Surface modification of high-density polyethylene by plasma treatment

The extent of the surface crosslinking of high-density polyethylene (HDPE) under various plasma treatment conditions was investigated. The plasma modification efficiency was studied by surface energy and adhesive bond strength measurements. The results show that the surface crosslinking of HDPE takes place as soon as the HDPE is exposed to the plasma and that the crosslinking rate is a function of the plasma conditions. The surface energy and the adhesion of HDPE are greatly increased by the plasma treatment and these improvements are independent of the depth of surface crosslinking. Based on these results and our previous studies on the surface chemical composition and free radical density on the surface of HDPE after plasma treatment, the relationships among various surface changes and the surface modification efficiency are discussed.