Application of poly(diphenolic acid‐phenyl phosphate)‐based layer by layer nanocoating in flame retardant ramie fabrics

Poly(diphenolic acid‐phenyl phosphate) [poly(DPA‐PDCP)], obtained from diphenolic acid (a well‐known biomass chemical), was used together with polyethylenimine (PEI) to construct a flame retardant surface coating for ramie fabric using layer‐by‐layer self‐assembly. Attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) and scanning electron microscope (SEM) equipped with an energy dispersive X‐ray spectrometer (EDX) were used to confirm the successful formation of layer by layer assembly. Assessment of the thermal and flammability properties for poly(DPA‐PDCP)/PEI‐coated ramie fabrics showed that the thermal stability, flame retardancy, and residual char were enhanced as the concentration of poly(DPA‐PDCP) and the BL number in the LbL process increased as well as the treatment of KH550 was applied. SEM and EDX analysis of the char residue confirmed further the intumescent flame retardant mechanism. This work demonstrated the great potentials of poly(DPA‐PDCP)/PEI flame retardant nanocoating constructed by LbL assembly method in the application of ramie fabric. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44795.     

Durable flame‐retardant and antidroplet finishing of polyester fabrics with flexible polysiloxane and phytic acid through layer‐by‐layer assembly and sol–gel process

A three‐layer functional coating was prepared through layer‐by‐layer (LbL) assembly and a sol–gel process. The multilayered coating was composed of a phytic acid (PA) coating dipped between two layers of flexible polysiloxane coatings and was deposited on the polyester fabric by LbL assembly. Flammability tests indicated that the multilayer coating prevented droplet generation during combustion. The PA also absorbed the reactive free radicals to reduce the flame‐burning rate. After being soaked for only 20 min in PA solution, the fabric exhibited self‐extinguishing properties and antidroplet effect during the vertical flame test, while cone calorimetry confirmed that the coated fabric exhibited a 65% decrease in the peak heat release rate and reduced the total amount of smoke released by 72%. After washing the coated fabric 45 times, there was no significant decrease in the phosphorus content and the limiting oxygen index of coated fabrics. Thus, the coating synthesized in this study is an effective method of constructing durable, functional coatings on the surface of fabrics. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46414.     

水性膨胀型防火涂料的研制

采用聚有机硅氧烷乳液、自交联丙烯酸酯乳液和水溶性三聚氰胺甲醛树脂作为成膜剂,配合P—C—N膨胀阻燃体系,以聚磷酸铵（APP）为脱水催化剂、双季戊四醇（DPER）为碳化剂、三聚氰胺（MEL）为发泡剂,制备了一种水性膨胀型防火涂料。介绍了水性膨胀型防火涂料的阻燃性能、机械性能等。     

Char Formation in Flame‐Retarded Fibre–Intumescent Combinations. Part V. Exploring Different Fibre/Intumescent Combinations

Previous research work in our laboratory has indicated that the efficiency of certain flame‐retardant fibres can be further enhanced if certain interactive intumescents are dispersed on their surfaces. In our previously reported work we have successfully observed interactions between certain commercially available flame‐retardant cellulosic and regenerated cellulose (viscose) fibres and two melamine and phosphoric acid‐based intumescent systems. In the present work we have explored the use of other intumescent systems—melamine cyanurate, melamine borate, melamine oxalate, melamine pyrophosphate and an inorganic silicate‐based intumescent, Cylatherm. Two non‐cellulosic fibres—the novoloid (Kynol) and melamine‐formaldehyde (Basofil) were also explored in combination with different intumescent systems. These systems were studied by thermal analytical techniques to observe any possible interaction between FR fibre and intumescent components. Of these intumescents, only melamine borate and melamine pyrophosphate showed interactions with flame retardant cellulosic fibres and both Kynol and Basofil indicated char interactive tendencies with some of the phosphorus‐containing intumescents. Copyright © 2002 John Wiley & Sons, Ltd.     

