Sticky Hydrophobic Behavior of Cellulose Substrates Impregnated with Alkyl Ketene Dimer (AKD) via Sub- and Supercritical Carbon Dioxide

Publication date: Available online 3 October 2018Source: Colloids and Surfaces A: Physicochemical and Engineering AspectsAuthor(s): Kolawole Adenekan, Brenda Hutton-PragerAbstractCellulose fibers were impregnated with alkyl ketene dimer (AKD) dissolved in n-heptane and carbon dioxide via sub- and supercritical impregnation techniques. The mechanistic pathways and hydrophobic performance at short and long times were investigated by contact angle (CA) analysis, scanning electron microscopy (SEM) with micrographs analyzed using Image-Pro Premier, and Fourier Transform Infrared (FTIR) analysis. The sizing development was significant after two days of treatment, and hydrophobic performance became uniform after two weeks regardless of the impregnation conditions investigated. Samples prepared at 100 and 200 bar produced more rapid development than those at higher and lower impregnation pressures, with the average CA at 200 bar and 21 °C being 140 ± 5°. ‘Sticky’ hydrophobicity was observed on surfaces treated at 200 and 250 bar at long times (> 140 days), and adhesive forces between the droplet (> 20 µL) and surface were observed at surface tilt angles between 0 – 180°. SEM micrographs of the impregnated samples showed a reduction in substrate pore-size area (PSA) as hydrophobicity developed with time. There was little evidence of reaction-based sizing as the characteristic ketone and ester peaks were not observed in FTIR studies. The lactone ring remained intac...

Source: Colloids and Surfaces A: Physicochemical and Engineering Aspects - October 6, 2018 Category: Chemistry Source Type: research