Synthetic fibre glass

The filters used for gas cleaning separate the solid particles by a combination of impingement and filtration the pore sizes in the filter media used are too large simply to filter out the particles. The separating action relies on the precoating of the filter medium by the first particles separated which are separated by impingement on the filter medium fibres. Woven or felted cloths of cotton and various synthetic fibres are commonly used as the filter media. Glass-fibre mats and paper filter elements are also used. 

Polyurethane adhesives are used for bonding wood, plastics, metals and leather. They can bond rubber to rubber, metal, glass or synthetic fibres. 

As might be expected from the heterogeneous nature of their structure, synthetic fibres do not have a clearly defined melting point. Brown Textile Research Journal XXV, 1955, 891) investigated the phenomenon known as second order transition, or also as the glass rubber transition. His method was to record the stiffness of the fibre which is the load required to produce 1 per cent elongation multiplied by 100 divided by the denier of the sample at various temperatures. 

Recipes for the positive and negative active masses are well known and are aimed at achieving a positive mass that is as porous as possible and a negative mass that can withstand the formation process, which can involve very high temperatures. The majority of separators are pure glass-mats, but present research is focusing on the use of synthetic fibre additives to make manufacturing simpler and cheaper. 

A wide range of physical properties can be achieved by varying the molecular weight of the epoxy component, the type of hardener and by adding catalysts and plasticizers. Epoxy polymers can be reinforced with glass, carbon and synthetic fibres prior to curing to increase strength and flexibility. 

Many synthetic fibres are available such as organic fibres based on petrochemicals. The most common of these are polyester, polyamide, acrylic and modacrylic, polypropylene, polyvinylalcohol, the segmented, high elastic polyurethanes (elastanes) and high performance fibres like glass, carbon, aramid, LCP, UHMWPE and PBO. 

Commonly used natural fibres are cotton and silk, but also included are the regenerated cellulosic fibres (viscose rayon) these are widely used in non-implantable materials and healthcare/hygiene products. A wide variety of products and specific applications utilise the unique characteristics that synthetic fibres exhibit. Commonly used synthetic materials include polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, glass, and so on. 

Fibre-reinforced concrete is a mixture of concrete with a dispersion of discontinuous fibres. The fibres may be steel fibres, synthetic fibres (micro-synthetic or macro-synthetic), glass fibres (alkali-resistant only, AR glass fibres) or natural fibres. 

Surface veils are lightweight thin surfacing materials usually constructed from swirl mats either in glass or from a synthetic fibre. Their main use is to act as a decorative surface, shielding from view the texture of the underlying structural reinforcement. But they also may be used in conjunction with gel coats for added support. C-glass surface veils are... 

Natural fibres such as flax, hemp, silk, jute, sisal, kenaf, cotton, etc are being used to reinforce matrices mainly thermoplastics and thermosets by many researchers. The principal synthetic fibres in commercial use are various types of glass, carbon, or aramid although other fibres, such as boron, silicon carbide, and aluminium oxide, are used in limited quantities. All these fibres can be incorporated into a matrix either in continuous lengths or in discontinuous (short) lengths. Both these fibres have some advantages and disadvantages. 

Natural fibres can be derived either from plants (such as flax or hemp), produced by animals (such as silk or spider silk) or from minerals (such as asbestos). Table 6.1 shows the comparison of selected physical properties between natural fibres and synthetic fibres. Although the mechanical properties of natural fibres are very much lower than those of conventional synthetic fibres, such as glass or carbon fibres. 

Although natural fibres are highly comparable to conventional glass fibres on a per weight basis, the major drawback arises from the inherent variabUity of natural fibres [22]. Natural fibres can vary in terms of their dimensions and mechanical properties, even within the same cultivation. This situation is different from synthetic fibres, which can be manufactured uniformly (e.g., Toray s T700S carbon fibre has only a variability of 10% in its tensile strength and modulus [Commercial documentation - No AQ.866-9 (September 2003), Personal communication], 3% in its diameter). All natural fibres are hydrophilic in nature due to the presence... 

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