Abstract
This work presents comprehensive study of high density polyethylene (HDPE) and polyethylene terephthalate (PET) surface properties after exposed to 1.5, 3, 4.5 and 6 min oxygen (O-2) plasma. The polymer surface structure is analyzed by Raman spectroscopy, which revealed surface restructuring modifications. The contact angle of HDPE and PET decreased gradually, and the work of adhesion is improved with O-2 plasma. The water contact angle is reduced from 61.6 degrees to 36.3 degrees for HDPE and from 72.4 degrees to 37.5 degrees for PET by increasing plasma time from 1.5 to 6 min. The surface free energy is enhanced from 27.8 mJ m(-2) to 69.0 mJ m(-2) for HDPE and from 29.8 mJ m(-2) to 67.2 mJ m(-2) for PET, when the plasma time increased from 0 to 6 min. The polar groups significantly reduced the hydrophobicity of the irradiated films, and consequently the surface wettability is improved. The results showed observed improvement in surface properties of HDPE and PET polymeric films to be use in different applications such as printings, coatings and optoelectronics.