Preparation And Application Of Functionalized Multi-walled Carbon Nanotube PVDF Blend Membrane Materials

The main contents of this paper are preparation of MWCNTs/PVDF composite membranes by solution blending.The effects of different molecular weights of PVDF and different carboxyl groups of MWCNTs on the thermal stability,crystal structure,surface and cross-section morphology,surface hydrophilicity,surface roughness,mechanical property,pore structure of composite membranes were carried out.Various characteristics of MWCNTs/PVDF composite membranes were analyzed comprehensively and systemly by infrared analysis(FTIR),field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),physical and chemical adsorption(BET),contact angle meter,atomic force microscopy(AFM)et al.The adsorption ability of composite membranes to metal ions and dye solution was discussed preliminary.DSC analysis showed that the 450 KDa pure PVDF membrane started to decompose at 450 ?,and the thermal decomposition temperature of the composite membrane increased to about 455 ? by adding MWCNTs,for 800 KDa PVDF membrane the decomposition temperature also increased by about 5 ?.The existence of MWCNTs helped to strengthen the thermal stability of the composite membrane.XRD analysis showed that for MWCNTs/PVDF composite membranes,the diffraction peak at 20.3 degree enhanced,which indicated that the bonding of MWCNTs to PVDF substrate could change the crystalline form of PVDF,the composite membranes prepared by PVDF with high molecular weight of 800 KDa was more obvious.From the surface morphology of the composite membrane,carboxyl content in MWCNTs and molecular weight of PVDF had an important influence on the pore structure,composite membranes with 800 KDa possessed more dense membrane surface,while the surfaces of 450 KDa composite membrane contained larger pores,which may be because a fast evaporation rate of low concentration solution resulted in rapid phase separation process.BET results showed that the composite membranes had higher specific surface area and pore volume than pure PVDF membrane,but the degree of increase was different.This suggested that the addition of MWCNTs to the PVDF membranes did promote pore formation.Adding MWCNTs could improve the mechanical properties and surface hydrophilicity of PVDF membranes.Compared with 450 KDa PVDF membranes,the roughness parameters of 800 KDa PVDF composite membranes were smaller,for high molecular weight of composite membranes,the higher degree of carboxyl MWCNTs led to larger roughness of composite membranes.And the composite membranes had certain adsorption effect on copper ion and methylene blue dye.