Effect of Low-Temperature Plasma Treatment on Surface Modification of Polycaprolactone Pellets and Thermal Properties of Extruded Filaments

Polycaprolactone (PCL) polymer has been surface modified using oxygen low-temperature plasma and melt extruded into single filaments. Oxygen plasma was generated using a radiofrequency source with power of 150 W. The PCL polymer samples were treated with plasma for various durations of 5 min, 10 min, and 20 min. Water contact angle measurements were carried out to assess the wettability, revealing that the treatments reduced the contact angle by up to 11°. Changes in the chemical bonding and surface compositions were characterized by using x-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy, revealing a high concentration of oxygen functionalities on the surface. Crystallinity changes were studied by using x-ray diffraction analysis. The surface morphology of the polymer was investigated using field-emission scanning electron microscopy. The thermal degradation and melting behavior was studied using thermogravimetric analysis and differential scanning calorimetry, respectively.