Thermoplastics molding compounds

The crosslinking reaction may be catalyzed by a small amount of suitable organometalUc catalysts. The blends typically contain ca. 5-20% silicone. Injection molded or extruded parts are further heat-treated to complete the curing reactions. There is, of course, a significant level of phase separation. In the thermoplastic molding compounds such as glass-filled PA and PBT, addition of the silicone semi-IPN in small amounts (ca. 5-10%) is reported to reduce the mold shrinkage, improve mold release, and increase wear and friction resistance. Polyamide-silicone blends have already been discussed under PA blends section. 

Further classification of polymers in the groups of additional polymers and condensation polymers has been on monomer composition, because this provides an orderly approach, whereas classification based on polymer uses, such as plastics, elastomers, fibers, coatings, etc. would result in too much overlap. For example, polyamides are used not only as synthetic fibers but also as thermoplastics molding compounds and polypropylene, which is used as a thermoplastic molding compound has also found uses as a fiber-forming material. 

Polyurethanes (PU or PUR) and polyureas are classified as TS resins, but their chemistry is so flexible that they can be formulated different ways. There are moldable solid and expanded TSs, with (RPUR) or without reinforcement, flexible and rigid foams, elastomers and thermoplastic molding compounds. As RPs they are important in reinforced reaction injection molding (RRIM) (Chapter 5) and are also available as reinforced thermoplastic molding compounds. A variant on the process employs a structural preform of the reinforcement that is placed in the mold cavity and is called structural reaction injection molding (SRIM). 

Thermoplastic Molding Compounds, Material Design, Material Selector Issue, Penton Publishing,... 

Courtaulds developed many products [153] based on carbon fibers prepreg as warp sheet and tape, random fiber mats, preferred orientation mats, chopped fiber, thermoset and thermoplastic molding compounds and polytetrafluroethylene (PTFE) impregnated tow. Oxidized PAN fiber was available as continuous tow, tops, yarns, woven and knitted fabrics. 

ASTM D 3641 covers the practice of mold design for the injection molding of test specimens from thermoplastic molding compounds and a design option with the mold join on the diagonal is preferred. 

Figure 21.83 Typical route to manufacture a carbon fiber filled thermoplastic molding compound using a twin...

Table 21.9 Recommendations for molding thermoplastic molding compounds...

Gears fabricated from carbon fiber reinforced nylon thermoplastic molding compound have been used in gearboxes of railway engines. 

Table 23.11 lists the companies manufacturing carbon fiber filled thermoplastic molding compounds and indicates the types of polymer matrices available. 

Table 23.11 (cont d.) List of carbon fiber filled thermoplastic molding compounds suppliers... 

Rossi-Peakes tester n. An instrument for measuring the temperature at which a given amount of a molding powder will flow through a standard orifice in a prescribed period of time and pressure (ASTM Test D 569). The instrument tests a peculiar combination of properties of a thermoplastic molding compound that may relate to its moldability. 

The thermoplastic molding compound comprises a propylene bloek copolymer with a nucleating agent. The nucleating agent is either sodium benzoate, or 2,2 -methylene-bis-(4,6-di-tert-butylphenyl) phosphate sodium salt which is marketed under the trade name ADK STABNA-11. ... 

The most common of the polyketones are PEK, PEEK, and PAEK. All are available as thermoplastic molding compounds. PAEK is available as a compression molding compound from Amoco (Kadel). PEEK is available as a compression molding, extrusion and injection molding compound from Victrex, Compound Technologies, DSM Engineering, LNP and RTP. PEK is available as an injection molding compound from RTP. 

Similar to die casting of metals. A thermoplastic molding compound is heated to plasticity in a cylinder at a conti-olled temperature and forced under pressure through sprues, runners and gates into a mold the resin solidifies rapidly, the mold is opened, and the parts ejected with certain modifications, thermosetting materials can be used for small parts. 

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