Nanoparticle networks reduce the flammability of polymer nanocomposites

Synthetic polymeric materials are rapidly replacing more traditional inorganic materials, such as metals, and natural polymeric materials, such as wood. As these synthetic materials are flammable, they require modifications to decrease their flammability through the addition of flame-retardant compounds. Environmental regulation has restricted the use of some halogenated flame-retardant additives, initiating a search for alternative flame-retardant additives. Nanoparticle fillers are highly attractive for this purpose, because they can simultaneously improve both the physical and flammability properties of the polymer nanocomposite. We show that carbon nanotubes can surpass nanoclays as effective flame-retardant additives if they form a jammed network structure in the polymer matrix, such that the material as a whole behaves rheologically like a gel. We find this kind of network formation for a variety of highly extended carbon-based nanoparticles: single- and multiwalled nanotubes, as well as carbon nanofibres.     

The effect of flame-retardants on the properties of acrylic and modacrylic fibres

In this study, flame-retardant additives such as tributyl phosphate, tri(dibromopropyl) phosphate, aluminium hydroxide powder and aluminium hydroxide gel are used for acrylic fibre (acrylonitrile and vinyl acetate copolymer), and calcium phosphate and antimony oxide are introduced into modacrylic fibre (acrylonitrile and vinylidene chloride copolymer). Investigations are carried out on the effect of these flame-retardants on the thermal properties, mechanical properties, morphology and flammability of acrylic and modacrylic fibres. The results show that the effect of additives on the rate of coagulation during spinning can be understood from the changee of morphology of the fibres. Tri(dibromopropyl) phosphate and antimony oxide are good flame-retardant and good synergistic flame retardant, respectively.     

Harakeke (phormium tenax) fibre–waste plastics blend composites processed by screwless extrusion

Most plastic packaging products are discarded after a single use resulting in an abundant supply of waste plastics. Natural fibres are light in weight, abundant and inexpensive. The stiffness and strength of polymers have been shown to improve with the incorporation of natural fibres. Hence, composite materials made of natural fibres and waste plastics would result in the reduction of plastic wastes and the use of fibres from renewable resources. Composite specimens and sheets consisting of fibres from the New Zealand flax plant, phormium tenax or Harakeke as it is known in Maori, and waste plastics have been produced through screwless extrusion followed by injection moulding. The tensile and impact properties of these composites have been determined. The formability of these composites has been assessed through thermoforming.     

Lignocellulosic fibre mediated rubber composites: An overview

The rising concern towards the reduction in the use of petroleum-based, non-renewable resources and the need for more versatile polymer-based composite materials have led to increasing interests on natural polymer composites filled with natural organic fillers, i.e. coming from renewable and biodegradable sources. This paper reviews wood flour and other lignocellulosic fibres filled rubber composites, including cellulosic rubber composites, cellulosic thermoplastic elastomers, nanocellulose based rubber nanocomposites, with the aims at providing the most state of the art information for directing further scientific research, possible commercialization and design of cellulosic rubber composites. It has been found that 1) the surface properties of natural cellulose, hence the compatibility and interface of the natural cellulose and matrix rubber/plastics, are crucial for the successful development of the composites, such, physical and chemical modification and additives have been widely attempted to improve the incompatibility and poor interfacial adhesion between the filler and matrix; 2) the curing characteristics, mechanical properties, thermal stability and morphologies of the composites are complex but closely related to not only the interfacial properties, but also the compositions (e.g. the concentration of cellulosic materials) and other processing parameters; 3) the nature of hydrophilic cellulosic and hydrophobic matrix rubber and/or plastics requires an accurate introduction of coupling agent, one end of its structure shall be compatible to hydrophilic and the other to hydrophobic. The reviews on the main paths and results of study on the advanced nanocellulose reinforced rubber nanocomposites and sandwiches indicate much potentials and needs for further in-depth studies.     

Silane coupling in carbon fibre-reinforced polyester resin

Previous work has suggested that organosilanes applied to carbon fibres do not improve the interlaminar shear properties of reinforced plastics containing these fibres. However, by first oxidising the fibres in an aqueous environment, hydroxyl groups can be put onto the surface and the silanes are then able to form silanol bonds to the fibre surface as they do in glass fibre-reinforced plastics.This has been shown to occur in polyester resins containing carbon fibres that were first boiled in 70% nitric acid and then coated with two epoxysilanes. Tensile and interlaminar shear properties of these composites are presented, together with Stereoscan studies of the fracture surfaces.     

