Free surface energy of modified polyethylene extrusion product
Garbacz Tomasz
DEPARTMENT OF POLYMER PROCESSING, TECHNICAL UNIVERSITY OF LUBLIN
POLAND
Keywords: extrusion, polyethylene, auxiliary agents
Widely used nowadays in telecommunicational technics, optotelecommunication cables are made from thermoplastic materials. External coast of cable should characterises with large mechanical durability, high resistance to activity of chemical substances, resistance to low temperatures, good isolating properties and low cost of production. PE - MD and PE-HD satisfactorily meet above mentioned conditions and are comparatively cheap.
The aim of the studies was to closely with the course and efficiency of the extrusion process and selected properties of polyethylene modified by selected auxiliary agents. The utilitarian aim of the studies is estimation of examined plastic considering new requirements for outer layer of the cables. In the studies medium density polyethylene was used. Polyethylene was modified by foaming agent and antistatic agent in the form of polyethylene concentrates. The studies of the extrusion process were conducted on the Brabender laboratory extruder. The line consisted of the head for extruding panels, the cooling machine which was rolls calibrator and the receiving device.
Extensive studies of physical and mechanical properties of the modified polyethylene were conducted. Estimating the influence of auxiliary agents on selected mechanical properties of extrusion product it was found that the influence is unique only in case of the foaming agent. Efficiency of extrusion process is determined also by selected proprieties of surface layer of a mill cake of polyethylene. Free surface energy has been calculated in Owens-Wendt method. As testing liquids following agents have been used namely glycerine and diodomethane.
Antistatic agent causes diminishing of wettability and adsorption of surface layer and eventually increase of free surface energy of surface layer. Utilitarian successes can be used in companies producing extrusion products, especially products from polyethylene, and producing outer layer of the cables.