Brazilian clays as synergistic agents in an ethylenic polymer matrix containing an intumescent formulation

The effect of two different Brazilian montmorillonitic clays in intumescent ammonium polyphosphate and pentaerythritol formulations was evaluated. Ethylene and butyl acrylate copolymer was used as polymeric matrix. The clays were added both to the pure polymer and to the polymer containing intumescent mixture. The influence of these mineral fillers on flame retardancy was investigated by thermogravimeric analysis (TG). The results show that these inorganic additives have a synergist effect in the polymeric composite containing the intumescent formulation.     

Influence of clays on the flame retardancy and high temperature viscoelastic properties of polymeric intumescent formulations

A natural Brazilian montmorillonite clay was submitted to organophilization treatments to evaluate the effect of these treatments on the flame retardancy potential of polymer composites containing an intumescent ammonium polyphosphate and pentaerythritol formulation. An ethylene-butyl acrylate copolymer was used as the polymer matrix. Natural or organophilic clays were added both to the pure polymer and to the polymer containing the intumescent mixture. The influence of these mineral fillers, and of their organophilization treatments, on flame retardancy was investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 rating standard, heating microscopy, rheological measurements and cone calorimetry. The results show that these inorganic additives have a synergistic effect on composites containing the intumescent formulation.     

铁铝复合柱撑粘土的制备、柱结构和稳定性(I)

用两种方法合成了一系列不同Fe/Al比的铁铝复合柱撑牯土(FeAl-PlLC). 用~(27)Al-NMR、UV、ESR等手段考察了柱溶液的结构和状态, 用XRD、DTA、UV-DRS 等技术对其结构、稳定性进行了研究. 结果表明, 铁铝柱撑粘土的底面间距为1.98～1.55 nm, Fe/Al比对其柱结构、比表面积、热稳定性均有较大影响. Fe/Al<0.5时, 层间柱主要呈现Keggin结构, Fe/Al≥0.5时, 可能为三聚结构. 随Fc/Al比的增加, d(001)值, 比表面面、热稳定性逐渐下降.     

Stabilization of hydroxyl-group-terminated SERS-marker molecules on microAg particles by silanization

Surfactant modified montmorillonitic clays synthesized by ion exchange using the hydrothermal reaction method have been compared using XRD and thermal analysis. X-ray diffraction (XRD) shows the changes in the surface properties of organoclays through expansion with surfactant loading. A polynomial relationship exists between the basal spacing and the CEC loading described by the equation y=0.3232x(2) + 0.2052x+1.2834 with R(2)=0.9955. Different arrangements of the surfactant molecules in the organoclays are inferred from the changes in basal spacings. para-Nitrophenol also causes the expansion of the montmorillonite clay and affects the arrangements of the surfactant molecules within the clay layers. Changes in the surfactant molecular arrangements were analyzed by thermogravimetry. Additional thermal decomposition steps were observed when para-nitrophenol is adsorbed on the organoclay.     

Effects of Halloysite Nanotube Reinforcement in Expandable Graphite Based Intumescent Fire Retardant Coatings Developed Using Hybrid Epoxy Binder System

In this study, the effects of halloysite nanotubes (HNTs) reinforcement in expandable graphite based intumescent fire retardant coatings (IFRCs) developed using a polydimethylsiloxane(PDMS)/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients (ammonium polyphosphate/melamine/boric acid/expandable graphite, APP/MEL/BA/EG). The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy (FESEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared analysis (FTIR). The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH(3), due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis (TGA) of intumescent coating formulations. Reference formulation, SH(0) with no filler, degraded at 300 °C and lost 50% of its total mass but SH(3), due to synergistic effects between PDMS and HNTs, degraded above 400 °C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect of HNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.     

Adsorption of nitrobenzene andn-pentanol from aqueous solution on hydrophilic and hydrophobic clay minerals

The sorption of nitrobenzene andn-pentanol from dilute aqueous solution on swelling clay minerals and their organophilized derivatives (organo clays) was studied. Adsorption excess isotherms were obtained by the immersion method. The basal spacings of the clay minerals were determined by X-ray diffraction measurements. By combining these two independent methods, composition and structure of the interlamellar space could be calculated. On the hydrophilic surface of montmorillonite negative adsorption of the organic component was observed at low molar fractions of nitrobenzene or pentanol, i.e., water was preferentially adsorbed. On organophilized montmorillonite and vermiculite adsorption of nitrobenzene and pentanol was positive over the whole range of liquid composition. The amount of interlamellar alkyl chains which is determined by the surface charge of clay mineral inversely affected the adsorption of both solutes.     