粘土/塑料纳米复合材料的新发展

粘土的特殊层状硅酸结构,使其成为无机/有机纳米复合材料中纳米无机组分的最热门来源。几年来,旨在改进层状硅酸盐与聚合物的相容性并增进其在聚合物基体中的分散性研究和工业化技术逐步完善,纳米复合材料的性能优点得到了体现。纳米复合PET树脂及其改性材料在塑料啤酒瓶等高阻隔包装物、耐温高强电子电器用工程塑料制件、阻挡紫外线防老化发射红外线阻燃等多功能特殊纤维等制成品中具有重要价值。纳米复合PC、纳米复合PS树脂呈现良好的耐划痕性能,纳米复合PP具有高耐热性能。     

塑料食品包装材料添加剂迁移的数值模拟

应用有限元法建立塑料包装材料添加剂向食品迁移的数学模型和计算仿真模型.以BHT向模拟食品(酒精)的迁移为例,分析了塑料包装材料在共挤和储存过程以及溶胀情况下添加剂的扩散.建立的模型可用来预测混合边界条件下的添加剂迁移,给出了食品包装中添加剂迁移的解决方案,简化了迁移的研究手段.     

玻璃纤维对硬质聚氨酯泡沫塑料增强机理的探讨

研究了硬质聚氨酯泡沫塑料的微观结构形态，通过实验探讨了玻璃纤维对聚氨酯泡沫塑料的增强作用，并分析了增强泡沫塑料的压缩破坏机理。     

陶瓷材料的超塑性

虽然陶瓷材料在本质上是一种脆性材料；然而研究已表明细晶陶瓷材料具有超塑性，在高温下能产生很大的拉伸形变．本文综述了超塑性的特征和Y2O3稳定四方ZrO2多晶体这种典型的超塑性陶瓷材料的形变机理，形变特征以及动态晶粒生长、玻璃相和产生孔穴对其超塑性形变的影响，此外，还总结了其他陶瓷材料，包括Al2O3、Al2O3－Y2O3稳定四方ZrO2、纳米陶瓷和玻璃陶瓷的超塑性行为和特征．     

Kohlenstoff-Fäden und deren Verwendung in Verbundwerkstoffen

Carbon fibres and carbon fibre composite materials. Carbon fibres are a new reinforcement for high performance composite materials. Their most interesting property is the high Young's modulus. The tensile strength of carbon fibres exceeds 200 kp/mm², the Young's modulus 50,000 kp/mm². Carbon fibre reinforced plastics are mainly used where high stiffness is needed. In most cases, carbon fibre composite components are manufactured by filament winding burt also by lamination and moulding. Data about the different processes for the production of carbon fibres as well as mechanical properties are given. In addition to the different manufacturing methods of composite materials a survey about the today applications is given.     

Möglichkeiten der Geruchsmessung und ‐minderung bei Naturfaserverbunden

Possibilities of Odour Measurement and Reduction of Natural Fibre Plastics The critical attitude of the German public concerning environmental questions has also invaded the world of odours. The evaluation and reduction of odours when using plastic materials has gained increasing significance in the last years. The packaging industry that produces wrapping materials for food and other consumables was the first to test for odours. During the last years the automobile industry has also shown increased interest in pinpointing and measuring odours, not only because of the increased usage of natural fibre reinforced plastics in car interiors, but also because of the general increase of concern over clean air. Natural fibre reinforced plastics, besides having advantages compared to glass‐ and carbon reinforced materials (mechanical properties/weight, CO₂‐equilibrium) also have properties that limit their application possibilities. Emissions and unpleasant odours at certain temperature and humidity conditions are of concern. To determine the origin of odour in bonded materials the single component, production step or their combination causing it has to be found. To achieve odour neutrality in plastics is difficult since production methods or additives can only be determined through prolonged testing and where the human nose is still more important than all the physical electronic measuring methods. The origin of odours and their importance for the well being and health of the population is questioned and forces not only the plastics industry to react. The is why both, plastics‐ and automobile industries are trying to react to the tendencies of the market place and it is the goal of the auto industry to deliver the most odour‐neutral new car.     

玻璃纤维增强硬质聚氨酯泡沫塑料的微观结构及破坏机理研究

本文探讨了玻璃纤维增强硬质聚氨酯泡沫塑料的微观结构形态;分析了增强泡沫塑料的拉伸破坏机理;并对增强用最佳纤维长度进行了初步探讨.      

