Reduced Micro-cracking in PMR-15 Type Resin Modified with Silsesquioxane Diamine Monomer
Abstract
With the goal of replacing methylene dianiline (MDA) in PMR-15 (polymerizable monomeric reactant), a known toxin to humans, a thermally stable polyhedral oligomeric silsequioxane (POSS) dianiline featuring an aromatic periphery was co-polymerized as a "dropin" replacement. The chain length of the experimental oligomers was varied to study effects of cross-link density and nadic endcap concentration. It was shown that the bulky monomer addition improved moisture resistance (80% decrease in ultimate moisture absorption) and processability (uncured glass transition temperature (Tg) and rheology) were improved. Uncured Tg values decreased by as much as 85 deg C and complex viscosity decreased by three orders of magnitude. However, thermal properties such as cured Tg and long-term thermal oxidative stability (TOS) along with composite strengths were hindered. Shortening of the chain length, which increases cross-link density, is shown to improve cured Tg. The decreased chain length causes increased nadic endcap concentration and lowers the thermal stability of the polyimide.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 06, 2022
- Accession Number
- AD1181902
Entities
People
- Andrew J. Guenthner
- Gregory R. Yandek
- Jason T. Lamb
- Joseph M Mabry
- Michael D. Ford
- Timothy S. Haddad
Organizations
- Air Force Research Laboratory