Accession Number : AD1016526


Title :   Polyhedral Oligomeric Silsesquioxane (POSS) Dianiline as a Replacement for Toxic Methylenedianiline in PMR-15: Chemistry and Properties


Descriptive Note : Technical Report,01 Aug 2016,31 Aug 2016


Corporate Author : Air Force Research Laboratory (AFMC) AFRL/RQRP Edwards AFB United States


Personal Author(s) : Lamb, Jason T


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1016526.pdf


Report Date : 22 Aug 2016


Pagination or Media Count : 79


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.


Descriptors :   oligomers , composite materials , Moisture content , glass transition temperature , thermoplastic resins , materials science


Subject Categories : Polymer Chemistry
      Plastics


Distribution Statement : APPROVED FOR PUBLIC RELEASE