Characterization of heterogeneous structure in a polymer object manufactured by stereolithography with low-frequency microechography

Abstract

Low-frequency microechography is a non-destructive technique, which is particularly suitable for the observation of surface defects and structure inside polymeric materials. Indeed, this method is based on the reflection of an acoustic wave at the surface of the sample which is primarily a function of the density and elastic properties of the material. A frequency of 25 MHz was chosen owing to the high absorption of the investigated material at high frequency. The purpose of this paper is to show the application of this technique to the local visualization of structure difference occurring in a polymer object manufactured by stereolithography. In particular, these differences are due to the variations of crosslinking density in photopolymers.