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Journal of Materials Science

, Volume 29, Issue 22, pp 5808–5816 | Cite as

Silica fracture

Part II A ring opening model via hydrolysis
  • J. K. West
  • L. L. Hench
Article

Abstract

A quantitative model of environmentally sensitive crack growth of amorphous silica (a-silica) is based upon semiempirical molecular orbital (MO) calculations (AM-1 method) of a water molecule interacting with strained three- and four-fold silica rings and a five-fold ring-chain structure. The energy barrier for hydrolysis of strained 3-fold rings is only 7 kcal mol−1, the energy barrier for hydrolysis of strained four-fold rings is 29 kcal mol−1; for a five-fold ring-chain it is 39 kcal mol−1. Thus, the MO model predicts that the energetics of Region 1 slow crack growth is controlled primarily by the distribution and hydrolysis of three-membered silica rings in the a-silica structure, and Region III is controlled by the distribution and energy of contraction of four and four + membered rings.

Keywords

Polymer Hydrolysis Water Molecule Energy Barrier Material Processing 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • J. K. West
    • 1
  • L. L. Hench
    • 1
  1. 1.Advanced Materials Research Center, Department of Materials Science and EngineeringUniversity of FloridaGainesvilleUSA

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