Production and characterisation of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) flat sheet membranes

World population is increasing day by day, therewith demand on World resources is increasing too. Water is one of the most limited resources of the nature. Behavior of water use and protecting the water resources is very important. Because of industrialization and chancing consuming behaviors of society natural balance is getting deteriorated. In this case, managing the pollution is becoming very important. Environmental Technologies take a strategic role on the production of solution. Membranes are one of the most common filtration elements used in commercial and industrial applications. Membrane is a selective barrier that allows the passage of constituents and retains the others. Membrane properties such as durability, reliability, stability, high permeability and selectivity make membranes essential for use in variety of applications. Most of the membranes are used in water & wastewater treatment and pharmaceutical and medical use sectors. The demand for membranes for use in industrial gas processing industry and pharmaceutical & medical use industry are major drivers of the membranes market in the coming years (URL-1). The need and growth of membrane technology systems are improving and increasing year-on-year basis. Presently, the global membrane technology market is rapidly growing stronger due to growth drivers such as challenges pertaining to water shortages, environmental degradation and regulations, water sanitation, exploration of new applications, advancement in the field of material science, enhancing process technologies, and much more. The membrane technology market is also witnessing significant growth due to the rising number of membrane technology applications and increase in pharmaceutical production worldwide. Due to these factors, growth of membrane technology is insistently driven in pharmaceutical, biopharmaceutical and life sciences industries, and also across several emerging regions such as North America, Europe, and Asia (URL-2) In recent years, significant improvements have been achieved in environmental technologies. Research and development investments on environmental technologies started being supported by governments and industry. Environmental investments have a significant effect on the economy of industrial applications, because of that reason technologies for environment must have as less effect as possible on costs. At is point, membrane technologies for environmental applications come to the fore. In areas such as reuse of wastewaters, advanced treatment, desalination, improvement of conventional treatment systems, membrane systems has many advantages. Developments in membrane filtration systems make membrane systems more efficient than chemical treatment systems. Global demand on membrane modules in water treatment and industrial uses combined was valued at approximately US$15.6 billion in 2012. Growing by 8% annually in the coming years, the market is expected to reach US$21.22 billion by 2016 and to approach US$25 billion by 2018 (URL-3). Membrane production is the most important point for membrane prosess applications. But, there is not a company or a center which is manufacturing the membrane material on a commercial scale in our country. In this context, polymers are very important for membrane production. The most common polymers that are used for commercial membrane production are polymers like polyvinilidenflorid (PVDF) and polyacrylonitrile (PAN). When rewieving the literature it is possible to see that the most important problem with PVDF membranes is their hydrophobicity. However the physical strength of PVDF membranes is higher than the membranes which are produced by other materials. On the other hand, PAN mambranes have higher hydrophilicity. From this point, PAN/PVDF mixed polymeric membranes are investigated. Production and characterization of the PAN, PVDF single membranes and the PVDF/PAN mixed membranes are the main purpose of this thesis. At first 12% (w/w), 14% (w/w) and 16% (w/w) PAN membranes are produced. Each concentration category has four types; one of them is pure PAN membrane and others are %2, %4, %6 (w/w) PVP added PAN membranes. To determine the effect of PVP molecular weight on membrane structure; 10 kDa and 40 kDa PVP are used for each concentration. To determine the effect of coagulation bath temperature on PAN membrane character, casting of membranes is done with 25 oC coagulation bath temperatures for each membrane and 50 oC for selected membranes, Three types of pure PVDF membranes are produced which have the concentrations of 14% (w/w), 16% (w/w) and 18% (w/w). Each concentration category has four types; one of them is pure PAN membrane and others are %2, %4, %6 (w/w) PVP added PVDF membranes. Only 10 kDa molecular weight of PVP is used for casting PVDF membranes. To determine the effect of PVDF on the mechanical strength of PAN membranes PAN/PVDF blend membranes were casted in laboratory scale at 25 and 50 oC. 16% and 18% total polymer (PAN+PVDF) concentrations were chosen for fabrication. For each total concentration different ratios of PAN/PVDF (PAN:PVDF=50:50, PAN:PVDF=60:40, PAN:PVDF=70:30, PAN:PVDF=80:20, PAN:PVDF=90:10) membranes casted. For all of casted membranes casting solution viscosity, permeability, molecular weight cut off (MWCO), dynamic mechanic analysis (DMA), contact angle, surface roughness with AFM and scanning electron microscopy measurements are done during the characterizatiın study.