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Chemical Structure
Key features
- Excellent resistance to inorganic acids & bases
- Withstands repeated exposure to steam sterilization
- Excellent resistance to hot water
- Good thermal properties - Heat deflection temperature at 264 psi (1.8 MPa) is 174°C
- Approved for use with food, water and medical applications
Applications
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Membranes (hemodialysis, drinking and ultra-pure waters, gas separation, food & beverage concentration, dairy)
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Medical (surgical trays, nebulizers, humidifiers)
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Food service (microwave cookware, beverage and food dispensers, milking machine parts)
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Plumbing (hot water fittings, manifolds, mixer tap cartridges)
UDEL Polysulfone is an amorphous high performance polymer, which is characterized by excellent thermal properties, good resistance to inorganic acids and bases, and outstanding hydrolytic stability against hot water and steam sterilization.
It is toxicologically inert and has extensive regulatory clearance.
In its natural and unmodified form Tg= 190°C; HDT/A= 174°C; RTI= 160°C
Cyclic Dimer in UDEL® Polysulfone
For some membrane producers, the level of Cyclic Dimer (CD) can be important to their processing efficiencies and fiber quality.
Too much cyclic dimer can result in:
- Filtered dope solutions becoming cloudy
- White solid material clogging the process filters
Standard Grades of UDEL Polysulfone:
- Contain 1.5% by weight of cyclic dimer
- In solution and in the presence of non-solvents such as pore-formers, crystallization may occur
- Even on prolonged aging, only a small amount precipitates.
LCD (Low Cyclic Dimer) Grades of UDEL Polysulfone
- Contains 1.20% by weight of cyclic dimer
- Remain clear (reduced precipitation) for a longer period of time than standard grades of UDEL polysulfone.
- For example, at 40°C, UDEL P-3500 LCD dope solution is 10 times clearer than
UDEL P-3500 NT 11
The Benefits to Membrane Producers of the LCD Grades are:
1. Economic, Less precipitation in process equipment (vessels, pumps...) resulting in :
- Longer shelf-life for dope solutions
- Longer filter life
- Fewer shut-downs for cleaning
- Longer continuous runs
2. Technical, LCD resins have 10% higher Mn (Number Average Molecular Weight) for a given Mw (Weight Average Molecular Weight)
- Higher fiber strength
- Fewer fiber breakages
- Fewer surface defects, and therefore fewer rejects
- Higher-performing membranes
To read a Technical Paper that appeared in the journal "Desalination" in 2002, Volume 144, discussing cyclic dimer in polysulfone, click here.
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