LANTHANUM(III) COMPOUND ACTS AS PROCESSING AID OF LINEAR LOW DENSITY POLYETHYLENE

A mixed complex of trivalent lanthanum stearate with stearin (LaC) was used as a processing aid of linear low density polyethylene (LLDPE) and the efficacy was assessed. Torque rheometry experiments revealed that the incorporation of 5 mass% LaC into LLDPE resulted in 20.1%, 12.5% and 17.1% reduction of maximum torque, equilibrium torque and plasticization energy, respectively. Capillary rheometry examination showed that the LaC considerably improved the rheological properties of LLDPE. The LLDPE whth 0.25 mass% of LaC had a lower apparent viscosity, slightly smaller activation energy for flow than these of LLDPE without LaC had. The blown film extrusion showed that LaC was effective in relieving or eliminating surface roughness and had no harmful effect on the mechanical properties of film. The addition of 0.25% of LaC decreased the extruder current approximately 9.2% under identical extrusion condition. All these improvements demonstrated that LaC is an effective processing aid of LLDPE.