Thermogravimetric analysis of organoclays intercalated with the gemini surfactants

Sodium montmorillonite has been modified via cation exchange reaction using gemini surfactants. Montmorillonite modified by cetyltrimethyl ammonium bromide (CTAB) is used for comparation. Basal spacings and thermal stability of these organo-montmorillonite clays have been characterized using X-ray diffraction analysis and thermogravimetric analysis. The d(001) spacings of montmorillonite-Gemini14, montmorillonite-Gemini16, montmorillonite-Gemini18 can reach above 35 Å compared with the 23.66 Å of the montmorillonite-CTAB at 2.2CEC. The thermogravimetric analysis show four-step degradation which corresponds to residual water desorption, dehydration, followed by decomposition of the organic modifier and the dehydroxylation of the organo-montmorillonite. In addition, DTG enables two different structural arrangements of gemini surfactant molecules intercalating the montmorillonite to be proposed that is different from montmorillonite-CTAB.     

Diffusion of polyphosphates into (poly(allylamine)-montmorillonite) multilayer films: flame retardant-intumescent films with improved oxygen barrier

The present paper relies on the original idea to design multifunctional coatings, and in particular highly efficient intumescent flame retardant coatings, based on the diffusion of polyphosphates (PSPs) in exponentially growing "layer-by-layer" films made from montmorillonite (MMT) and poly(allylamine) (PAH). Here, we used polyphosphates as an acid source, polyallylamine as both a carbon source and a swelling agent, and finally clays to reinforce the intumescent char strength and also for their oxygen barrier property. The coatings made from the alternated deposition of n = 60 layer pairs of PAH and MMT reach a considerable thickness of ～18 μm with well-defined ordering of the MMT in the direction parallel to the substrate. Structural, morphological, mechanical, gas barrier, and fire resistance properties of these films have been studied. Excellent oxygen barrier properties and extraordinary fire resistance properties are demonstrated based on the basis of a strong increase of the time to ignition and on a decrease of the heat release rate of polylactide substrates during mass loss calorimeter tests. This new and innovative intumescent flame retardant system based on (PAH-MMT)(n)-PSP coatings is a promising universal treatment for current polymeric materials.     

一种二价季铵盐在粘土矿物上的吸附

研究了一种不显著降低界面张力的二价季铵盐化合物(MD膜驱剂)在粘土矿物上的吸附. 选取蒙脱土(Su-M)和膨润土(B)两种粘土矿物作为研究对象，其阳离子交换容量(CEC)分别为0.44和0.88 mmol•g^-1. 研究结果表明，MD膜驱剂在低的加入浓度下，MD膜驱剂分子在两种粘土矿物上能全部被吸附，此外，其在Su-M上的饱和吸附量达到100% CECSu-M，而在B上仅为77%CECB. MD膜驱剂只能吸附在粘土矿物的负电荷点上，而不能吸附在单元层外表面的Si-OH中性点上. XRD数据显示，随MD膜驱剂添加浓度的增大，两种粘土矿物的干态层间距略有减小，并根据分子的理论空间尺寸，认为MD膜驱剂在粘土层间只能以单层平卧方式排列.     

Influence of chemical shell structure on the thermal properties of microcapsules containing a flame retardant agent

Microcapsules containing ammonium phosphate as the acid source for an intumescent system were prepared by various processes. The microcapsules have different morphologies, load content and various types of polymeric shell. The polymers for our microcapsule shell are polymers considered as carbon source for intumescent formulations. In this paper we discuss the influence of polymeric shell and phosphate content of the microcapsules on the capacity to produce a thermally stable residue at high temperature, one of the characteristics for an intumescent formulation.     

Thermoset Epoxy-Clay Nanocomposites: The Dual Role of α,ω-Diamines as Clay Surface Modifiers and Polymer Curing Agents

Diprotonated forms of polyoxypropylene diamines of the type α,ω-[NH₃CHCH₃CH₂(OCH₂CHCH₃)_xNH₃²⁺ with x=2.6, 5.6, and 33.1, have been intercalated into montmorillonite and fluorohectorite clays and subsequently evaluated for the formation of glassy epoxy-clay nanocomposites. The intercalated onium ions functioned concomitantly as a clay surface modifier, intragallery polymerization catalyst, and curing agent. Depending on the chain length of the diamine, different orientations of the propylene oxide chains were adopted in the clay galleries, resulting in basal spacings from ∼14 Å (lateral monolayer, x=2.6) to ∼45 Å (folded structure, x=33.1). The initial clay basal spacings were correlated with the formation of intercalated and exfoliated clay-epoxy nanocomposites with improved mechanical properties and high thermal stabilities. In comparison to clay-monoamine intercalates, the use of diamine intercalates greatly reduced the plasticizing effect of the alkyl chains on the polymer matrix, resulting in improved mechanical properties while at the same time reducing the cost and time needed for nanocomposite fabrication.     

