Polyhedral Oligomeric Silsesquioxane (POSS) Dianiline as a Replacement for Toxic Methylenedianiline in PMR-15: Chemistry and Properties
Abstract
With the goal of replacing methylene dianiline (MDA) in PMR-15 (polymerizable monomeric reactant), which is a known toxin to humans, a thermally stable, polyhedral oligomeric silsequioxane (POSS) dianiline, which features an aromatic periphery, was copolymerized as a drop-in replacement. The chain length of the experimental oligomers was varied to study effects of cross-link density and nadic endcap concentration. The resultant oligomers were characterized for various neat resin and composite properties. The POSS dianiline has shown previously in 6-FDA-ODA-PEPA type polyimides to improve moisture resistance and processability. It was shown that the bulky monomer addition improved moisture resistance (80 decrease in ultimate moisture absorption) and processability (uncured Tg and rheology) were improved. Uncured Tg values decreased by as much as 85C and complex viscosity decreased by 3 orders of magnitude. Viscosity is low enough that resintransfer molding (RTM) is possible. However, thermal properties such as glass transition temperature (Tg) and long-term thermal oxidative stability (TOS) along with composite strengths were hindered. Shortening the chain length, which increases cross-link density is shown to improve cured Tg and can be manipulated. The decreased chain length causes increased nadic endcap concentration which has been shown to lower the thermal stability of the polyimide.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 22, 2016
- Accession Number
- AD1016526
Entities
People
- Jason T. Lamb
Organizations
- Air Force Research Laboratory