AbstractsThe local elastic properties of a semi-crystalline polymer (isotactic polypropylene) have been investigated with the use of scanning acoustic microscopy (SAM) techniques. The operating frequency was 775 MHz and the temperatures ranged between 25 and 60°C. A new and effective signal processing method was developed to process the material signature V(z) curve. This method avoids complicated calibration procedures involved with operating the SAM lens at different temperatures. Longitudinal velocities VL(α) and VL(β) in individual α and β-type spherulites of isothermally crystalized samples have been measured. Acoustic velocity of a quenched sample was also obtained. It was found that vL(α) and VL(β) were nearly equal but the acoustic impedances of α and β-spherulites were unexpectedly very different.
Signal processing method based on energy ratio for detecting leakage of SG using EVFM