR values by more than 60% [133]. ...
... The process is schematically shown in Figure 7. By adding lowmolecular-weight FR compounds into the CH network, the number of BLs passing the HFT was reduced from 25 BLs of APP/CH-U to 15 BLs, while the pHRR was reduced by 35% relative to untreated fabric [138]. A summation of polyelectrolytes used to achieve FR of polyamide fabrics is provided in Table 4. ...
A detailed review of recent developments of layer-by-layer (LbL) deposition as a promising
approach to reduce the flammability of the most widely used fibers (cotton, polyester, polyamide, and their blends) is presented. LbL deposition is an emerging green technology, showing numerous advantages over current commercially available finishing processes due to the use of water as a solvent for a variety of active substances. For flame-retardant (FR) purposes, different ingredients are able to build oppositely charged layers at very low concentrations in water (e.g., small organic molecules and macromolecules from renewable sources, inorganic compounds, metallic or oxide
colloids, etc.). Since the layers on a textile substrate are bonded with pH and ion-sensitive electrostatic forces, the greatest technological drawback of LbL deposition for FR finishing is its non-resistance to washing cycles. Several possibilities of laundering durability improvements by different pretreatments, as well as post-treatments to form covalent bonds between the layers, are presented in this review.
... The greener, formaldehydefree alternatives for curing FRs and antibacterial finishes on cellulosic fabrics are polycarboxylic acid-based curing agents [8,9]. Another environmentally friendly approach could be layer-by-layer (LbL) deposition, which uses deionized water as a solvent for various active compounds (polymers, nanoparticles, small molecules, etc.) and is applicable to nearly any charged surface, such as textiles [10,11]. In LbL deposition, the charged fabric is immersed into oppositely charged polyelectrolyte solutions to deposit a layered nanocoating in the form of layers [12]. ...
Environmentally benign layer-by-layer (LbL) deposition was used to obtain flame-retardant and antimicrobial cotton. Cotton was coated with 8, 10, and 12 phytic acid (PA) and chitosan (CH)-urea bilayers (BL) and then immersed into copper (II) sulfate (CuSO4) solution. Our findings were that 12 BL of PA/CH-urea + Cu2+ were able to stop flame on cotton during vertical flammability testing (VFT) with a limiting oxygen index (LOI) value of 26%. Microscale combustion calorimeter (MCC) data showed a reduction of peak heat release rates (pHRR) of more than 61%, while the reduction of total heat release (THR) was more than 54%, relative to untreated cotton. TG-IR analysis of 12 BL-treated cotton showed the release of water, methane, carbon dioxide, carbon monoxide, and aldehydes, while by adding Cu2+ ions, the treated cotton produces a lower amount of methane. Treated cotton also showed no levoglucosan. The intumescent behavior of the treatment was indicated by the bubbled structure of the post-burn char. Antibacterial testing showed a 100% reduction of Klebsiella pneumoniae and Staphylococcus aureus. In this study, cotton was successfully functionalized with a multifunctional ecologically benign flame-retardant and antibacterial nanocoating, by means of LbL deposition.
... On the other hand, Polyamide is a semi-crystalline thermoplastic biodegradable polymer that is used for several engineering applications. With all these interpretations, its heat distortion temperature is low, and it is water absorber for the presence of amide functional groups in its molecular chain, which exacerbates its mechanical properties, tribological properties and dimensional stability severely [10,11]. So as to achieve to inhibit these shortages, chitosan nanoparticles, as a very well-known biocompatible and biodegradable material, has been blended with polyamide to obtain a polymer composite with distinguished properties [12,13]. ...
