Polypropylene is an incredibly common membrane filter material with a large range of available uses. However, there are a variety of factors to consider when determining if polypropylene filters are a suitable choice for your application’s needs. Keep reading to find out about the different characteristics, pros, and cons of this versatile filter.
What to Know About Polypropylene Filters
Polypropylene filters, commonly referred to as PP, are a naturally hydrophobic thermoplastic polymer filter that is produced via chain-growth polymerization from monomer propylene. As it is a member of the polyolefins group, it is partially crystalline and non-polar.
The density of polypropylene is between 0.895 and 0.92 g/㎤, of all of the commodity plastics it has the lowest density which allows it to be particularly suitable for aqueous filtration applications. PP is tough and flexible with a Young’s modulus between 1300 and 1800 N/㎟. It becomes especially tough and flexible when copolymerized with ethylene.
Polypropylene filters are resistant to fats and nearly all organic solvents, non-oxidizing acids, and bases. Commercial isotactic polypropylene holds up to heat well and has a melting point between 320℉ to 331℉ however, it will become brittle at temperatures past 32℉.
Where to Use Polypropylene Membrane Filters
Polypropylene membrane filters are used at the pre-filtration and final filter stages within food and beverage industries, chemical applications, water and air processing, and various biomedical industries including pharmaceutical applications.
Benefits of Polypropylene Filtration
- Both Hydrophobic and Hydrophilic Options Available
- Abrasive Resistant
- Strong Chemical Resistance
- Excellent Strength
- Electrostatic Charge
Both Hydrophobic and Hydrophilic Options Available
While most filters are solely hydrophilic or hydrophobic, polypropylene can be either depending on its application.
Hydrophilic polypropylene is available within our line of syringe filters which are designed for aqueous or organic solutions with high levels of debris. As the filters are hydrophilic they will wet and spread easily allowing for high throughput and debris removal.
Alternatively, hydrophobic polypropylene filters are also available and are best suited for filtration of gas and chemicals. Our hydrophobic polypropylene has extremely low extractable levels and are suitable for sensitive chromatography applications.
Abrasive Resistant
Polypropylene also has a high melting temperature, which means it can withstand heat and pressure associated with abrasive materials. This feature allows polypropylene filters to withstand the damaging effects of abrasive materials while allowing other materials through.
Strong Chemical Resistance
Polypropylene has strong chemical resistance to most acids, alkalies, bleaches, and solvents with additional resistance to indirect sunlight. Finally, polypropylene membrane filters are also nonporous and mildew resistant.
Excellent Strength
In addition to strong chemical resistance, polypropylene filters demonstrate excellent strength making them an ideal filtration solution for heavy duty uses.
Electrostatic Charge
Polypropylene contains an inherent electrostatic charge that is enhanced by friction of airflow over a honeycomb woven surface allowing for a high efficiency air filter that is able to be washed and reused.
Polypropylene Membrane Filters vs Polypropylene Syringe Filters
In considering the proper type of polypropylene filter, it is essential likewise to consider both syringe filters and membrane filters. Each can provide the quality features and abilities required for any form of sampling and testing.
A polypropylene syringe filter is hydrophilic and a good choice for filtration of biological samples in addition to aggressive organic solutions. A polypropylene syringe filter will provide cleaner sample extracts by removing the interfering materials and related particles down to the rated pore size. When added before chromatographic injection, syringe filtration ensures more consistent and reliable results.
Alternatively, a polypropylene membrane filter will provide more general clarifying and prefiltration applications. This can include filtering solvents, deionized water, and bioburden. Polypropylene membrane filters have a broad thermal compatibility thus ensuring a wide range of applications.
Polypropylene Membrane Roll Stock
Polypropylene membrane roll stock is pure hydrocarbon material. This allows safe disposal, especially when comparing its halogen content with other hydrophobic membranes such as PTFE and PVDF.
Polypropylene roll stock does not requite to be pre-wet and is suitable for a wide range of medical grade sterilizations within aqueous and organic solvents.
Polypropylene Applications
There are a number of applications for polypropylene including but not limited to:
- House Water Filters
- AC Filters
- Environmental Filtration: Such as Oil Spills on Rivers
- Air Filtration Against Infectious Disease (spunbound polypropylene)
How to Select the Proper Polypropylene Filter Characteristics
When it comes to selecting a polypropylene filter for any task there is a prescribed process involved which requires four simple steps. These steps can be done with a filter media selector and include:
- Deciding on the necessity of prefiltration for the application.
- Choosing a membrane filtration material based on qualities such as aqueous, non-polar, and protein.
- Selecting a diameter typically of <10ml, <100ml, or <250ml to determine the mm diameter of the filter.
- Ensuring the pore size, based on micron size of the column of >3um or <3um.
As with anything else, it is of utmost importance to ensure the filter’s chemical compatibility with your application needs. Consider this chemical compatibility guide to determine what chemicals your polypropylene membrane filter is compatible with. This can include:
- All acids
- Bases
- Alcohols
- Propylene Glycol Acetate
- Methyl Cellosolve Acetate
- Dioxane/ Tetrahydrofuran
- DMSO
And, more. Polypropylene maintains a large compatibility with most chemicals thus proving useful in a wide-reaching variety of applications.
Polypropylene Filters Can Help You with Your Filtration Needs
Extremely versatile, polypropylene filters are abrasive resistant, hydrophobic and hydrophilic, have excellent chemical compatibility ability and are able to properly withstand pressure while maintaining flexibility. For all of these reasons and more, Tisch polypropylene filters are an excellent and affordable choice for filtration applications and when utilized correctly will deliver reproducible, accurate, and timely results.