Plasma treatment of high-density polyethylene blow moulded substrates to improve surface adhesion properties: Increase in bondability to label films

This study involved the plasma surface modification of polyethylene with gliding arc plasma at atmospheric pressure to enhance the adhesion of labels to these surfaces and prevent label detachment. Optical emission spectroscopy (OES) analysis was conducted to identify the plasma elements. Contact angle measurement was done to evaluate the surface hydrophilicity. The water contact angle was 66.53° before surface treatment and decreased to 46.96° after 40 s treatment, confirming the improvement of the hydrophilic behavior of the surface. Surface free energy calculation indicated that the surface free energy was raised from 42.20 mJ.m −2 to 60.32 mJ.m −2 after plasma treatment. Changes in the physico-chemical properties of the surfaces were investigated using various analyses such as XPS, AFM, and SEM. XPS verified the formation of oxygen-containing functional groups on the surface. SEM showed an increase in pores and surface protrusions, and AFM confirmed an increase in roughness from 47.18 nm to 59.87 nm after plasma treatment. Conventional adhesion tests, including loop tack, peel, static and dynamic shear tests, corroborated the enhanced adhesion properties of the plasma-treated samples.