Solid, reshaped

Like glass recycling, the process of recycling aluminum is fairly simple. Previously used aluminum packaging is shredded into small solid pieces, which are then melted inside a furnace to produce a thick liquid. At this point, the molten aluminum is identical to raw aluminum being processed for the first time. It is reshaped and reprocessed to create new products and packaging. 

Despite all our efforts of recent years, then, health care costs continue to increase... There is undoubtedly waste in the health care system, but no solid proposals have been advanced to recapture the 100 billion, plus or minus, that some believe can be saved. I believe that we will not reshape our national health policy agenda unless and until we achieve a broad consensus on the key issues. Do the American people, for example, desire to ensure access to health care for the entire population In that case they must agree to pick up a sizable additional tab, which they have thus far avoided. 

Unlike thermoplastics, which are simply melted, thermoset resins chemically react from low-viscosity liquids to solid materials during processing, a process termed curing. Structurally, thermosets differ from thermoplastics because of the presence of cross-links in the former, which means that thermosets cannot be reshaped or recycled once the chemical reaction occurs. One advantage of thermosets vs. thermoplastics is that wetting the filler becomes much easier with a low-viscosity material. By far the most common thermoset composite is automobile tires, which consist of a polymer made from styrene and butadiene monomers and carbon-black filler. The actual recipe used is much more complicated, and can include other monomers or polymers, as well as other fillers. In the absence of filler, the cured resin is rubbery at room temperature, which makes tires a... 

The properties of block copolymers differ from those of a blend of the correponding homopolymers or a random copolymer (Chapter 7) with the same overall composition. An important practical example is the ABA-type styrene/butadiene/styrene triblock copolymer. These behave as thermoplastic elastomers. Ordinary elastomers are cross-linked by covalent bonds, e.g., vulcanization (see Chapter 2) to impart elastic recovery property, as without this there will be permanent deformation. Such cross-linked rubbers are therraosets and so cannot be softened and reshaped by molding. However, solid thermoplastic styrene/butadiene/styrene triblock elastomers can be resoftened and remolded. This can be explained as follows. At room temperature, the triblock elastomers consist of glassy, rigid, polystyrene domains... 

Basically, all methods for producing rayon filaments or fibers depend on solubilizing cellulose, then reshaping it into long-fibered products by extrusion through the small holes of a spinnerette, immediately followed by conversion into solid cellulose. Although there are a number of ways in which this can be done, the viscose rayon process is by far the most important and widely practiced. 

Polymer matrix materials are categorized into thermoplastics and thermosets. Thermoplastics soften and melt above a specific temperature and become solid when cooled. They can be formed by repeated heating and cooling. In contrast, thermosets normally cure by irreversible chemical reaction (between two components, a resin and a hardener, for example, for epoxy (EP)) and chemical bonds are formed during the curing process. This means that a thermoset material cannot be melted and reshaped once it is cured. Thermosets are the most common matrix materials used for FRP composites in construction nowadays. The most common thermosets are unsaturated polyester (UP), EP, and vinylester (VE) [9]. Because of their organic material nature, aU of these matrix materials are sensitive to elevated temperatures and fire. 

One of the major application and commercial properties of polymers is the capacity of the solid to be reshaped under temperatures low in comparison to the molding temperatures of metals. A listing of several thermal forming processes for plastics is given in Table 10. 

Plastics are polymeric solids that can be formed into various shapes, usually by the application of heat and pressure. There are several types of plastics. Thermoplastics can be reshaped. For example, plastic milk containers are made from the thermoplastic polymer polyethylene. These containers can be melted down and the polymer recycled for some other use. In contrast, a thermosetting plastic (also called a thermoset) is shaped through irreversible chemical processes and, therefore, cannot be reshaped readily. Another type of plastic is the elastomer, which is a material that exhibits... 

Polymers which form 3D network solids are thermosetting and decompose when heated and thus cannot be reshaped once they have set. A selection of the common polymers is listed in Table 11.3. 

Thermoplastics, by the very definition of the word, denotes polymeric materials which can be made to soften and take on new shapes by the application of heat and pressure. In their original raw material form, themu iastics are available in solid state as chips, granules, or powder. These are melted and reshaped to form various plastic products. For details regarding engineering aspects and properties of plastics, readers could refer to some of the available hancRxwks [168-171]. 

FIGURE 21.8 SEM micrograph of the extremity of a eombined AFM-SECM probe fabrieated by reshaping a Pt-in-epoxy disk microeleetrode using FIB, to form a sharp epoxy cone to be used as an AFM tip. (From Davoodi, A. et al, Electrochem. Solid State Lett, 8, B21, 2005. With permission.)... 

Mahon PJ (2009) Convolutive reshaping with applications for voltammetry. J Solid State Electrochem 13(4) 573-582. doi 10.1007/sl0008-008-0664-6... 

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