Glass fiber-reinforced epoxy composites

Glass fiber-reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethane

1 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane.

(TGDDM) and tetraglycidyl bis(o-toluidino)-methane

2 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-bis(o-toluidino)methane.

(TGMBT) using various amines like 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.     

New thermosetting resins for high performance composites

Investigations leading to the development of a new family of heat-stable thermosets, the Xylok

1 Registered trademark.

resins, are outlined. These polymers are the condensation products of aralkyl ethers or halides with phenols, and in some instances other classes of aromatic, heterocyclic and organometallic compounds, in the presence of a Friedel-Crafts catalyst. They are fast curing and Xylok composites have been prepared with glass, asbestos and carbon fibre reinforcement, which give excellent high-temperature mechanical strength and strength retention on prolonged exposure up to 250°. A comparative evaluation of the mechanical and electrical properties of a series of glasscloth laminates prepared with various classes of thermosetting resins has shown the Xylok resins to give outstanding overall performance. In addition, the chemical and radiation resistance, and ablative, wear and frictional properties of the Xylok composites suggest that they will find use in chemical plant, aircraft aerospace and bearing applications. Asbestos flour-filled Xylok moulding compounds have been shown to give similar flow and curing characteristics to phenolic based products, but the mouldings are significantly more heat stable.     

Grafting of methyl methacrylate on isoprene rubber

Methyl methacrylate has been grafted on artificial isoprene rubber (IR) latex, with use of redox initiation. The properties of latices containing up to 40 phr

1 Parts per hundred parts of rubber.

methyl methacrylate (MMA) as well as solid products containing up to 80 phr of this compound were studied. Compared with ungrafted IR latex with the same solids content, the grafted IR latices had a lower viscosity, owing to their particle size being larger. Vulcanised films obtained from the grafted latices showed a considerably higher modulus, particularly at large deformations, than those based on IR or blends of IR with polymethyl methacrylate. by incorporation of certain reinforcing white fillers in the MMA-grafted IR latices, a further increase in the modulus of the latex films was effected.     

Properties of standard materials for reflection

This article gives a short survey of some literature on the calibration, suitability, properties, and use of various materials which are used as standards of reflectance. The classical ultimate reference standard, smoked magnesium oxide, is discussed briefly, and information is given on the properties of materials presently used: BaSO₄, Russian opal glasses, ceramic tiles, and Halon.

1 Halon is a registered trade name of the Allied Chemical Corporation.

The suitability of these materials for use as transfer standards or working standards is discussed.     

Effects of polyvinylsilicone oil with condensed aromatics on the radiation resistance of heat‐curable silicone rubber

Polyvinylsilicone oil with condensed aromatics (called C₁ gum) was synthesized by Diels‐Alder reaction of polyvinylsilicone oil and acenaphthenecyclone, and was used as an additive in heat‐curable silicone rubber. The resistance to irradiation of the silicone rubber obtained was investigated by γ‐rays at doses up to 300, 500, and 1000 kGy in vacuum. The dose rate was 150 kGy/min. After irradiation, the average molecular weight between crosslinks (M_c) and mechanical properties of the silicone rubber were determined. The results show that C₁ gum can effectively improve the radiation resistance of silicone rubber. When the amount of C₁ gum used in silicone rubber changes from 2 to 14 parts per hundred silicone gum, the radiation protection effects increase with increasing amount of C₁ gum. The radiation protection mechanism of C₁ gum was also discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1937–1942, 2006     

Alumina trihydrate as a flame retardant filler for flexible vinyl compounds

In those flexible vinyl compounds which can accept fillers, alumina trihydrate can significantly improve flame resistance as measured by oxygen index

1 It should be appreciated that degrees of flammability as measured by small-scale tests such as oxygen index may in no way reflect the relative hazard of these same materials when involved in a fully developed fire.

