Structure-to-Property Relationships in Addition Cured Polymers. 4. Correlations between Thermo-Oxidative Weight Losses of Norbornenyl Cured Polyimide Resins and Their Composites
Abstract
The purpose of this study was to identify any relationships between the thermo-oxidative stability (TOS) at 316 deg C of a wide variety of PMR (polymerization of monomeric reactants) addition cured polyimide resins and their corresponding graphite fiber composites. Weight loss results at 316 deg C confirmed the expected relationship of increasing aliphatic endcap content with decreasing TOS. More importantly, the resin TOS study also showed an unexpected linear correlation of decreasing weight loss to increasing ratio of benzylic diamine to aliphatic endcap in the range of the stoichiometries studied. Furthermore, only after long-term 316 deg C aging does the dianhydride used with the benzylic diamines become an additional factor in influencing the amount of PMR resin and composite weight losses. Additionally, the benzylic systems also consistently showed significantly lower resin and composite weight losses at 316 deg C than the corresponding nonbenzylic/norbornenyl resins and composites, except when the nonbenzylic diamine monomer does not contain a connecting group, e.g., paraphenylenediamine. Instead, this diamine resulted in a 316 deg C resin and composite weight loss that was only competitive with benzylic type diamines, e.g. 4,4'-diaminotriphenylmethane or 4,4'-diaminodiphenylmethane (methylenedianiline, MDA).
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1992
- Accession Number
- ADA253050
Entities
People
- William B. Alston
Organizations
- National Aeronautics and Space Administration