Surface characterization of nylon 66 by inverse gas chromatography and contact angle

The surface properties of nylon 66 were quantitatively analyzed by inverse gas chromatography (IGC) and contact angle. Five n-alkanes (C6, C7, C8, C9, and C10) were chosen as apolar probes to characterize the dispersive component of surface free energy. Dichloromethane (CH2Cl2), acetone, and tetrahydrofuran (THF) were chosen as polar probes to detect the Lewis acid-base parameters. The dispersive component of free energy was found to be 37.4, 42.7, 46.8, and 47.5 mJ/m2 at 70, 80, 90, and 100 °C, respectively. The dispersive component of surface free energy of nylon 66 was 11.6-13.1 mJ/m2 measured by contact angle at 20 °C. The results of IGC and contact angle were uniform. The Lewis acid number Ka of nylon 66 was 2.03, and the base number Kb was 7.17, which means nylon 66 is a Lewis basic polymer.