Doctor of Philosophy, Case Western Reserve University, 2020, Materials Science and Engineering
Poly(methyl methacrylate), also know as acrylic, has excellent optical properties, light weight, good mechanical properties, and weatherability.
Due to the balance of these outstanding properties with cost efficiency, poly(methyl methacrylate)s are widely used in architecture, medicine, electronics, agriculture, paints, aircraft, and automotive industries.
However, the lifetime of poly(methyl methacrylate)(PMMA) is reduced in outdoor applications because of exposure to solar radiation, temperature, and moisture.
During the polymer degradation process, a variety of environmental stressors act on the polymer leading to degradation of its properties.
Although standardized durability and weathering tests are widely used to collect failure information and evaluate durability of materials based on the typical pass/fail criteria, degradation modes, mechanisms, and rates are not clearly understood.
Therefore, a better understanding of degradation modes, mechanisms, and rates is critical.
To optimize and extend the service life of polymer materials to more than 25 years in the outdoor environment, a domain knowledge-based and data-driven approach has been utilized to quantitatively investigate the temporal evolution of degradation modes, mechanisms and rates under various stepwise exposure conditions.
Six grades of PMMA were studied, including one unstabilized and five stabilized PMMAs exposed 3200 hours in three weathering conditions.
The unstabilized PMMA showed a significant YI increase of over 25, whereas a highly-stabilized PMMA showed a slight YI increase only between 0.5 to 0.7.
The degradation of unstabilized acrylic, revealed by Urbach edge analysis, arises from the presence of residual MMA monomer, with a shift of absorption edge from 4.35 eV to 3.11 eV under UVA-340 irradiation.
For unstabilized and partially-stabilized PMMA formulations, quantitative degradation rates (the Induced absorbance to dose (IAD)) indicates that the UVA-340 irradiation (Hot (open full item for complete abstract)
Committee: Roger French Dr. (Advisor); Mark De Guire Dr. (Committee Member); Laura Bruckman Dr. (Committee Member); Michael Hore Dr. (Committee Member)
Subjects: Materials Science; Polymer Chemistry