Rheology

solvent extraction and scanning electron microscopy (SEM) were employed to investigate the influence of hydrophilic nano-SiO2 on the co-continuity interval of immiscible poly(methyl methacrylate) (PMMA)/polystyrene (PS) blends.For unfilled systems

the co-continuity intervals of PMMA/PS blends measured by the three methods were nearly consistent.However for filled blends

SEM and solvent extraction means showed that increasing the filler content will broaden the co-continuity interval.The preferential distribution of hydrophilic SiO2 particles in more affinitive PMMA phase led to a strong increase both in melt viscosity and elasticity of PMMA and further slowed down all relaxation processes associated with the destruction of the co-continuous structure such as breakup or retraction.However

the co-continuity interval obtained by rheology was found to be narrower than that by SEM and solvent extraction

which was contrary to unfilled system.It was proposed that the enhancement in the melt viscosity and elasticity of PMMA/PS blends due to the incorporation of hydrophilic nano-SiO2 particles could significantly prolong the relaxation time of sample loaded before beginning the rheological tests.When the sample was subjected to high temperature for a long time before test

its co-continuous structure would be easily coarsened and disintegrated under the driving of interfacial tension.Furthermore

the higher filler content the more time consumed

which might seriously destroy the co-continuous structure.It was proposed that SEM and solvent extraction might be more suitable in detecting the co-continuity interval of filled PMMA/PS blends than rheological test.Finally

the advantages

disadvantages and applicable range of three methods were compared and summarized.