Silica/poly(methyl methacrylate) grafting composites (SiO2/PMMA) with higher silica content were used as pre-dispersed masterbatches and melt-mixed with PMMA resin to prepare a series of SiO2/PMMA composites with lower silica content.The dispersion evolution of accumulated silica particles during melt-mixing process was monitored by section-TEM.It was found that the effect of grafting states of pre-dispersed masterbatches on the dispersibility of accumulated silica particles was obvious.Non-grafted silica particles were easily agglomerated into sub-micron level aggregation in PMMA melt due to their poor compatibility.Taking silica particles as cross-linking points

three-dimensional cross-linked structure was generally formed in complex grafted pre-dispersed masterbatche

and as a result the accumulated silica particles cant be released and then diffused into the matrix phase.Only the simple grafted pre-dispersed masterbatche can be swelled by the matrix polymer and then be torn by the strong shear field force

in this case the accumulated silica particles can constantly migrated from pre-dispersed masterbatche phase into matrix phase

and finally can be uniformly dispersed in the entire matrix phase at a primary-particles size level.This high silica dispersion was of benefit to improving the composite properties.