Determination of Elastic Modulus of Thermosetting Polymers by means of Ultrasonic Pulse Echo Testing

• Main Author: Athalia Candra, Thea
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/33828
• Institution: Institut Teknologi Bandung

Modulus of elasticity or elastic modulus is one of the important properties in material. Thermoset polymers have a wide range of the modulus for each kind. During its application, thermoset polymers could be degraded followed with modulus decay.Thus modulus of elasticity determination for these polymers is necessary in order to prevent further failure. Generally elastic modulus could be obtained by destructive tests. However those methods are not favored by the industries. One of the nondestructive tests, ultrasonic testing, could be used to determine elastic modulus of material with proven results for metallic materials. There are two methods in ultrasonic testing, through-transmission and pulse-echo. Pulse- echo method is more practical in industries for being able to be conducted with only one side available. This study aims to determine the elastic modulus of thermoset polymers by using ultrasonic testing pulse-echo method. Three polymers were used in this study which were unsaturated polyester, vinyl ester, and epoxy. The study began by determining and evaluating the used ultrasonic probes which were probe of 24 mm diameter 1 MHz, probe of 12.7 mm diameter 1.5 MHz with delay line, and probe of 12.7 mm diameter 1.5 MHz without delay line. The results showed that probe of 12.7 mm diameter 1.5 MHz with delay line could be used to determine longitudinal ultrasonic velocity with minimum thickness of 2.82 mm. Errors of elastic modulus by ultrasonic testing were 54% for vinly ester, 102% for epoxy, and 159% for polyester. High errors were caused by the exprienced attenuation and the formula used which still needed to be modified. The attenuation that occured by ultrasonic testing pulse echo method for thermoset polymers were affected by its density.