Microintumescent mechanism of flame‐retardant water‐based chitosan–ammonium polyphosphate multilayer nanocoating on cotton fabric

Layer‐by‐layer (LbL) assembly of nanocoatings on fabric substrates has been very successful in terms of reduction of flammability. In particular, an LbL system comprised ammonium polyphosphate as the polyanion and chitosan as the polycation, applied to cotton fabric, dramatically reduced cotton flammability. At this point, the fire‐retardant (FR) mechanism of action of this system has never been fully elucidated. Sonicated and nonsonicated coated cotton fabrics were evaluated using a vertical flame test and mass loss calorimeter. Coating morphology was investigated before and after burning. Thermal analyses and chemical analyses in the condensed phase (and in the gas phase) were conducted to reveal the FR mechanism of action. At the cotton surface, a combination of both condensed (formation of aromatic char) and gas phase (release of water and highly flammable gases) mechanisms impart the FR behavior, promoting a kind of “microintumescence” phenomenon. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43783.     

A facile one‐step synthesis of flame‐retardant coatings on cotton fabric via ultrasound irradiation

This article reports a facile one‐step methodology to increase fire resistance properties of cotton fabric. The flame‐retardant coating for cotton fabric was synthesized with methyltriethoxysilane and organophosphates (M102B) through an ultrasound irradiation process. The coating structure and surface morphology of uncoated and coated fabrics were investigated by Fourier transform infrared spectroscopy and scanning electron microscope, respectively. The flame‐retardant properties, bending modulus, air permeability and thermal stability were studied by vertical burning test, cantilever method, air permeability test and thermogravimetric analysis (TGA). As a result, the cotton fabric coated with 29.2% (mass increased) of flame‐retardant coating was able to balance the flame retardant property and wearing comfort of the fabrics. The TGA results showed that the residue char of cotton was greatly enhanced after treatment with the coating, which has a high char forming effect on cellulose during testing. Furthermore, flame‐retardant property of coated fabrics did not change significantly after 10 washing cycles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45114.     

Flame‐retardant finishing in cotton fabrics using zinc oxide co‐catalyst

In this article, N‐Methylol dimethylphosphonopropionamide (FR) in combination with a melamine resin (CL), phosphoric acid (PA) catalyst and zinc oxide (ZnO) or nano‐ZnO co‐catalyst were used (FR‐CL‐PA‐ZnO or nano‐ZnO system) to impart flame‐retardant property on cotton fabrics. FR‐CL or FR‐CL‐PA‐treated cotton specimen showed roughened and wrinkled fabric surface morphology, which was caused by the attack of the FR with slightly acidity. In addition, FTIR analysis showed some new characteristic peaks, carbonyl, CH₂ rocking and CH₃ asymmetric and CH₂ symmetric stretching bands, in the chemical structure of treated cotton specimens. Apart from these, the flame ignited on the flame‐retardant‐treated fabrics (without subjected to any post‐wet treatment) extinguished right after the removal of ignition source. However, FR‐CL treated specimens were no longer flame‐resistant when the specimens subjected to neutralization and/or home laundering, while FR‐CL‐PA treated specimens showed opposite results. By using 0.2% and 0.4% of ZnO or nano‐ZnO as co‐catalyst, the flame spread rate of neutralized and/or laundered test specimens decreased, even the specimens were undergone 10 home laundering cycles. Moreover, flame‐retardant‐treated cotton specimens had low breaking load and tearing strength resulting from side effects of the crosslinking agent used, while addition of ZnO or nano‐ZnO co‐catalyst could compensates for the reduction. Furthermore, the free formaldehyde content was dropped when ZnO and nano‐ZnO co‐catalyst was added in the treatment. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improving the flame retardant properties of polyester-cotton blend fabrics by introducing an intumescent coating via layer by layer assembly

