The anti-dripping intumescent flame retardant finishing for nylon-6,6 fabric

Nylon-6,6 fabric has been widely used in military and civilian area for many years. However, the melting drip problem has not been effectively solved despite the efforts made in the last two decades. An intumescent flame retardant system, containing ammonium polyphosphate, melamine and pentaerythritol, has been proved to be effective on preventing melting drip during burning of nylon-6,6 fabric in this study. The LOI and the vertical flammability test indicate that this IFR (intumescent flame retardant) system could improve the flame retardancy and impart dripping resistance to nylon-6,6 fabric. Thermal behaviour of nylon-6,6 fabric treated with IFR system was investigated by thermogravimetric (TG) and differential scanning calorimetric(DSC) experiments. The results indicate that char residue of treated samples are above 13%, and the highest value could reach up to 24% at 750 °C which is much higher than that of the untreated fabric. SEM graphs of residue of treated and untreated nylon-6,6 fabric show that IFR could promote formation of residual char which impart anti-dripping property to nylon-6,6 fabric. The tensile property test shows that tensile strength of treated fabric decreased.     

Electrospinning of nylon-6,6 solutions into nanofibers: Rheology and morphology relationships

The relationship between the rheological properties of nylon-6,6 solutions and the morphology of their electrospun nanofibers was established. The viscosity of nylon-6,6 in formic acid(90%) was measured in the concentration range of 5 wt%-25 wt% using a programmable viscometer. Electrospinning of nylon-6,6 solutions was carried out under controlled parameters. The chemical structure, morphology and thermal properties of the obtained nanofibers were investigated using Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM) and differential scanning calorimetry(DSC), respectively. Entanglement concentration(ce) was found to be 15 wt% and a power law relationship between specific viscosity and solution concentration was observed with exponents of 2.0 and 3.3 for semi-dilute unentangled(c ce) and semi-dilute entangled(c ce) regimes, respectively. The diameter and uniformity of the nanofibers were found to be dependent on the viscosity. Moreover, the average diameter of electrospun nanofibers was found to be dependent on zero shear rate viscosity and normalized concentration(c/ce) in a power law relationship with exponents of 0.298 and 0.816, respectively. For nylon-6,6 solutions, the entanglement concentration(ce = 15 wt%) provides the threshold viscosity required for the formation of a stable polymeric jet during electrospinning and producing uniform beadless fibers. For concentrations less than ce, beaded fibers with some irregularities are formed. DSC analysis showed an increase in crystallinity of all electrospun samples compared to original polymer. Furthermore, Based on FTIR spectroscopy, α phase is dominant in electrospun nanofibers and minor amount of β and γ phases is also available.     

Flame retardancy mechanisms of aluminium phosphinate in combination with melamine polyphosphate and zinc borate in glass-fibre reinforced polyamide 6,6

The fire retardancy mechanisms of aluminium diethylphosphinate in combination with melamine polyphosphate and zinc borate was analysed in glass-fibre reinforced polyamide 6,6. The influence of phosphorus compounds on the polyamide decomposition pathways was characterized using thermal analysis (TG), evolved gas analysis (TG-FTIR), and FTIR-ATR analysis of the residue. The Lewis acid-base interactions between the flame retardants, the amide unit, and the metal ions control the decomposition. The flammability (LOI, UL 94) and performance under forced-flaming conditions (cone calorimeter using different irradiations) were investigated. Fire residues were analysed with FTIR-ATR, SEM-EDX, and NMR. Aluminium phosphinate in polyamide 6,6 acts mainly by flame inhibition. Melamine polyphosphate shows some fuel dilution and a significant barrier effect. Using a combination of aluminium phosphinate and melamine polyphosphate results in some charring and a dominant barrier effect. These effects are improved in the presence of zinc borate due to the formation of boron-aluminium phosphates instead of aluminium phosphates.     

Improving the flame retardancy of PET fabric by photo-induced grafting

Photo-induced surface grafting with glycidyl methacrylate (GMA) as monomer in association with a pad-curing treatment by using a flame retardant (FR) solution which contains 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP) and sulfamic acid (H₂NSO₃H) has been used to improve the fire performance of PET fabric in this study. The effects of initiator concentration, monomer concentration and the irradiation time on the grafting percentage were investigated. The chemical structure of grafted surface of the PET fabric was characterized by an attenuated total reflection-infrared (ATR-IR) spectroscopy. The fire performance was evaluated by the LOI and the vertical flammability tests, and the results indicate that the photo grafting treatment could improve the flame retardancy and dripping resistance of PET fabric. Thermal behaviour of treated PET fabric samples was investigated by thermogravimetric (TG) and differential scanning calorimetric (DSC). The morphology of the sample char residue was also investigated by scanning electron microscope (SEM).     

