Filters Manufacture
Making membranes is technically challenging. What is particularly difficult is achieving the level of uniformity in the polymers used in the manufacturing process. These polymers must also be free of contaminants that can adversely affect specific applications in which the membrane is being used.
Making UF Membranes
Ultrafiltration (UF) membranes are the most complex to manufacture because the very thin UF membrane is very weak and must be combined with other filtering materials. Millipore casts a very thin UF membrane onto a thicker porous membrane and, in some cases, puts that combination onto a composite structure that involves some type of nonwoven material. The challenge is making the entire structure integral to prevent loss of precious proteins through pores or defects in the UF layer.How Polymers are Made
Polymers are made by bulk chemical building processes that generate populations of molecules across a wide range of molecular weight. Fractionation is used to isolate from the complex mixture a single population of molecules with a defined molecular weight. This process may be only partially effective and result in molecules of undesirable molecular weight being carried through to the point of membrane manufacture. Slight variations in molecular weight distribution manifest themselves by changing the performance of the polymer during membrane manufacture. Beyond this challenge, care must be taken during membrane manufacture to ensure that undesirable contaminants are not introduced into the membrane. Membranes undergo rigorous testing to assure that they are free of defects and contaminants.Precipitation
Precipitation is another challenging element of membrane manufacturing. Conditions that set up the precipitation must be very tightly controlled and reproducible, cast lot after cast lot. Extensive engineering goes into the equipment and processes to accomplish this goal.The Millipore Team
When Millipore decides to make a particular type of membrane, we pull together a team of chemists and chemical engineers who are:
- Experts in polymer chemistry
- Involved in derivatizing and putting different chemistries onto the membrane
- Experienced in continuous phase processes on casting machines and able to make equipment modifications needed to make an effective product
Use the following links to explore these topics in more detail: