Study on char reinforcing of different inorganic fillers for polyethylene composites

Ceramifiable polymer composite is an excellent method for enhancing the flame retardancy of the materials. In case of fire, ceramifiable polymer composites are converted into a ceramic barrier that can impede heat transfer, segregate combustible material from oxygen and prevent the polymer matrix from pyrolysis. The ceramic fillers added to the composites play a key role in the ceramic forming process of the composites. Here, the effects of three types of Si-based mineral fillers on the ceramifiable and mechanical properties of polyethylene composites were investigated. Wollastonite (CaSiO₃), silica powder (SiO₂), or pyrophyllite (Al₂Si₄O₁₀(OH)₂) was incorporated into low-density polyethylene with glass powder to prepare the composite materials. The composites were subjected to sintering at various temperatures (600, 800, and 1000 °C). The ceramic residues formed were characterized by flexural strength, apparent porosity, linear shrinkage, and thermogravimetric measurements. All these three fillers greatly enhanced the ceramifiable properties of the polyethylene composites and the mechanical properties of the ceramic residues. X-ray diffraction analysis and scanning electron microscopy reveal that the filler molecules were firmly connected by the molten glass while the pores in the ceramic residues were released at elevated temperatures, leading to a dense ceramic structure with excellent mechanical properties.     

Study on mechanical properties and fire resistance of porous ceramic silicone rubber

Porous ceramic silicone rubber (PCSR) has an excellent ablative resistance because of its strong carbon layer structure after burning. However, as a marine sealant material, it also needs to have better mechanical properties for better application. In this study, PCSR composites were prepared by compounding with different additives and different viscosity base adhesives, and their fire resistance, tensile properties, and bond strength of multiple substrates at different temperatures were investigated and compared. When the ratio of 20,000 to 80,000 viscosity matrix adhesive is 3:7, the material prepared by adding deketoxime crosslinker and silane coupling agent containing amino and epoxy groups together can reach more than 1.4 MPa tensile shear strength at 150°C. Sintering experiments have shown that PCSR composites can still maintain the strength and integrity of the carbon layer structure, and the results of the A-60 standard fire resistance test for cable and pipe penetration devices have shown that marine PCSR sealants can effectively prevent flame propagation.     

Effects of inorganic fillers on the flame‐retardant and mechanical properties of rigid polyurethane foams

Rigid polyurethane foam (RPUF) composites filled with expandable graphite (EG), hollow glass microspheres (HGM), and glass fibers (GF) have been synthesized and characterized by limiting oxygen index, radiation ignition, compressing and torsion testing, and scanning electron microscopy. The results indicate HGM and GF benefit to the mechanical properties, while EG is good for flame retardancy. Proper ingredient of additive can lead to good flame retardancy and mechanical properties of the RPUF. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40253.     

阻燃硅橡胶的研制

通过测定硅橡胶试片的离火熄灭时间及燃烧速率来判定热硫化硅橡胶的阻燃性。结果表明，氢氧化铝对热硫化硅橡胶具有良好的阻燃效果；随着氢氧化铝用量的增加，硅橡胶的物理机械性能下降。通过对氢氧化铝进行表面处理，并与氯铂酸等阻燃剂配合，可制得符合美国UL-94V-0阻燃标准的硅橡胶制品。在本实验条件下的最佳配比为：100份混炼硅橡胶，45份氢氧化铝，50份氯铂酸(以铂质量计／10^-6)，2份乙炔炭黑及铁锡复合氧化物，制品拉伸强度大于5MPa。     

Toward an understanding of how red phosphorus and expandable graphite enhance the fire resistance of expandable polystyrene foams

Flame retardant expandable polystyrene (EPS) foams were prepared by coating method. Red phosphorus (RP) and expandable graphite (EG) were chosen as the flame retardants to be coated on the surface of expanded PS beads. By the presence of 33 phr RP/EG with a mass ratio of 1:1, the limiting oxygen index of EPS foam could reach up to 26.9%, with V-0 rating obtained in UL-94 test. The peak heat release rate could also decrease to 180.67 kW/m², which was 72.9% lower than that of neat EPS sample. Thermogravimetric analysis revealed an obvious increase of thermal stability and residue char amount by the presence of RP and EG. From the observation and analysis of char residue, it could be proposed that there existed a significant synergistic effect between RP and EG. RP could be oxidized and further react with graphite by the presence of oxygen at high temperature, forming isolated char layer and releasing nonflammable gases. Moreover, P radicals were generated at high temperature and could capture the radicals formed during the combustion of polystyrene and eliminate the burning chain reactions.     

