The melting mechanism of Polyvinyl Chloride (PVC) powder in a counter-rotating twin-screw extruder was studied by using an ultrasound in-line monitoring system. Ultrasound signal patterns were obtained at various processing conditions. The experimental results revealed that the dissipative or dispersed melting phenomenon was dominant in most melting process of PVC in the counter-rotating twin-screw extruder. The melting status of PVC particles was analyzed by ultrasound signal amplitude ratios. The changes of amplitude ratio showed that the material melting level in region Ⅰ (between barrel and flight) was much higher than region Ⅱ (between barrel and screw root), due to the combined effect of viscous shearing and heat conduction from barrel. It also revealed that PVC particles melted more uniformly at higher feeding rate due to the energy dissipation from particle interactions.
展开▼