国内外食品接触材料标准及法规概述

本文比较了国内外食品接触材料相关标准及法规现状,阐述了食品接触材料相关法规及其添加剂检测标准现状,并对食品接触材料的研究方向及我国食品接触材料标准体系的发展趋势进行了展望。     

Terahertz spectroscopy to study the orientation of glass fibres in reinforced plastics

We employ terahertz time-domain spectroscopy (THz TDS), a novel, non-destructive testing method, to study the fibre orientation and fibre content in reinforced plastics. The birefringent properties of plastics filled with differing amounts of short glass fibres are measured at frequencies from 100 GHz up to 1 THz. To predict the permittivity of the experimentally examined composite materials, we use an effective medium theory first introduced by Polder and van Santen. On the basis of the measured data and this model, we deduce the additive content ξ, the preferential orientation of the fibres φ and the fraction of orientated fibres a. Our findings agree well with corresponding mold flow simulations performed with commercially available software.     

热塑性饱和聚酯塑料的阻燃

介绍了热塑性饱和聚酯阻燃的机理，适用阻燃剂的种类及其聚酯阻燃最新的技术发展动向，讨论了不同的阻燃聚酯加工及其性能的影响，并以此分析了设计聚酯阻燃塑料配方的关键所在，给出了几种适用于ＰＥＴ，ＰＢＴ塑料的阻燃配方实例。     

Plastic parts with a good electromagnetic shielding effect in the high frequency range

The methods of making plastics impermeable to high frequency electromagnetic waves are by the incorporation of electrically conducting additives or the application of a conducting coating. This paper reviews these procedures and describes some new technology.     

Electron emission and acoustic emission from the fracture of graphite/epoxy composites

In past studies it has been shown that the fracture of materials leads to the emission of a variety of species, including electrons, ions, neutral molecules, and photons, all encompassed by the term fracto-emission (FE). In this paper we examine electron emission (EE) from the fracture of single graphite fibres and neat epoxy resin. We also combine measurements of EE with the detection of acoustic emission (AE) during the testing of graphite-epoxy composite specimens with various fibre orientation. The characteristics of these signals are related to known failure mechanisms in fibre-reinforced plastics. This study suggests that by comparing data from AE and FE meausrements, one can detect and distinguish the onset of internal and external failure in composites. EE measurements are also shown to be sensitive to the locus of fracture in a composite material.     

Improved anti-oxidation properties of electrospun polyurethane nanofibers achieved by oxyfluorinated multi-walled carbon nanotubes and aluminum hydroxide

Polyurethane fibers were fabricated using an electrospinning method with aluminum hydroxide and multi-walled carbon nanotubes (MWCNTs) as flame-retardant additives to improve the thermal oxidation stability of the polyurethane fibers. The MWCNTs were incorporated into the polyurethane fibers after oxyfluorination treatment to improve the dispersivity and compatability. The thermal properties and anti-oxidation stabilities of these polyurethane fibers were investigated under nitrogen and oxygen flows from room temperature to 600 °C to determine the effects of the MWCNTs and aluminum hydroxide additives. The aluminum hydroxide acted as an energy storage tank by releasing water, resulting in an endothermic reaction. The MWCNTs promoted the formation of a charred layer that acted as a protective film to prevent the decomposition of the polyurethane by oxygen radicals. The flame-retardant properties were also improved by an enhanced gel-type structural network generated by the MWCNTs. The integral procedure decomposition temperature and activation energy increased significantly, indicating that the flame-retardant properties of the polyurethane fibers improved. These results are attributed to the aluminum hydroxide, MWCNT additives, and the oxyfluorination treatment.     

Optimization of CFRP laminate dynamic properties using combinations of short/continuous fibres and stiff/flexible resin matrices

High volume fraction carbon fibre-reinforced plastics (CFRPs) have a stiffness-to-weight ratio much greater than some conventional metallic materials but the material damping is low. Damping may be increased by the use of short fibres or a matrix material with high dissipation. Experimental and theoretical studies are described which show that a lamina can be made which has high damping; the effects of lamina properties on those of the laminate have been investigated. The effects of fibre length, matrix type and fibre orientation have been assessed with the objective of optimizing the dynamic properties of laminated CFRP plates using combinations of short/continuous fibres and conventional/highly dissipative resin matrices.     

Determination of the fibre orientation in composites using the structure tensor and local X-ray transform

Computed tomography is a non-destructive testing technique based on X-ray absorption that permits the 3D-visualisation of materials at micron-range resolutions. In this article, computed tomography is used to investigate fibre orientation and fibre position in various fibre-reinforced materials such as ceramic matrix composites, glass fibre-reinforced plastics or reinforced concrete. The goal of this article is to determine the quantitative orientation of fibres in fibre-reinforced materials. For this purpose, a mathematical technique based on the structure tensor is used to determine the local orientation of fibres. The structure tensor is easy to implement and results in a fast algorithm relying solely on local properties of the given reconstruction. In addition, the local X-ray transform is used to denoise fibres and to segment them from the matrix.