The principal intention of this work is to fabricate and characterize the polyamide/chitosan nanocomposite by a novel single solvent method through the electrospinning procedure. The thermal properties and morphology of prepared nanocomposite are studied by thermogravimetric analysis (TGA) and field-emission scanning electron microscopy (FE-SEM). TGA exposed that the primary decomposition temperature is reduced with rising of chitosan content in the nanocomposites and origin disintegration temperature for polyamide/chitosan nanocomposites is perceived to be in the range from 300 to 500°C. Also, FE-SEM images demonstrated that the nanofibers of chitosan have good adhesion on the matrix and are well-oriented. Besides, the crystallinity and structural characteristics of the polyamide/chitosan nanocomposites are investigated by using X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR), respectively. The results of XRD proved that the successful blending of chitosan in polyamide is achieved via the electrospinning method. FT-IR results demonstrate that the nanofibers are consist of amine groups. Also, the electrical properties of the nanocomposite improved with the increasing content of chitosan and the conductivity of the polyamide/chitosan 5 wt% demonstrates the maximum current of 0.3 nA. Besides, the sheet resistance of the composite reduced 118 to 20 × 10 ⁹ Ω with raising the chitosan volume from 0 to 5 wt%.
Environmentally benign pH-indicating wound dressing comprised of carbohydrates chitosan (CH) and pectin (P), and anthocyanin grape (AG) dye is created via layer-by-layer assembly. Cotton fabric coated with eight bilayers of (CH-AG)4/(P-AG)4 deposited 1.97 % AG-dye. It exhibited a visible and immediate color change from pink to violet-blue while increasing its pH value from 6 to pH 7, matching the turning pH point of healing into an infected wound. Color transition of AG-dye in water-based buffers, tested by VIS-spectroscopy, shows the same color change when the pH value increased from 6 to 7. This coating imparts excellent antimicrobial activity against Gram-positive bacteria Staphylococcus aureus and yeast Candida albicans, moderate antibacterial activity against Gram-negative Escherichia coli bacteria, and no cytotoxicity on human fibroblast cells (MRC-5). This research proposes a sustainable, low-cost, and simple method for obtaining smart wound dressing that provides real-time monitoring of the wound pH.
Phytic acid (PA)-coated zinc oxide (ZnO) nanoparticles were developed to produce high-efficiency flame-retarding (FR) additives for coating formulations. These hybrid (organic/inorganic) additives were fabricated using a layer-by-layer (LBL) approach to harness the FR properties of PA and ZnO on a single-platform nanoscale scaffold. These nanoparticles can be uniformly dispersed in a polyurethane (PU) coating for applications on metal substrates. The incorporation of the PA/ZnO layer-by-layer nanoparticles at 20 wt% of the polymeric resin did not adversely affect the physico-mechanical properties of the coatings. Flame-retardant properties of PU samples containing nanomaterials, showed a 50% reduction in flame spread rate than that observed from the samples prepared with only ZnO nanoparticles. Cone calorimeter studies performed on the metal panels coated with 20 wt% PA/ZnO nanoparticles-infused PU resins showed a 25% reduction in peak heat release rate and a 50% reduction in total heat release (THR) compared to control coatings prepared without nanoparticles. Scanning electron microscopy images revealed the presence of bubble-like morphologies in the burnt samples containing the nanoparticles, indicating char formation and obstruction of escaping gases produced during the burning of the coating materials. This study clearly reveals that the coatings prepared with PA/ZnO hybrid nanoparticles can protect metal substrates against fire-related damage.
An environmentally benign nanocoating for flame retardant cotton was developed by pairing positively charged egg white proteins (EWP) and a negatively charged mixture of magnesium lignosulfonate (LS)–diammonium phosphate (DAP) solution. Egg white proteins are cheap and easy to prepare nitrogen-containing polyelectrolyte with strong char ability. Five bilayers of 0.5 % EWP3/(1 % LS–10 % DAP)4 add 6.8 % weight gain and impart selfextinguishing behavior to cotton on a vertical and horizontal flame test. This nanocoating, which creates a conformal cover of cotton fibers, reduces peak heat release by 60.1 %, total heat release by 59.3 %, and fire growth capacity up to 81.5 %. The results of this investigation show the potential of EWP to be used as a charforming material with high nitrogen content in intumescent systems.