Thermal degradation and fire behaviour of unsaturated polyesters filled with metallic oxides

Nano-alumina and submicron alumina trihydrate particles were incorporated into an unsaturated polyester resin at various loadings. The morphologies of composites showed that only nano-alumina was correctly dispersed. The thermal degradation behaviour of the composites was studied using thermogravimetric analysis and Py-GC/MS, while their fire behaviour was investigated using cone calorimeter and pyrolysis combustion flow microcalorimeter. Synergistic effects on thermal stability and heat release rate were observed for combinations between both submicron filler and nanofiller. The best result for fire behaviour was obtained for a global loading of 10wt% with an equal mass ratio for both kind of particles. Mass loss curves also showed increased char yield. The interest of combining particles with different sizes has been discussed as well as the role of water release, regarding activations energies of degradation processes.     

Thermal and combustion behavior of polyethersulfone-boehmite nanocomposites

In this paper, we report a thorough study on the thermal stability and fire behavior of polyethersulfone (PES) filled with 2 wt% nano-sized aluminum oxide hydroxide particles (boehmite). The nanocomposite was prepared through melt compounding technique in a co-rotating twin screw extruder. The obtained morphology of the composite was studied by scanning electron microscopy (SEM) coupled with elemental analysis, proving that an even distribution of sub-micron boehmite particles was obtained. PES shear modulus, measured by DMA, is increased by 30% in the boehmite nanocomposite. Thermal stability of the produced materials was studied through thermal gravimetric analysis (TGA), whereas the combustion behavior through cone calorimeter and vertical burning (UL-94) tests. Cone calorimeter results show that a significant overall flame retardant effect was observed due to the presence of boehmite nanoparticles, which could not be detected by UL-94 fire scenario where neat PES is already top ranked V0.     

Thermal degradation and flame retardancy of polynorbornene by a zeolite

The relation between the thermal decomposition and flammability of polynorbornene (PNB) synthesized by addition polymerization was analyzed. In a small-sized vertical combustion test, the PNB did not combust or drip, and the first ignition was extinguished in the combustion test with a cone calorimeter. The decomposition products of PNB were of some low molecular weight compounds with random scissions on the norbornene structure, and alkene (with 12 carbons in the PNB used in this study) was selectively generated by retro-Diels-Alder reaction. When the zeolite was added, the decomposition was accelerated and low molecular weight products increased, especially H₂O. These results suggested that the flammability of the thermal decomposition gas was caused by the zeolite, which changed the composition of decomposition products. The lower flammability limits calculated in Le Chatelier's equation were increased from 0.9 to 1.3 by the zeolite. The flame retardancy of PNB was observed because the amount of H₂O as an inert gas and the lower flammability limit was increased.     

Synthesis, characterization and ion-exchange properties of a new and novel ‘organic-inorganic’ hybrid cation-exchanger: Nylon-6,6, Zr(IV) phosphate

Organic-inorganic hybrid materials enable the integration of useful organic and inorganic characteristics within a single molecular-scale composite. Unique ion-exchange properties of these types of materials have been observed, and many others can be envisioned for this promising class of materials. In this paper, we describe the ion-exchange and physico-chemical properties of one family of self-assembling organic-inorganic hybrid based on nylon-6,6, framework with Zr(IV) phosphate an inorganic ion-exchanger. The physico-chemical properties of this hybrid material were determined using atomic absorption spectrophotometry (AAS), CHN elemental analysis, ICP-MS, UV-vis spectrophotometry, FTIR, TGA-DTA and scanning electron microscope (SEM) studies. Ion-exchange capacity (IEC), thermal stability and distribution behavior, etc. were also carried out to understand the cation-exchange behavior of the material. On the basis of distribution studies, the material was found to be highly selective for Hg(II), a highly toxic environmental pollutant. Its selectivity was examined by achieving some important binary separations like Hg(II)-Mg(II), Hg(II)-Zn(II), Hg(II)-Fe(III), Hg(II)-Bi(III), etc. Thus, the relatively new field of “organic-inorganic” hybrids offers a variety of exciting technological opportunities to decrease the environmental pollution.     

