Hot-press molding

With hot-press molding the most convenient method is to use a preformed molding compound to which all the necessary ingredients have been added. Two commonly used molding compounds are SMG (sheet molding compound) and BMC (bulk molding compound). 

SMC is composed basically of five principal ingredients unsaturated polyester resin, shrink-reducing thermoplastic, reinforcement, fillers, and additives (see 

A parallel technology to SMC is bulk molding compound (BMC). BMC consists basically of the same ingredients as SMC (see Table 16.7). However, its production method, appearance, and properties differ. 

BMC is commonly manufactured by using high-speed plowshare mixers. The different components of the paste are fed into the mixer and mixed until the compound is fully homogeneous. The chopped-glass fibers are introduced at the end of the process to prevent too much fiber degradation. 

BMC may be used in compression as well as in injection molding. In the latter process the compound is conveyed from the hopper to the nozzle of the barrel by screw rotation or plunger displacement. The metered charge is fed into the heated mold by fast translation of the screw or plunger. Similarly to SMC-based composites, BMC products are characterized by stiffness, temperature resistance, and di- 

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Work on production of RPs from jute fiber by hot press molding with TP films (at Ho Chi Mihn City University of Technology, Polymer Research Centre, Vietnam) has shown that they have a potential use in replacement of wood and also glass fiber RPs, provided that the high water absorption and poor interfacial adhesion can be eliminated. A... 

Without use of accelerators, external heat is required, making a system suitable for mechanical processes, such as hot press molding and continuous impregnation of sheet and profile. Temperatures in the range 120-160C (248-320F) are used to cure in a short cycle accelerators offer no advantage as the rate of cure depends on thermal decomposition of the peroxide, and typical cycle times are 1-10 min. 

H or h = hot press molding (SMC/BiVlC) 1 or i = hot press molding (granular molding compound)... 

Y. Ohama, T. Kobayashi and K. Demura Improvement in water resistance of macrodefect-free (MDF) cements by application of hot press molding process (in Japanese). Journal of the Society of Materials Science, Japan Vol. 50, No.8 (2001), pp.873-876. 

Compression molding Injection molding Hot embossing Hot press molding Polymer casting Replica molding Thermoforming... 

Phenolic resins are cured by a condensation reaction using hot press molding and are relatively cheap, having good high temperature performance (230°C), excellent fire and smoke resistance and good resistance to acids. 

Di(tert. butylperoxy) trimethyl cyclohexane liquid high activity 50% solution in aliphatics Versatile type for curing above 80°C Quickset in range 120-150 C for hot-press molding SMC or BMC can be accelerated by promoters. Special for SMC/BMC at 130-160°C without accelerator not sensitive to fillers pigments and promoters FGH gh... 

TABOR ABRASION AND STIFFNESS MEASURED WITH HOT PRESS MOLDED SPECIMENS. OTHER ITEMS MEASURED WITH INJECTION-MOLDED SPECIMENS. ALL ITEMS MEASURED AT 20°C, 65% R.H. 

Chen and co-workers (Chen, 2007) reported the preparation of PHBV/hydroxy-apatite nanocomposites by using hot-press molding for thermal arrd physical tests in order to consider potential medical applications. 

Injection molding Hot embossing Polymer casting Thermoforming Compression molding Hot press molding Replica molding... 

Cold-press molding Resin infusion (vacuum) Light resin transfer molding (p > 1 bar) Resin transfer molding (p > 1 bar) Hot-press molding (BMC/SMC)... 

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