Saturday 6 January 2024

Design Properties for Engineers: Superior Gas Barrier Properties of PolyArylAmide (PARA; MXD6)

Hello and welcome to this new blog post. We discussed several outstanding properties of PolyArylAmide (PARA; MXD6) in detail here

However, another impressive property is the superior gas barrier against oxygen and carbon dioxide in film applications. PARA is able to outperformance other commercial available Polyamides, and can compete with well established materials such as ethylene-vinylalcohol copolymers (EVOH),acrylonitrile copolymers (PAN) and vinylidenchloride copolymers (PVDC). 

Film extrusion and crystallization speed of PARA (MXD6)

PARA crystallizes similarly to PET allowing PARA to stay in an amorphous state easily if it is cooled immediately after the extrusion or injection moulding process. 150°C to 170°C is the temperature range where PARA crystallizes the fastest.  The moderate crystallization speed opens up a wider operation window compared to other Polyamides in the thermoforming or the orientation process for film making.

Gas barrier properties 

Figure 1 shows the oxygen permeation rate of PARA (MXD6) films (stretch ratio 4x4) and other barrier polymers. The data indicates that the oxygen barrier property of PARA is much less moisture sensitive than that of EVOH. PARA with its high heat stability and wide processing window can be co-extruded and co-injection moulded with PET, PP, and PE in order to make multilayer containers or films.  Also, the gasoline barrier properties are outstanding and therefore it is used in the fuel system of Internal Combustion Engines (ICE) cars. In case the Polyamide will be coated with PVDC, moisture influence can be kept on a stable level. In another post we will discuss the oxygen and water barrier properties of Polyvinylidene chloride (PVDC). 

Figure 1: oxygen permeation rate of PARA-MXD6 films compared to EVOH and PA 6 (PVDC coated) [1].

In case you want to read more on PolyArylAmide - check out "The ABCs of Polyarylamide (PARA; MXD6)".

Thank you for reading this post and #findoutaboutplastics.


Herwig Juster

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