Consolidants thermosetting resins

Centrifugal casting is used to produce water softener tanks and pipe by saturating a reinforcement with thermosetting resin within a mold that is then rotated at high speed to consolidate the laminate before curing. 

To process formulations, thermoplastic and thermosetting resins are used. For thermoplastic resins such as VAAR, the binder is dissolved in a solvent and then mixed with Mg and sodium nitrate until the solvent is evaporated. This formulation can then be stored and used whenever needed. No curing is required after consolidation. On the other hand, the epoxy-PS blend is mixed with an amine... 

Time, temperature, viscosity models are another useful element in understanding the science of thermoset resin processing. They perform a number of valuable functions such as defining the proper point for consolidation pressure application in FRP lamin-... 

Thermoplastics in the form of a lacquer have poorer mechanical strength than the thermosetting resins but are more easily removed, should this prove necessary. Polyvinyl acetate and polyurethane are good examples of this class of consolidants, particularly on wrought iron artefacts. Many of the copper and copper-based alloys, such as bronzes and brasses recovered from the Mary Rose, were consolidated with a solution of acrylic resin dissolved in toluene (Incralac). 

There are a number of ways in which fibres or reinforcements can be impregnated with thermosetting resin during production. In the early days of composite manufacture the resin system was hand mixed and then applied by bmsh to each layer and consolidated using pressure applied through a hand-held roller. 

If the filaments are not wound onto a mandrel but simply gathered into relatively large bundles and led slowly into a heated consolidation zone, emerging from a die partly or completely cured, the primitive essentials of pultrusion are present (Fig. 2.3(b)). This process began as the thermosetting resin equivalent of extrusion, that is, it was a continuous operation for manufacturing profiles, such as rod and channels. The method has been extended to fibre reinforced thermoplastics. 

Curing of Polyimlde Resin. Thermoset processing involves a large number of simultaneous and interacting phenomena, notably transient and coupled heat and mass transfer. This makes an empirical approach to process optimization difficult. For instance, it is often difficult to ascertain the time at which pressure should be applied to consolidate the laminate. If the pressure is applied too early, the low resin viscosity will lead to excessive bleed and flash. But if the pressure is applied too late, the diluent vapor pressure will be too high or the resin molecular mobility too low to prevent void formation. This example will outline the utility of our finite element code in providing an analytical model for these cure processes. 

Instead of using mechanical force to pressurize a composite and force consolidation/shape, air pressure can be used if a low-viscosity thermoset is the resin. An autoclave is a large pressure vessel that allows the simultaneous application of heat and pressure during the manufacture of thermosetting composite laminates. Internal work space of commercial autoclaves can be as large as 10 m in diameter and 30 m in length. Fig. 6 depicts a small autoclave with a 90-cm diameter internal work space. 

Traditional Methods. Traditional approaches to strength and integrity restoration center around consolidation systems. These consist of natural or synthetic resins that are impregnated into the wood. The natural resins are usually waxes or oils. Synthetic resins are either thermosetting (based on epoxy s, polystyrene, or a poly methyl methacrylate) or thermoplastic (such as poly(vinyl acetate)s, poly(vinyl butyral)s, or acrylics). In general, all of these consolidation systems do not penetrate the cell wall because they are not polar enough or because their molecular size is too large. 

The lay-up, which consists of a mixture of reinforcement (usually glass cloth or fibers) and resin (usually thermosetting), is placed in mold by hand, rolled to improve consolidation, and allowed to harden without heat or pressure. 

Decorative Board n (decorative laminate) A special term for laminates used in the furniture and cabinetry industries, which are defined by the Decorative Board Section of NEMA as ... a product resulting from the impregnation or coating of a decorative web of paper, cloth, or other carrying medium with a thermosetting type of resin and consolidation of one or more of these webs with a cellulosic substrate under heat and pressure of less than 500 pounds per square inch . This includes all boards that were formerly called low-pressure melamine and polyester laminates, but does not include vinyls. Cellulosic here means impregnated paper, wood, or plywood. 

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