Study On Microcellular PVC Wood Composite

PVC wood composite possesses the advantages of vegetable fiber and polymer material, instead of wood. It effectively releases the poverty of forest resources and the short supply of wood in china. Because of the composition of wood in the material, the material reduces its ductility and impact strength, enlarges its brittleness and its density was two times bigger than traditional woods. It limited its extensive application. For improving the property, the application of impact modifier improves the property of impact strength, but it's invalid to improve the ductility and reduce the density. Nowadays using the method of microcellular molding gets rid of the above drawbacks. Because of the existence of good foam structure, Microcellular PVC wood composite can inactive the crack and stop the expansion of the crack. So it obviously improves the properties of impact strength and ductility, and largely reduces the product's density. The extrusion microcellular molding is the principal method, because its lower cost, high effective, short consuming time and it is easy to realize industrialization.Because of the special property of microcellular PVC wood composite, the requirement to the extrusion equipment and the control of the process condition is strict. The design of the extruder's die, especially for microcellular product, is largely extent to affect the quality of the microcellular product. So is the design of the screw. But the research involved in this area is few.Through modeling the field of the die using POLYFLOW FEM software, it shows that the effect of the parameter of the die on the pressure drop and the pressure drop rate, and the filed of the distribution of shear rate. Modeling the field of the metering section in extruder with DOE, the optimizing design to the screw parameter is goal with pumping rate,axial forces and power consumption. According to the above result, it is shown that the experiment can guide the design of the die and the achievement of the best microcellular product.