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Epoxy‐amine networks with varying epoxy polydispersity
Author(s) -
Mc Aninch Ian M.,
Palmese Giuseppe R.,
Lenhart Joseph L.,
La Scala John J.
Publication year - 2015
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.41503
Subject(s) - epoxy , dispersity , materials science , glass transition , composite material , dynamic mechanical analysis , modulus , thermal expansion , polymer chemistry , polymer
Solid, high molecular weight DGEBA‐based epoxies were blended with high purity liquid DGEBA to create several resins with equivalent epoxy equivalent weights, but with polydispersity indices (PDIs) ranging from 3 to over 10. The resins were cured with a stoichiometric amount of polyetheramine and compared to a nonblended epoxy with PDI of 1.8. Modulus, glass transition temperatures, and molecular weight between cross‐links were measured using dynamic mechanical analysis. Coefficients of thermal expansion (CTE) were measured and used to extend room temperature density measurements as a function of temperature. Fracture properties were also measured. Overall, the increased polydispersity has almost negligible effect, with the main difference occurring in the slope of the glassy CTE, with more polydisperse epoxies having a slower increase in CTE. In comparison to previous work where bimodal amines were blended with DGEBA, we conclude that epoxy resins are far more sensitive to distributions in the flexible portion, rather than the more rigid one. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41503.