Abstract

The morphology (dispersed phase composition, size distribution, and particle/matrix interface shapes) of epoxy resins modified with 5–15 parts by weight (pbw) of carboxyl (CTBN) and amine (ATBN) terminated butadiene acrylonitrile rubber have been characterized. The characterization techniques were transmission electron microscopy coupled with energy dispersive X-ray analysis, differential scanning calorimetry and proton and 13C nuclear magnetic resonance. ATBN modified epoxies have a diffuse-appearing interface between the dispersed rubber phase and the epoxy matrix, in contrast to the sharp boundaries of CTBN particle interfaces. Interface mixing of epoxy and rubber, hypothesized initially to explain the interface diffuseness in ATBN modified epoxy, was not found in either CTBN or ATBN modified epoxy. The difference in interface appearance is attributed to ATBN particles having highly irregular shapes compared to the nearly spherical CTBN particles. Bimodal particle size distributions are observed with both modifiers. Both rubber modifiers also produce essentially identical toughness values which do not increase with rubber content in the range 5–15 pbw despite a commensurate increase in the population of large particles.Modified Amine Resin

 

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