| dc.contributor.author | Fisk, Aron Mark | |
| dc.description.abstract | Incorporating reinforcement within a polymer (i.e. composite) can obtain
substantial performance increases. However, composites may he susceptible to conditions
that could have a significant impact on their performance. The objective of this study was
to characterize SpaceAge Synthetics (SAS) fiberglass-reinforced rigid, closed-cell
polyurethane foam (PU) after subjected to various environmental conditions.
SAS composites were characterized as a function of material composition after
conditioned to extreme temperatures, moisture, ultraviolet irradiation (UV), or a
combination thereof. The experimental process involved accelerated conditioning to further
induce property changes and assure long-term integrity.
Empirical expressions for SAS composites were generated to represent performance
changes for different environmental conditions. Increasing temperature 93 °C from ambient
showed an 18% decrease in strength and 24% decrease in stiffness for a 450 kg/m3 foam
density reinforced with 7.6% fiber volume fraction. This performance loss resulted from
the ductility of the polymer increasing with temperature. Decreasing temperature 68 °C
from ambient showed a 56% increase in strength and 26% increase in stiffness. When SAS
composites were subjected to moisture at room temperature, no statistical difference was
observed after being exposed to l 00% RH for 72 h duration. These mechanical
performance analyses included varying material parameters such as: foam density, fiber
content, void content, and thickness. The addition of heat to the l 00% RH moisture
drastically reduced mechanical performance up to 33% in strength and 22% in stiffness. Ultraviolet irradiation caused chemical changes within the SAS composites, which
was first noted by the pronounced color shift within the yellowness index (YI). Additional
reinforcement near the surface created a 269% lower shift in YI. It was observed that
initially cross-linking occurred while at the same time chain scission was occurring at a
larger rate. Fourier Transform Infrared Spectroscopy proved that UV penetrated 0.25 mm
within the surface, showing the effects occur mainly on the surface.
Finally, SAS composites exhibited a 31 % increase in strength and a 12% increase in
stiffness with a post cure process. Post curing for 4 h at 100 °C raised the glass transition
temperature from 119 °C to 128 °C. The performance increase was attributed from the post
cure process inducing additional cross-linking within polymer chains. | en_US |
| dc.publisher | North Dakota State University | en_US |
| dc.rights | NDSU policy 190.6.2 | en_US |
| dc.title | Impact. of Environmental Conditions on Fiberglass-reinforced Polyurethane Foam Composites | en_US |
| dc.type | Thesis | en_US |
| dc.date.accessioned | 2024-03-16T18:22:26Z | |
| dc.date.available | 2024-03-16T18:22:26Z | |
| dc.date.issued | 2010 | |
| dc.identifier.uri | https://hdl.handle.net/10365/33738 | |
| dc.subject.lcsh | Composite materials -- Effect of environment on. | en_US |
| dc.subject.lcsh | Polyurethanes -- Environmental testing. | en_US |
| dc.subject.lcsh | Glass-reinforced plastics -- Environmental testing. | en_US |
| dc.rights.uri | https://www.ndsu.edu/fileadmin/policy/190.pdf | en_US |
| ndsu.degree | Doctor of Philosophy (PhD) | en_US |
| ndsu.college | Engineering | en_US |
| ndsu.department | Mechanical Engineering | en_US |
| ndsu.program | Mechanical Engineering | en_US |
| ndsu.advisor | Ulven, Chad A. | |
