Under-reinforced

At one point in the meeting. Smith asked Brown to validate or endorse his structural concept, one which, to Brown, appeared workable by surface cosmetic and general conceptual standards, but did not have the underlying reinforcement fibers oriented to react to any of the critical load conditions this bicycle frame would see in use. In response. Brown stated that he apparently did not have the same insight and awareness of the problem as [Smith] and that [Smith s] understanding of the dynamics and intricacies of his concept surpassed [Brown s] own. Brown offered to refrain from commenting until he understood the process as well as its author. ... 

When the polymeric component forms the continuous phase, spheres, cylinders, or platelets may be added, as illustrated under reinforced polymers. The fiber composites are the most highly researched, as far as different modes of mixing are considered. The filaments may be continuous or discontinuous, or oriented or random in the matrix, with many subclasses of partial orientation possible (not shown). The tape composites are interesting since in some quarters these may be considered a two-dimensional analog of the highly oriented, continuous fibers embedded in a plastic matrix. The reinforced elastomers differ from the reinforced plastics in two ways the mechanical properties of the polymeric substrate, and the size of the reinforcing particles with respect to polymer chain dimensions. Because of the poor properties often obtained, it is rare to see a research paper on large particles dispersed in an elastomer. 

During injection into the gap, there will be some seepage of resin into the underlying reinforcement. Seepage will be more significant for materials with relatively large transverse permeability, such as random mats, than for those with smaller permeabilities such as woven or stitched continuous fibre reinforcements. This transverse flow has been modelled a number of times in the context of flow through distribution media, for example... 

LORUS is also used for inspection of piping that has been on supports or sleepers for some time, to see whether corrosion has developed at the contact points. But the technique can also be used for corrosion detection under insulation, inspection of pipelines at dike and road crossings, nozzle reinforcement pads or craek detection in suspension systems for railway cars. 

Dry chlorine has a great affinity for absorbing moisture, and wet chlorine is extremely corrosive, attacking most common materials except HasteUoy C, titanium, and tantalum. These metals are protected from attack by the acids formed by chlorine hydrolysis because of surface oxide films on the metal. Tantalum is the preferred constmction material for service with wet and dry chlorine. Wet chlorine gas is handled under pressure using fiberglass-reinforced plastics. Rubber-lined steel is suitable for wet chlorine gas handling up to 100°C. At low pressures and low temperatures PVC, chlorinated PVC, and reinforced polyester resins are also used. Polytetrafluoroethylene (PTFE), poly(vinyhdene fluoride) (PVDE), and... 

Two approaches have been taken to produce metal-matrix composites (qv) incorporation of fibers into a matrix by mechanical means and in situ preparation of a two-phase fibrous or lamellar material by controlled solidification or heat treatment. The principles of strengthening for alloys prepared by the former technique are well estabUshed (24), primarily because yielding and even fracture of these materials occurs while the reinforcing phase is elastically deformed. Under these conditions both strength and modulus increase linearly with volume fraction of reinforcement. However, the deformation of in situ, ie, eutectic, eutectoid, peritectic, or peritectoid, composites usually involves some plastic deformation of the reinforcing phase, and this presents many complexities in analysis and prediction of properties. 

High performance composites may be laminates wherein veils of carbon fiber ate treated with an epoxy resin, stacked up to the desired final product thickness, and then laminated together under heat and pressure (see Composite materials Carbon and graphite fibers). Simply mixing together carbon or glass fibers and polymeric resins to form a reinforced plastic leads to a composite material, but this is not a laminate if not constmcted from discrete phes. 

During the press operation, which is actually a form of compression mol ding, the resin-treated laminate pHes are heated under pressure and the resins cured. The initial heating phases cause the resin to melt and flow into voids in the reinforcing ply and bond the individual pHes together. The appHed heat simultaneously causes the resin to polymerize and eventually to cross-link or gel. Therefore, resin viscosity reaches a minimum during the press cycle. This is the point at which the curing process becomes dominant over the melt flow process. Dynamic mechanical and dielectric analyses (11) are excellent tools for study of this behavior. 

Strength. Prediction of MMC strength is more compHcated than the prediction of modulus. Consider an aligned fiber-reinforced metal-matrix composite under a load P in the direction of the fibers. This load is distributed between the fiber and the matrix ... 

Liquid Fabric Softeners. The principal functions of fabric softeners are to minimize the problem of static electricity and to keep fabrics soft (see Antistatic agents). In these laundry additives, the fragrance must reinforce the sense of softness that is the desired result of their use. Most fabric softeners have a pH of about 3.5, which limits the materials that can be used in the fragrances. For example, acetals cannot be used because they break down and cause malodor problems in addition, there is the likelihood of discoloration from Schiff bases, oakmoss extracts, and some specialty chemicals. Testing of fragrance materials in product bases should take place under accelerated aging conditions (eg, 40°C in plastic bottles) to check for odor stabiUty and discoloration. 

Gel coats are pigmented polyester coatings appHed to the mold surface and are an integral part of the finished laminate. Gel coats are used widely on hand lay-up and spray-up parts to enhance surface aesthetics and coloration as weU as to provide an abrasion-resistant waterproof surface that protects the underlying glass-reinforced stmcture. 

Proprietary blend formulations based on polysulfone, polyethersulfone, and polyphenylsulfone are sold commercially by Amoco Corporation to meet various end use requirements. The blends based on polysulfone are sold under the MINDEL trademark. A glass fiber-reinforced blend based on PES is offered under the trade name RADEL AG-360. This offers most of the performance characteristics of 30% glass fiber-reinforced polyethersulfone but at a lower cost. Two blend product lines are offered based on PPSF. These are designated as the RADEL R-4000 and R-7000 series of products. The former is a lower cost alternative to RADEL R PPSF homopolymer offering most of the performance attributes unique to PPSF. The R-7000 series of resins have been formulated for use in aircraft interiors for civil air transport. They exhibit a very high degree of resistance to flammabihty and smoke release. 

In concrete, triethanolamine accelerates set time and increases early set strength (41—43). These ate often formulated as admixtures (44), for later addition to the concrete mixtures. Compared to calcium chloride, another common set accelerator, triethanolamine is less corrosive to steel-reinforcing materials, and gives a concrete that is more resistant to creep under stress (45). Triethanolamine can also neutralize any acid in the concrete and forms a salt with chlorides. Improvement of mechanical properties, whiteness, and more even distribution of iron impurities in the mixture of portland cements, can be effected by addition of 2% triethanolamine (46). Triethanolamine bottoms and alkanolamine soaps can also be used in these type appUcations. Waterproofing or sealing concrete can be accompUshed by using formulations containing triethanolamine (47,48). 

Reinforced Thermoplastic Sheet. This process uses precombined sheets of thermoplastic resin and glass fiber reinforcement, cut into blanks to fit the weight and size requirements of the part to be molded. The blanks, preheated to a specified temperature, are loaded into the metal mold and the material flows under mol ding pressure to fiU the mold. The mold is kept closed under pressure until the temperature of the part has been reduced, the resin solidified, and demolding is possible. Cycle time, as with thermosetting resins, depends on the thickness of the part and the heat distortion temperature of the resin. Mol ding pressures are similar to SMC, 10—21 MPa (1500—3000 psi), depending on the size and complexity of the part. 

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