Fibers in composites

In contrast, there is also current interest in investigating PAN-based fibers in low thermal conductivity composites [62], Such fibers are carbonized at low temperature and offer a substitute to rayon-based carbon fibers in composites designed for solid rocket motor nozzles and exit cones. 

Yet, the development of processing and modification methods is not finished. Further improvements need to be expected so that it might be possible to substitute technical fibers in composites even more widely. Natural fibers are reusing raw materials and they are recyclable. When recognizing the need for recycling and preserving natural resources, such a substitution is very important. 

Several amphiboles are fibrous and fibers from them can be processed to give heat-insulating materials. Among these are tremolite and crocidolite. These minerals are also used as fibers in composites. 

Inorganic polymers are widely employed in the construction and building businesses, as abrasives and cutting materials, as fibers in composites, as coatings and lubricants, and as catalysts. They also serve as the basis of rocks and soils. 

The organofunctional portion bonds with the resin in the adhesive or the organic medium, and the silane portion bonds to the inorganic or substrate surface. Silane coupling agents are commonly used between the adhesive and the adherend, between resin matrix and reinforcing fibers in composites, and between resin matrix and mineral fillers in compounds. The resulting interface provides... 

Applications. Nondestructive method of determination of carbon fiber reinforced composites. Damage of woven fiber reinforced composites, distribution of filler due to flow in molding techniques, distribution of fiber in composite, and dispersion of carbon black are examples characterizing potential applications of the method. 

LCP content (or the glass fiber) in composite is 30 wt-%. Source Kiss, 1987. 

The utility of oxide fibers in composites can also be enhanced by using heat treatments to produce in-situ interface coatings. For instance, Nextel 312 (which contains 14 percent... 

Kevlar fibers are temperature-resistant special fibers used, for instance, in bulletproof vests. The main application of Kevlar is, however, as a reinforcing fiber in composites. One drawback here is the lack of compression strength of the fibers, presumably due at least in part to the mantle-core structures produced by spinning from sulfuric acid solutions. Helical kink band defects appear when Kevlar is compressed. Composites with Kevlar as a reinforcing fiber therefore do not fail due to rupturing of the fibers or matrix, but rather due to an elastic fault caused by shearing forces. 

The fibers are naturally drawn during the production process. The LS and HS fibers serve as filter mediums, catalyst carriers, and reinforcing fibers in composites. They have excellent ablation properties. Their relatively low electrical resistance has led to their use in flexible heating elements and wherever a bendable, nonme-tallic conductor is required. 

The Saffil fiber which contains 4% of silica is produced by the blow extrusion of partially hydrolyzed solutions of some aluminum salts with a small amount of silica, in which the liquid is extruded through apertures into a high velocity gas stream. The fiber contains mainly small 8-alumina grains of around 50 run but also some a-alumina grains of 100 run. The widest use of the Saffil type fiber in composites is in the form of a mat which can be shaped to the form desired and then infiltrated with molten metal, usually aluminium alloy. It is the most successful fiber reinforcement for metal matrix composite. 

Figure 5. Load vs. displacement graph of pitch fiber in composite CC-A21. Sample loaded in fiber axis direction.

R. M. Gill, Carbon Fibers in Composite Materials, Iliffe Books, London, 1972. 

The most obvious area of application are as fibers for composites. There are a number of metallic whiskers that are employed as high-strength fibers in composites. These composites are among the strongest known. The mechanical and electrical properties of the fibers also need to be studied. It is possible that the... 

Wang and Chung [186] have observed apparent negative electrical resistance in interfaces between layers of carbon fibers in composite material in a direction perpendicular to the fiber layers. 

Fiber content Amount of fiber in composite, expressed as % volume or % mass. 

Summarizing, it is necessary to emphasize the increase of role of the renewable bast fibers in replacing inorganic filler and reinforcement materials, e.g., glass fibers in composites. 

Natural fibers are preferred to synthetic fiber in composites because of the many benefits of the latter it requires less energy for fiber processing, it is a nonhazardous, replenishable resource, is biodegradable, and has low density and high specific strength, and is cost effective. As plant fibers are hydrophilic, the adhesion between the fibers and hydrophobic polymer matrices is not adequate. To achieve sufficient interfacial bonding, either surface modification of the fiber or plasticization of the fibers is required [18, 58, 59, 96],... 

Using sisal fiber in composites provides several advantages in terms of product design flexibility, noise absorption, insulation impact resistance in a crash followed by weight reduction contributes to saving fuel [154]. 

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