Modifications of epoxy resins for improved mechanical and tribological performances and their effects on curing kinetics.

Description:

A commercial epoxy, diglycidyl ether of bisphenol-A, was modified by two different routes. One was the addition of silica to produce epoxy composites. Three different silane coupling agents, glycidyloxypropyl trimethoxy silane (GPS), -methacryloxypropyl trimethoxy silane (MAMS) and 3-mercaptopropyltriethoxy silane (MPS), were used as silica-surface modifiers. The effects of silica content, together with the effects of chemical surface treatment of silica, were studied. The results indicate that epoxy composites with silica exhibit mechanical and tribological properties as well as curing kinetics different than the pure epoxy. The optimum silica content for improved mechanical and tribological properties (low friction coefficient and wear rate) was different for each type of silane coupling agent. An unequivocal correlation between good mechanical and improved tribological properties was not found. Activation energy of overall reactions was affected by the addition of silica modified with MAMS and MPS, but not with GPS. The second route was modification by fluorination. A new fluoro-epoxy oligomer was synthesized and incorporated into a commercial epoxy by a conventional blending method. The oligomer functioned as a catalyst in the curing of epoxy and polyamine. Thermal stability of the blends decreased slightly at a high oligomer content. Higher wear resistance, lower friction coefficient and higher toughness were found with increasing oligomer content; thus in this case there was a correlation between good mechanical and improved tribological properties. The results indicated that increasing toughness and formation of a transfer film contribute to improved tribological performances.

Creator(s): Chonkaew, Wunpen
Creation Date: May 2008
Partner(s):
UNT Libraries
Collection(s):
UNT Theses and Dissertations
Usage:
Total Uses: 925
Past 30 days: 39
Yesterday: 1
Creator (Author):
Publisher Info:
Publisher Name: University of North Texas
Place of Publication: Denton, Texas
Date(s):
  • Creation: May 2008
  • Digitized: August 8, 2008
Description:

A commercial epoxy, diglycidyl ether of bisphenol-A, was modified by two different routes. One was the addition of silica to produce epoxy composites. Three different silane coupling agents, glycidyloxypropyl trimethoxy silane (GPS), -methacryloxypropyl trimethoxy silane (MAMS) and 3-mercaptopropyltriethoxy silane (MPS), were used as silica-surface modifiers. The effects of silica content, together with the effects of chemical surface treatment of silica, were studied. The results indicate that epoxy composites with silica exhibit mechanical and tribological properties as well as curing kinetics different than the pure epoxy. The optimum silica content for improved mechanical and tribological properties (low friction coefficient and wear rate) was different for each type of silane coupling agent. An unequivocal correlation between good mechanical and improved tribological properties was not found. Activation energy of overall reactions was affected by the addition of silica modified with MAMS and MPS, but not with GPS. The second route was modification by fluorination. A new fluoro-epoxy oligomer was synthesized and incorporated into a commercial epoxy by a conventional blending method. The oligomer functioned as a catalyst in the curing of epoxy and polyamine. Thermal stability of the blends decreased slightly at a high oligomer content. Higher wear resistance, lower friction coefficient and higher toughness were found with increasing oligomer content; thus in this case there was a correlation between good mechanical and improved tribological properties. The results indicated that increasing toughness and formation of a transfer film contribute to improved tribological performances.

Degree:
Level: Doctoral
Discipline: Materials Science
Language(s):
Subject(s):
Keyword(s): Epoxy resin | friction | wear | tribology | curing kinetics
Contributor(s):
Partner:
UNT Libraries
Collection:
UNT Theses and Dissertations
Identifier:
  • OCLC: 262616096 |
  • ARK: ark:/67531/metadc6123
Resource Type: Thesis or Dissertation
Format: Text
Rights:
Access: Public
License: Copyright
Holder: Chonkaew, Wunpen
Statement: Copyright is held by the author, unless otherwise noted. All rights reserved.