The use of nanoclay in preparation of epoxy anticorrosive coatings

Epoxy/clay nanocomposites (NC) have become a very interesting topic among researchers in the past two decades because nanoclays have a positive effect on the mechanical, thermal and especially barrier and anticorrosive performances of the polymers. In this study epoxy NCs and NC-based epoxy coatings were prepared by the solution intercalation method using Cloisite 30B as nanoclay. WAXD and SEM analyses revealed that a mainly exfoliated structure was obtained in epoxy NC with 1 wt% clay content, while higher clay loadings reduced the number of exfoliated clay nanolayers and produced a mainly intercalated structure. EIS, TGA and DMA analyses showed that epoxy NCs with clay content below 5 wt% exhibited increased corrosion stability, thermal stability, glass transition temperature (T_g) and storage modulus (G′), in both glassy and rubbery states due to the nanoscale dispersion of Cloisite 30B and the barrier effect of individual nanolayers. Enhanced mechanical properties were also noticed at higher clay loadings, but the rate of improvement was lower. The highest extent of exfoliation and the most homogeneous macromolecular network was found for NC with 1 wt% of clay, leading to the highest improvement of thermal and anticorrosive properties. The salt spray test results showed that anticorrosive properties of epoxy coatings in the presence of 3 wt% and especially 1 wt% of Cloisite 30B were significantly better, thus indicating that nanoclay efficiently modifies the commercial epoxy coatings.     

氧化石墨烯提高钢结构水性膨胀防火涂料的防火性能研究

以水性丙烯酸树脂为基体,聚磷酸胺、季戊四醇和三聚氰胺为膨胀阻燃体系,加入少量氧化石墨烯制备水性膨胀防火涂料。采用小板燃烧法研究了氧化石墨烯用量对膨胀型防火涂料的阻燃性能的影响。结果表明:加入极少量氧化石墨烯(<0.01%),可提高涂料的阻燃性,当氧化石墨烯含量在0.005%时,涂层的耐燃时间可达432 s,炭层膨胀高度较未加氧化石墨烯涂层增加了13.04%。结合红外光谱(FT-IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)等表征手段对炭层形貌进行分析可知,加入氧化石墨烯后炭层在300~500 ℃范围的热稳定性提高,燃烧炭层完整密实,隔热性能提高,耐燃时间提高。     

Comparative study of the fire protection performance and thermal stability of intumescent fire-retardant coatings filled with three types of clay nano-fillers

The fire protection and thermal stability properties of intumescent fire-retardant coatings filled with three various clay nano-fillers (layer double hydroxide [LDH], montmorillonite [MMT], and sepiolite) were compared by fire protection tests and thermo-gravimetric analysis. The fire protection tests show that the incorporation of three fillers improves the fire protection properties of the intumescent fire-retardant coatings and the addition of 1 wt% sepiolite exhibits the lowest flame spread rating of 9.9 and equilibrium backside temperature of 164.5°C at 900 seconds. TG analysis shows that the incorporation of nano-fillers imparts a considerable enhancement of thermal stability and char formation to the intumescent coatings. Especially, the coating with 1 wt% sepiolite acquires the highest residual weight of 34.2% among the samples. Char residue analysis presents that the introduction of clay nano-fillers plays a positive role in enhancing the compactness and anti-oxidation ability of the char residues, and this positive effect as well as the flame-retardant efficiency depends on the types of clay nano-fillers. The three types of layered clay nano-fillers exhibit synergistic flame-retardant effectiveness in the order of sepiolite > MMT > LDH.     

钢结构用超薄型水性环氧防火防腐涂料的研制

以液体环氧树脂为基料树脂,以水性胺为固化剂;以聚磷酸铵、三聚氰胺、季戊四醇、氯化石蜡为膨胀阻燃体系;以纳米TiO2、可膨胀石墨为增效剂;以复合铁钛粉为防锈颜料,制备了钢结构用超薄型防火防腐涂料。当环氧涂层的交联度达到理论交联度的50％～70％时,涂层既有优良的防火隔热性能,又有优良的防腐蚀性及机械性能。     

水性膨胀型钢结构防火涂料研究进展

综述了近年来水性膨胀型钢结构防火涂料的研究进展,分析了其隔热机理,介绍了经典膨胀阻燃体系、新型协同阻燃体系和耐水性改善措施,阐述了丙烯酸树脂、环氧树脂、水性聚氨酯和有机硅等常用的成膜物质及其改性技术,并对颜填料和纳米材料的阻燃增效作用进行了详细探讨。最后,对水性膨胀型钢结构防火涂料未来的研究方向进行了展望。     

