Surface and bulk properties improvement of HDPE by a batch plasma treatment

Abstract

ABSTRACTHigh‐density polyethylene (HDPE) pellets were modified via atmospheric plasma treatment using nitrogen flushing. The new application of plasma treatment was introduced in this work, namely a batch treatment on plastic pellets just prior to its feeding to the extrusion process in comparison with the conventional surface treatment of the plastic sheet. The effect of treatment time (15–120 s) on wettability, chemical, thermal, and mechanical properties of the modified HDPE were investigated and compared with the typical surface‐treated HDPE and untreated HDPE. The pellet treatment distributed well the hydrophilicity groups so that both surface and bulk properties were improved. It showed an enhancement of wettability similar to surface treatment at short treatment time (15 s). Attenuated total reflection‐Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy revealed the presence of new chemical groups (nitrogen and oxygen up to 5 and 42 at %, respectively). In addition, crosslinked structure was also disclosed by solvent extraction (gel content of 3.5–5.5 wt % increased with treatment time) and significantly affected to decrease the crystallinity from 76% in the untreated sample to 63%. The decomposition process of the pellet treatment samples was delayed. Lastly, pellet treatment yielded advantages in remaining hydrophilicity during aging and improving mechanical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43011.