Doctor of Philosophy, Case Western Reserve University, 2020, Macromolecular Science and Engineering

Epoxy adhesives constitute a large majority of the structural adhesive market. Most of these adhesives are 2-component systems consisting of a bisphenol A based resin and an amine based hardener. Bisphenol A is an endocrine disruptor and a known carcinogen, as well as derived from petroleum which in itself is a finite resource. Due to these disadvantages, BPA has been banned in multiple countries and replacements for BPA based resins are persistently sought. One of the most common amine curing agents used in epoxy adhesives is petroleum derived isophorone diamine (IPDA) which has been found to be toxic and a skin sensitizer. The need for adhesive systems that can replace bisphenol A based resins and petroleum based IPDA has never been more urgent. A family of biobased epoxies derived from diphenolic acid (DGEDP epoxies) were recently synthesized that have an estrogen binding capacity of an order of magnitude less than BPA but similar thermo mechanical properties to the diglycidyl ether of bisphenol A (DGEBA), the most commonly used epoxy resin derived from BPA. This family of resins, differing amongst each other only in ester chain length in terms of structure exhibited excellent potential as suitable replacements to DGEBA. Their curing kinetics with regards to IPDA were studied to determine which resin would be suitable for adhesive applications. Isoconversional analysis indicated that the resins cured via an autocatalytic mechanism and modeling of the curing behavior using the Kamal Sourour model showed that the methyl ester resin (DGEDP-methyl) exhibited unusually high curing rates. This resin was then chosen for further development as the resin component for a biobased adhesive. However, when lap shear samples on aluminum were prepared, DGEDP-methyl when cured with IPDA exhibited extremely brittle behavior failing at very low stresses. A commercially available highly aliphatic biobased epoxy resin (NC-514) derived from cashew nut shell liquid was hypot (open full item for complete abstract)

Committee: Ica Manas-Zloczower Prof. (Committee Chair); Donald Feke Prof. (Committee Member); Gary Wnek Prof. (Committee Member); Rigoberto Advincula Prof. (Committee Member) Subjects: Materials Science; Polymers; Sustainability