Extrusion systems delivery methods

For continuously extruded products, such as sheet and profile extrusions, thickness uniformity is a key quality factor, and it is directly linked to flow oscillations or flow disturbances at the die. Many sources of flow oscillations in the extrusion system are identified, and methods are shown on how to configure the melt delivery system to minimize their transmission to the die. These methods are illustrated with a model based on the theory of hydraulic transients. 

There are numerous options for combining phospholipids with an aqueous phase, but two major methods are used to make liposomal systems for drug delivery. The first is simple hydration (swelling) of the phospholipid. This is followed by high-intensity agitation using sonication or a high-shear impeller. Liposomes are then sized by filtration, extrusion or elutriation. The second method is an emulsion... 

The lactide/glycolide bioresorbable polymers are thermoplastics which can be processed by many methods, including fibre spinning, extrusion, and injection moulding, which means they can be fabricated into a variety of wound closure items (e.g. sutures), implantable devices (e.g. bone plates, bone screws), and drug delivery systems, which include microspheres, fibres, films, rods and others. 

The methods of production of archeosomes are by lipid hydration method, detergent dialysis method, reverse phase evaporation method, sonication, membrane extrusion, freeze and thaw method (Weiner and Cannon, 1989 Relini et al, 1994 Watwe and Bellare, 1995). As carrier vehicles in vaccine formulations, as delivery systems for drugs, genes, or cancer screening agents (Allen, 1997). Primary work on mouse has been carried out which consists of intravenous, oral and subcutaneous administration of these archaeosomes and it has reported to be non-toxic and safe (Patel et al., 2004). 

Thickness uniformity is a major concern for many continuously extruded products, such as sheet and profile extrusions. Any flow oscillation or disturbance at the die will manifest itself in a comparable thickness variation in the product. Therefore, diagnosing and eliminating flow disturbances in the melt delivery system is key to good thickness uniformity. This first involves identifying the sources of flow disturbances so that they may be eliminated or minimized. Secondly, a method is shown on how to design the delivery system to minimize the transmission of flow disturbances to the product. 

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