Phase inverted, thermoplastic modifier

Woo et al. (1994) studied a DGEBA/DDS system with both polysul-fone and CTBN. The thermoplastic/rubber-modified epoxy showed a complex phase-in-phase morphology, with a continuous epoxy phase surrounding a discrete thermoplastic/epoxy phase domain. These discrete domains exhibited a phase-inverted morphology, consisting of a continuous thermoplastic and dispersed epoxy particles. The reactive rubber seemed to enhance the interfacial adhesive bonding between the thermoplastic and thermosetting domains. With 5 phr CTBN in addition to 20 phr polysul-fone, Glc of the ternary system showed a 300% improvement (700 Jm-2 compared with 230 J m 2 for the neat matrix). 

Several basic morphologies are observed in thermoplastic-modified epoxies and, indeed, other thermosets. Homogeneous [Fig. 6(A), in which no phase separation is observed] and particulate [Fig. 6(B), in which the modifier phase separates to produce small domains] morphologies occur at low concentrations of modifier. In these cases, the thermoplastic modifier is encapsulated within a thermoset matrix, whereas in the phase-inverted morphology, [Fig. 6(C)] the minor thermoplastic component is the continuous phase surrounding large, discontinuous domains of the major... 

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