Vinyl Esterĝ€"Glass Hollow Particle Composites: Dynamic Mechanical Properties at High Inclusion Volume Fraction

This study entails the analysis of dynamic mechanical properties of hollow particle filled composites, called syntactic foams. A theoretical model is developed to predict the dynamic mechanical behavior of composite materials containing particle volume fraction up to the packing limit. The modeling approach is based on a differential scheme that extrapolates the properties of infinitely dilute dispersions of hollow particles (microballoons) to high inclusion volume fraction. The model is capable of predicting storage modulus and loss tangent in a wide frequency band of mechanical vibrations. Theoretical predictions are validated with experimental results on 16 compositions of vinyl esterĝ€"glass microballoon syntactic foams. Vibration methods are used to assess the dependence of dynamic mechanical properties of syntactic foams on microballoon wall thickness and volume fraction. Theoretical predictions are in close agreement with experimental findings over a wide range of vibration frequencies. Results show that loss tangent generally decreases as the inclusion volume fraction increases and is almost unaffected by microballoon wall thickness and that storage modulus increases with increasing microballoon wall thickness. Therefore, the loss tangent and the storage modulus can be tailored by means of microballoon volume fraction and wall thickness.