tj if I A SUMMARY There are two ainis of this study. First is; to obtain the parameters which are effective on the ©2 and COg transfer through porous polypropylene membrane; mathematical modelling of gas transfer through these membranes and to investigate the applicability of these to the design of membrane oxygenators. The second purpose is to coat the surface of polypropylene membranes with a very thin, blood- compatible and non- porous film without reducing the gas transfer rates., therefore, to eliminate the side effect, such as cell deposition on the iTienibrane surface, micro- emboli and ultrafiltration which are observed in clinical applications of membrane oxygenators. in this study Celgard® 2400 porous FP membranes were used. For surface modification blood side sui-f&c&s of the membranes were coated with a silicone based film by plasma polymerisation technique. The surface properties of the coated and uncoated meinhr&n&s were investigated by SEM, İR and ESC A techniques. To test the bioodcompatibiiity of the membranes, in vitro bloodcompatibiiity studies, i.e. both in continuous and in batch fashion were performed with heparinised fresh human blood for two different coating thickness (26,2 and 69,0 jig/cm2) and two different blood flow rates (25 and ÎOÖcmVmin). On the other hand, in order to de termine effect of coating on physical properties of mem brane, mechanical tests were applied to both the uncoated and coated membranes. In this research, the effects of coating film and film thickness on gas transfer were also investi gated. The gas flow rate, the gas side O2 partial pressure, the liquid flow rate, the liquid flow channel depth and the coating thickness were varied in the range of 250-2500 cm5 /min.668,2-883,0 mrnHg, 50-400 crnVrnin, 0,018-0,144 cm and 0,0- 69,0 jig/cm2, respective! >~. Gas-gas and liquid-gas experiments ?were performed at 37°C in order to obtain the Gg and COg transfers, the effects of the gas flow rate, the gas side O2 partial pressure, the liquid flow rate and the liquid flow channel depth on the gas transfer. In gas-gas experiments, the O2 side gas flow rate, the Oj partial pressure and the CÖ2 partial pressure were varied in the range of 7,2-1388,9 cm/s, 700-1000 mmHg and 50-700 mm Kg, respectively. Same ex periments were repeated with membranes which have different coating thickness, i.e. C-6Sjig/cra2, and thus, the effect of film thickness on the gas transfer were examined, in liquid- gas experiments, the gas flow- rate, the gas side O2 partial pressure, the water flow rate, the water flow chan nel depth were varied in the range of 250-2500 crnVmin, 669,2-887,1 mmHg, 50-1600 cm3 /min and 0,018-0,288 cm, respectively. A mathematical model -was proposed for 0g transfer through the porous membranes and availability of this model -was evaluated by comparing experimental and model results. The results obtained in this study were summarised as given below. î. By applying coating procedure, a cross-linked polymeric film containing Si, O and C atoms have formed on the surface. 2. The presence of PîsP(HîVîDS) film increases the membranes ' bioodcompatibiii ty. 3. The mechanical stability of membrane decreases in plas ma media. However, coating film avoids partially the membrane from the effect of electrical discharge. 4. Gas-gas experimental results showed that, the gas side ressistance is not an important parameter -which affects the transfer rate.