部份层无序铝交联蒙脱土结构的研究

应用非完整晶体的XRD衍射及阳离子交换量的测定等实验数据, 得出了铝交联蒙脱土的三维结构模型. 结构中Al(III)多数以十三聚体形式进入层间, 层间距为1.97 nm, 几率为0.65, 少数以六聚体形式进入层间, 层间距为1.5 nm, 几率为0.25, 其余10%的层间仅为水分子. 并给出了交联柱子在层间的分布与层单元之间的连接方式. 目前通用的以Bragg公式计算所得的d_(001)值来表征交联浆脱土的层间距是不确切的.     

Montmorillonite-poly(ethylene oxide) nanocomposites: interlayer alkali metal behavior

Clay-PEO nanocomposites can have large electrical conductivities that make them potential electrolyte materials for rechargeable lithium batteries, but the origin of these large conductivities, especially for Li-containing materials, is poorly understood. This paper presents X-ray diffraction (XRD), TGA-DTA, and (7)Li and (23)Na NMR data for PEO nanocomposites made with natural (SWy-1) and synthetic (MNTS) montmorillonite clays that provide new insight into interlayer structure. An increase in basal d(001)-spacings demonstrates successful intercalation of PEO in all samples, and X-ray line narrowing shows that this intercalation improves the layer stacking order. The basal spacings of 17.9-19.4 A are consistent with a helical or bilayer structure of PEO in the interlayer. TGA-DTA provides quantitative results for the hydration state of the nanocomposites, demonstrates PEO intercalation, and shows that the composites prepared from the synthetic montmorillonite are less stable than those made with SWy-1. (7)Li NMR shows that the nearest neighbor hydration state of Li(+) is unaffected by PEO intercalation and suggests weak interaction of Li(+) with PEO. (23)Na NMR shows that PEO intercalation results in the conversion of the multiple Na(+) hydration states observed for the pristine clay into inner sphere sites most likely formed through coordination with the basal oxygens of the clay. These differences between lithium and sodium suggested that tighter binding of the Na to the clay may be the origin of the conductivity of Li-montmorillonite-PEO nanocomposites being as much as 2 orders of magnitude larger than those of Na-montmorillonite-PEO nanocomposites. The results confirm the idea that polymer oxygen atoms do not participate in sequestering the exchangeable cations and agree with the jump process for cation migration advanced by Kuppa and Manias (Kuppa, V.; Manias, E. Chem. Mater. 2002, 14, 2171).     

Etude de la Degradation Thermique du Polystyrene Choc Ignifuge

The authors studied the ignifugation and the kinetic of thermal degradation of the Styrene-Butadiene copolymer with an intumescent system Ammonium polyphosphate-Pentaerythrinol-Melamine. For that, they used the thermogravimetric and oxygen index techniques. The best formulation of intumescent system which can give the optimum results is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Invariant values of kinetic parameters — Evaluation of fire retardancy application to the PP-APP/PER system

A method allowing the determination of the formulation leading to the best fire retardancy properties is presented in the case of intumescent systems. The method consists in the determination of invariant physicochemical parameters deduced from TG analysis: invariant activation energy and invariant preexponentiel factor. The relation between the values given by an evaluation test (LOI) and the invariant activation energy is then discussed.     

Kinetic analysis of the thermal degradation of an epoxy-based intumescent coating

The aim of this work is to analyse and to simulate the kinetics of pyrolysis of an intumescent formulation designed to protect steel in the case of hydrocarbon and jet fires. The coating is based on a thermoset epoxy-amine resin system into which two fire retardant agents, boric acid and ammonium polyphosphate derivative have been incorporated. Industrial tests (jet fire tests) are usually used to evaluate the degradation mode of an intumescent coating. But these tests are quite expensive, and as the heating rates are extremely high (between 500 and 800 °C/min), it is not possible to evaluate the thermal degradation behaviour of the intumescent coating directly by thermogravimetric analyses. That is why it is necessary to develop predictive models of kinetics of degradation of these intumescent coatings. In this work, the coating has been pyrolyzed at different heating rates and a predictive model of its kinetics of degradation has been developed.     

