1999 REU Participants

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Margaret Broz

Margaret is majoring in Chemistry and minoring in Music at Gustavus Adolphus College.

Blends of Epoxy Resins with Epoxidized Isoprene/Butadiene Block Copolymer
Margaret Broz
Gustavus Adolphus College

Barney Grubbs and Frank Bates
Department of Chemical Engineering and Materials Science, University of Minnesota

A series of epoxidized isoprene/butadiene block copolymers (IxB) were synthesized from poly(1, 4-isoprene)-block-poly(1, 2-butadiene) (IB). A copolymer IB was epoxidized with in situ generated dimethyl dioxirane. The epoxidation reaction was selective for 1, 4-isoprene repeat units. The epoxidized 1, 4-isoprene had varying levels of epoxidation, ranging from 96 % down to 10%. The series of colpolymer IxB was then used to form copolymer/epoxy resin blends at 5 wt % copolymer IxB and 20 wt % copolymer IxB. The blends were composed of copolymer IxB and stoichiometric amounts of poly(Bisphenol A-co-epichlorohydrin) and methylene dianiline. These blends were visually observed at room temperature, after a 70 hour cure at 55 ¡ C, and after a one hour cure at 200 ¡C. It was observed that as the percent epoxidation of copolymer IxB in the blend increased, the copolymer miscibility with the epoxy resin increased, and the domain size decreased. DSC and IR was used to analyzed the cure of the blends, and they both showed evidence of the copolymer IxB epoxy groups reacting with the epoxy resin precursors. Further work will be done to characterize the microstructures in the blends, and to determine when and how copolymer IxB reacts with the epoxy precursors during the cure.