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In this work, a microwave expansion process to produce thermoset-matrix syntactic foam containing thermoplastic foam beads was designed and developed. Expandable polystyrene (EPS) microspheres and epoxy resin were chosen as a model material system. This process is featured with a capability to effectively expand EPS microspheres in syntactic foam with high EPS loading. The resin viscosity and specific microwave energy are found to be the two primary control parameters determining the process window. Mechanical characterization showed that the specific flexural strength and modulus of the syntactic foam are similar to those of the neat epoxy. By comparison, the flexural moduli over density squared or cubed of the foam are much higher, especially at high EPS loadings, than those of the neat resin. The foamed EPS microspheres can also effectively toughen the syntactic foam, preventing propagation of cracks. Furthermore, the microwave expansion process was found to be capable of molding syntactic foam parts of relatively sophisticated geometry with smooth surfaces., INTRODUCTION Syntactic foam is a special kind of gas-filled polymeric materials in which microballoons or foamed microspheres are embedded uniformly in a polymer matrix designated as a binder [1]. Different [...]

This paper reports on an enhanced implementation of the spectral-domain analysis (SDA) of boxed multistrip or multislot transmission lines embedded in a layered medium, including biaxial materials. Very high numerical efficiency is attained by a suitable basis and mixed SDA and spatial-domain technique to calculate the entries of the Galerkin matrix. Convergence properties of SDA are drastically improved, making it competitive with other analytical techniques [such as regular singular integral equation (RSIE)]. The method allows quick and accurate computation of current/field distributions. Index Terms - Analytical methods, planar lines, spectral-domain analysis.