Fiber reinforced polymers production

The fibers or the yarn or rovings made therefrom can be processed to fleeces or mats (non-oriented semi-finished product) and textiles, lattices or meshes (oriented semifinished products) and can be utilized as such e.g. for thermal insulation or as filter materials, or in composites with other materials e.g. for fiber-reinforced polymers, metals or ceramics. Fibers are generally marketed after surface treatment (chemical modification, annealing, smoothing) to optimize their application and processing properties. 

Clear polymer, mol wt 22,000-45,000, mp 283-319. d 1,20 (solution-cast film). Insol in most solvents. Sol in formic acid. Slightly sol in tnfluoroacetic acid. use Industrial fiber fiber-reinforced rubber products. 

Fibers have been widely used in polymeric composites to improve mechanical properties. Cellulose is the major substance obtained from vegetable fibers, and applications for cellulose fiber-reinforced polymers have again come to the forefront with the focus on renewable raw materials. Hydrophilic cellulose fibers are very compatible with most natural polymers. The reinforcement of starch with ceUulose fibers is a perfect example of a polymer from renewable recourses (PFRR). The reinforcement of polymers using rigid fillers is another common method in the production and processing of polymeric composites. The interest in new nanoscale fillers has rapidly grown in the last two decades, since it was discovered that a nanostructure could be built from a polymer and layered nanoclay. This new nanocomposite showed dramatic improvement in mechanical properties with low filler content. Various starch-based nano-composites have been developed. 

The presence or absence of a yield stress is of great importance in the molding of filler filled or fiber reinforced polymers, and also for the physical stability of many industrial products. Casson proposed an equation describing the steady state shear flow properties of the suspensions of solid particles in Newtonian liquids (Casson, 1959), so as to easily evaluate yield stresses ... 

Processing techniques used for basalt fibers are similar to the traditional techniques used for glass fibers (fabric, filament, staples, glass fiber-reinforced polymer [GFRP]). Thanks to their excellent properties, basalt fibers are employable in heat-resistant as weU as alkaline-resistant products (containers, pipes, GFRP, materials for thermal insulation). 

All bast (stem) fibers (flax, kenaf, ramie, nettle, hemp, jute) as well as hard fibers (caroa, sisal) are suitable as for reinforcing fibers for natural fiber reinforced polymer composites, if they have a high tensile modulus and sufficient tensile strength. In addition to cultivation site, type and harvest, the properties of natural fibers depend significantly on the fiber extraction method. An extraction to technical fiber grades, i.e. production of bundles with different number of single fibers, is generally sufficient for use in plastics composites. The properties of such extracted fibers may be described as follows ... 

Fiber-reinforced polymer structures are typically laid up by hand, consolidated (compressed together) with the polymer resin matrix material, and cured with heat and pressure. This method is capable of producing uniquely shaped, strong, and lightweight structural pieces. Fiber-reinforced polymers can also be used in mass-production methods thermoplastic materials can be employed to produce many relatively simple shapes that do not call for high strength. Variations on these methods, such as extrusion and pultrnsion, represent combinations of these methodologies. 

Pultrusion. Another method by which thermoplastic fiber-reinforced polymers are produced is pultrusion. In pultrusion, an appropriately designed bundle of continuous fiber strands is drawn through a die along with a molten thermoplastic matrix material. The die serves to consolidate the material combination, and as the matrix material solidifies on exiting the die, a continuous fiber-reinforced structure is produced. Examples of pultruded products include fiberglass rods and reinforced water hoses. 

As the value of fiber-reinforced polymers became apparent and accepted in electrical applications, recreation products, and corrosive environments, these synthetic materials began to penetrate virtually every other market worldwide, from automotive and marine to primary structural elements of aircraft and bridges. Such widespread growth in product applications mandated corresponding growth in materials technology, design approaches, and fabrication processes. 

The focus of this chapter has been to give a general overview of the many manufacturing processes available today for the manufactrrre of fiber reinforced polymer composites. Most of the technologies discussed are subject to continuous improvements as manufacturers from the aerospace, automotive, construction and consumer products industries strive to improve manufacturing costs and overall product quality. 

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