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Christine's Project Page - RISE Summer 2008 |
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Intern: Christine Carpenter, Materials Engineering, California Polytechnic State University, San Luis Obispo
Mentor: S. Scott Wasko
Faculty Supervisor: Herbert Waite
Department: Molecular,Cellular, & Develomental Biology |
CHARACTERIZING THE Ph AND SALT DEPENDANCE OF NEUROFILAMENT GRAFTING DENSITIES
MODELING THE PHASE TRANSITION THERMODYNAMICS OF WHELK EGG CAPSULE BIOPOLYMER
Whelk egg capsules from Busycon canaliculatum were analyzed with tensile testing to understand the relationship
between temperature and mechanical properties of the biomaterial. Under tensile loading, the proteins in the whelk
egg capsule biopolymer (WECB) transition from ordered a-helices into random coils and ß-sheets. Previous studies
indicated relationships between the stiffness of the material and temperature but with large variation in the data. The
goal of this research is to make statistically significant conclusions and mathematically model the relationships
between temperature and mechanical properties of WECB. Several samples were tensile tested over temperatures
ranging from -4°C to 90°C to show the behavioral trends of transition stress, elastic modulus, and transformation
strain. While previous studies suggested that the material may be elastomeric, test results show behavior contrary to
entropic elasticity. The elastic modulus was found to instead have an inverse relationship to temperature. The
results of this study show that WECB exhibits phase transition behavior more similar to the diffusion-free
thermoelastic martensitic transformations in shape memory alloys (SMA). The transition stress has a linear
relationship with temperature that matched Clausius-Clapeyron models of thermoelastic martensitic transformations.The transformation strain is not influenced by temperature, however, so the SMA model does not apply to all
properties of WECB.
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