关键词: 稳态流变, 动态流变, 两相模型, 炭黑, 聚苯乙烯, 复合体系

Abstract:

Steady and dynamic rheological behavior of carbon black(CB) filled polystyrene(PS) composites were investigated. The CB/PS composites exhibit percolation transition at critical CB volume fraction(φ) of 0.06. The nonlinear rheology from dynamic strain sweep was related to the breakdown of particle-particle and particle-polymer interactions at small strains and the disentanglements of macromolecular chains at large strains. Analyzing the linear dynamic rheology of the composites according to the two-phase model revealed that the strain amplification factor A_f(φ), characteristic moduli and relaxation factor of the filler phase varied as a function of temperature. Dependence of A_f(φ) on φ followed the Guth equation and the diffusion-controlled cluster-cluster aggregation model. The shape factor and fractal dimension of the "filler phase" decreased with increasing temperature, suggesting that, as temperature was increased, the diffusion-controlled CB particle aggregation process was accelerated and the strain amplification effect was weakened. The elastic and viscostic characteristic modulus components of the "filler phase" exhibited scaling dependences on φ. At φ>0.06, both characteristic moduli of the "filler phase" and their scaling exponents demonstrated decrease tendencies with increasing temperature and the variation of the elastic component was slightly higher than the viscostic component revealing different temperature dependences of the elastic and viscostic characteristic modulus components of the "filler phase".

Key words: Steady rheology, Dynamic rheology, Two-phase model, Carbon black(CB), Polystyrene(PS), CB/PS composities