Layer by layer (LBL) assembly technique was used to deposit multilayer coating containing phosphorus-nitrogen onto the surface of fibers to improve the flame retardancy of polyester-cotton (PET-COT) blended fabric. Ellipsometer results confirmed that polyallylamine hydrochloride (PAH), melamine (MEL), and ammonium polyphosphate (APP) grew linearly on silicon wafer during the LbL process. The LOI value of coated PET-COT fabric was increased from 20.8% of pristine fabric to 28.4% by the presence of about 9 wt% coating. Besides, this intumescent nanocoated PET-COT fabric was self-distinguished during the vertical burning test. Thermogravimetric analysis under both nitrogen and air atmosphere revealed that the initial degradation temperature of the coated sample was decreased and the char residue amount was significantly improved during combustion. The flame resistance performance evaluation by pyrolysis combustion flow calorimeter indicated that this coating effectively reduced the peak heat release rate of PET-COT matrix. The scanning electron micrographs of char residue demonstrated that the char formation in the condensed phase and free radical caption in the gas phase was responsible for the improved flame retardancy. It is suggested this unique facile coating technology with low cycles and high efficiency has great potential to produce commercially available flame retardant polymeric-cotton blend fabrics.     

Fabrication and properties of PEI/APP layer-by-layer coated ramie fabric combined with low-temperature plasma treatment

The present work demonstrates a surface pretreatment of reducing assembly layers for flame retardant modification of ramie fabric used by layer-by-layer (LbL) assembly. In order to achieve this goal, low-temperature plasma (LTP) pretreatment was chosen. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscope (SEM) were used to confirm the effect of LTP pretreatment on polyethylenimine/ammonium polyphosphate (PEI/APP) flame retardant coating constructed on the surface of ramie fabric using LbL assembly. The thermal property and flame retardancy of PEI/APP coated ramie fabrics were analyzed by TG, LOI, UL94 vertical burning, and cone calorimeter tests. The results indicated that the decomposition rate of ramie fabrics was reduced and the char forming ability at high temperature was improved by PEI/APP coating on the ramie surface. Its LOI increased markedly to 30.6% and ramie fabric achieved self-extinguishing effect. Meanwhile, LTP-O₂-(PEI/APP)₂₀ ramie fabric exhibited the low flammability and high fire safety. It was proved that LTP pretreatment under oxygen atmosphere could endow ramie fabric with better flame retardancy due to more PEI/APP adsorbed on its surface. These findings have significant implications for the application of LTP pretreatment to flame retardant modification of ramie fabric by LbL assembly.     

Effect of chicken‐feather protein‐based flame retardant on flame retarding performance of cotton fabric

A new kind of eco‐friendly chicken‐feather protein‐based phosphorus–nitrogen‐containing flame retardant was synthesized successfully with chicken‐feather protein, melamine, sodium pyrophosphate, and glyoxal. And its structure was characterized by Fourier transform infrared spectroscopy, and the thermogravimetry of the agent was analyzed. Then the flame retarding performances of the chicken‐feather protein‐based flame retardant and in combination with the borax and boric acid in application to a woven cotton fabric were investigated by the vertical flammability test and limited oxygen index test. In addition, the surface morphologies of the treated and untreated fabrics were conducted by the scanning electron micrographs (SEM), and the thermogravimetric analyses of the treated and untreated cotton were explored, and the surface morphologies of char areas of the treated and untreated fabrics after burnt were tested by the SEM. The results showed that the flame retardancy of the cotton fabric treated by the chicken‐feather protein‐based flame retardant in combination with borax and boric acid was improved further, and the combination of the chicken‐feather protein‐based flame retardant and borax and boric acid could facilitate to form a homogenous and compact intumescing char layer, and the combination of them plays a good synergistic effect in the improvement of the flame retardancy of the treated cotton fabric. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40584.     

