Effect of some Processing Parameters on the Mechanical Properties of Hollow Fiber Membranes

Abstract

The present work covers in details the impacts of modified domestic microwave (MW) heating on morphological, surface roughness and mechanical properties of the as-spun polyethersulfone (PES) hollow fiber membranes (HFMs). Results indicated the promising feature of MW heating as a possible substitution of conventional heating mechanisms. The maximum relative value of dimensional change, depicted as membrane wall thickness, is 75% for MW heating in air at 85˚C and 15 minutes. Also, the maximum Young’s modulus value is about 36.1% at conventional air heating at 150˚C and 15 minutes while the maximum relative change is 47.4% for MW post-treated HFMs in 4% lithium chloride (LiCl) at 55˚C for 5 minutes. The corresponding results for maximum absolute effect on tensile stress at break and strain at break are manifested by MW post-treatment in air at 55˚C for 15 minutes and MW post-treatment in 4% LiCl solution at 55˚C for 3 minutes, respectively. Moreover, as far as surface roughness is considered, the maximum achieved relative value is 40.4% for MW heating in distilled water media at a temperature of 45˚C for 15 minutes while the maximum absolute roughness changes of 79.5% occurred in MW posttreated HFMs in air at 85˚C for 3 minutes. The results indicated the validity of MW heating as a tuning tool for target fiber properties as intended by the subsequent use. Moreover, working in saline media confirmed contribution and interaction of water dipole rotational mechanism and ionic conduction mechanism. These results avail a reliable, efficient matrix for appropriate MW heating conditions as a possible fast and environmentally clean and reliable heating method. 6.2. RECOMMENDATIONS FOR FUTURE WORK Future research endeavors are still needed to explore different saline media with variable concentrations and to explore other possible benefits and drawbacks of this technology. Moreover, mixed organic/inorganic liquid media should also be investigated to improve mechanical characteristics of MW heating as a post treatment for hollow fiber. Also, experiments should be carried out to investigate the effect of MWs on other polymeric hollow fiber membranes.