Polymer composite structures fibrous composites

Tobolsk AV (1960) Properties and structure of polymers, John WUey, New York, p 166 Kolarik J (1987) In High modulus polymer fibers and fibrous composites. Academia Press (Czech), Prague, p 10... 

The structural variety of the compounds that form fibers is as diverse as their chemistries. From glasses (fiberglass), and partially crystalline materials (carbon), to special three-dimensional arrays, including polymers, the small, elongate solids may have aspect ratios up to 5000. From our research and compilation (Appendices 1, 2) we noted many mineral and synthetic compounds that have structures characterized by basic linear units. Amphi-boles, the major mineral group mined as asbestos, are characterized as doublechain structures. Many of the minerals in Appendix 1 are polymorphic (di-or trimorphs), and where one member of a mineral series has been described as fibrous the others in the same series are likely to be able to grow as fibers as well. Probably all compounds with similar structures and compositions, mineral or synthetic, can form fibers, even though they are not presently listed. It is also clear that fibrous formation is not confined to compounds with linear structural units indeed the variety of crystalline structure patterns is remarkably diverse. 

Fibrous composites are a relatively new technology and there are too many material and structural variables to discuss fully all the details of their mechanical behaviour. Therefore, the present chapter will concentrate on certain categories of fibre reinforced composites, all with polymer matrix systems. 

Composites are engineered materials that contain two or more constituents with different properties that remain distinct from one another within the structure. POCs are a subset of the larger polymer composites group. The increased synthesis of POCs with different additives is necessary to satisfy the industrial demand that cannot be fulfilled by pure polymers. Additive materials can be classified as micro-and nanofillers depending on the applications of the composites. The fillers may be further subdivided as natural (plant fibers) or synthetic (glass fibers, CNT, etc.), different shapes (long or short length), flaky, fibrous, and spherical or disk-like [6]. The conventional addition of filler materials lowers the cost and improves the... 

Composites from natural cellulose fibers or other fibrous components are containing conventionally polyolefin or poly (vinyl chloride) fibers. Molded composite structures may contain up to 50% of binder polymer. One of the limitations of conventional articles is their lack of biodegradability when composted, which is due to the nature of the binder polymer used (32). 

It is not uncommon for there to be as many as 20 or more additives in one polymer, all present in relatively small amounts, but nevertheless essential to ensure that the performance of the base polymer is acceptable for a particular end use. Many products are blends of two or more polymers or comprise two or more materials combined in a strategic way. For example, packaging materials commonly have a sandwich structure of three or four different polymers polymer composites are an important class of engineering materials containing substantial amounts of particulate or fibrous reinforcing agents. 

A decade ago, it was believed that the most common polymer composites, comprising about 30% glass fibers, would replace the nanocomposites having as reinforcement only 2 to 5 wt% nano-sized minerals. Unfortunately, this expectation turned out to be false [5]. For this reason, researchers started to look for alternative ways to replace classical glass fibers with natural, biodegradable materials, mostly with fibrous structures. The potential of this approach is demonstrated in [6],... 

Wood, a lignocellulosic polymer composite, contains a fibrous structure of cellulose, hemicellulose, and a three-dimensional network of lignin and several extractives (Table 4.7). Figure 4.18 shows the chemical components of a typical softwood cell wall [650]. 

Cellulose, which is more fibrous than wood flour, is used as a filler for urea and melamine plastics. Melamine dishware is a laminated structure consisting of molded resin-impregnated paper. Starch and soybean derivatives are biodegradable, and the rate of disintegration of resin composites containing these fillers may be controlled by the amount of these fillers present in polymers. 

Many polymeric materials have a fibrous texture in which elongated particles with an ordered internal structure are preferentially aligned parallel to a particular direction termed the fiber axis. Diffraction patterns obtained from such materials contain information about both the particles and the matrix in which they are embedded. This matrix may consist of amorphous polymer of the same or different composition to the particle or may be a liquid. 

Subclass B2 is formed by the so-called structural composites, in which an outspoken mechanical reinforcement is given to the polymer. Subgroup B21 consists of blends of polymers with compatible anti-plasticizers subgroups B22 are the most important the fibre-reinforced polymer systems. The two components, the polymer matrix and the reinforcing fibbers or filaments (glass, ceramic, steel, textile, etc.) perform different functions the fibrous material carries the load, while the matrix distributes the load the fibbers act as crack stoppers, the matrix as impact-energy absorber and reinforcement connector. Interfacial bonding is the crucial problem. 

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