Comparative study of the mechanical and flame‐retarding properties of polybutadiene rubber filled with nanoparticles and fly ash

A comparative study was performed of fly ash and nano‐CaCO₃ as fillers in polybutadiene rubber with 0, 4, 8 and 12% fly ash and nano‐CaCO₃. Uniform sheets were prepared of well‐compounded rubber. Nano‐CaCO₃ was synthesized by in situ deposition. The CaCO₃ nanoparticles as reinforcing agents improved the tensile strength more than 50% than fly ash, and the toughness and hardness also increased significantly. Up to a 75% reduction in flammability and a 100% improvement in the tear strength were observed with nano‐CaCO₃.© 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 6–9, 2005     

Enhancement in electrical and thermal performance of high-temperature vulcanized silicone rubber composites for outdoor insulating applications

High-temperature vulcanized silicone rubber composites are highly desirable as outdoor insulating materials due to their immense thermal and electrical performance. The aim of this work is to study the role of co-combined fillers (modified fumed silica [MFS], titanium dioxide [TiO₂], with graphene [G]) on electrical and thermal properties of silicone rubber (S) composites. The dielectric response of S/MFS_10 phr and S/TiO₂_20 composites tailored with 2 phr G was characterized by broadband dielectric spectroscopy. The hybrid filler/composites were found to show higher thermal stability when 2 phr G was added. In addition, a low quantity of G filler was found to slightly increase the AC dielectric breakdown strength of the S/MFS_10 and S/TiO₂_20, where an improvement of 3 and 5% was found, respectively. Several steps were observed in the thermal decomposition of the S rubber composites by thermogravimetric analysis-Fourier-transform infrared spectroscopy. Our findings revealed great potentials for fabricating hybrid-filler/silicone rubber composites with enhanced electrical and thermal properties for outdoor insulating applications.     

橡胶填充增强剂的研究概况

综述了各类橡胶填充增强剂用材料,重点介绍了纳米型材料橡胶填充增强剂的特性。指出了今后橡胶填充增强剂的发展方向。     

导热填料对室温硫化硅橡胶性能的影响

分析比较了氮化硅、氧化锌、勃姆石、氮化铝、碳化硅和石英粉等6种填料对室温硫化硅橡胶性能的影响,优选出氮化硅作为导热填料。比较了不同粒径的氮化硅性能,制备了综合性能较好的导热室温硫化硅橡胶。     

膨胀石墨对乙烯基硅橡胶的阻燃作用研究

将可膨胀石墨(EG)添加到乙烯基硅橡胶中并采用过氧化物硫化制备了硅橡胶材料,对其阻燃性能和燃烧行为进行了研究.结果表明,当EG的添加量为5份时,材料在垂直燃烧测试中通过了UL 94 V-0级,且能离火自熄,极限氧指数达到了33.0％;与纯硅胶材料相比,EG的加入有效降低了材料的热释放和烟释放;材料与火焰接触区域,EG完...     

Natural mineral fire retardant fillers for polyethylene

In this article, we study the behaviour of common and low cost mineral fillers into a polyethylene matrix when exposed to mass loss calorimeter conditions. The different systems are made of linear low‐density polyethylene (LLDPE), with 50 wt% of calcium carbonate (CaCO₃), magnesium carbonate or talc treated with stearic acid or nontreated. These systems were exposed to an external heat flux of 50 kW/m ² and their burning behaviours were compared. Significant decrease of heat release rate peaks (PkHRR) was obtained with all these mineral fillers; however, even better results were obtained when particles were treated with stearic acid. Indeed, the system with CaCO₃‐treated stearic acid leads to a surprising intumescent behaviour. A rheological study showed no impact of stearic acid on the viscosity of the system and did not explain the appearance of the intumescent phenomenon. However, scanning electron microscopy (SEM) shows that stearic acid enhances the dispersion of particles into the polymer and acts as a dispersive agent. The results also show that the aspect ratio of the particles, the cation nature of the carbonates and the polarity of the polymer matrix have an effect on the appearance or not on the intumescent phenomenon. Copyright © 2010 John Wiley & Sons, Ltd.     

