Morphology and Fracture Properties Relationship of Epoxy-Diamine Systems Simultaneously Modified with Polysulfone and Poly(ether imide)

M.I. GIANNOTTI, C.R. BERNAL, M.J. GALANTE, P. A. OYANGUREN

Brujas, Bélgica

Simposio; 8th European Symposium on Polymer Blends - Eurofillers 2005; 2005

Ni idea

 One of the most frequently used methods to toughen thermosetting materials is the modification of thermosetting matrices with high-Tg thermoplastic polymers as a second phase. The thermoplastic rich phase may be incorporated as a second phase dispersed in the initial formulation, or can be generated during the course of polymerization (polymerization induced phase separation). The toughening induced by thermoplastic modification is closely related to diverse structural factors such as volume fraction and morphology of the dispersed phase. The simultaneous modification of the thermosetting precursors with two thermoplastic polymers is an alternative to obtain different properties according to the diverse morphologies generated due to different phase behaviours of the blends. Through the analysis of fracture properties and morphology, the simultaneous modification of an epoxy-diamine system with two immiscible thermoplastics, was studied as an alternative to obtain toughened systems without the incorporation of great quantities of modifier, that otherwise may lead to high viscous systems difficult to process. For 10 or 15 wt % thermoplastic (PEI) modified epoxy-amine systems, small additions of a second modifier (PSF) lead to important changes in final morphologies, and so in fracture properties, when is compared to the system modified only with PEI. When the thermoplastic-rich phase shows continuity, increases in toughness up to 40 % are achieved. Hence, by varying PSF/PEI ratio for a constant total modifier concentration -and so keeping formulation´s viscosity constant- appropriate morphology changes can be induced. Therefore, materials with better fracture properties are obtained as compared with systems with only one thermoplastic modifier. As an additional advantage, no important changes in the elastic modulus of the final material are found. For systems where morphology consists of a thermoset continuous matrix, either particulate or "island" type, resistance to crack propagation is enhanced, even when toughening is not achieved.