Microwave Cross-linking of LDPE: Experimental Modelling of Gel Content by Taguchi Method and Optimum Processing Conditions.

Low density polyethylene (LDPE) properties could be modified by cross-linknig. In this research, crosslinking of LDPE was studied under microwave irradiation. Moreover, carbon and chlorinated paraffin were added to LDPE as UHF-active aids. Carbon, chlorinated paraffin, and peroxide contents, as well as irradiation time were determined as the most important and effective parameters based on some initial experiments. LDPE compound was prepared in an internal mixer. Torque-time curve, during the mixing process was measured an the indication of the suitable compounding with no partial cross-liking. The gel content of cross-linked LDPE (XLPE) was studied as a measure of cross-linking degree. In theoretical section, Lg orthogonal array method (Taguchi design) was applied as the design of experiments (DOE). Results were analyzed using Minitab and Qualitek4 softwares. Various statistical criteria were applied on the results showing the same conclusion on the parameters behaviour. It was found that an experimetal relationship (by regression) may be offered between the gel content and the main parameters. Consequently, optimum cross-linking condition was determined. The result may be used as a quantitative relationship in product design applications.