Influence of processing conditions on frequency ()-dependent dynamic rheology of vapor grown carbon nanofiber (VGCF) filled polystyrene (PS) melt (200℃) with different VGCF volume fractions (=0~0.05) was studied in the framework of a modified two phase model.In comparison with the composites processed in a strong-shear mixing condition (190℃; 120 r/min-10 min)

VGCF formed aggregates to a higher degree in those processed in a weak-shear mixing condition (190℃; 30 r/min-5 min).The filler aggregation was characterized by a higher value of strain amplification factor Af() and a smaller relaxation exponent n related to the filler phase.Furthermore

strain ()-dependent amplification factor

Af(

)

and characteristic elastic and viscous moduli

Gf' (

c) and Gf (

c)

were introduced to the two phase model for discussing the nonlinear rheology with increasing .The results showed that the two phase model allowed discussing dynamic rheology of filled melts qualitatively.The processing condition influenced the dispersion of VGCF in the matrix while it did not influence relationships of elastic contribution Rf' () against n for -dependent rheology as well as elastic modulus Gf' (

c) against nonlinear strain exponent x and viscous modulus Gf (

c) against nonlinear strain exponent y

suggesting that the viscoelastic contribution of the filler phase was closely related to its relaxation and structural stability.