Abstract
The fluidity of a molten polymer plasticized by ultrasonic vibration was characterized by spiral flow testing based on an Archimedes spiral mold with microchannels. Mold inserts with various channel depths from 250 to 750 µm were designed and fabricated to represent the size effect under micro-scale. The effect of ultrasonic plasticizing parameters and the mold temperature on the flow length was studied to determine the rheological nature of polymers and control parameters. The results showed that the flow length decreased with reduced channel depth due to the size effect. By increasing ultrasonic amplitude, ultrasonic action time, plasticizing pressure, and mold temperature, the flow length could be significantly increased for both the amorphous polymer polymethyl methacrylate (PMMA) and the semi-crystalline polymers polypropylene (PP) and polyamide 66 (PA66). The enhanced fluidity of the ultrasonic plasticized polymer melt could be attributed to the significantly reduced shear viscosity.