Session: 12-07-01: Mechanics of Soft Materials
Paper Number: 95221
95221 - Effect of Dual Environment Aging on Flexible Polyurethane Based Adhesives
Polyurethane-based elastomeric adhesives have been used in structural applications such as glass sealants for more than three decades. They present significant advantages in terms of damping, impact, fatigue, and safety which are critical factors in the automotive industry in particular. Assessment of the durability of elastomers for these applications has been of much interest among the research community for quite some time now. All polymeric materials undergo degradation when in contact with aggressive environmental agents like humidity, water, and temperature. This degradation naturally increases with the intensity of the ambient environmental agents involved. But during service life, these materials are never subjected to constant environmental loading. Real-time applications expose the material to multiple weather conditions at different instances; ranging from dry to humid or fully wet conditions. While there exists some understanding about aging environments in isolation, we intend to investigate the effect of multiple environments on the constitutive behavior of the material. The extent of damage can be accessed by analyzing the changes in constitutive behavior of aged material. The experiment was designed around two-way aging regimes involving combinations of thermo-oxidation, hydrolytic and hygrothermal aging environments. We selected a polyurethane-based flexible adhesive which is commonly used in the automotive industry as a glass sealant.
Dual effect aging experiment is designed in 60̊C and 80̊C. Samples were aged at the same temperature for the complete aging duration. The aging was done considering the following environmental regimes:
a. 80%RH to 0%RH (thermo-oxidation)
b. Submerged to 0%RH (thermo-oxidation)
c. 0%RH to 80%RH (hygrothermal)
d. 0%RH to submerged (hydrolytic)
To distinguish with ease, the above regime names are dictated by the phase-2 environment. During this study, the specimens of the understudy adhesive were subjected to two-phase aging. For thermo-oxidative dual-aging, samples were kept in hygrothermal/ hydrolytic (phase-1) conditions for 30 days and then were shifted to phase-2 in thermo-oxidation (0%RH) aging for 3, 10, and 30 days. Whereas for hygrothermal and hydrolytic dual-aging, in phase-1, specimens were aged in thermo-oxidation (0%RH) condition and after 10 days all batches were shifted to phase-2 which were hygrothermal (80%RH) and hydrolytic (submerged) aging conditions for 3, 10, and 30 days. The aged specimens were subjected to uniaxial tensile tests and variation in material toughness and constitutive behavior was analyzed to ascertain the mechanics involved in case of each environmental exposure. This study will help to better understand and model the damage mechanics involved in exposure to multiple environmental conditions.
Presenting Author: Mamoon Shaafaey Michigan State University
Presenting Author Biography: Mamoon Shaafaey completed his BSc in Civil Engineering from the National University of Sciences and Technology (NUST), Pakistan in the year 2011. He joined MSU in Fall 2017 for masters in Structural Engineering and graduated in Summer 2019. Mamoon is continuing his pursuit of knowledge as a Ph.D. student in the Department of Civil & Environmental Engineering MSU since Fall 2019 under the supervision of Dr. Roozbeh Dargazany and has been contributing as a member of High Performance Materials Group. Presently he is studying the constitutive behavior of adhesives in hydrolytic and hydrothermal aging conditions.
Authors:
Mamoon Shaafaey Michigan State UniversityAmir Bahrololoumi Michigan State University
Roozbeh Dargazany Michigan State University
Effect of Dual Environment Aging on Flexible Polyurethane Based Adhesives
Paper Type
Technical Paper Publication