SiO_2纳米粒子对PMMA/PS共混物共连续相结构退火粗化过程的影响

考察了亲水性纳米SiO2粒子的加入对聚甲基丙烯酸甲酯/聚苯乙烯(PMMA/PS)共混体系的共连续相结构在静态高温退火时形态稳定性的影响,发现静态高温退火条件下,填充体系共连续组成范围变窄幅度较小、特征结构尺寸的粗化速率减慢.流变测试表明纳米SiO2粒子加入之后PMMA/PS共混体系的黏弹性显著提高,从而能减缓破坏构成共连续相结构的纤维断裂或回缩等松弛过程的速率,有效地抑制PMMA/PS共混体系的共连续相结构粗化进程,提高相结构的稳定性.根据现有的两种粗化理论的定性分析表明,在高填充量的共混体系中,加入纳米SiO2粒子导致共混体系的黏弹性的显著改变是影响PMMA/PS共混体系在静态高温退火时共连续相结构粗化速率的主要因素,相对而言界面张力的变化对共连续相结构在静态高温退火时的粗化速率影响则应该较小.

INFLUENCE OF SILICA NANOPARTICLES ON THE COARSENING OF CO-CONTINUOUS PMMA/PS BLENDS DURING ANNEALING

The influence of hydrophilic SiO₂ nanoparticles on the stability of co-continuous structure in poly(methyl methacrylate)/polystyrene (PMMA/PS) blends under quiescent melt annealing was investigated.It was found that the filled blends displayed broader co-continuous interval and less coarsened structure than those of unfilled blends after annealing.The result indicated that the morphological stability of co-continuous blends can be improved effectively by the addition of SiO₂ nanoparticles.Rheological measurements showed that the viscosity and elasticity of filled PMMA/PS blends,which were associated with the destruction process of the co-continuous structure such as breakup or retraction,were enhanced significantly.The influence of the change in the viscoelasticity and interfacial tension of blends upon the addition of SiO₂ nanoparticle was analyzed qualitatively based on two available theories describing the coarsening process of the co-continuous structure of polymer blends.It was proposed that the change in the viscoelastic properties of PMMA/PS blends instead of the interfacial tension plays a dominant role in the coarsening rate of the co-continuous structure during the quiescent annealing in melt state.