Low pressure SMC

Low-pressure SMC Low-pressure sheet molding compounds can present problems due to difficulty in controlling the chemical thickening process at low viscosity levels, and achieving a dry, tack-free easily handled compound without any resin separation. New technology from Union Carbide is claimed to overcome this, offering wide process latitude for thickener control, with dry easily handled compounds of stable viscosity. 

Depending on the resin preparation, the material in or around a mold can be cured with or without heat, and commonly without pressure. Curing needs include room temperature conditions, heat sources, vacuum bags, pressure bags, autoclaves, etc. An alternative is to use preimpregnated, B-stage TS polyester or sheet molding compound (SMC), but in this case heat is applied with low pressure via a impermeable sheet over the material. This process can produce compact... 

Low pressure molding compound (LPMC) is an SMC kind of material. TMPC is made by replacing the chemical thickening mechanism with a physical thickening mechanism using crystic polyester. The material is first... 

SMC-II SMC, low-pressure molding SRPE solid redox polymerization electrode... 

RPURs can also be formulated for use as SMC type materials, foamed panels, and filament winding. The RIM process operates at low pressure, allowing inexpensive materials to be used for molds, and the mixing/ injection head is usually flushed out between injection cycles. Because of the need for accurate dosing, and the speed and sensitivity of the reaction, the process is often controlled by computer. 

Compression molding, bulk molding compound (BMC), sheet molding compound (SMC), low-pressure molding compound (LPMC), transfer molding, and thermoset injection molding... 

Rigid Flexible High Unidirectional Glass Preformed, Chopped Roving Premix, Chopped Glass Woven Cloth SMC SMC, BMC Low-density SMC Low-pressure... 

The media is the artery s middle layer, composed of mainly smooth muscle cells (SMCs) in a circumferential arrangement, alternating with elastin sheets and, to a lesser extent, collagen fibers. SMCs become contractile in maturity and are responsible for regulating vessel size. Elastin provides high comphance since it is responsible for high arterial deformation capacity at low pressures. 

Alkyd thermoset compounds are based on unsaturated polyester resins, which are combined with cross-linking monomers, catalysts, reinforcements, lubricants, and fillers. They are similar to TS polyesters, but have lower levels of monomers. They are part of the group that includes the bulk-molding compounds (BMCs) and sheet-molding compounds (SMCs). Their fast molding cycles at low pressure make them easier to process than other TSs by vacuum, compression, transfer, or injection molding. 

The cost per unit part dictated the choice of moulding process as the properties are similar. The graph indicates that as the production quantity increases, the SMC process first at low pressure and then at high pressure becomes more cost effective. 

Gurliat, A. and Ollive, C. (1988) Low pressure and temperature moulded SMC parts for the Renault Espace car — four years of results. Engineering Plastics 1(4). 

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