Thermogravimetric studies on Polyamide-6,6 modified by electron beam irradiation and by nanofillers

This paper reports the results of thermogravimetric studies on: (a) Polyamide-6,6 (abbreviated henceforth as PA66) specimens which were modified by electron beam radiation in air, (b) organic-inorganic hybrid nanocomposite films of PA66/silica prepared by the sol-gel technique and (c) unmodified multi-walled carbon nanotube (abbreviated henceforth as MWCNT) reinforced PA66 films. The activation energies were determined using the Kissinger and the Flynn-Wall-Ozawa methods, which do not require knowledge of the reaction mechanism. The results showed that PA66 specimens which received an irradiation dose of 200 kGy in air had a higher thermal stability than both the neat PA66 and PA66 specimens which received a radiation dose of 500 kGy in air. The PA66/silica hybrid nanocomposites up to a silica loading of 1.5 wt% also showed higher thermal stability over neat PA66 films. At MWCNT loadings of 0.5-1.0 wt% the composite films exhibited higher activation energies than the neat PA66 film but at higher MWCNT loading the activation energy was lower than that obtained for the neat PA66 film.     

Thermal and flammability properties of polyethersulfone/halloysite nanocomposites prepared by melt compounding

This paper presents a study of polyethersulfone (PES)/halloysite nanotube (HNTs) nanocomposites prepared by melt compounding either through a simple extrusion process or via a water-assisted extrusion procedure. Scanning and transmission electron microscopy techniques are combined with rheological measurements to assess the influence of polymer end groups (–Cl or –OH) and water injection on the HNTs dispersion state. A morphological transition form microcomposite to nanocomposite is achieved when replacing –Cl chain ends of PES by –OH groups, especially when water is injected during processing. By a combination of Soxhlet extraction and thermogravimetric analysis, we show that some PES(OH) chains are covalently bonded onto the aluminosilicate surface during extrusion. A mechanism describing the physico-chemical action of water is presented. The best system in terms of clay dispersion has been retained to characterize PES-HNTs nanocomposites with respect to their thermo-mechanical, thermal and fire (mass loss calorimetry and UL-94) properties. Dynamic mechanical analysis shows a significant enhancement in the storage modulus of halloysite-based nanocomposites when compared to the unfilled matrix. The improved thermal and thermo-oxidative stability of PES in presence of HNTs is mainly attributed to the labyrinth effect provided by individually dispersed nanotubes, which is reinforced during the decomposition process by the formation of a protective charred ceramic surface layer. The mechanism of action of HNTs for fire retardancy of PES presumably arises from a synergistic effect between physical (i.e. ceramic-like structure formation and mechanical reinforcement of the intumescent char) and chemical (i.e. charring promotion) processes taking place in the condensed phase. According to this study, the straightforward and cost-effective melt compounding route could pave the way for future development of high-performance nanoscale polymeric materials combining enhanced thermal properties and excellent flame retardant behaviour.     

含磷全芳族热致液晶共聚酯的合成及热性能

全芳族热致液晶聚酯因其优良的力学性能、热稳定性及较低的熔融粘度而倍受关注 ,是当今最有前途的特种高分子材料之一 .但是 ,全芳族聚酯的刚性结构使其熔点较高 ,难以加工 ,因而通过分子设计制备熔点较低的热致全芳香族聚酯液晶成为研究的热点 .在主链型热致液晶高分子的分子设计中 ,通常采用共聚或在高分子链中引入取代基、柔性链段、扭结成分等方法来达到降低聚合物相转变温度的目的[1～ 6 ] .本文以对羟基苯甲酸、对苯二甲酸、间苯二甲酸和含磷二元酚化合物为单体 ,合成了一类具有较低熔点或流动温度的新型全芳族热致共聚酯液晶 ,其分子…     

固相萃取-超高效液相色谱法测定卷烟主流烟气中丙烯酰胺

建立了一种固相萃取-超高效液相色谱法(SPE-UPLC)快速检测主流烟气中丙烯酰胺的方法。使用剑桥滤片和吸收瓶捕集主流烟气后,蒸馏水做萃取溶剂,采用C18固相萃取小柱对样品液进行纯化,用UPLC检测,外标法定量。UPLC方法采用ACQUITY UPLCTMBEH C181.7μm 2.1×50 mm色谱柱,柱温30℃,流动相为V(乙腈)∶V(水)=6∶94,流速为0.15 mL/min,紫外检测器(TUV)检测波长为202 nm,分析时间为6 min。烤烟型香烟主流烟气中丙烯酰胺的含量为4.75μg/cig。方法的线性范围为0.1~10 mg/mL,线性相关系数为0.9999;平均回收率为98.7%;检出限为10 ng/mL(S/N=3);相对标准偏差为2.3%。该方法适合主流烟气中丙烯酰胺的快速检测。     

