STARCH COMPOUNDING ON THE CO-ROTATING TWIN SCREW EXTRUDER: STARCH AS AN ENCAPSULATION MEDIUM FOR A CONTROLLED RELEASE APPLICATION

摘要

The encapsulated herbicides produced on the corotating twin screw extruder display slow release properties. Pelletizing the extrudate with a die face cutter is the preferred method to form the final product. Process parameters can be modified to control the release properties of encapsulated herbicide. In addition, the pellet size or size distribution can be tailored to meet the end user's needs.The data generated from processing herbicides on the 57-mm twin screw extruder also provides information necessary for scale up calculations for predicting production rates on larger extruders. Some future work will be needed to optimize die design. Release rate investigations will reveal desired pellet sizes for various applications and new die designs will be required. Throughput rates can increase by as much as the cube of the screw diameter of the extruder. This will create further restrictions on the design of the die, ie. pressure drop and subsequent heat generation, physical size of the die face and mechanical strength of a large die face [5].