Effects of nanosized organic‐rectorite fillers on the morphologies and properties of PVDF UF membrane

Abstract

AbstractIn this study, polyvinylidene fluoride/organic rectorite (PVDF/OREC) organic–inorganic nanocomposite membrane was prepared by phase conversion method. TEM and X‐ray diffraction (XRD) results demonstrate the successful fabrication of nanocomposite ultrafiltration membranes. When the OREC is less than 3 wt%, the nanosheets are mainly stripped and dispersed in the polymer matrix, with different numbers of intercalations. When the impurity content is 5%, the intercalation distribution dominates. When the impurity content increases to 7% and above, it becomes increasingly difficult for PVDF chain segments to enter the OREC interlayer and the OREC particles are dominated by simple blends on the order of micrometers in the polymer matrix. The inclusion of inorganic fillings significantly improved the mechanical properties of the membrane. The yield strength and tensile modulus of the membrane were increased by 53.7% and 574.9%, respectively, with an inorganic filler content of 5 wt%, while the elongation at the break was slightly decreased to 16.2%. This suggests a strong interaction between the OREC nanosheets and the polymer matrix. XRD and FTIR analyses indicate that OREC particles are effective heterogeneous nucleating agents that favor the formation of β‐phase crystals in the film. SEM surface and cross‐section results show that when joining can significantly reduce the average pore size of the membrane surface, large holes tend to reduce the number of holes in the skin layer distribution more uniformly. The AFM results show that the addition of OREC can significantly alter the surface roughness of ultrafiltered membranes, and that the changes in surface roughness and surface pore morphology of membranes with different clay contents are closely related to the distribution of nanoscale silicate sheets in the PVDF matrix.Highlights Prepared PVDF/OREC nanocomposite membranes via a phase‐inversion process. OREC acted as a potent nucleation agent, favoring β crystal formation. OREC resulted in smaller pore sizes and fewer large pores in the skin layer. The hydrophilicity of PVDF membranes was reformative by filling OREC. OREC led to increased water flux and BSA rejection due to pores and hydrophilicity.