Phosphorus/Nitrogen/Silicon-Containing Polyelectrolyte Complexes For Flame-Retardant Surface Treatments Of Polyester/Cotton Blended Fabrics

Polyester/cotton(T/C)blended fabrics are applied widely due to the outstanding performance.However,T/C blended fabrics are extremely flammable because of the special“scaffolding effect”of polyester and cotton components which cause rapidly burning rate,copious amounts of smoke and exhibit a serious fire hazard.Thus,flame-retardant T/C blended fabrics should be developed in the fields where the defined fire-safety standards are required.Flame-retardant surface treatments are the feasible ways to endow the high specific surface area materials with satisfactory fire safety and comprehensive performance.Recent years,great efforts have been made to reduce the flammability and smoke toxicity of T/C blended fabrics through building efficient flame-retardant coatings by layer by layer self-assembly and sol-gel technologies.However,the insufficiently flame-retardant efficiency is still a problem,and further developing design ideas of flame-retardant surface coatings is a feasible way to obtain high-efficiency flame-retardant fabrics.It has been found that intumescent flame-retardant coatings are relatively efficient for T/C blended fabrics.Accordingly,in this work,several phosphorus/nitrogen/silicon-containing polyelectrolyte flame-retardant coatings were constructed through different surface technologies;also,the interaction among polyelectrolyte components and flame-retardant mechanism of the coatings were studied.Consequently,some efficient systems for flame-retardant T/C blended fabrics and high-performance flame-retardant textiles are developed.1.By using layer-by-layer self-assembly(Lb L)technology,ammonium polyphosphate(APP)and?-paperazinylproplymethyldimethoxy silane(GP-108)were deposited on the surface of the fabrics via the ion exchange reaction between NH₄⁺and-NH₂ groups.In the system,APP and GP-108 were used as anionic and cationic components,respectively.Scanning electronic microscope equipped with energy dispersive X-ray spectrometer(SEM-EDX)and X-ray photoelectron spectroscopy(XPS)were applied to analyze the morphologies and constituents of the nano-coatings.Limiting oxygen index(LOI),vertical flame test(VFT),and cone calorimetry test(CCT)were carried out to study flame retardancy and combustion behaviors of the samples.It was found that with 15 bilayer Lb L coatings(15.5%weight increased),the fabric achieved self-extinguishing in VFT and exhibited an LOI about 23%;besides,during CCT,the time to ignition(TTI)was delayed,and peak heat release rate(PHRR)and total heat release(THR)decreased by 37%and 22%,respectively.The change of gas volatiles during combustion was detected by thermogravimetric analysis/infrared spectrometry(TG-IR),and the micro-morphology of VFT residues was analyzed by SEM-EDX.Phabrometer style test was employed to evaluate the influence of coatings on the handle style of T/C blended fabrics.2.To develop a one-step method for efficient intumescent coating,a kind of sol-gel system was further adopted in this work,in which diethylenetriamine penta-(methylenephosphonic)acid(DTPMP),melamine(MEL)and 3-aminopropyl triethoxysilane(APTES)were used as dopants and precursors.Hybrid colloidal silica was obtained through facile acid-base reactions among DTPMP,MEL,and APTES,and then was coated on the surface of T/C blended fabrics by the sol-gel technology.SEM-EDX,XPS,TG,LOI,horizontal flame test(HFT),VFT,CCT and Phabrometer style test were used to analyze the surface characterization,flame retardancy,combustion behaviors and handle style of T/C blended fabrics.With 8.2%weight increased,the coated T/C blended fabrics achieved self-extinguishing in HFT;besides,with 15.3%weight increased,the LOI of coated T/C blended fabrics increased to 26%and the sample achieved self-extinguishing in VFT.In addition,their TTI also increased,while the PHRR and THR decreased by 46%and 26%,respectively.The change of gas volatiles during combustion was detected by TG-IR,and the micro-morphology of VFT residues was observed by SEM-EDX.3.To obtain a durable flame-retardant coating,a chitosan(CH)/montmorillonite(MMT)polyelectrolyte complex coating was developed via ion exchange reaction between protonated CH and MMT.Acetic acid(AC)/CH/MMT(ACM)and phosphorous acid(PA)/CH/MMT(PCM)coatings were constructed in this work by using AC-and PA-protonated CH.PA was introduced into the organic-inorganic hybrid coating to achieve a phosphorus/nitrogen/silicon-containing flame-retardant polyelectrolyte coating.The polyelectrolyte complex coatings were coated on surface of T/C blended fabrics by the doctor-blading technique.SEM-EDX,ATR-FTIR,TG,LOI,VFT,CCT and Phabrometer style test were used to analyze the surface characterization,flame retardancy,combustion behaviors and handle style of T/C blended fabrics.It was found that with 13.1%weight increased,the LOI of PCM sample increased to 65%and it achieved self-extinguishing in VFT,while ACM sample exhibited unsatisfactory flame retardancy.In addition,the PHRR,THR and TSP of PCM sample respectively decreased by 46%,66%and 59%,suggesting excellent inhibition effect of smoke and heat release.TG-IR and SEM-EDX were used to study the change of gas volatiles and the micro-morphology of VFT residues,respectively.The wash durability of PCM sample was evaluated according to AATCC Test Method 61-2003 1A standard.Interestingly,the LOI of the sample after 50 home launderings reached43.5%,indicating excellent wash durability of the PCM coated fabrics.