Effect of Mineral Fillers on the Heat Resistance and Combustibility of an Intumescent Fireproofing Formulation on Silicone Base

An intumescent fireproofing formulation on silicone base, modified with mineral components (calcium carbonate, wollastonite, aluminosilicate microspheres), was studied by synchronous thermal analysis (Netzsch SТА 449 F5 Jupiter®). Introduction of 2–20 wt % wollastonite or aluminosilicate microspheres enhances the heat resistance (the ash residue increases by 27–40%) and reduces the combustibility of the modified fireproofing formulations (the total thermal effect of thermolysis of the fireproofing formulation decreases by a factor of more than 3). The optimum content of wollastonite and aluminosilicate microspheres is 5 wt %. Addition of calcium carbonate gave no complex positive effect.     

部份层无序锆交联蒙脱土结构的研究

通过锆交联蒙脱土的X射线衍射、阳离子交换量及孔径分布等实验测定,利用部分无序层状结构的衍射公式,建立了相应的三维统计结构模型.交联剂中Zr(Ⅳ)主要以四聚及三聚的方式存在,在与Na-Mt交联过程中,四聚及三聚Zr(Ⅳ)离子先吸附一定量的水,与水共同支撑开蒙脱土层,使层间距分别达到2.55nm和2.10nm,如此层间距的层在整体结构中分别占35％和27％.水分子进入了其余层间域,层间距为1.26nm.     

Thermal analysis of hexadecyltrimethylammonium-montmorillonites

Na-montmorillonite (Na-MONT) was loaded with hexadecyltrimethylammonium cations (HDTMA) by replacing 41 and 90% of the exchangeable Na with HDTMA. The organoclays were labeled OC-41 and OC-90, respectively. Freeze-dried Na-MONT, OC-41, and OC-90 were heated in air at 150, 250, 360, 420, 550, 700, and 900 °C. The thermally treated samples were suspended in water, air-dried, and desiccated over silica during 40 days. All samples were diffracted by X-ray and fitting calculations were performed on each diffractogram. These calculations gave information on basal spacings, relative concentrations, and homogeneity of the different tactoids obtained at each temperature, before and after suspending and desiccating. HDTMA-MONT tactoids with spacing ≥1.41 nm appeared between 25 and 250 °C. OC-41 or OC-90 intercalated monolayers or bilayers of HDTMA, respectively. At 250 °C OC-41 was air-oxidized to a smaller extent than OC-90, resulting in charcoal-MONT tactoids. With further heating the organic matter was gradually oxidized and at 700 °C both clays were collapsed. During the thermo-XRD-analysis of both organoclays three types of charcoal-MONT complexes appeared: (1) LTSC-MONT tactoids with a basal spacing 1.32–1.39 nm, between 250 and 420 °C in both clays; (2) HTSC-α-MONT tactoids with spacing 1.22–1.28 nm, between 360 or 250 and 500 or 550 °C in OC-41 or OC-90, respectively; (3) HTSC-β-MONT with spacing 1.12–1.18 nm, between 360 and 550 °C in both clays, where LTSC and HTSC are low- and high-temperature stable charcoal, respectively. HTSC-β-MONT differs from HTSC-α-MONT by having carbon atoms keying into the ditrigonal holes of the clay-O-planes.     

Intercalation behavior of calcium phenylphosphonate dihydrate CaC6H5PO3·2H2O

Intercalates of calcium phenylphosphonate dihydrate with 1-alkylamines (C₂–C₁₀), 1-alkanols (C₃–C₁₀), 1,ω-amino alcohols (C₂–C₅), pyridine, morpholine, piperazine, aniline and 1-naphthylamine were prepared and characterized by powder X-ray diffraction and thermogravimetric analysis. The intercalates of alkanols and alkylamines are unstable at ambient conditions and the guest molecules are tilted to the host layers at an angle of 40°. The amino alcohol intercalates are stable and their basal spacings are very similar for all amino alcohols used and, in the case of ethanolamine and propanolamine, they contain co-intercalated water. Also arylamines and nitrogenous heterocycles form stable compounds. The general formula of these intercalates is CaC₆H₅PO₃·xH₂O·y(guest) and their basal spacings are from 15.39 to 15.78 Å.