Fibrous woven

Stability and performance of AEM prepared using poly(4-vinyl pyridine-costyrene), quaternized with 1-bromooctane, and deposited on fibrous woven paper was unsatisfactory [189]. Sanchez and coauthors [190] discussed problems related to the use of certain AEMs. They pointed out that the so-called Hoffman degradation that involves attack of a hydroxyl on a-hydrogen in p-position to a quaternary ammonium attached to an aliphatic chain may cause its removal, followed by release of a tertiary amine and formation of a double bond at the end of a broken chain. Attachment of DABCO on short leash prevented chain break due to Hoffman degradation, but release of DABCO and generation of a double bond attached to the chain could take place. Perhaps thermal cross-linking by DABCO of poly(vinyl benzyl chloride) may solve this problem. Sulfonated polymers prepared by polymerization or copolymerization of phosphazene, siloxans, styrene, vinylidene fluoride, and various monomers with aromatic backbones, and possibly with aliphatic spacers, have been used. Various imides as well as PPS, PEK, PEEK, PSU, PEEKK, and PPSU can also be used [190,191]. 

Fibrous Composites. These composites consist of fibers in a matrix. The fibers may be short or discontinuous and randomly arranged continuous filaments arranged parallel to each other in the form of woven rovings (coUections of bundles of continuous filaments) or braided (8). In the case of chopped strand mat the random arrangement is planar. In whisker (needle-shaped crystals or filaments of carbon and ceramics) reinforced materials the arrangement is usually three-dimensional and the resulting composites are macroscopically homogeneous. 

The use of thermal insulation dates back to ancient times, when primitive man used animal skins for clothing and built structures for protection from the elements. Primitive insulation included fibrous materials such as animal fur or wool, feathers, straw, or woven goods. Bricks and stone, while not highl y efficient thermal insulation, provided protection from the elements, reduced the loss of heat from fires, and provided large masses that moderate temperature changes and store heat. 

Fibrous structured catalysts consist of threads that are knitted or woven into fabrics, felts, cloths, and so on or are formed by chemical or mechanical processing of ceramic or metal sheets. Figure 9.2a,b shows typical examples. A review can be found in [66]. 

Nylons belong to the class of polymers known as engineering polymers that is, they are strong, tough, and heat resistant. We can readily extrude and mold nylons to form a wide variety of useful objects, such as tubing, furniture casters, and automotive air intake ducts. Nylons are commonly spun into filaments or fibers. These can be used directly, or braided, or twisted to form threads, yarns, cords, and ropes, which may be further woven to make fabrics. In their fibrous forms, nylons are used in carpets, backpacks, and hosiery. 

Fibrous materials with a high melting point are used to form fire resistant boards and blankets. The fibers are derived from glass minerals or ceramics. They may be woven into cloths and are used as blankets around the object to be protected. 

Recently, scanning electron microscopy has been used in our laboratory to investigate the effects of abrasion on the morphology of fibrous cellulose copolymers (36). For example, cotton cellulose was woven into fabric form (print cloth construction and weight). Cellulose copolymer fabrics were prepared by irradiating a sample of this fabric, followed by copolymerization of the irradiated fabric with a binary mixture of acrylo-... 

In the last 10 years, significant advances in fibrous monolithic ceramics have been achieved. A variety of materials in the form of either oxide or nonoxide ceramic for cell and cell boundary have been investigated [1], As a result of these efforts, FMs are now commercially available from the ACR company [28], These FMs are fabricated by a coextrusion process. In addition, the green fiber composite can then be wound, woven, or braided into the shape of the desired component. The applications of these FMs involve solid hot gas containment tubes, rocket nozzles, body armor plates, and so forth. Such commercialization of FMs itself proves that these ceramic composites are the most promising structural components at elevated temperatures. 

Bast is the inner bark of a plant, composed of the phloem and other fibrous cells. Hard fiber, which comes from leaves, is used mostly for cordage (rope, twine, cord) and the rough fabric used for making sacks and other containers. Soft fiber, which comes from plant stems, is used to make thread and finer fabrics like linen, cotton, and woven hemp. 

In a simple model for this case, which, as in the 3-D case, ignores fiber straightening and anisotropy of the fibrous network, a plane stress version of Eqn. (35) can be developed. As such, it can only be used for plane stress states. Consider the x-y plane to be that in which the fibers are woven or the whiskers are lying. The strain rates in this plane are taken to be homogeneous throughout the composite material and crzz, axz and ayz are taken to be zero. The resulting law is... 

Indeed, materials in a fibrous form have been used by mankind for a long time. Fiber yams have been used for making fabrics, ropes, and cords, and for many other uses since prehistoric times, long before scientists had any idea of the internal structure of these materials. Weaving of cloth has been an important part of most ancient societies. The term fabric is frequently employed as a metaphor for society. One talks of the social fabric or moral fiber of a society, etc. It is interesting to note that an archeological excavation of a 9000-year-old site in Thrkey led to the discovery of a piece of fabric, a piece of linen, woven from the fibers of a flax plant (New York Times, 1993). Normally, archeologists date an era by the pottery of that era. It would appear from this discovery that even before the pottery, there were textile fabrics. There is also recorded use of sutures as stitches... 

Fibers can be made into a variety of very useful product forms. Most of these can be classified under the categories of woven or nonwoven. Most of the woven product forms are based on fibrous yams. Nrat we describe some of these product forms involving yam. 

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