Effect of oscillations during extrusion on rheology and mechanical properties of polymers

An experimental study associated with the applications of sound and ultrasonic waves to extrusion is conducted. Two laboratory setups are developed for these purposes incorporating orthogonal and parallel superposition of oscillations on pressure flow during extrusion. The orthogonal superposition of sound oscillations is imposed in an annular die. The parallel superposition of ultrasound oscillations is imposed in a circular die. Several materials including unfilled and filled thermoplastics, thermoplastic elastomer, and elastomer are tested. Die characteristics, power consumption, and die swell are determined during extrusion. The rheological properties, molecular weight, tensile properties, and impact strength of materials with and without sound and ultrasound treatment are investigated, indicating permanent changes in these properties. The observed effects are found to depend on melt temperature, flow rate, nature of polymer system, and oscillating parameters such as frequency and deformation amplitude.