Abstract:

The influences of asymmetric degree of miscibility gap on the microstructure evolution and kinetics in binary polymer blends were investigated by the phase-field method. By using the semi-implicit Fourier spectral scheme, the nonlinear Cahn-Hilliard-Cook diffusion equation was numerically solved, and then the effects of asymmetric degree of miscibility gap on the thermodynamics and kinetics of binary polymer blends were explored. The results showed that the asymmetric degree of miscibility gap significantly affected microstructure evolution and kinetic process of the system. At the same time, the initial composition played a key role in determining the evolution path of system. For the asymmetric polymer system, the novel structure transition mechanisms were found, which was attributed to asymmetric kinetics of two phases. In addition, it was found that other kinetic characters were affected by the asymmetric degree of the system, i.e., the structure factor and characteristic size. The results could reveal the phase separation process of asymmetric polymer system, and would provide a theoretical basis for synthesizing polymer composites with controllable microstructure and physical properties.

Key words: asymmetry, polymer blends, microstructure, phase-field simulation

摘要：

采用相场法，研究了混溶间隙的非对称程度对二元高分子共混体系微观组织演化及动力学的影响。通过使用半隐式傅里叶频谱法，求解了非线性Cahn-Hilliard-Cook扩散方程，并探索了混溶间隙的非对称程度对二元高分子共混体系热力学和动力学的影响。结果表明，混溶间隙的不对称程度显著地影响了体系的微观组织演化及相分离动力学。此外，初始成分对体系组织演化的路径也起着关键作用。对于非对称高分子共混体系，在现有的研究基础上发现了液滴-交联和交联-液滴新的结构转变机制，其归因于两相非对称的动力学过程。此外，体系的非对称程度也会影响其他动力学特征，即结构因子和特征尺寸。结果有助于揭示非对称高分子体系的相分离过程，为合成具有可控微观组织及物理性能的高分子复合材料提供了理论依据。

关键词: 非对称, 高分子共混体系, 微观组织, 相场模拟