Technology

Hydrophobic materials

Advancing innovation with hydrophobic materials

Hydrophobic Material for Venting and Filtration

Hydrophobic materials repel water with low surface energy, allowing water molecules to shed contact with a solid surface, maintaining a contact angle of more than 90 degrees. This contact angle is also a measure of a material’s hydrophobicity. Porex’s hydrophobic material comes in a wide variety of polymer options that can be applied across multiple venting, filtration, and reflecting applications. These materials can be used as protection vents in electronics, automotive battery vents, sensor components, or anything that requires airflow and water resistance.

Hydrophobic Material illustration shows how water molecules separate from Hydrophobic material.

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Hydrophobic material manufacturing process

Sintered polymers like polyethylene, polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride are naturally hydrophobic with excellent water-repellent properties. These porous plastics are created by heating and applying pressure to fuse materials while preventing them from melting and maintaining their properties. This creates a porous medium that can be customized for your device’s performance needs, including optimizing pore size, pore volume, flow resistance, and filtration or venting capabilities.

sintered porous plastic manufacturing process

Types of hydrophobic materials

Selecting the right material is paramount when designing hydrophobic porous plastics. At Porex, we understand that material choice directly impacts pore size, pore volume, operating temperature, chemical compatibility, and additive compatibility. As your innovation partner, we offer expertise and guidance to ensure you make informed decisions. We offer four different types of hydrophobic materials

Polyethylene (PE) is widely used and offers pore sizes from 5 to 250 microns. This strong, lightweight thermoplastic is inherently hydrophobic and can withstand significant process variation. The next hydrophobic material, Polypropylene (PP), is ideal for applications requiring strength and larger pore sizes. PP shares chemical and additive compatibilities with PE and is naturally water-resistant. Next, Polytetrafluoroethylene (PTFE) is chemical resistant, durable, and ultra-hydrophobic. It’s pure, PFOA-free, excels in filtration down to 0.1 microns, and prevents fluid ingress. Lastly, Polyvinylidene Fluoride (PVDF) offers resistance to aggressive chemicals, extreme temperatures, and superior mechanical strength. Inherently hydrophobic, it’s an excellent choice for applications in harsh environments, electronics, and electrical engineering.

Porex is your partner in harnessing the full potential of these hydrophobic materials. Whether you need strength, chemical resistance, or ultra-hydrophobicity, our team of experts will assist you in selecting the ideal material for your project.

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When designing with hydrophobic materials, it’s critical to consider three key physical properties which impact device function:

Pore Size: the size of the voids in a porous media. Depending on the material selected, pore size can range from very small (< 1 micron) to quite large (up to 300 microns), depending on the device’s application. Pore size impacts key device functions such as wicking speed, wicking distance, filtration efficiency, and flow resistance, which dictate its ability to handle gases or liquid materials effectively.
Pore Volume: the percentage of air in the sintered plastic part compared to the total volume of the part. This directly correlates to a device’s absorption volume and flow resistance capabilities. Sintered plastics can create large or small voids which provide the appropriate amount of particle retention needed for the device to perform as intended.
Operating Temperature: the temperature range at which the final sintered plastic part will be required to operate. This application requirement will dictate what material options are available to you.

Below is a chart that details the physical properties of our most common hydrophobic materials.

Polymer	Pore Sizes (microns)	Pore Volume (%)	Operating Temperature (F)
Polyethylene (PE)	5 to 250	25-60	180
Polypropylene (PP)	100 to 300	30-40	250
Polyvinylidene Fluoride (PVDF)	20 to 30	30-40	300
Poly (PTFE)	<1 to 60	30-70	400

Chemical properties

When choosing a hydrophobic material for your sintered porous plastic component, it’s important to consider the chemicals it will contact. To help with this decision, we’ve provided a compatibility table below that shows which typically used chemicals are compatible with our most commonly used sintered porous plastics.

Chemicals	PE	PP	PTFE	PVDF
Acids (non oxidizing)	Good	Good	Good	Good
Bases	Good	Good	Good	Poor
Oil	Fair-Good	Fair-Good	Good	Good
Aromatic solvents	Poor	Poor	Good	Good
Non-polar aliphatic solvent	Fair	Fair	Good	Good
Polar-aprotic solvents	Fair-Good	Fair-Good	Good	Poor
Polar-Protic solvents	Fair-Good	Fair-Good	Good	Good
Halogenated solvent	Poor	Poor	Good	Good
Oxidizing agents	Poor	Poor	Good	Good

Polymer	Pore Sizes (microns)	Pore Volume (%)	Operating Temperature (F)
Polyethylene (PE)	5 to 250	25-60	180
Polypropylene (PP)	100 to 300	30-40	250
Polyvinylidene Fluoride (PVDF)	20 to 30	30-40	300
Poly (PTFE)	<1 to 60	30-70	400

Additives and treatments open the door to many possibilities for your sintered plastic component. Below are some additives and treatments used with the common polymers listed above:

Sintered Polyethylene (PE) and Sintered Polypropylene (PP) accept:

Color change
Ion exchange
Bactericidal / bacterial static
Carbon, potable water, odor elimination

Sintered PTFE accepts:

Oleophobic treatment
Polypropylene scrim support

One of the key advantages of sintered porous plastics is the ability to design and manufacture it to accommodate a variety of geometric needs – from sheets and rolls to more complex 3D structures. There are very few limitations in what size or shape the sintered porous plastic can take which offers significant flexibility as you begin planning your design and manufacturing process. Various geometric options to consider include:

Standard sheets or rolls
Rods
Tubes
2D plugs
Simple and complex 3D shapes

As your partner in innovation, our engineers study your manufacturing process and design goals to determine the material size, shape, and dimensions you need.

There are many options to consider when assembling and converting our sintered porous plastics. These include:

Thermal & ultrasonic welding
Overmolding
Die-cutting
Press fit
Pressure-sensitive adhesive (PSA)

As our engineers learn how your final product or device will be assembled, they can develop a strategy of combining multiple parts into one custom-engineered part to reduce assembly time and complexity.

Common applications for hydrophobic materials

Filter

In the field of healthcare, sintered porous plastics can offer filtration capabilities that facilitate measured pharmaceutical delivery of inhalers, nebulizers, spray pumps, and other medical devices. In addition, they can be used to maintain the device’s sterility when utilizing antimicrobial additives.

Vent

This is one of the most common applications. Protective vents are used in many products, from electrical enclosures and container venting to medical devices and EV batteries. Our durable hydrophobic materials are the perfect option to support your needs.