Processing, thermosets compression molding

Thermosets are processed by compression molding, transfer molding and injection molding or by extrusion, depending on their structure. The pressing temperatures are about 150 to 190°C. Corresponding requirements are placed on the pigments. Dyes are often also used to color thermosets. 

Thermoplastics, thermosets, and rubbers can be processed by compression molding. For thermoplastics, this technique is an exception. 

For molding urea and melamine materials, pressures of approximately one and one-half times that needed for phenolic material are necessary. In compression molding of thermosets the mold remains hot throughout the entire cycle. After the molded part is ejected, a new charge of molding powder is introduced. Unlike thermosets, thermoplastics must be cooled to harden. So before a molded part is ejected, the entire mold must be cooled, and as a result, the process of compression molding is slow with thermoplastics. 

A very old polymer-processing operation, compression molding was adopted because of the large impact of thermosetting resins, such as phenolics, in the marketplace. In about 1910, thermosets were about 95% of total plastics production. Later, however, increased production of thermoplastic polymers led to the use of other polymer-processing operations. Today, only about 3% of plastics are thermosets. 

Thermosetting resins are usually processed by compression molding, filament winding, hand lay-up, pultrusion, reaction injection molding (RIM, RRIM), resin transfer molding (RTM) and vacuum bagging. 

Duranik T, Ruzbarsky J, Manlig F. Proposal for possibilities of increasing production productivity of thermosets compression molding with using process simulation software. Appl Mech Mater 2013 308 191. ... 

Compression Molding. Whereas the previous polymer processing techniques are used primarily for thermoplastic polymers, compression molding, also called matched die molding, is used almost exclusively for molding thermoset polymers. In... 

Recendy, storm doors have been constmcted of advanced thermoplastic composites. Stampable, glass-mat reinforced polypropylene sheet is used to create a high strength outer skin. These compression molded skins are welded together using a friction or ultrasonic process then injection molded with a polyurethane foam core to produce an insulated structure. New technology for window frames incorporate the pultrusion of frame channels to produce a thermoset composite channel that can be filled with fiber glass for further insulation enhancement (12,31,33,34,48,49,54—56,60—67). 

Compression molding is an old and common method of molding thermoset (TS). It now processes TS plastics as well as other plastics such as thermoplastics (TP), elastomers (TS and TP), and natural rubbers (TS). By this method, plastic raw materials are converted into finished products by simply compressing them into the desired shapes... 

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