A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry     

The flammability of expandable polystyrene foams coated with melamine modified urea formaldehyde resin

Urea formaldehyde resin (UF) was modified by introducing melamine during the condensation in order to reduce the amount of free formaldehyde and increase the solid content. The melamine modified UF (MUF) was firstly mixed with intumescent flame retardant (IFR) and then coated on the surface of pre‐expanded polystyrene (PS) particles to prepare flame retardant expandable PS (EPS) foams. The flammability of EPS foam samples was characterized by limiting oxygen index (LOI), UL‐94 vertical burning and cone calorimeter tests, and the results indicated that the peak heat release rate was significantly reduced from 406 to 49 kW/m² and LOI value could reach 36.3 with V‐0 rating in UL‐94 test after coated with IFR. The smoke density test indicated that the maximum smoke density was decreased by the addition of IFR. Thermal analysis suggested that the thermal stability and char formation were significantly improved by the presence of coated flame retardants. The residual char observation revealed that MUF and IFR were beneficial to form integrated char layers with hollow stents, which could be the main reason for the improvement of flame retardant properties. The mechanical properties of flame retardant EPS foams can still meet the standard requirements for industrial applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44423.     

Layer‐by‐layer assembly of halogen‐free polymeric materials on nylon/cotton blend for flame retardant applications

Thin films of environmentally safe, halogen free, anionic sodium phosphate and cationic polysiloxanes were deposited on a Nyco (1:1 nylon/cotton blend) fabric via layer‐by‐layer (LbL) assembly to reduce the inherent flammability of Nyco fabric. In the coating process, we used three different polysiloxane materials containing different amine groups including, 35–45% (trimethylammoniummethylphenythyl)‐methyl siloxane‐55‐65% dimethyl siloxane copolymer chloride salt (QMS‐435), aminoethylaminopropyl silsesquioxane‐methylsilsesquioxane copolymer oligomer (WSA‐7021) and aminopropyl silesquioxane oligomers (WSA‐991), as a positive polyelectrolyte. Thermo‐gravimetric analysis showed that coated fabric has char yield around 40% at 600 °C whereas control fabric was completely consumed. The vertical flame test (VFT) on the LbL‐coated Nyco fabric was passed with after flame time, 2 s, and the char length of 3.81 cm. Volatile and nontoxic degradation products of flame retardant‐coated fabric were analyzed by pyrolysis gas chromatography mass spectroscopy (Py‐GCMS). Surface morphology of coated fabrics and burned fabric residues were studied by scanning electron microscopy. Copyright © 2014 John Wiley & Sons, Ltd.     

植酸在聚合物材料阻燃应用领域的研究进展

植酸具有较高含量的阻燃元素磷,作为一种重要的有机磷系添加剂已被广泛地应用在食品、医药等领域,而作为阻燃剂的应用目前尚有较大的发展空间。按照织物阻燃、塑料阻燃、搭建绿色阻燃膨胀体系将植酸在聚合物材料阻燃应用上的研究成果分为3类,并对一些优秀科研成果的研究思路、内在原理、改性效果进行了简要介绍。最后,提出了未来在植酸阻燃应用发展方向的思考。     

Synthesis of amino trimethylene phosphonic acid melamine salt and its application in flame‐retarded polypropylene

Amino trimethylene phosphonic acid melamine salt (MATMP) was synthesized and used as acid source and blowing agent in intumescent flame‐retarded polypropylene (PP); its compositions were characterized by Fourier transform infrared spectroscopy and X‐ray powder diffraction. An intumescent flame retardant (IFR) system composed of MATMP, pentaerythritol (PER), and PP was tested by limiting oxygen index (LOI), UL‐94, cone calorimeter tests, and thermogravimetric analysis and compared with an ammonium polyphosphate (APP)/PER system. The results showed that MATMP had better water resistance than APP, the LOI value of PP/MATMP/PER composite can reach 30.3%, and a UL‐94 V‐0 rating can be reached at 25 wt % IFR loading. The amount of residual char of IFR MATMP/PER was 20.3 and 9.5 wt % at 400 and 600 °C, respectively. A thermooxidative degradation route and a possible flame‐retardant mechanism of IFR were proposed according to the analysis of evolved gases and residual chars. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46274.     

