Ultrasonic evaluation of filled polymers II. Elastic moduli of a resin filled with iron inclusions of different aspect ratios

An ultrasonic technique is used for the nondestructive evaluation of elastic moduli of polymer composites. Samples with varying amounts of randomly oriented iron inclusions, having aspect ratios p = 0.20 (flakes) and p = 20.0 (short fibers), were fabricated and fully characterized. The results for the moduli are discussed in terms of available theoretical models. It is demonstrated that models which account for the microscopic details of the material offer a good description of the bulk properties. Also, experimental evidence is obtained for the effect of particle contiguity and allows not to evaluate the influence of particle/particle interaction.