Idris Cerkez

Fabrication and characterization of electrospun poly(e-caprolactone) fibrous membrane with antibacterial functionality

This research study is mainly targeted on fabrication and characterization of antibacterial poly(e-caprolactone) (PCL) based fibrous membrane containing silver chloride particles. Micro/nano fibres were produced by electrospinning and characterized with TGA, DSC, SEM and mechanical analysis. It was found that addition of silver particles slightly reduced onset of thermal degradation and increased crystallization temperature of neat PCL. Silver-loaded samples exhibited higher tensile stress and lower strain revealing that the particles behaved as reinforcing agent. Moreover, addition of silver chloride resulted in beaded surface texture and formation of finer fibres as opposed to the neat. Antibacterial properties were tested against Gram-negative and Gram-positive bacteria and remarkable biocidal functionalities were obtained with about six logs reduction of Staphylococcus aureus and Escherichia coli O157:H7.

Antibacterial polyacrylonitrile nanofibers produced by alkaline hydrolysis and chlorination

Antibacterial polyacrylonitrile (PAN) nanofibers were developed by alkaline hydrolysis and subsequent chlorination. It was shown that the hydrolyzed nanofibers could serve as an N-halamine precursor through chlorination of the amide groups obtained by partial hydrolysis of the nitrile groups. The hydrolysis conditions were optimized, so that sufficient chlorine for effective antibacterial activities could be obtained on the surfaces. The chemical and physical structural changes were well characterized with FTIR, TGA, DSC and SEM. It was found that even though the hydrolyzed nanofibers cyclized with ionic and free radical mechanisms, the chlorinated nanofibers cyclized with only free radical mechanism as evidenced by its higher onset of cyclization temperature. On the other hand, the hydrolysis and chlorination process significantly improved the mechanical properties of the nanofibers. Moreover, the chlorinated nanofibers showed potent antibacterial activities against S. aureus and E. coli with about 6 logs inactivation. The developed antibacterial PAN nanofibers possess great potential for use in various fields, medical industry in particular.

N -Halamine-Based Antimicrobial Coatings

N -halamine-based coatings draw great attention in both academia and industry, since they are one of the most effective biocides. These compounds are simply defined as “oxidative halogen stabilizers,” and they possess long-lasting and rechargeable antimicrobial activities. They are suitable to use as biocidal coatings for soft and hard surfaces. Various N -halamine-based coatings are reported in the literature in the last two decades. In this regard, this chapter discusses structure and bioactivity relationship of N -halamine compounds, applications areas of N -halamine-based coatings, the strategies for surface functionalization with N -halamine compounds, and the future trends in N -halamine technology.

Airlaid nonwoven panels for use as structural thermal insulation

Abstract Thermal-bonded airlaid nonwoven webs consisting of fiber glass and polyester bicomponent fibers were manufactured, and then multilayer webs were formed into composite panels using compression molding technique. The consolidation process was optimized and the effect of bulk density on air permeabilites, mechanical properties, and thermal resistance was studied. Increasing binder amount and bulk density improved the flexural and tensile strength. Thermal resistance of the panels were found to be very dependent on the bulk density such that the resistance increased exponentially with an initial increase in density, then leveled off and decreased linearly with further increment in density. Depending on the composition and bulk density, the panels provided thermal resistance between 0.52 and 0.88 Km2/W, tensile strength between 2 and 7 MPa, and flexural strength between 600 and 3500 kPa. The findings revealed that airlaid nonwoven panels can be designed to use as structural thermal insulation materials in constructions.

Swelling Behavior of Hydrogels within Auxetic Polytetrafluoroethylene Jacket

An acrylamide type hydrogel consisting of 2-acrylamido-2-methyl-1-propanesulfonic acid was synthesized using free radical suspension polymerization. Hydrogel particles were then loaded within an auxetic polytetrafluoroethylene jacket. It was found that the swelling ratio of the hydrogels within the jacket can be controlled by changing the loaded particle’s amount and size without the wear and tear of jacket due to the auxetic effect. Increasing swelling ratio with finer hydrogel particles was observed due to higher surface area. On the other hand, increasing hydrogel particle amount resulted in a decrease in water absorption due to diminished free volume for swelling within the jacket. GRAPHICAL ABSTRACT