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 degrees. 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.