Composite Materials Production Processes

There are several production processes of composite materials, among which the most widespread are the following  

Vacuum infusion (resin infusion under flexible tooling, RIFT) 

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This process of conversion from a metals production environment to a composite materials production environment is much more involved than just laminate layup and curing. Issues of inspection arise to make certain that the composite product is put together properly. Some of those inspection techniques are much more complicated than they were for a metallic structure. Truly, the picture is not totally rosy for composite materials. It would be quite unrealistic to say (1) there are no problems and (2) composite materials are absolutely the best way to go. 

This chapter will consider contemporary aspects of the classihcation, composition, properties, production, processing, and consumption of the depot lipids of land animals. For a more detailed discussion, the reader is referred to the recent comprehensive animal fats text (1). Additional discussions of the material covered here, and related topics, are found in excellent contemporary texts (2-4). Some consideration of greases will also be included here, because these are largely handled by and traded within the animal fats sector of the lipid industry. Discussions of mUk-fats and hsh oils can be found elsewhere in this series. 

Colomban, P, Menet, M., Mouchon, E., Courtemanche, C., and Parlier, M., Composites ceramique-ceramique multicouches elabo-res en utihsant un precur-seur d interface et un precurseur de matrice [Multilayer fiber-matrix ceramic composite material and process for its production], French Patent nos. (ONERA) FR 2672283 (Feb. 4, 1991) and EP 0 498 698 (Jan. 29, 1992), and U.S. Patent no. 07/830.904. 

S. Djokic, Deposition products, composite materials and processes for the production thereof, US Patent 7,300,673 (2007). 

Newman, S. Introduction to composite materials technology mass production techniques. In Composite Materials Technology-Processes and Properties Mallick, P.K., Newman, S., Eds. Hanser Publishers New York, 1990 10-24. 

U.S. Pat. Nos. 6,117,924 [92] and 6,984,676 [93] (both by Crane Plastics Co., TimberTech) describe an extrusion process of making a cellulose-plastic composite material the process includes a significantly higher compression ratio through which the extrusion product must pass. Plastics include polyethylene, polypropylene, PVC, LDPE, and other commercial polymers. 

To avoid committing ourselves to specific applications too early, we set out to familiarise ourselves with the new material and understand it as fully as possible. We therefore tried out various chemical compositions and production processes and dispersion in various media... 

RIM is a relatively new process. It can be used for processing of unfilled resin as well as fibre-reinforced composites. The process was discussed in Chapter 1. The process is similar to RTM (discussed previously) with some variation in mould release and reinforcement sizing to optimise resin chemistry with the process. The low viscosity reactant systems facilitate composite materials production, so-called structural RIM composites [19, 20] in which continuous fibre reinforcement mats are placed in mould cavities before injection. Capital investment and operational cost in RIM are therefore much less than those for conventional injection moulding. Polymerisation of a monomer is usually initiated by heat. However, in RIM, the polymerisation is initiated by impingement mixing (not by heat). Hence it is possible to activate polymerisation at relatively low temperature. Unlike RTM, in RIM the mould-fill times are very low ( 1 s) and a cycle time of <60 s is typical. The process is used for the rapid and automated production of large, thin and complex-shaped parts. 

LPC Product Quality. Table 10 gives approximate analyses of several LPC products. Amino acid analyses of LPC products have been pubhshed including those from alfalfa, wheat leaf, barley, and lupin (101) soybean, sugar beet, and tobacco (102) Pro-Xan LPC products (100,103) and for a variety of other crop plants (104,105). The composition of LPCs varies widely depending on the raw materials and processes used. Amino acid profiles are generally satisfactory except for low sulfur amino acid contents, ie, cystine and methionine. 

The reinforcing ply acts as the carrier for the plastic resin during intermediate processing steps known as saturation and B-staging. It is this ply that together with the resin makes a laminate a composite material, and the layering of these pHes that makes the final product a laminate. 

Phenohc resins (qv), once a popular matrix material for composite materials, have in recent years been superseded by polyesters and epoxies. Nevertheless, phenohc resins stiU find considerable use in appHcations where high temperature stabiHty and fire resistance are of paramount importance. Typical examples of the use of phenoHc resins in the marine industry include internal bulkheads, decks, and certain finishings. The curing process involves significant production of water, often resulting in the formation of voids within the volume of the material. Further, the fact that phenoHcs are prone to absorb water in humid or aqueous conditions somewhat limits their widespread appHcation. PhenoHc resins are also used as the adhesive in plywood, and phenohc molding compounds have wide use in household appliances and in the automotive, aerospace, and electrical industries (12). 

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). 

All processes may be classified as batch, continuous, or semibatch depending on how materials are transferred into and out of the system. Also, the process operation may be characterized as unsteady state (i.e., transient) or steady state, depending on whether the process variables (e.g., pressure, temperature, compositions, flowrate, etc.) are changing with time or not, respectively. In a batch process, the entire feed material (i.e., charge) is added instantaneously to the system marking the beginning of the process, and all the contents of the system including the products are removed at a later time, at the end of the process. In a continuous process, the materials enter and leave the system as continuous streams, but not necessarily at the same rate. In a semibalch process, the feed may be added at once but the products removed continuously, or vice versa. It is evident that batch and semibatch processes are inherently unsteady state, whereas continuous processes may be operated in a steady or unsteady-state mode. Start-up and shut-down procedures of a steady continuous production process are examples of transient operation. 

The physicochemical properties of carbon are highly dependent on its surface structure and chemical composition [66—68], The type and content of surface species, particle shape and size, pore-size distribution, BET surface area and pore-opening are of critical importance in the use of carbons as anode material. These properties have a major influence on (9IR, reversible capacity <2R, and the rate capability and safety of the battery. The surface chemical composition depends on the raw materials (carbon precursors), the production process, and the history of the carbon. Surface groups containing H, O, S, N, P, halogens, and other elements have been identified on carbon blacks [66, 67]. There is also ash on the surface of carbon and this typically contains Ca, Si, Fe, Al, and V. Ash and acidic oxides enhance the adsorption of the more polar compounds and electrolytes [66]. 

The difficulty of obtaining pure / "-material for the electrolyte has been tackled in many production processes worked out in the past. Unless precautions are taken, sintering of a -alumina-derived / "-alumina compositions invariably results in the duplex microstructure and a low-strength ceramic. Therefore a balance has to be struck between conductivity and strength. The problem arises because the conversion from —alumina to / " -alumina is slow... 

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