Design Properties for Engineers: Ionic Contamination of High Performance Polymers

Hello and welcome back to another post on design properties for polymer engineers. Today we discuss the ionic contamination of high performance polymers. I hope this data set supports you in case it is needed during your next polymer material selection project. More plastics design data can be found in my “start here” section.

Why is ionic contamination of plastics  important to know?

Imagine you would like to use plastics in high purity applications found in industries such as the semiconductor or photovoltaic industry. Also high levels of purity play a key role in the bio-, pharma-, and medical device industry. In particular, ions which leach out can cause due to their electrical loading a contamination of high purity processes. 

In Table 1 ionic concentration of selected high performance polymers can be found. In order to obtain the concentration, material samples were burned and the remaining ashes were checked regarding ions. In general, the selected polymers show low levels of contamination. PEEK shows a very low ionic contamination. Polyimides show higher values only at certain ions. 

Table 1: ionic concentration of selected high performance polymers [1]. 

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Greetings

Herwig Juster

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Literature:

[1] https://www.polytron-gmbh.de/downloads-uebersicht.aspx

[2] SAECHTLING KUNSTSTOFF TASCHENBUCH, Auflage: 31. Ausgabe Baur, Brinkmann, Osswald, Rudolph, Schmachtenberg

Design Properties for Engineers: Outgassing Behavior of High Performance Polymers

Hello and welcome back to another post on design properties for polymer engineers. Today we discuss the outgassing behaviour of high performance polymers in order to support you in your next polymer material selection project. More plastics design data can be found in my “start here” section.

Outgassing behaviour - total mass loss (TML)

In general, the outgassing behaviour of polymers is estimated by the total mass loss (TML) and the collected volatile condensed material (CVCM). Accepted values regarding high end applications (for example applications operating in vacuum) are for TML below 1% and for CVCM below 0.01%.

Table 1 shows the outgassing behaviour of high performance polymers. For Polyimides, TML values are ranging above 1% since they are hygroscopic polymers. However, looking at the CVCM values of Polyimides, it can be stated that they are in the same range as other high performance polymers (except PBI).  Nevertheless, Polyimides are suitable materials for applications operating in vacuum and proper drying must be ensured before application. Polyimides show excellent tribological properties for dynamic vacuum applications. 

Table 1: outgassing behaviour of high performance polymers (TML and CVCM) [1].

Thanks for reading and #findoutaboutplastics!

Greetings

Herwig Juster

📚My Polymer Material Selection Book - Available Here

📊 Discover your Polymer Material Selection score by taking quick test here

🎥Join my YouTube channel community 

🔎Join my inner circle (monthly newsletter)

Literature:

[1] https://www.polytron-gmbh.de/downloads-uebersicht.aspx

[2] SAECHTLING KUNSTSTOFF TASCHENBUCH, Auflage: 31. Ausgabe Baur, Brinkmann, Osswald, Rudolph, Schmachtenberg

Design Properties for Engineers: Radiation Resistance of High Performance Polymers

Hello and welcome back to another post on design properties for polymer engineers. Today we discuss the radiation resistance of high performance polymers to consider if needed in your next polymer material selection project. More plastics design data can be found in my “start here” section.

Resistance against radiation - radiation index

For evaluating plastics towards the suitability for radiation exposed applications, the so-called radiation index (Ri) can be used (IEC 60544-4). It is defined as the logarithm of base 10 of the absorbed radiation dose in Gray (J/kg) at which the flexural strength of the material is still minimum 50 % of the original value. The tests are done at room temperature and at a radiation dose of 200 kJ/kg per hour. 

In Table 1 (and Figure 1) the radiation index values of high performance/temperature polymers are shown. It can be seen that Polyimides PI and PAI have an extraordinary resistance towards radiation. Fluoropolymers do not show such a high resistance and PVDF even cross-links when exposed to high energy radiation. Additionally, Figure 2 shows the radiation index of often used commodity and engineering polymers.

Table 1: radiation resistance of high performance polymers [1].

Figure 1: radiation index of high performance polymers [1].

Figure 2: radiation index of commodity and engineering polymers [3].

Thanks for reading and #findoutaboutplastics!

Greetings

Herwig Juster

📚My Polymer Material Selection Book - Available Here

📊 Discover your Polymer Material Selection score by taking quick test here

🎥Join my YouTube channel community 

🔎Join my inner circle (monthly newsletter)

Literature:

[1] https://www.polytron-gmbh.de/downloads-uebersicht.aspx

[2] SAECHTLING KUNSTSTOFF TASCHENBUCH, Auflage: 31. Ausgabe Baur, Brinkmann, Osswald, Rudolph, Schmachtenberg

[3] https://contentmedia.lappcdn.com/e/lapp/WpLriclteLc9qgekEAj7bQ~~

Design Properties for Engineers: Hydrolysis Resistance of High Performance Polymers

Hello and welcome to this post on design data for polymer material selection in which we discuss the hydrolysis resistance of high performance polymers. More plastics design data can be found in my “start here” section.

Hydrolysis resistance - the resistance to attack by water

In general, hydrolytic resistance can be defined as the resistance to attack of the polymer structure by water. Hydrolysis resistance is part of the chemical resistance spectra and is important since water is very aggressive to many polymers. There are different tests on the estimation of hydrolytic resistance. One quick test is the immersion of a plastic specimen in boiling water for several days. Another method is to place a specimen 3 hours long at 105°C or even 5 hours long at 121°C in the steam autoclave.

For example, the mechanism of hydrolysis of Polyester polymers (PET, PBT) is the reaction of water with ester groups at high temperature. Also with Polyamide 6, reaction with water at high temperature will result in a split into caprolactam and oligomers. Polyurethanes will split into polyols and amines at high temperature and water exposure. 

Hydrolysis resistance data of high performance polymers

Table 1 shows the hydrolysis resistance data of high performance polymers and Figure 1 compares the hot water resistance of an aliphatic Polyamide 6.6 and a Polyphenylene sulfide (PPS) at 110°C and 6000 hours. Already around 2000 hours a delta of almost 10% can be seen which increases even more with time. Important for both material is that the glass fiber used has a hydrolysis resistant sizing. 

Table 1: hydrolysis resistance data of high performance polymers.

Figure 1: hot water resistance of a PA and a PPS, 110°C, 6000 hours. 

Thanks for reading and #findoutaboutplastics!

Greetings

Herwig Juster

📚My Polymer Material Selection Book - Available Here

📊 Discover your Polymer Material Selection score by taking quick test here

🎥Join my YouTube channel community 

🔎Join my inner circle (monthly newsletter)

Literature:

[1] Polytron - Materialeigenschaften Hochleistungskunststoffe

[2] https://www.solvay.com/en/brands/radel-ppsu

[3] Grivory HT - Enhanced properties at high temperatures

[4] https://www.curbellplastics.com/materials/applications/hydrolysis-resistant/

[5] https://www.fastradius.com/resources/hydrolysis-resistant-plastics/

[6] https://eu.mitsuichemicals.com/sites/default/files/media/document/2018/f-01-06_boiling_water_resistance.pdf

[7] http://www.bosy-online.de/Korrosion/Alterung_SA.pdf