Multifunctional syntactic foams: Thermal, mechanical and electrical properties

Syntactic foams are light weight closed-cell composite foams obtained by dispersing hollow filler particles in a matrix medium. The existing applications of syntactic foam are mainly based on their compressive properties. The goal of the present research is to understand the fundamentals of structure-property correlations for syntactic foams that can help in developing multifunctionality in these composites, which can enable their applications in armors, electronic packaging, automobiles and aerospace structures. In this work, syntactic foams are characterized for thermal, electrical and mechanical properties. Experimental results obtained are helpful in identifying the relation between the syntactic foam microstructural parameters with the evaluated thermal, electrical and mechanical properties. Theoretical models are developed to obtain capabilities for predicting the properties and the model predictions are validated with experimental results. The model predictions are used to develop a method that can help in tailoring two or more properties at the same time and make the material multifunctional. For example, hollow glass microballoon reinforced vinyl ester matrix syntactic foam that is designed for a dielectric constant of 3 can be designed to have coefficient of thermal expansion and density values in the range of 29.9 - 69.2 x106 m/m/°C and 800 - 925 kg/m3, respectively. This possibility of tailoring of syntactic foams makes them attractive multifunctional materials that can be used in imparting weight saving in structures.