Low-molecular-weight thermoplastic modifiers as effective healing agents in mendable epoxy networks. (January 2014)

• Record Type: Journal Article
• Authors: Varley, Russell J; Dao, Buu; Pillsbury, Christopher; Kalista, Stephen J; Jones, Frank R
• Other Names: Bond Ian P guest-editor.; Trask Richard S guest-editor.; Varley Russell J guest-editor.
• Is Part Of: Journal of intelligent material systems and structures. Volume 25:Number 1(2014:Jan.)
• Page Start: 107
• Page End: 117
• Publication Date: 2014-01
• Subjects: Polymer networks -- self-healing -- thermoplastic healing; Smart materials -- Periodicals; Intelligent control systems -- Periodicals; Artificial intelligence -- Periodicals; Matériaux intelligents -- Périodiques; Commande intelligente -- Périodiques; Intelligence artificielle -- Périodiques; 620.11
• DOI: 10.1177/1045389X13507348
• Languages: English
• ISSNs: 1045-389X

Abstract

Solid-state healing of epoxy networks is shown to be an effective and robust mechanism for highly cross-linked epoxy networks. Using diglycidyl ether of bisphenol A epoxy resin and diethyltoluenediamine, the cured epoxy network is transformed into a mendable system using phenoxy resin and low-molecular-weight polybisphenol A-co-epichlorohydrin) thermoplastic modifiers. Using functionally terminated low-molecular-weight poly(bisphenol A-co-epichlorohydrina) thermoplastic modifiers as healing agents reveals that salicylic acid or neutralized sodium salicylate groups produce healing similar to high-molecular-weight non-functional phenoxy resin as measured using single-end notched beam testing. The miscibility of both thermoplastics in the diglycidyl ether of bisphenol A/diethyltoluenediamine system was evaluated using differential scanning calorimetry and dynamic mechanical thermal analysis and identified as being important to promoting healing. Near-infrared spectroscopy showed that the network structure was unaffected by the thermoplastic modification, suggesting that healing occurred primarily through physical or non-covalent mechanisms rather than covalent bonding. The potential for self-assembly of the salicylic acid and neutralized sodium salicylate groups to form a high-molecular-weight thermoplastic in situ was also discussed as being a possible reason for the improved level of healing with the low-molecular-weight thermoplastic.