Polymer composites products

The total use of advanced composites is expected to grow to around 250-300 million by 1996. The market sectors for advanced polymer composites are 40% aerospace, 30% recreational, 20% industrial, 4% transport and 6% others in 1987. The fastest growing area is aerospace which, according to actual forecasts, will use up to 65% of the total advanced polymer composites production in 1996. 

Injection molded polymer composite products containing liquids are characterized by minimal residual stresses. Cracking under internal stresses is not evidently characteristic for this type of materials at all. Shrinkage of the articles of inhibited composites depends on the liquid phase content and does not surpass 2-3% for PE- and PA-based materials. 

With CNTs becoming easier to produce and much cheaper to buy, CNT-based manufacturing could potentially overtake that of the carbon fibre industry and result in a number of new commercial polymer composite products. However, there are still many challenges in this area including the development of functionalised CNTs as additives for polymer reinforcement. 

Figure 13.53 Photographs of polymer composite products from NR and PS (author s experiment).

Natural fiber (jute fabric) and industrial wastes are used along with polymer to make composite wood substitute products. In this process, processed fabric of jute fiber and industrial wastes such as fly ash/red mud/marble sluny dust with polymer were synthesized in molds of required length and width. The composite laminates were fabricated with requisite pressure and cured at room temperature. Various products such as full size door shutters and panels can be fabricated and designed according to requirement. The industrial waste-based polymer composite products are comparable to natural wood and thus could be used as a wood substitute for doors, windows, ceilings, flooring, partitions, and furniture, etc. The products are cost-effective and no further maintenance is required. This is an environment friendly product with fruitful utilization of fly ash/red mud/marble slurry dust (Table 22.14). The salient features of the products are ... 

Searching for a use for lignocellulosic agro-residual materials in industry started as an alternative to wood in particleboards. More sophisticated research efforts have taken place in the polymer composite production area [10]. 

There is an increasing movement of scientists and engineers who are dedicated to minimizing the environmental impact of polymer composite production. LCA is of paramount importance at every stage of a product s life, from initial synthesis through to final disposal and a sustainable society needs environmentally safe materials and processing methods. With an internationally recognized team... 

The importance of polymer composites arises largely from the fact that such low density materials can have unusually high elastic modulus and tensile strength. Polymers have extensive applications in various fields of industry and agriculture. They are used as constructional materials or protective coatings. Exploitation of polymers is of special importance for products that may be exposed to the radiation or temperature, since the use of polymers make it possible to decrease the consumption of expensive (and, sometimes, deficient) metals and alloys, and to extent the lifetime of the whole product. 

Crimp. The tow is usually relaxed at this point. Relaxation is essential because it gready reduces the tendency for fibrillation and increases the dimensional stabiUty of the fiber. Relaxation also increases fiber elongation and improves dye diffusion rates. This relaxation can be done in-line on Superba equipment or in batches in an autoclave. Generally saturated steam is used because the moisture reduces the process temperatures required. Fiber shrinkage during relaxation ranges from 10 to 40% depending on the temperature used, the polymer composition used for the fiber, and the amount of prior orientation and relaxation. The amount of relaxation is also tailored to the intended apphcation of the fiber product. 

Economic Benefits. The traditional costs of a product include raw materials, processing, overhead, and so forth. Designers and engineers considering potential composite appHcations cannot compare material costs only. Polymer composites, except for inexpensive fillers and small amounts of additives, consist mostly of resin and reinforcement, whose materials costs are usually higher than traditional materials. 

J. A. Youngquist, A. M. Krzysik, and J. H. Muehl, Wood Fiber Polymer Composites Fundamental Concepts, Processes, and Material Options (M. P. Wolcott, ed.), U.S. Forest Products Society, Wisconsin, p. 79 (1993). 

Analog-to-glass fibers silanes are used as coupling agents for natural fiber polymer composites. For example, the treatment of wood fibers with product A-175 improves wood dimensional stability [53]. In contrast, a decrease of mechanical properties was observed for coir-UP composites after a fiber modification with di-chloromethylvinyl silane [54]. The treatment of mercer-... 

The development of new products (which may be mixtures rather than pure materials, as for example a polymer composition, or a metallic alloy) also... 

The influence of changes in these other variables on MWD in a homopolymerization has not yet been tested, but whatever perturbations are introduced to the feed in a radical polymerization in a laboratory-scale CSTR, they are unlikely to introduce dramatic changes in the MWD of the product because of the extremely short life-time of the active propagating chains in relation to the hold-up time of the reactor. This small change in MWD could be advantageous in a radically initiated copolymerization where perturbations in monomer feeds could give control over polymer compositions independent of the MWD. This postulate is being explored currently. 

The development of polymers and polymer composites will benefit greatly from the availability of better computers and better algorithms. The inherent properties of a polymer are governed by the chemical structure of its molecules, but the properties of a finished polymer product are affected by the interactions... 

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