Optimization of processability and physical and mechanical properties of extruded polyethylene- Tetra Pak cartons composites by experimental design

Abstract

A scanning experimental design that uses Taguchi methodology allowed to apply an orthogonal type model L12 to determine the optimal formulation and process variables—in two levels—to obtain extruded polyethylene (PE) composites with Tetra Pak multilayer cartons. The variables of the first type were the following: types of PE and mixtures of ethylenic copolymer processing aids; particle size; content of milled Tetra Pak containers, zinc oxide lubricant, mixtures of ethylenic copolymer processing aids, calcium carbonate, stearic acid, and titanate coupling agent. The variables of the second type were the speed and temperature profile of the extruder. This methodology applied two criteria for the evaluation of results, the separate analysis and the evaluation of multiple criteria of response parameters. The results showed the most important independent variables that affected the response parameters, being the extrusion speed with 49.8%, the type of PE with 18.4%, and the mixture of ethylenic copolymer processing aids with 8.1%. The optimal run showed the expected favorable results, such as plasticity with 89.6 cm/cm, mass flow with 0.80 kg/h, density with 1.11 kg/m3, torque with 574 mg, molten mass pressure of 111 lbf/in2, temperature of fusion of 149°C, impact resistance of 32 J/m, tensile strength of 11 MPa, and flexural modulus of 314 MPa.