Products, fiber-reinforced polymer composites

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 ... 

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. 

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. 

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. 

Kitano, T. Nagatsuka, Y. Lee, M Kimijima, K Oyanagi, Y. (1994). A Method for the Production of Randomly Oriented Fiber Reinforced Thermoplastic Composites and Their Mechanical Properties. Seikei-Kakou (the Journal of Japanese Society of Polymer Processing, in Japanese), Vol.6, No.l2, pp. 904-915 ISSN 0915-4027... 

Hierarchy can be described in analogy to rope (stretched polymer molecules in domains that make up nanofibers, combined to microwhiskers, bundled into fibers that are spun into yarn that is twined to make up the rope). Wood and tendon are biological examples that have six or more hierarchical levels. Compared to these, fiber-reinforced matrix composites made up of simple massive fibers embedded in a metallic, ceramic, or polymer matrix are primitive. Hierarchical inorganic materials, as discussed in Chapter 7, can be made with processes for fractal-like solid products spinodal decomposition, diffusion-limited growth, particle precipitation from the vapor, and percolation. Fractal-like solids have holes and clusters of all sizes and are therefore hierarchical if the interactions... 

Schirp A et al (2006) Production and characterization of natural fiber-reinforced thermoplastic composites using wheat straw modified with the fungus Pleurotus ostreatus. J Appl Polym Sci 102(6) 5191-5201... 

Pineapple (Ananas comosus), which is native to Brazil, is a tropical plant with leaves rich in cellulose. Being relatively inexpensive and abundantly available, pineapple fiber may be considered for polymer composite reinforcement. Today, pineapple leaves are a by-product of pineapple cultivation [3]. Devi et al. [43] investigated the dynamic mechanical behavior of pineapple leaf fiber-reinforced polyester composites. Threepopnatkul et al. [44] studied the effects of fiber surface treatments on the performance of pineapple leaf fiber-carbonate composite. 

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