Natalie Duprez
Advisors: Prof. Luettgen and Prof. Yao will defense a master’s thesis entitled,
Aqueously Degradable Poly(ethylene terephthalate) Films Containing a Latent Metal Oxide Reagent
on
Tuesday, November 22 at 11:00 a.m. Paper Tricentennial Building Room 521
Abstract

The widespread use of plastics, combined with their durability and persistence in the environment, 
has created a tremendous environmental burden. Flexible packaging in particular, including films 
and polymer coatings, has a particularly low recycling rate. Substantial efforts have been made to 
replace these typically single-use materials with biodegradable options, but high costs, 
difficulties with processing, and unsuitable mechanical properties often prevent their widespread 
use. In this work, polyethylene terephthalate (PET), one of the most affordable and commonly used 
plastics available, is made to be degradable by the addition of CaO via melt-mixing. This allows 
the PET to undergo alkaline hydrolysis upon exposure to water, ultimately converting to ethylene 
glycol and calcium terephthalate (CaTP), a salt of terephthalic acid. Due to the inert nature of 
CaO relative to other alkaline reagents, it may be mixed into PET and processed without hydrolyzing 
the polymer chain, and the material degrades only in the presence of water. In this work, this 
latent hydrolysis reaction is studied via the full and partial degradation of PET/CaO composite 
films at different concentrations and temperatures. Testing and characterization of the samples 
verified that the alkaline reagent CaO does not degrade the PET during processing, but instead 
reduces thermal degradation. The films were seen to be able to hydrolyze completely in water, 
forming the expected CaTP product, given that there was adequate CaO to drive the reaction to 
completion. Identification and observation of intermediates in the series of degradation reactions 
validated the proposed mechanism for latent degradation. Based on the proposed mechanism, a kinetic 
model was developed to predict the conversion of PET depending on key system parameters. This model 
was shown to describe the behavior of the system and provide more of an understanding of how to 
control the reaction via formulation and degradation conditions. While films were used to study the 
degradation reaction, it was also shown that this composite may be applied as a coating to a paper 
substrate. This may be done to allow the coating to be more easily removed to recycle the paper. In 
fact, once adequate degradation was achieved, the polymer coating was easily removed, demonstrating 
the potential benefits of using this composite material as a coating.

Committee
•  Prof. Christopher Luettgen – School of Chemical and Biomolecular Engineering
•  Prof. Donggang Yao – School of Materials Science and Engineering
•  Prof. Carson Meredith – School of Chemical and Biomolecular Engineering