Thermal Properties Improvement of Bismaleimide Resin by a New Phosphorus‐containing Polycyclic Bismaleimide

A new phosphorus‐containing polycyclic bismaleimide resin (BMPI) was prepared by the reaction of bis(3‐maleimidophenyl) methylphosphine oxide (BAMP) with benzene‐1,2,4,5‐tetracarboxylic dianhydride (BTD) and maleic anhydride (MA). BMPI was confirmed by infrared (IR), ¹H‐ and ¹³C‐NMR spectroscopies. Its thermal properties were carried out by a differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) that revealed that the polymers have excellent thermal properties in the high temperature region and a high char yield of up to 53～65%. Furthermore, three conventional bismaleimide resins were prepared from different phosphorus‐free bismaleimides for comparison, e.g. 4,4′‐bismaleimidodiphenylmethane (BDM), 4,4′‐bismaleimidodiphenylether (BDE), 4,4′‐bismaleimidodiphenylsulfone (BDS).     

Unsaturated polyester resins modified with phosphorus-containing groups: Effects on thermal properties and flammability

A novel reactive phosphorus-containing monomer [1-oxo-2,6,7-trioxa-1- phosphabicyclo-[2.2.2]octane-methyl diallyl phosphate, PDAP] was synthesized, and various amounts of PDAP were combined with unsaturated polyester by radical bulk polymerization. The resulting flame-retardant unsaturated polyester resin (FR-UPR) samples were investigated by thermogravimetric analysis (TGA), microscale combustion calorimetry (MCC), and limiting oxygen index (LOI) tests. Due to the relatively high phosphorus content of PDAP (18.2 wt%), incorporation of this monomer into unsaturated polyester resin (UPR) led to a marked decrease in the heat release capacity (HRC), the total heat release (THR), an increase in the LOI and the char yield upon combustion. In order to elaborate the interactions between the UPR and PDAP in degradation, differences between the experimental and theoretical mass losses of a FR-UPR sample were evaluated. Furthermore, thermogravimetry-Fourier transform infrared (TG-FTIR) and real-time Fourier transform infrared (RTIR) spectroscopy were employed to investigate the degradation behavior of UPRs, providing insight into the degradation mechanism.     

Flame retardancy and flame retarding mechanism of high performance hyperbranched polysiloxane modified bismaleimide/cyanate ester resin

A novel kind of modified bismaleimide/cyanate ester (BCE) resins by copolymerizing with hyperbranched polysiloxane including high content of phenyl (HBPSi) was first reported. The effect of HBPSi on the curing mechanism, and that on the dielectric properties and flame retardancy of cured networks were systemically investigated. Results show that compared with BCE resin, HBPSi/BCE resin has obviously different cross-linked structure, and thus leading to simultaneously improved dielectric properties and flame retardancy. The reactions between HBPSi and the decomposition structure of BCE resin change the thermo-oxidative degradation mechanism of the first step in the thermo-oxidative degradation; in addition, the presence of HBPSi in BCE resin also significantly reduces the mass loss rate (MLR) and increases char yield at 800 °C under an air atmosphere. Therefore, the positive effect of HBPSi on improving the flame retardancy is attributed to the condensed phase mechanism. On the other hand, HBPSi/BCE resins exhibit improved dielectric properties (including decreased dielectric constant and loss) with increasing the content of HBPSi. More importantly, this investigation demonstrates that designing new polysiloxane with suitable chemical structure is important to develop high performance resins with attractive flame retardancy and dielectric properties.     

表面化学接枝改性阻燃棉织物的制备与性能

采用高碘酸钠对棉织物表面进行选择性氧化生成醛基,选取乙二胺与醛基反应,通过膦氢化加成反应将阻燃剂亚磷酸二甲酯接枝到棉织物表面,最后通过三羟甲基三聚氰胺对棉织物表面进行接枝改性,制备了含三羟甲基三聚氰胺/乙二胺/亚磷酸二甲酯阻燃棉织物.通过傅里叶红外光谱（FTIR）对改性后棉织物的结构进行了表征,通过极限氧指数（LOI）测试研究了其阻燃性能,通过锥形量热测试研究了其燃烧行为,通过在40℃皂水中洗涤10次考察了其耐水性能,通过扫描电子显微镜测试了其表面及燃烧后炭层的形貌.研究结果表明,经表面改性后,棉织物的LOI值由（19.5±1.0）%提高到了（43.1±1.0）%,经耐水洗测试后,LOI值仅下降至（42.6±1.0）%,保持了非常好的阻燃性能,表明通过表面接枝方法制备的三羟甲基三聚氰胺/乙二胺/亚磷酸二甲酯阻燃棉织物具有非常好的耐水洗性能.表面阻燃改性提高了棉织物在燃烧过程中的成炭性能,形成的连续膨胀的炭层较好地保护了内部织物,抑制了织物的降解和燃烧,从而提高了棉织物的阻燃性能.     

