CEE Master's Defense Notice

Event Date/Time
Event Location
Zoom Meeting Link: https://msu.zoom.us/j/91306810098
Meeting ID: 913 0681 0098
Speaker
Abdo Korayem
Event Description
EFFECTS OF PHOTO-OXIDATION ON THE MECHANICAL BEHAVIOR OF POLYMERIC MATERIALS: AN EXPERIMENTAL STUDY

EFFECTS OF PHOTO-OXIDATION ON THE MECHANICAL BEHAVIOR OF

POLYMERIC MATERIALS: AN EXPERIMENTAL STUDY

By

Abdo Korayem

Advisor: Dr. Roozbeh Dargazany

Friday, May 7, 2021

12:30 P.M.

Zoom Meeting Link: https://msu.zoom.us/j/91306810098

Meeting ID: 913 0681 0098

ABSTRACT

Here, an experimental study is carried out to understand the degradation of crosslinked polymeric materials by exposure to coupled thermo- and  photo-oxidation, and their effects on mechanical behavior of the material. Our investigation   specifically focuses on two cured elastomeric adhesives: (i) a silicon-based and (ii) a polyurethane-based adhesive. Samples were prepared and subjected to UV radiation at three different temperatures namely 45, 60 and 80 oC, for different aging periods ranging from 1 to 150 days. Chemical damage is characterized by  the FTIR, DSC and Swelling tests which help us to  monitor the change in the chemical composition of the materials along the aging durations and conditions. Mechanical damage is characterized by uniaxial tensile  failure test, cyclic tensile test and  permanent set test. These tests revealed the change of behavior of our materials along the aging periods and conditions. The changes in mechanical behavior vary depending on the material, aging temperature and duration. We show that behavior of the materials aged in the photo-oxidative environment is in fact a result of a combination of two separable modes of damage, Mechanical and Environmental.  Accordingly, We are able to further separate the environmental damage mode into one created by the effects of temperature and another created by the combination of temperature and radiation. This separability has been confirmed with a Neo-hookean model, which proved that for a combined state of aging such as photo-oxidation the material cannot be characterized by models which consider only single modes of damage. Such regimes would require approaches such as the micro-mechanical approach to fully consider the effects by all the damage modes found in complex aging phenomena.