Graduation Year

2021

Document Type

Thesis

Degree

M.S.M.S.E.

Degree Name

MS in Materials Science and Engineering (M.S.M.S.E)

Degree Granting Department

Chemical Engineering

Major Professor

Venkat Bhethanabotla, Ph.D.

Co-Major Professor

Nurettin Sahiner, Ph.D.

Committee Member

John Kuhn, Ph.D.

Keywords

Polymer, Surface modification, Surface functionalization, Geosynthetic

Abstract

High-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and polyvinyl chloride (PVC) geomembranes were treated with air and oxygen plasma. The purpose of air and oxygen plasma treatment of geomembrane surface is to increase the surface wettability of these materials, thereby increasing adhesive properties. Increasing adhesive properties enables a surface to be coated with a desired material with antibacterial, antioxidant, and UV resistant characteristics, without changing bulk material properties. To protect the geomembranes from oxidation degradation, UV degradation and biological degradation, it is important to increase the antibacterial, antioxidant, and UV resistant properties of geomembrane. Before and after the plasma treatments of HDPE, LLDPE, and PVC geomembranes, the changes in surface properties were investigated via contact angle (CA) measurements, surface free energy analysis (SFE), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), surface roughness analysis, and Fe(II)-chelating activity. For HDPE and LLDPE geomembranes, the best results were observed for oxygen plasma treatment, and for PVC geomembranes, the best result was observed for air treatment. The contact angle values decreased from 91.4±0.8° to 40.0±2.3° for oxygen treated HDPE; from 96.9±1.9° to 47.7±0.5° for LLDPE; and from 92.8±1.1° to 35.8±1.1° for PVC geomembrane samples. The surface free energy (SFE) was calculated by using the Owens–Wendt–Rabel–Kaelble (OWRK) method. The oxygen treated HDPE sample’s surface free energy increased from 21.04±2.1 mJ/m2 to 54.23±4.5 mJ/m2, oxygen treated LLDPE samples surface free energy increase from 21.31±2.7 mJ/m2 to 47.29±1.2 mJ/m2, and air treated PVC samples surface free energy increase from 16.48±0.6 mJ/m2 to 60.65±1.3 mJ/m2. XPS analysis demonstrates an increase in C–O (C–OH) groups upon oxygen plasma treatment, and this finding was supported by the SEM, roughness analysis, and Fe(II)-chelating capability of the geomembrane surfaces. SEM images and roughness analysis demonstrate an increase of surface roughness by air or oxygen treatment. Fe(II)-chelating capability shows the oxygen functional formation on the surface by air or oxygen treatment.

Download

Share

COinS