Processing of bioresorbable and other polymers for medical applications

Processing of bioresorbable and other polymers for medical applications 

Key words biopolymers, extrusion, molding, calendering, solvent casting. 

The main steps in polymer manufacturing can be summarized broadly as follows (Osswald and Hemandez-Ortiz, 2006)  

One or more of these steps can be involved in polymer processing. However, most parts require shaping operations such as extrusion, which is discussed in more detail below. 

In the extrusion process, a polymer melt is pumped through a shaping die and formed into a profile which can be, for example, a plate, a film, or a tube (Osswald and Herndndez-Ortiz, 2006). For this purpose, ram and screw extruders are used. The ram extruder uses a positive displacement pump based on pressure. In this process, the volume is reduced, the fluid is moved from one point to another and the pressure rises. A screw extruder is a viscosity pump based on the pressure gradient and fluid deformation. Currently, single-screw extruders are the most common equipment used in the polymer industries. Twin-screw extruders are widely used as mixing and compounding devices. 

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