A New Syntactic Foam Manufacturing Method and Study on Its Properties

Hollow particle filled composites, called syntactic foams, are widely used in deep sea applications. The traditional way of producing syntactic foam is to embed glass hollow sphere into a mixture of epoxy hardener solution and then mix them until complete mixing. The mixture is degassed for several minutes and cast in mould at last. This method is in the mainstream position according to statistics of published literature. In recent years, the second way to produce the syntactic foams is to inject the resin into a closed mould by a high injection pressure in which the hollow glass microspheres are filled. This method need resin injection facilities and defined as resin transfer moulding (RTM) which is commonly used as a technology for the manufacture of FRP composites. The present study focuses on a new manufacturing method involving syntactic foams with low gas porosities or entrapped voids which can be called Vacuum Assisted Resin Infusion (VARI). VARI processing is very common in FRP industry, but there are no published literature reports on how to produce syntactic foams by VARI. The porosity inside of the syntactic foams can be controlled at a low level without any additional impressed injection pressure but a vacuum pump. Syntactic foams of 500kg/m(3) similar to 600kg/m(3) were produced by changing the volume percentage of hollow glass spheres using the processing of VARI in this paper. The compressive property is from 35MPa to 49MPa. These syntactic foams can meet the demand of 4900m sea water depth. Little porosity could be found from cross-section photograph of SEM. Results indicated that the higher volume content of hollow microspheres led to lower resin penetration rate under given conditions of temperature, injection pressure and resin type. Two kinds of studied microspheres show a similar trend with increased filler content.