. Over a range of plasticizer concentrations, the lower the concentration of burnable plasticizer, the greater the contribution of hydrate to flame retardancy. Combinations of alumina trihydrate with antimony oxide are especially effective for improving the flame resistance of flexible vinyl compounds.     

Effects of polymethylvinylsilicone oil with side tetraphenylphenyl groups on the radiation resistance of addition‐type silicone rubber

Polymethylvinylsilicone oil with side tetraphenylphenyl groups (called C₂ gum for short) as a low molecular additive was used in two kinds of addition‐type silicone rubber, polymethylvinyl silicone rubber and poly (dimethyl‐diphenyl) silicone rubber, and the radiation resistance of silicone rubbers obtained was investigated by γ‐rays radiation with the dose rate of 117 Gy/min at doses up to 350, 500, and 850 kGy, respectively. Moreover, the average molecular weight between crosslinks and mechanical properties of silicone rubbers after irradiated in air and N₂ were determined by toluene‐swelling method and on a XLS‐A rubber test instrument, respectively. The results show that C₂ gum can effectively improve the radiation resistance of silicone rubber. When C₂ gum is used in poly(dimethyl‐diphenyl) silicone rubber, phenyl groups and tetraphenylphenyl groups may have synergistic effect, and the radiation resistance is improved greatly. The suitable amount of C₂ gum used in silicone rubber is 10– 14 phr. The crosslinking density of vulcanizates irradiated in N₂ is higher than that of vulcanizates irradiated in air because of the oxidative degradation. The radiation protection mechanism of C₂ gum was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4144–4148, 2007     

Effect of CeO2 on UV aging of composite insulators prepared by template-spraying method

When the silicone rubber composite insulator is exposed outdoors for a long time, it will be affected by high-temperature ultraviolet environments. In order to ensure the operation of silicone rubber composite insulators, a super-hydrophobic composite insulator with antiaging characteristics was prepared by mixing cerium dioxide (CeO₂) with silicone rubber and spraying CeO₂ on the surface of silicone rubber. This article studied the aging characteristics of the base and surface of silicone rubber composite insulator by CeO₂ in ultraviolet environment. The properties of silicone rubber composite insulators before and after aging were tested by mechanics, contact Angle, rolling Angle, bounce, and icing experiments. The aging mechanism of silicone rubber was analyzed by Fourier transform infrared spectroscopy and search engine marketing. This study prepared composite insulators with excellent mechanical, hydrophobic, and antiicing properties. The aging resistance of silicone rubber composite insulators is improved by adding CeO₂ into silicone rubber matrix and spraying CeO₂ on the surface, which also ensure the use of composite insulators in high-temperature ultraviolet environment.     

Solvent replacement in the synthesis of persubstituted phosphonitrilic hydroquinone prepolymer materials

A desirable solvent replacement has been effected in the synthesis of persubstituted phosphonitrilic hydroquinone prepolymer materials. The replacement of carbon tetrachloride with cyclohexane has no adverse effect on the composition and quality of the material prepared. The overall yield of the reaction increases from 65 to 70% and the toxicity of the reaction mixture and of the waste generated from the reaction are greatly reduced. The particularly close match of solvent properties between carbon tetrachloride and cyclohexane makes this an excellent solvent replacement. Such changes to less-expensive, less-toxic, and less-environmentally damaging solvents are on the increase. A brief list of some known replacement solvents for use in polymer and coatings applications is presented. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Synthesis and characterization of melt-polymerizable aminophthalocyanine monomers

The strategy, synthesis, and characterization of a soluble amine-functionalized phthalocyanine monomer and two examples of its polymerization into optically transparent glasses are reported. A simple, fast, and versatile method for incorporating metal ions into the metal-free phthalocyanine is demonstrated. Measurements of the nonlinear optical properties associated with a lead-substituted phthalocyanine/urethane copolymer are also reported. © 1995 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

