Crystallization and concentration fluctuation of miscible poly(vinylidene fluoride)/poly(methyl methacrylate) blends containing carbon nanotubes: Molecular weight dependence of poly(methyl methacrylate)

Abstract

In this work, poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blend (50/50, wt/wt) and its blend composites containing carbon nanotubes (CNTs, 0.2 and 0.5 wt%) were prepared. Two types of PMMA with relatively large (PMMA-L) and small (PMMA-S) molecular weights were used to prepare the materials. It was observed that PVDF had higher crystallization ability in the samples containing PMMA-S. CNTs exhibited nucleation effect on the crystallization of PVDF and their nucleation efficiency was influenced by the molecular weight of PMMA. Rheological measurements showed that concentration fluctuation occurred during the melt annealing process even if the blend should be miscible at this temperature range, and more apparent concentration fluctuation was observed for the samples containing PMMA-S. Incorporating CNTs restrained the concentration fluctuation of the blend under the shear condition. Further results showed that larger concentration fluctuation in the melt state facilitated the higher crystallization ability of PVDF in the subsequent cooling process.