Non-Destructive Evaluation of Thermal Aging in EPDM Rubber Using Electromagnetic Techniques

Area of Science:

• Materials Science
• Polymer Science
• Electromagnetism

Background:

• Accelerated thermal aging significantly alters rubber properties.
• Understanding these changes is crucial for material durability and performance.
• Ethylene propylene diene monomer (EPDM) rubbers are widely used and susceptible to aging.

Purpose of the Study:

• To investigate the effectiveness of eddy-current technology and impedance spectroscopy in sensing property changes in EPDM rubber after accelerated thermal aging.
• To analyze the impact of carbon black (CB) and graphene content on the electromagnetic response of aged EPDM.
• To evaluate the role of graphene as a substitute for CB in enhancing electromagnetic properties.

Main Methods:

• Electromagnetic analysis using eddy-current sensing and electrical impedance spectroscopy.
• Measurement of in- and out-of-phase responses as a function of excitation frequency.
• Thermal aging of EPDM rubber samples with varying CB and graphene content.
• Detection of the electrical percolation threshold by adjusting CB concentration.

Main Results:

• Both eddy-current and impedance spectroscopy detected changes in EPDM rubber properties post-aging.
• The electrical percolation threshold was identified by varying CB content (0-40 wt%).
• Substitution of CB with graphene flakes (0-5 wt%) in 30 wt% CB samples enhanced eddy-current and impedance responses.

Conclusions:

• Electromagnetic analysis techniques are feasible for assessing the extent of thermal aging in EPDM rubber.
• Graphene incorporation can improve the electromagnetic sensing capabilities for aged rubber materials.
• Eddy-current and impedance spectroscopy offer sensitive methods for non-destructive evaluation of rubber degradation.