微胶囊红磷对电气绝缘用硅橡胶的阻燃改性研究

研究改性氢氧化铝(m-ATH)/微胶囊红磷无卤复合阻燃剂对电气绝缘用甲基乙烯基硅橡胶物理性能、电性能和阻燃性能等的影响,并与m-ATH/十溴二苯乙烷复合阻燃剂进行对比。结果表明,m-ATH/微胶囊红磷无卤复合阻燃剂对甲基乙烯基硅橡胶具有良好的阻燃协效作用。     

碳酸钙和氢氧化镁对加成型硅橡胶性能的影响

比较了碳酸钙和氢氧化镁对加成型硅橡胶力学、耐热、阻燃和防火性能的影响,分析了填料对硅橡胶热失重过程的影响。结果表明,碳酸钙可以提高硅橡胶的力学和防火性能;氢氧化镁可以提高硅橡胶的阻燃性能,但不能赋予硅橡胶防火性能;碳酸钙和氢氧化镁对硅橡胶防火阻燃性能的影响差异在于填料本身分解温度和硅橡胶燃烧分解温度的匹配性;两种填料并用可以赋予硅橡胶良好的防火、阻燃和耐热性能。     

Hydrophilisation of silicone rubber for medical applications

Silicone rubber is one of the biomaterials used for preparation of medical implants. The properties of silicone rubber and methods of their evaluation are surveyed with respect to the medical applications. For some applications the hydrophobic character of silicone rubber is undesirable and possibilities of its hydrophilisation are presented in this review as well. Special attention is paid to the process of preparation of hydrophilic silicone rubber–hydrogel composite materials based on acrylic and methacrylic acids derivatives and to the properties of such materials. Copyright © 2003 Society of Chemical Industry     

Effects of water content on the properties of starch/poly(ethylene–vinyl alcohol) blends

The physical properties of unmodified starch, poly(ethylene vinyl alcohol), glycerol, and water mixtures are reported. Thermal and melt-flow properties of the preprocessed, physically mixed materials were determined along with the tensile properties and morphology of injection-molded microtensile samples. Melt-flow properties were measured by a capillary rheometer, and the water content was varied from 4 to 18%. The morphology, rheology, and tensile properties are all highly related to the percentage of water present. A transition in the tensile properties and morphology of the blends was observed at approximately 11% moisture content. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

高温硫化硅橡胶改性及老化研究进展

高温硫化硅橡胶由于其优异的高低温性能、耐候性、表面性能等特点而在航天、电力和医疗器械等领域中得到广泛应用。本文主要介绍了最近五年来,通过化学或物理方法对硅橡胶表面性能和低温性能等进行强化方面的相关研究,以及在实现产品功能化方面取得的进展。此外还介绍了在加速老化条件下不同硅橡胶材料的力学、介电性能等变化及其机理,以及在老化研究方法的精确化、可靠化和可视化方面的研究进展,重点关注多因素影响下的材料寿命分析和预测;并特别关注了水在硅橡胶老化过程中的作用及机理研究成果。最后,对高温硫化硅橡胶改性和老化研究的前景进行了展望。未来,极端环境下的硅橡胶功能化研究以及多因素影响下的材料寿命分析和预测将成为重要的发展方向。     

Effect of KH550 on the Preparation and Compatibility of Carbon Fibers Reinforced Silicone Rubber Composites

Silicone rubber has good heat resistance, but its mechanical properties are poor. To improve the mechanical properties of the silicone rubber, the carbon fiber / silicone rubber composites were prepared in this paper, in which the silicone rubber was used as the matrix, the high-performance carbon fiber (CF) treated with coupling agent is used as the reinforcement. The best composite formulation, the types and content of coupling agent are determined by testing mechanical properties of the composites. The morphology structures of the composites were observed by scanning electron microscope (SEM), the compatibility between carbon fiber and silicone rubber was studied by infrared spectrum analysis (IR), dynamic thermal mechanical analysis (DMA) and X-ray photoelectron spectroscopy (XPS). The results show that the best composite formulation is silicone rubber of 100 phr, carbon fiber of 12 phr, coupling agent KH550 of 2.5 phr. The best first curing conditions are at 175 ^°C under 10 MPa for 30 min, the postcuring conditions are at 200 ^°C for 2h. The compatibility between carbon fiber treated with KH550 and silicon rubber is the best by SEM, IR, DMA and XPS analysis, and confirm that the coupling agent KH550 plays a compatilizer role in the preparation process of the carbon fiber/silicone rubber composites.     

