Accession Number:

ADA555878

Title:

Effects of Silicon Substitution in the Main Chain Network Segments of Polycyanurates

Descriptive Note:

Conference paper

Corporate Author:

AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE SPACE AND MISSILE PROPULSION DIV/PROPULSION MATERIALS APPLICATIONS BRANCH

Report Date:

2011-11-29

Pagination or Media Count:

4.0

Abstract:

The incorporation of silicon into thermosetting polymers at the molecular level has been shown to have several significant effects, beyond improving thermo-oxidative stability, as demonstrated by studies of silicon-containing cyanate ester resins. These effects are generally traceable to the enhanced flexibility afforded by the substitution of C-Si and C-C bonds, and include increased free volume and thermal expansion. In cyanate esters, the increased specific volume leads to a decrease in cyanate ring density, which may explain the reduced water uptake in silicon-containing cyanate esters at high conversions. In addition, the increased flexibility provides for a greater degree of cure at lower temperatures than would otherwise be possible, leading, counterintuitively, to a higher glass transition temperature for a given cure schedule. Due to the molecular level mechanisms involved, many of these effects are expected to be present in other silicon-containing thermosetting resins as well.

Subject Categories:

  • Inorganic Chemistry
  • Polymer Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE