Technology, processing molding

As mentioned above, the binder/filler ratio determines the fluidity and hence the process technology for a given syntactic composition. The solid line in Fig. 1 shows how the apparent density depends on the relative microsphere concentration in syntactic compounds, provided there are no air inclusions. The lower limit of apparent density is at the concentration at which the filler is most densily packed at this point the material has its highest specific strength (strength per unit apparent density). Experience has shown that the closest packing of the spheres within the binder is obtained when the material is mixed and cast or molded under vacuum 8 10). 

Thermoplastics. This segment of fibrous glass composites came out of its infancy in the 1960s. The potential of these materials is tremendous because no new molding process technology is required. Advances will be in the area of materials performance. 

Whereas all conventional thermoplastic fabrication techniques have been successfully employed to convert pellets of HIPS into useful articles, extrusion (film, sheet, profile and multi-layer) and injection molding (solid, structural foam and gas-assist) are the predominant processing technologies. Innovative hardware technologies, in both extrusion and injection molding, have provided means to combine less expensive materials, such as polystyrene, with polymers or structures offering key performance characteristics. 

Biodegradable thermoplastics, like PHB and PLA, can be processed by conventional thermoplastic processing technologies, such as extrusion, injection molding, melt spinning, blowing film, and melt blown, for a wide range of application as enviromnentally friendly materials and for medical applications. 

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