Effect of fiber-matrix adhesion on the properties of short fiber reinforced ABS

The tensile strength, fracture energy, and impact strength of ABS reinforced with discontinuous crystalline fibers such as Fybex

1 Du Pont trademark.

can be controlled by manipulating fiber-matrix interfacial adhesion. In “good bonding” situations composite tensile strength, thermal expansion coefficient, and elastic moduli are significantly improved over the unfilled resin. The excellent impact strength of unreinforced ABS can be retained by lowering the fiber-matrix interfacial adhesion. This results in a corresponding reduction in the improvements in tensile and flexural strength. However, the elastic moduli and thermal expansion coefficients are relatively insensitive to changes in adhesion. Consequently, a material with high modulus (>500,000 psi), high Izod impact resistance (7.0 ft-lb/in.), and low expansion coefficient (3.0 × 10^?5 in./in./°F) can be obtained. A material with this unique combination of properties should find use in large parts such as camper tops, truck grilles, and snowmobile bodies. Fiber-matrix adhesion was measured directly by an x-ray analysis technique which could be employed because of the fiber's crystallinity and unique growth habit. This independent measurement allowed a correlation between bonding and composite properties. The interfacial bond strength was manipulated by a variety of fiber coatings and resin additions.     

Morphology and properties of the PA66/PC/silicone rubber composites

The research focused on the PA66/PC/silicone rubber composites. By adding silicone rubber as a toughener, the composites were prepared via dynamic vulcanization. The morphology and properties of the composites were characterized by FTIR, TEM, SEM, XRD, etc. The FTIR spectrum of the composites presented an increase of the 1730, 1240, and 1450 cm^?1 that can be due to the C?O interaction and the presence of the O? CO? O group, and this fact can mean the formation of the PA66–PC copolymer. The crosslinking of silicone rubber in the PA66/PC matrix formed the net‐like structure like semi‐IPN, which is propitious to enhance the interaction between PA66 matrix and PC and in further makes the PC particles embed in PA66 matrix closely. Novel composites are gained with outstanding mechanical properties and high temperature resistance, so the combine toughening by silicone rubber and PC is an ideal toughening system owing to the synergistic effect. In addition, the PA66/PC/silicone rubber/OMMT composite exhibits better flexile strength and flexile modulus without weakening other mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

耐热型热硫化混炼胶的研制

以甲基乙烯基硅橡胶为生胶,添加气相法白炭黑、耐热添加剂等制得耐热型热硫化硅橡胶,研究了生胶中羟基含量、白炭黑种类、白炭黑处理剂种类以及耐热剂种类对硅橡胶耐热性能的影响。结果表明,当采用羟基质量分数≤15×10^-6、乙烯基摩尔分数为0.19%的甲基乙烯基硅橡胶生胶时,其抗降解表现更好;不同类型白炭黑在不同的老化温度下对硅橡胶的影响不同,225℃及以下温度条件下,亲水型白炭黑的耐热效果优于疏水型白炭黑,225~300℃及以上温度条件下,疏水型白炭黑更优;在白炭黑处理剂对硅橡胶耐老化影响方面,采用聚二甲基二苯基硅氧烷RP140PH比常规低黏度羟基硅油和六甲基二硅氮烷更好;耐热剂对硅橡胶体系耐老化效果提升极为明显,其提升效果由高到低依次为AD105、AD111、AD104、AD110。