The influence of the surface cross‐linking of the high‐density polyethylene induced by plasma treatment on the durability of treatment efficiency

Abstract

Abstract The structure of the surface cross‐linking layer of high‐density polyethylene (HDPE) produced by plasma treatment was studied by DSC, X‐ray diffraction, elemental analysis, and infrared analysis. The relationship between the cross‐linking and the durability of the modification efficiency provided by the plasma treatment was investigated. The results of the structure analysis indicated that the polar groups introduced by the plasma just locate on the upper surface of the cross‐linking layer and the chemical constitution and structure of the inner part of the cross‐linking layer is similar to that of the uncross‐linking HDPE. The cross‐linking density of the gel decreases from the surface to the inside with a large gradient and the average cross‐linking degree of the whole gel is rather low. Nevertheless, the experiment proved that this cross‐linking layer can limit the mobility of the molecules in the cross‐linking layer and hinder the decay of the treatment efficiency significantly. When the surface cross‐linking induced by plasma reaches a certain extent, the treatment efficiency will remain relatively constant in storage. © 1993 John Wiley & Sons, Inc.