Tensile properties and interfacial adhesion of silicone rubber/polyethylene blends by reactive blending

Two‐phase blends of silicone rubber (SR) and linear low density polyethylene (LLDPE) were prepared by reactive blending using peroxide crosslinking agent of SR. The tensile strength and elastic modulus of the SR were found to be increased by reactive blending with LLDPE without sacrifice of the elongation. The improvement of the tensile properties is attributed to the strong adhesion at the interface between SR matrix and LLDPE domain due to the chemical reaction by peroxide. The observation by polarized optical microscopies revealed that the debonding did not occur at the interface, but the LLDPE domains were elongated to longer one. Despite the elongation of the LLDPE domain, the blends exhibited good deformation recoverability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46192.     

Effect of various efficient vulcanization cure systems on the compression set of a nitrile rubber filled with different fillers

Effect of various efficient vulcanization (EV) sulfur cure systems on the compression set of a nitrile rubber filled with carbon black and silica/silane fillers was examined. The cure systems had different amounts of thiuram and sulfenamide accelerators and elemental sulfur, whilst the loading of zinc oxide and stearic acid activators was kept constant. The fillers had surface areas from 35 to 175 m²/g. In this study, the lowest compression set was measured for the rubber filled with carbon black with 78 m²/g surface area, which was cured with an EV cure system made of a small amount of elemental sulfur and large amounts of the two accelerators. Interestingly, a small change in the amount of elemental sulfur had a bigger effect on the compression set than did large changes in the loading of the accelerators in the cure system. Among the fillers, carbon black caused less compression set of the rubber vulcanizate than the silica/silane system did. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41512.     

Preparation of poly(methyl methacrylate‐co‐butyl methacrylate) nanoparticles and their reinforcing effect on natural rubber

Poly(methyl methacrylate‐co‐butyl methacrylate) [P(MMA‐co‐BMA)] nanoparticles were synthesized via emulsion polymerization, and incorporated into natural rubber (NR) by latex compounding. Monodispersed, core‐shell P(MMA‐co‐BMA)/casein nanoparticles (abbreviated as PMBMA‐CA) were produced with casein (CA) as surfactant. The chemical structure of P(MMA‐co‐BMA) copolymers were confirmed by ¹H‐NMR and FTIR analyses. Transmission electron microscopy demonstrated the core–shell structure of PMBMA‐CA, and PMBMA‐CA homogenously distributed around NR particles, indicating the interaction between PMBMA‐CA and NR. As a result, the tensile strength and modulus of NR/PMBMA‐CA films were significantly enhanced. The tensile strength was increased by 100% with 10% copolymer addition, when the molar ratio of MMA:BMA was 8:2. In addition, scanning electron microscopy and atomic force microscopy results presented that the NR/PMBMA‐CA films exhibited smooth surfaces with low roughness, and PMBMA‐CA was compatible with NR. FTIR‐ATR analyses also suggested fewer PMBMA‐CA nanoparticles migrated out of NR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43843.     

再生硅橡胶/甲基乙烯基硅橡胶共混物的性能

采用机械剪切破碎法制备再生硅橡胶,并将其掺入到甲基乙烯基硅橡胶中制备再生硅橡胶/硅橡胶共混物,研究了再生硅橡胶含量、硫化促进剂2,5-双(叔丁基过氧化)-2,5-二甲基己烷和沉淀法白炭黑用量对共混物硫化特性和力学性能的影响,通过傅里叶变换红外光谱、动态力学分析仪和扫描电子显微镜对共混物和硅橡胶进行了分析。结果表明,随着共混物中再生硅橡胶含量的增加,共混物的硫化速率变慢,力学性能降低,当再生硅橡胶质量分数为46.9%时,共混物的综合力学性能较好。当2,5-双(叔丁基过氧化)-2,5-二甲基己烷用量为0.5份(质量)且沉淀法白炭黑用量为15份时,共混物具有良好的力学性能。机械剪切破碎法没有引起再生硅橡胶化学性质的变化;共混物的玻璃化转变温度与硅橡胶接近,但其损耗因子峰值下降;共混物中填料的分散均匀性介于再生硅橡胶与硅橡胶之间。     

