Title page for etd-0727113-174818


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URN etd-0727113-174818
Author Wei-Chun Huang
Author's Email Address No Public.
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Department Mechanical and Electro-Mechanical Engineering
Year 2012
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title The stress effects on degradation rate of poly glycolic acid by the density functional theory and molecular dynamics studies
Date of Defense 2013-07-12
Page Count 91
Keyword
  • molecular dynamics
  • transition state theory
  • density functional theory
  • Polyglycolic acid
  • reaction rate
  • Abstract In this study, the degradation rate variation of polyglycolic acid molecule with mechanical stress are investigated by density functional theory (DFT) and molecular dynamics (MD), this study can be arranged into two parts:
    In part I: The biodegradation mechanism of polyglycolic acid (PGA) and PGA intermediate of hydrolysis under mechanical stress was studied by the DFT calculation. The variations of bending angle, torsion angle, bond length as well as the electronic properties of PGA and PGA intermediate at different strains were presented. From the stress-strain profile, it shows the variation of the stress of PGA intermediate is more sensitive to the strain as compared to that of PGA. The decrease of energy barrier for the dissociation of PGA intermediate to two PGA molecules under the increasing strains causes the promotion of PGA hydrolysis. Our DFT calculation results have provided a clear explanation for the experimental observation, which the mechanical loading can enhance the PGA degradation rate.
    In part II: This study, which employed molecular dynamics combine pcff potential parameters to construct polyethylene glycolic model with different molecular weight. Furthermore, the ultimate strength are obtained through tensile test of each model, and deduced that the ultimate strength of infinite molecular weight. Besides, the reaction rates under different stress are calculated by different barrier and frequency from part I. According to above-mentioned results, the relationship between degradation time and the ultimate strength under different stress are demonstrated by this simulation study, the degradation rate of polyglycolic acid indeed are accelerated under the stress effect.
    Advisory Committee
  • Jenn-Sen Lin - chair
  • Chang,Jee-Gong - co-chair
  • Jin-Yuan Hsieh - co-chair
  • Chuan Chen - co-chair
  • Shin-Pon Ju - advisor
  • Files
  • etd-0727113-174818.pdf
  • Indicate in-campus at 2 year and off-campus access at 3 year.
    Date of Submission 2013-08-27

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