Another look at epoxy thermosets correlating structure with mechanical properties
Abstract
All glassy epoxy polymers develop macroscopic properties at some degree of conversion. Our selected example, diglycidyl ether bisphenol‐A epoxy pre‐polymer, was cured with 3,3′‐diaminodiphenylsulfone at stoichiometric equivalents using a series of cure profiles to produce distinct variation in the degree of epoxy conversion and result in varying network and network connectivity. Activation energy of epoxy‐amine reaction in this selected system was ∼61 kJ/mol. The calculated reaction energy barrier was found to vary with the extent of epoxy conversion and is attributed to multimechanistic reactions. Epoxy‐amine conversion was tracked in situ via near infrared spectroscopic analysis. A single cure condition (90°C) was selected for experiments focused on preferential linear chain growth and minimal branching and/or crosslinking. The physical properties for matrix materials from samples prepared to varying degrees of conversion were characterized and tested for fracture toughness, tensile, flexural, compression properties, molecular weight between crosslinks/crosslink density, and glass transition temperature(s). An empirical equation was also designed to predict molecular weight between crosslinks based on chemical connectivity and extent of reaction. POLYM. ENG. SCI., 54:1990–2004, 2014. © 2013 Society of Plastics Engineers
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 14, 2013
- Source ID
- 10.1002/pen.23749
Entities
People
- Eric W. Fowler
- James W. Rawlins
- Monoj Pramanik
Organizations
- Office of Naval Research
- University of Southern Mississippi