Allyl phosphonium salt–modified clay for photocured coatings: Influence on the properties of polyester acrylate‐based coatings

In this study, bentonite clay was modified with a phosphonium salt and this modified clay was used to prepare polyester acrylate based coatings to improve their flame retardancy and mechanical properties. Photocured composites were prepared with 1, 2, and 3 wt% phosphonium salt modified clay and for comparison 1 wt% nonmodified clay containing composites were also prepared. Modified clay displayed good dispersion properties due to its increased basal spacing. Composites were characterized by FT‐IR and XRD measurements. According to XRD results, it was found that the modified clay was exfoliated in the composites. Furthermore, we investigated the effect of allyl phosphonium salt modified clay on the thermal, mechanical, and flame retardant properties of polyester acrylate based composites coatings. When compared with neat clay containing coatings, modified clay containing photocured coatings exhibited increased modulus and enhanced thermal properties due to increased crosslinking density. Moreover, the presence of the phosphonium salt enhanced the flame retardancy of the polyester based coatings. POLYM. COMPOS., 36:946–954, 2015. © 2014 Society of Plastics Engineers     

透明膨胀型氨基树脂基阻燃涂料的研究进展及趋势

分析了氨基树脂作为透明膨胀型阻燃涂料成膜物质的优势,综述了透明膨胀型氨基树脂基阻燃涂料的国内外研究进展,提出了现阶段该涂料产品存在的问题,阐述了透明膨胀型氨基树脂基阻燃涂料未来的研究方向。指出了透明膨胀型氨基树脂基阻燃涂料的研究重心已从关注其理化性能和膨胀阻燃性能,逐渐转向探求技术问题出现的根本原因。     

聚苯乙烯泡沫阻燃研究

从卤系阻燃剂和无卤阻燃剂两方面综述了近几年来国内外阻燃聚苯乙烯(PS)的研究现状。卤系阻燃剂主要介绍了溴化苯乙烯、十溴二苯醚(DPEDB)、溴化环氧树脂等。无卤阻燃剂介绍了膨胀型、金属氢氧化物及黏土类。分析了各类阻燃剂优缺点,未来占据阻燃剂主导地位的应是高效的环境友好型复配无卤阻燃剂。     

新材料在钢结构膨胀型防火涂料中的应用

介绍了改善和提高钢结构膨胀型防火涂料性能的几种新材料，其中晶须材料增加了防火涂料的施工厚度和耐火时间，石墨层间化合物增加了防火涂料的耐火时间和耐水性，氟素改善了防火涂料的理化性能和外观性能，双氢氧化物提高防火涂料的防火性能。     

Extrusion with ultrasound applied on intumescent flame‐retardant polypropylene

In this work, the effect of processing conditions on the production of an intumescent flame‐retardant system is studied in polypropylene‐based compounds. Two distinct procedures were used: ultrasonic assisted single screw (with a static mixer die) and twin screw extrusion. The flame‐retardant, thermal, mechanical, morphological, and rheological properties were measured. It was found that the flame‐retardant intumescent content can be diminished from 30 phr (as usually used) to 21 phr using the application of ultrasonic waves during extrusion and with the addition of chemically modified clay to obtain a V0 classification according to UL94‐V standards. In addition, the processed materials presented improvements in the mechanical properties such as impact resistance (Izod Notched), strain at break and tenacity upon ultrasound application. The online application of ultrasound through a die that produces extensional flows improved greatly the dispersion and distribution of the particles of the intumescent system and the chemically modified clay in the polymer matrix. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

固化剂对钢结构用超薄膨胀型水性环氧防火涂料性能的影响

以环氧乳液为基料,聚磷酸铵、三聚氰胺、季戊四醇(APP/MEL/PER)为防火助剂研制了超薄膨胀型钢结构防火涂料。通过调整环氧乳液/固化剂比例,研究了固化剂用量对涂料防火、防腐性能的影响。通过交联度测试进一步讨论了环氧乳液与固化剂比例对涂料性能的影响。结果表明:固化剂占环氧乳液含量20%时,涂层的防火性能和防腐性能均较好。     

Influences of glass flakes on fire protection and water resistance of waterborne intumescent fire resistive coating for steel structure

