Study of Crystallinity of High-density Polyethylene by Inverse Gas Chromatography

Method of inverse gas chromatography (IGC) has been used for the physico-chemical characterization of polymers for more than two decades. In this method the polymeric stationary phase could be characterized by using probe molecules. The retention volume of probe is a measure of the polymer-probe interaction and show changes in the polymer structure at melting point or glass transition temperature. Crystallinity of high-density polyethylenes (HOPE) of Poliran and Irapol from Iranian petrochemical companies was studied. The effects of the flow rates and the sample size on peak retention volume were investigated. Modified techniques for measurement of flow rate and coating were used. Retention diagram and degree of crystallinity were determined for a sample of low-density polyethylene and the results were compared with those obtained for HDPE. Experimental data of crystallinity and melting points showed that the Iranian HDPE is a polymer with suitable engineering properties. Key Words: high-density polyethylene (HDPE), crystallinity, inverse gas chromatography