Thermoplastics compression molding

Additional Considerations. Compared to injection molding of thermoplastics, compression molding is less capital intensive, more labor-intensive, and takes a longer... 

Fig. 2 Resistivities of graphite composites for a bipolar plate. In the sample names, S, P, C, and I mean thermoset, thermoplastic, compression-molded, and injection-molded, respectively...

Some specialized uses of PETN are summarized below. Expendable cartridges for small arms are made by coating unglazed grains or single base smokeless powder with PETN, spraying with plasticized thermoplastic binder and compression molding to the desired shape (Ref 99). Tucker et al (Ref 85) describe a spark detonator without primary expls. Secondary... 

The behavior of plastic structures under compression plays a critical role in numerous applications. It has been recognized that the buckling of metals under elevated temperatures presents important distinctions from the classical Eulerian case, [11]. During an experimental study, [12], buckling times were registered for a range of compressive loads applied to the top of compression molded and annealed thermoplastic samples (see Fig. 2). A typical time - load dependence is shown in Fig. 3. 

The isosorbide polyurethane based on the aliphatic diisocyanate P(I-HMDI) is flexible. It is a thermoplastic with a glass transition temperature of 110°C and softening temperature of 190°C. Both transitions are well below its degradation onset which occurs at approximately 260°C. It forms good films by evaporation from its solutions and colorless transparent compression moldings. 

An important step in the manufacture of any plastic product is the fabrication or the shaping of the article. Most polymers used as plastics when manufactured are prepared in pellet form as they are expelled from the reactor. These are small pieces of material a couple of millimeters in size. This resin can then be heated and shaped by one of several methods. Thermoset materials are usually compression molded, cast, or laminated. Thermoplastic resins can be injection molded, extruded, or blow molded most commonly, with vacuum forming and calendering also used but to a lesser extent. 

Molding employs a mobile prepolymer that may be thermoset or using a thermoplastic polymer. The polymer can be injection-molded (often for solid objects), blow-molded (for hollow objects such as bottles), rotation-molded, compression-molded, transfer-molded, or thermoformed. Casting is closely related to molding, except that the pressure is typically not used. 

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... 

The degree of bonding analysis has been verified for both compression molding and online consolidation of thermoplastic composites. In these studies, composite test specimens were consolidated under controlled processing conditions. The most common types of tests performed to measure the interply bond strength were the interlaminar (short beam) shear test [21,25] or the lap shear test [12,21,26]. 

ASTM D 4703-93, Standard Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or Sheets, ASTM, West Conshohocken, PA, 1997. 

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). 

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