Glass flake (GF) was used as a modifier to improve the fire protection and water resistance of waterborne intumescent fire resistive coating. The influences of GF on the properties of the coatings were investigated in detail by using TGA, XRD, X-ray fluorescence spectrometry (XRF), SEM and fire protection test. The TGA results proved that addition of GF could enhance the anti-oxidation of the char layers and increase the residue weights of the coatings. The XRF results indicated that anti-oxidation of the coatings modified by GF was improved. The SEM images demonstrated that addition of GF could improve the foam structure of the coatings. After immersed in water over 600 h, the results showed that the thermal stability and fire protection of the coating without GF were significant decreased, but the coatings modified by GF could still maintain the excellent intumescent effect and fire protection.     

超薄膨胀型钢结构防火涂料烃类火试验研究

钢结构建筑属于循环结构形式,由于钢材耐火性能差,温度超过600℃,材料强度和刚度都显著降低,因此必须对钢结构建筑进行防火保护。超薄膨胀型钢结构防火涂料逐渐应用到民用建筑钢结构防火保护中,而且GB14907—2002对其耐火性能评价方法有了具体规定,但是对石化烃类火环境下的耐火性能没有提及。本研究依据GB14907—2002的规定,参照UL1709的实验方法,对烃类火下超薄膨胀型钢结构防火涂料的耐火性能进行了测试。根据试验情况主要考察了涂料的发泡倍数,试验结果表明发泡倍数指标可以作为该类涂料的一个参考指标,并且对烃类火下超薄膨胀型防火涂料的施工养护和粘结强度等提出了建议。     

叶蜡石改性膨胀型涂料阻燃性能研究

为了提高木质胶合板的阻燃性能,以聚磷酸铵(APP)-季戊四醇(PER)-尿素为基础配方,叶蜡石粉作为改性添加剂制备膨胀型阻燃涂料(IFRC);采用锥形量热仪、静态接触角测量仪、扫描电镜、X射线衍射仪和拉力机等仪器对试样的阻燃性能、疏水性能和力学性能进行了表征,并且研究了叶蜡石粉含量对所制备涂料性能的影响。结果表明:在膨胀型阻燃涂料中加入适量的叶蜡石可以提高涂料的阻燃效果,当掺加叶蜡石粉的质量分数为2%时,涂料的火灾增长指数(FGI)降低了47%,火灾性能指数(FPI)增加了89%,并且阻燃性能指数(FRI)提高至2.5倍;叶蜡石粉的加入促进涂层在燃烧过程中形成连续致密的炭层结构,并形成了可以有效隔绝氧气和热量的熔融态物质,进一步增强了涂料的阻燃隔热性能;此时涂层的疏水性能和燃烧后木质胶合板的力学性能达到最佳,水接触角增大了8°,拉伸强度提高了45%,断裂伸长率也提高至8.5倍。本文研究结果对木质胶合板阻燃体系涂料配方的开发有一定的参考作用。     

无溶剂膨胀型环氧防火涂料及其在建筑领域的应用

目前市场上常用的钢结构防火涂料主要是厚型非膨胀型防火涂料,单组分溶剂型或水性防火涂料。相对于这几种类型的防火涂料,无溶剂膨胀型环氧防火涂料具有更加优越的综合性能和某些独有的特点。对不同类型的防火涂料进行分析和对比。结合市场上一款非常成熟的无溶剂膨胀型环氧防火涂料EP-FP产品进行介绍,分析其特点及主要的应用场合。     

空心微珠对膨胀型涂料防火性能的影响

以苯丙乳液为成膜物质,聚磷酸铵、三聚氰胺、季戊四醇为膨胀阻燃体系,以空心玻璃微珠为阻燃协效剂制备了几种防火涂料。用锥形量热仪和小室法研究其燃烧和耐火性能。试验结果表明,空心玻璃微珠会显著提高防火涂料的防火性能。     

Flame retardant polyurethane nanocomposite: Study of clay dispersion and its synergistic effect with dolomite

