Surface properties of polypropylene modified by chromosulphuric acid

摘要

Some methods of surface modification of isotactic polypropylene were described in previous papers [1-3]. In general, these methods belong to the class of methods altering the adhesive properties of the polymer surface by means of electric discharge. The result of this effect consists in extensive growth in hydrophilicity of the polymer at the surface layer, which manifests itself in a many times higher value of polar component of free surface energy when compared with original non-modified polymer [4], The drawback of the modification methods based on the use of electric discharge plasma is the relatively short lifetime (under 24 h) of the surface modification of polypropylene. The oxidizing chemical methods of polypropylene modification are equally efficient and in addition to this they give a more durable result. By using convenient oxidizing agents, such as chromosulphuric acid, the hydrophilicity in the fine surface layer of dimension between 2 and 10 /an increases while the original advantageous physico-mechanical properties of polymer are preserved, If an oxidizing method of modification is used it is important to examine the resulting properties of products because of possible degradation of the polymer, which is dependent on the oxidizing agent used and on the conditions of oxidation.