Surface treatment of lignocellulose biofiller for fabrication of sustainable polylactic acid biocomposite with high crystallinity and improved burning antidripping performance

In this work, we incorporated surface-treated coffee husks (CHs) into a polylactic acid matrix to fabricate environmentally friendly composites, with high crystallinity and satisfactory antidripping performance for flame retardancy. CHs are lignocelluloses that contain cellulose, hemicellulose, and lignin that are present as interlinked complex macromolecular structure. CH spectroscopic characterization confirmed that the phytic acid/amine silane agent was successfully attached and bonded with the cellulose portion of CHs. Morphological analysis of the composites revealed that the surface-treated CHs helped to improve the interfacial interaction between the filler and the matrix. Furthermore, the differential scanning calorimetry analysis showed that the crystallinity of the composites increased with CH loading. Flammability and combustion tests confirmed that the combined effect of P/Si/N on surface treatment improved the flame retardance behavior of the composites. The tensile strength and modulus of the composites exhibited a 28.7% and 34.4% increase compared with the corresponding composite with raw CHs.     

高效液相色谱法测定方便面中丙烯酰胺

建立了一种检测方便面中丙烯酰胺的液相色谱方法。萃取剂选择1g/L的蚁酸溶液,将萃取液以12000r/min,2℃离心18min,上清液再以14500r/min,0℃离心18min,可分离基质中淀粉、蛋白质、脂肪等干扰物;方法采用ZORBAX SB-C18(250mm×4.6mm,5μm)色谱柱,流动相为A(乙腈∶水=1∶24(V/V))和B(乙腈),流速0.5mL/min,在丙烯酰胺的最大吸收197nm处检测,提高了方法的检出限及回收率。该方法有良好的线性关系(r=1.00000),检出限为48.0μg/kg。回收率94.4%～109.8%,相对标准偏差为4.9%～5.6%。     

Effect of hybrid phosphorus-doped silica thin films produced by sol-gel method on the thermal behavior of cotton fabrics

The aim of this work was to prepare hybrid organic-inorganic silica thin films to provide cotton fabrics with flame retardant properties and to investigate the films’ influence on the thermal and burning behavior of the treated samples. The fabrics were modified with three different sols in order to study the effect of pure silica sol-gel precursor, γ-aminopropyltriethoxysilane (APTES), and that of the hybrid sols consisting of the APTES and the phosphorus compound diethylphosphite. Furthermore, in order to improve the cross-linking degree and the phosphorus-nitrogen synergistic effect on flame retardancy of the P-doped silica thin film the melamine-based resin was added in the third sol. To evaluate the chemical structure of the coating material, pure xerogels of the treatment solutions were applied to glass slides and tested by ATR FT-IR spectroscopy. The cotton fabrics were impregnated with the sols by a padding-squeezing process and then dried. Thermal behavior of the treated cotton samples was investigated by thermogravimetric/differential scanning calorimetry analysis (TGA-DTG/DSC) and compared to the untreated one. The flame retardancy was tested according to the ASTM D 1230 standard method. The results showed a substantial enhancement of char-forming properties and flame retardancy for the fabrics modified with the thin films.     

Influence of surface activation by plasma and nanoparticle adsorption on the morphology, thermal stability and combustion behavior of PET fabrics

Plasma surface activation at different process parameters (namely, power and etching time) has been combined with nanoparticle adsorption (i.e., a natural montmorillonite) in order to improve the thermal stability and flame retardancy of PET fabrics. Scanning electron microscopy coupled to elemental analysis has put in evidence a direct relationship between the distribution of nanoparticles on fibers and process parameters. The presence of the above nanoparticles affects the thermal stability of fabrics in air, as assessed by thermogravimetric analysis: a delay of the mass loss process has been observed for the treated samples.Combustion behavior has been investigated by cone calorimetry: plasma activated fabrics have shown a remarkable improvement in terms of time to ignition (up to 104%) and a slight reduction of the heat release rate (ca. 10%) as compared to neat PET.