Improvement of thermal and fire properties of polypropylene

In the present research, the thermal stability and fire properties of polypropylene (PP) have been improved through direct melt intercalation of PP, organically modified montmorillonite (OMMT), calcium carbonate (CaCO₃) nanoparticles, and conventional flame retardants, i.e., decabromodiphenyl oxide (DB) and antimony trioxide (AO). The morphology of the compound was characterized by means of X‐ray diffractometry and transmission electron microscopy. Thermogravimetry analysis (TGA), cone‐calorimetry, limiting oxygen index, UL‐94, and tensile tests were also employed to investigate thermal and mechanical properties as well as the flammability of the compounds. Data, obtained from TGA, indicated that simultaneous incorporation of both OMMT and CaCO₃ nanoparticles forms a synergistic effect to improve both the thermal and thermo‐oxidative stability. The kinetic analysis of polymer degradation showed that the presence of nanoparticles hindered the thermal degradation of PP. The combination of OMMT and CaCO₃ was more effective to improve fire properties than OMMT and DB/AO. The experimental results indicated that the incorporation of OMMT and CaCO₃ improved both the tensile (i.e., the increase of yield strength, tensile strength, and Young's modulus) and thermal properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

无机阻燃剂对单组分室温硫化硅橡胶性能的影响

试验研究氢氧化镁、氢氧化铝及其复合物对脱酮肟型单组分室温硫化（RTV-1）硅橡胶物理性能和阻燃性能的影响。结果表明，随着氢氧化镁用量的增大，RTV-1硅橡胶的硬度、拉伸强度和氧指数逐渐增大，拉断伸长率逐渐减小，氢氧化镁用量为50份时RTV-1硅橡胶具有阻燃性；氢氧化铝填充RTV1硅橡胶的硬度、拉伸强度和氧指数均高于相同用量氢氧化镁填充胶，氢氧化铝用量为40份时RTV-1硅橡胶具有阻燃性；氢氧化镁／氢氧化铝并用量为30份时RTV-1硅橡胶具有阻燃性，氢氧化镁／氢氧化铝质量比为1：4时其阻燃效果最佳。     

Mechanical property improvement and fire hazard reduction of ammonium polyphosphate microencapsulated in rigid polyurethane foam

Ammonium polyphosphate (APP) is an effective phosphorus-containing flame retardant. But APP also has excellent hygroscopic capacity and decreases the mechanical property of composite. The aim of the study was to microencapsulate APP with polymethyl methacrylate (PMMA) to prepare microencapsulated ammonium polyphosphate (PMAPP) in order to eliminate the harmful effects caused by the mechanical property of composite. The microcapsules are characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and hydroscopicity test and observed by scanning electron microscopy (SEM). Fire hazard of rigid polyurethane foam (RPUF) is evaluated using a cone calorimeter and limited oxygen index test. The mechanical property of RPUF is studied by compressive strength test. The results show that APP has been microencapsulated by PMMA successfully and the shell does not decrease the beneficial effect of APP on fire hazard of RPUF. Furthermore, the shell also reduces the damage of APP on the mechanical property of composite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48307.     

改性Mg(OH)2对脱醇型RTV硅橡胶性能的影响

以α.ω -二羟基聚二甲基硅氧烷为基胶、气相法白炭黑为填料、改性Mg(OH) 2 为阻燃剂 ,配制脱醇型室温硫化 (RTV)硅橡胶。研究了改性Mg(OH) 2 用量对脱醇型RTV硅橡胶性能的影响。结果表明 ,当 10 0份基料中加入 5 0份改性Mg(OH) 2 时 ,RTV硅橡胶的燃烧氧指数达到了 34 2 % ,具有较好的阻燃性能     

Effect of a type of triazine on the properties and morphologies of poly(butylene terephthalate) composites

Composites of poly(butylene terephthalate) (PBT), 2,4,6‐tris(2′,4′,6′‐tribromophenoxy)‐1,3,5‐triazine (TTA), and glass fibers were prepared, and the effect of TTA on the properties and morphologies of the composites was studied. The results showed that the addition of a suitable amount of TTA could improve the flame retardancy of PBT composites reinforced with glass fibers, and good resistance to TTA emigration from the inside of the composites onto their surfaces was obtained. Fourier transform infrared spectroscopy analyses of PBT, TTA, and their blend suggested that there might be no chemical bonds formed on the interfaces between PBT and TTA in the composite; a thermogravimetric study revealed that the weight loss of the PBT/TTA composite was very limited in the temperature range of 25–300°C, and scanning electron microscopy images of the blend demonstrated that the TTA particle sizes and their distribution in the PBT matrix remained thermally stable when the system was heated at 130°C for 3 h. This suggested good compatibility of TTA with PBT. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1291–1296, 2006