Monomer transfer molding

Monomer transfer molding is similar to compression molding in that a predetermined shape is filled to create a pre-fabricated composite, but instead of utilizing force, monomers are polymerized within a heated mold cavity. The monomer mixture remains enclosed in a mold until it has polymerized and fully cured. Using this method, surface-modified bioglass fiber/PCL biocomposites have been made (Jiang et al., 2(X)5a Khan et al., 2010), proving there is more than one way to produce a biocomposite with the same basic components. 

Methacrylate monomers are most effective with derivatives of bisphenol A epoxy dimethacrylates, in which the methacrylate—methacrylate cross-linking reaction proceeds at a much faster pace than with styrene monomer. This proves beneficial in some fabrication processes requiring faster cure, such as pultrusion and resin-transfer molding (RTM). 

Anionic polymerization of nylon-based polymer systems to produce finished parts directly from monomers or prepolymers can be carried out by several processes e.g., reaction injection molding, low-pressure casting, resin transfer molding, rotational casting. 

The cyanate ester monomers are available from low-viscosity liquids to meltable solids. Ciba-Geigy produces a series of cyanate esters imder the trademark AroCy L-10. Cyanate esters are used in manufacturing structural composites by filament winding, resin transfer molding, and pultrusion. 

Diallyl Phthalate Resin Thermoset supplied as diallyl phthalate prepolymer or monomer. Has high chemical, heat and water resistance, dimensional stability, and strength. Shrinks during peroxide curing. Processed by injection, compression, and transfer-molding. Used in glass-reinforced tubing, auto parts, and electrical components. Also called DAP. 

In addition to the standard processes of injection molding, there exist variants that may be applicable to a particular microfluidic device. These include reaction injection molding (aka RIM) where a monomer mixture is injected directly into a production mold where it polymerizes in the mold cavity and is then injected, resin transfer molding (aka RTM), gas-assisted... 

TPEs are molded or extruded on standard plastics-processing equipment in considerably shorter cycle times than those required for compression or transfer molding of conventional rubbers. They are made by copolymerizing two or more monomers, using either block or graft polymerization techniques. One of the monomers provides the hard, or crystalline, polymer segment that functions as a thermally stable component the other monomer develops the soft or amorphous segment, which contributes the elastomeric or rubbery characteristic. 

Polybutadiene-type resins n. Unsaturated, thermosetting hydrocarbons cured by a peroxide-catalyzed, vinyl-type polymerization reaction, or by sodium-catalyzed polymerization of butadiene or blends of butadiene and styrene. Liquid systems, curable in the presence of monomers, are used for casting, encapsulation, and potting of electrical components, and in making laminates. Molding compounds, often containing fillers and modified with other resins or rubbers, may be compression or transfer molded. Syndiotactic 1,2-butadiene, introduced in 1974 in Japan, is thermoplastic, with semicrystalline nature, with good transparency and flexibility without plasticization. In the presence of a photosensitizer such as p,p -tetramethyl... 

As already mentioned in Section 4.14.13.1, the activated anionic polymerization of CL has undergone interesting industrial developments in the field of well-established monomer casting process, as well as in the more recent areas of RIM (RIM and R-RIM), resin transfer molding (RTM), and rotational molding. In addition, reactive extrusion processes, already erqrlored since 1968, are now gaining renewed attention for the easy preparation of nanocomposites and nanoblends, as described in the following. 

Increasing the amount of cross-linking agent (divinyl compound) at expense of monomer causes a decrease in pore size, which is accompanied by a distinct increase in surface area [101-104]. Even if this has been observed for macroporous beads prepared by suspension polymerization, the results can directly be transferred to the fabrication of rigid monolithic materials in an unstirred mold by thermally [105,106] as well as photochemically [107] initiated free radical copolymerization. 

Transfer to monomer sets an upper limit to the molecular weight of the polymer that can be produced. This is not normally a problem, however, except with allylic monomers like propylene (Section 6.8.5). Cm is about 10 for styrene. The maximum DPp of polystyrene that can be achieved is then 10 [from Eq. (6-77) assuming very low [I] and vanishingly small / p]. This corresponds loan Mn of about 10. Commercial molding and extrusion grades of polystyrenes have... 

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