Sintered Porous Plastic

Physical properties

When designing a sintered porous plastic component, it’s critical to consider three key physical properties which impact device function:

1. 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 that dictate its ability to effectively handle gases or liquid materials.
2. 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 particle plastics can create large or small voids which provide the appropriate amount of particle retention needed for the device to perform as intended.
3. 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 sintered polymer materials.

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

Chemical properties

Considering the chemicals – if any – in which the sintered porous plastic component will come into contact with is another key consideration to make when selecting your porous material. Below is a table showing the compatibility of typically used chemicals with our most common sintered porous plastics.

 

Sintered porous plastics can be manufactured using a variety of materials which can be selected as part of the initial design and engineering process. As your partner in innovation, Porex can provide expertise and guidance on material selection based on the pore size, pore volume, operating temperature, chemical compatibility, and additive compatibility desired. These material options include:

Sintered Polyethylene (PE)
This is the most commonly used material with a large range of pore sizes available (5 to 250 microns). It is a strong, lightweight thermoplastic that can withstand more process variation than other materials.

Sintered Polypropylene (PP)
For strong applications where rigid structure and a large pore size is desired, PP thermoplastic material is an excellent option. It shares many of the same chemical and additive compatibilities as PE material.

Sintered Polytetrafluoroethylene (PTFE)
For applications in need of ultra-hydrophobicity, high temperature tolerances, high chemical resistance, and excellent robustness, sintered PTFE is a perfect choice. It is 100% pure, free of PFOA and can filter particles as small at 0.1 micron using depth filtration while resisting fluid ingress.

Sintered Polyvinyllidene Flouride (PVDF)
For applications where your device is subjected to oxidizing agents or solvents, sintered PVDF is a great option. It is a low-weight, highly pure thermoplastic that is durable with a strong resistance to solvents, acids, and bases.

While these four materials are most common, there are other options available including nylon (N6), ethyl vinyl acetate (EVA), polycaronate (PC), and elastomers among others. Working closely with your application engineering team, we can define your specifications and applicational requirements to select a material that is best for you.

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:

• Self-sealing, liquid barrier
• Hydrophilic treatments
• Colorants
• 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
• Nibs (for writing instruments)
• 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.