Polyurethane–clay nanocomposite adhesives were prepared by different synthetic routes and their microstructures were determined by X‐ray diffraction measurements and from transmission electron microscopy images. The preparation method of the polyurethane nanocomposite adhesives was systematically changed, that is, condensation either in the presence or absence of catalyst, concentration and type of nanoclay, premixing order of nanoclay (nanoclay was either premixed with the polyol or isocyanate part) and by using MDI surface treated nanoclays. Depending on the polymerization conditions cluster, intercalated, and exfoliated clay structures were obtained. The flame retardant properties of the manufactured nanocomposite adhesives and the synergistic effect of clay in combination with dolomite were investigated by cone calorimeter and UL 94 vertical burning tests. The results indicate that addition of nanoclay reduces burning time and the total heat evolved (THE) at flame out, and that the type of assembled clay structure (cluster, intercalated or exfoliated) had a significant effect on the flame retardant property. Nanocomposites with 3 wt % of clay loading gave the shortest burning time, the lowest THE and also UL 94 V‐2 ratings were reached, although the flame retardancy in terms of heat release rate and time to ignition was not improved. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influences of silicone emulsion on fire protection of waterborne intumescent fire-resistive coating

The combination of self-crosslinking polyacrylate emulsion and silicone emulsion was used as a binder for the preparation of waterborne intumescent fire-resistive coatings. The influences of silicone emulsion on fire protection and char formation of the coatings were investigated in detail by means of TGA, SEM, energy dispersive spectroscopy analysis, rheological measurement, and fire protection tests. The results showed that using silicone emulsion improved thermal stability and antioxidation ability of the coating and increased the residue weights of the char layer at high temperature. Furthermore, an appropriate amount of silicone emulsion could improve the rheological property of the mixed binders and be conducive to the increase of the intumescent factor of the coatings, thus improving the fire protection of the coating significantly. However, an excess amount of silicone emulsion can lead to uneven dispersion of silicone emulsion in the mixed binder and cause an uneven distribution of cell size of the char layer.     

Preparation and flame resistance properties of revolutionary self-extinguishing epoxy nanocomposites based on layered double hydroxides

Layered double hydroxides/epoxy (LDHs/EP) nanocomposites were prepared from organo-modified LDHs, a diglycidyl ether of bisphenol A monomer (DGEBA) and amine curing agents. The organo-modified LDHs were obtained by ionic exchange of a magnesium-aluminum carbonate LDH in an acid medium. X-ray diffraction and transmission electron microscopy showed a dispersion of the layers at a nanometer scale, indicating the formation of LDH/EP nanocomposites. The thermal degradation and flame resistance properties of LDH/EP nanocomposites, montmorillonite-epoxy (MMT/EP) nanocomposites, LDH/EP microcomposites and aluminum hydroxide-epoxy microcomposites were compared by thermogravimetrical analyses, simultaneous thermal analyses, UL94 and cone calorimeter tests. Only LDH/EP nanocomposites showed self-extinguishing behavior in the horizontal UL94 test; LDH/EP microcomposites and MMT/EP nanocomposites samples burned completely showing that the unique flame resistance of LDH/EP nanocomposites is related to both the level of dispersion and the intrinsic properties of LDH clay. Furthermore, cone calorimeter revealed intumescent behavior for LDH/EP nanocomposites and a higher reduction in the peak heat release rate compared to MMT/EP nanocomposites.     

Synergistic effect of vermiculite on the intumescent flame retardance of polypropylene

Synergistic effects of the natural clays unexfoliated vermiculite (VMT), exfoliated vermiculate (EVMT), and montmorillonite (MMT) on the intumescent flame retardance of polypropylene were investigated systematically with the usual fire testing methods. The limiting oxygen index (LOI) of flame‐retardant polypropylene (FRPP) filled with 30 wt % intumescent flame retardants (IFRs) composed of ammonium polyphosphate and pentaerythritol were increased from 30 to 33 vol % for VMT and MMT and to 36 vol % for EVMT when 1 wt % IFR was substituted for clay. The synergistic effectivities calculated on the basis of increases in the LOI values were 1.4 for VMT, 1.3 for MMT, and 1.6 for EVMT. Cone calorimetry also revealed the existence of a synergistic effect. EVMT had the best performance for lowering the peak values of the heat release rate and smoke production rate. The thermogravimetric analysis results show that EVMT had the best performance for increasing the char residue of FRPP higher than 650°C compared with VMT and MMT. The high content of iron and the small particle size of EVMT may have been responsible for its high synergistic effect at a low filling level. No remarkable variations of the diffraction peaks were observed in the X‐ray diffraction patterns of the original clay and the clay in FRPP. All of the formulations, with or without clay, exhibited small variations in the mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011