<p>Polymer thin films have been
developed in numerous industrial fields due to their cost efficiency and
productivity. A primary step in developing new products is characterizing the
properties of polymer thin films before implementing them in various
applications. Many studies have been conducted to determine the physical
properties of polymer thin films but there is still a need to further
understand and characterize their mechanical and interfacial properties.
Although there are standard testing methods to assess the mechanical and
interfacial properties of thin films, they can be challenging to use due to the
geometrical and physical limitations of polymer thin films. Hence, there is a
need to develop a new approach for mechanical and interfacial characterization
that has high sensitivity and can be broadly applied.</p>
<p>In this work, wrinkling and
delamination of a glassy thin film on an elastomeric substrate, a well-defined
and understood surface buckling instability, is adopted to investigate the
interfacial and mechanical properties of a glassy polymer thin film on a soft
elastomeric substrate. This new characterization tool utilizes the transition
from thin film wrinkling to delamination (W2D) from the elastomeric substrate
to subsequently measure the elastic modulus and the adhesion strength of a
glassy polymer thin film, which is difficult to characterize simultaneously
with conventional techniques due to the brittleness of glassy thin films.
Furthermore, the dependency of the elastomer’s bulk mechanical properties on
adhesion strength was investigated by expanding on the W2D technique. Further
exploiting the W2D technique, the delamination propagation rate of a thin film debonding
from a substrate is used to understand how the bulk mechanical properties of
the substrate affect the adhesion energy, termed the strain energy release rate
(G), of a thin film on an elastic substrate. Additionally, a new method for
determining the axial fracture mechanism and axial modulus of cellulose
nanocrystal (CNC) films has been developed by visualizing in-situ deformation and surface
instabilities (wrinkling). Lastly, new experimental approaches were
developed to understand the mechanical behavior of polymeric thin films using a
common test method. The effect of temperature on the adhesion and mechanical
behavior of polymeric thin films was studied by developing a double lap shear
fixture and temperature stabilization platform. Through these newly developed
or revised characterization approaches, measurement of the physical and
mechanical properties of polymer thin films that are commonly difficult to
measure have been overcome. </p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/17147765 |
| Date | 19 December 2021 |
| Creators | Hyeyoung Son (11813501) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | In Copyright |
| Relation | https://figshare.com/articles/thesis/Development_of_mechanical_and_interfacial_characterization_methods_for_polymer_thin_films/17147765 |
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