Development of a DOPO‐containing melamine epoxy hardeners and its thermal and flame‐retardant properties of cured products

In this study, a novel Schiff base of melamine used as flame‐retardant curing agent for epoxy resins, was synthesized via condensation reaction of 4‐hydroxybenzaldehyde with melamine, followed by the addition of 9,10‐dihydro‐9‐oxa‐10‐phosphaphen‐anthrene 10‐oxide (DOPO) to the resulting imine linkage. The structure of DOPO‐containing melamine Schiff base (P‐MSB) was characterized by Fourier transformed infrared spectroscopy, ¹H‐nuclear magnetic resonance (¹H‐NMR) and ³¹P‐NMR. The compound (P‐MSB) was used as a reactive flame retardant in o‐cresol formaldehyde novolac epoxy resin (CNE) to prepare flame‐retardant epoxy resins for electronic application. The thermal and flame‐retardant properties of the epoxy resins cured by various equivalent ratios phenol formaldehyde novolac (PN) and P‐MSB were investigated by the nonisothermal differential scanning calorimetry, the thermogravimetric analysis, and limiting oxygen index test. The obtained results showed that the cured epoxy resins possessed high T_g (165°C) and good thermal stability (T_5%, 321°C). Moreover, the P‐MSB/CNE systems exhibited higher limiting oxygen index (35) and more char was maintained in P‐MSB/CNE systems than that in PN/CNE system and the effective synergism of phosphorus–nitrogen indicated their excellent flame retardancy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

水性超薄膨胀型钢结构防火涂料的制备

以有机硅改性的丙烯酸酯乳液为基料,多聚磷酸铵(APP)、季戊四醇(PER)、三聚氰胺(MEL)为膨胀阻燃体系,制备水性超薄膨胀型钢结构防火涂料;采用硼酸和可膨胀石墨(EG)改性防火涂料。研究表明,同时用w(硼酸)=4%,w(EG)=5%改性防火涂料,涂层的耐火极限达到93 min,热失质量分析(TGA)测试表明w(硼酸)=4%,w(EG)=5%共同改性的防火涂料在700℃时最终残炭量是44%。扫描电镜(SEM)分析结果表明硼酸/EG改性的残炭层形成了致密的"蜂窝"状结构。     

Construction of multilayer coatings for flame retardancy of ramie fabric using layer‐by‐layer assembly

Complex multilayer coatings composed of α‐zirconium phosphate (ZrP), polyethylenimine (PEI), and ammonium polyphosphate (APP) were constructed via layer‐by‐layer assembly method for flame retardant ramie fabric. Bicomponent PEI/ZrP layers served as insulating barrier coating, and bicomponent PEI/APP layers served as intumescent coating. The flame retardancy of the coated ramie fabric was strongly dependent on the nature of the coatings and the layer‐by‐layer assembly patterns. The coated ramie fabric with inside PEI/ZrP layers and outside PEI/APP layers possessed the most uniform and consistent coating surface morphology, as well as the highest content of N and P elements, resulting in an excellent improvement in flame retardancy of ramie fabrics. When this kind of coated ramie fabric was heated, the inner PEI/ZrP layer effectively prevent oxygen and heat from penetrating into the substrate, and the outer PEI/APP layer exposed to air with good expansion during combustion. The synergistic effect was formed during the combustion process and could impart ramie fabrics with high flame retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45556.     

New developments in flame retardancy of glass‐reinforced epoxy composites

This work involves the development of novel glass fiber–reinforced composite materials containing a commercially available epoxy resin, a phosphate‐based intumescent, and inherently flame‐retardant cellulosic (Visil, Sateri) and phenol–formaldehyde (Kynol) fibers. The intumescent and flame‐retardant fiber components were added both as additives in pulverized form and fiber interdispersed with the intumescent as a fabric scrim for partial replacement of glass fiber. Thermal stability, char formation, and flammability properties of these novel structures were studied by thermal analysis, limiting oxygen index, and cone calorimetry. The results are discussed in terms of effect of individual additive component on thermal degradation/burning behavior of neat resin. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2511–2521, 2003