Miscibility,morphology and fracture toughness of epoxy resin/poly(vinyl acetate) blends |
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| Authors: | S Zheng Y Hu Q Guo J Wei |
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| Institution: | (1) Department of Materials Science & Engineering, University of Science and Technology of China, 230026 Hefei, PRC;(2) Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, 230026 Hefei, PRC |
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| Abstract: | Diglycidylether of bisphenol A (DGEBA)/poly(vinyl acetate) (PVAc) blends cured with 4,4 -diaminodiphenylmethane (DDM) were prepared. The miscibility and phase behavior were investigated by means of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The study results indicate that the epoxy precursor (DGEBA)/PVAc blends are clearly miscible at the entire composition and theTg values experimentally obtained are in a good agreement with those predicted by Fox equation. Cured at elevated temperature, all the DDM-cured blends underwent phase separation and display two-phase morphology. When PVAc content is more than 10 wt%, the thermoplastics-modified resins began to show a co-continuous phase structure. It is the cocontinuous structure that leads to a significantly-improved toughness inK
ic. Morphologic investigation of the surfaces of fracture mechanic measurement specimens indicates that the toughening effect of the thermoplastics-modified epoxy resins may arise mainly from the ductile yielding of PVAc. |
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| Keywords: | Epoxy resin poly(vinyl acetate) polymer blends phase separation morphology toughness |
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